- Combustion and sublimation calorimetric studies on acetylurea and trimethyl isocyanurate
-
Standard enthalpies of formation in the crystalline and gaseous states have been determined for acetylurea and trimethyl isocyanurate by oxygen bomb-combustion calorimetry and sublimation calorimetry.Derived values are as follows: .Stabilization energies related to intramolecular interaction between ?-electrons of carbonyl groups and lone-pair electrons of adjacent nitrogen atoms have been evaluated for acetamide and urea as well as for these compounds as enthalpy changes of "isodesmic" reactions using ethane as a reagent for the cleavage of CO-N bonds and are discussed.
- Imamura, Akira,Murata, Shigeo,Sakiyama, Minoru
-
-
Read Online
- Thermal decomposition of trimethylamine borane as a precursor to nanocrystalline CVD BC x N y films
-
We have studied the kinetics of BC x N y chemical vapor deposition through trimethylamine borane decomposition at atmospheric pressure. The rate constant of the heterogeneous interaction between trimethylamine borane and an adsorption center has been determined to be k s 0 = 2.7 × 107exp(-10560/T) cm/s. The obtained kinetic parameters of the reaction fully determine the growth rate of nanocrystalline carbonitride films under kinetic control. The film thickness has been determined as a function of time, temperature, reactant concentration, and reactor dimensions.
- Korobeinichev,Shmakov,Chernov,Kosinova,Sulyaeva,Kuznetsov
-
-
Read Online
- Poly(iminoborane)s: An Elusive Class of Main-Group Polymers?
-
The significance of inorganic main-group polymers is demonstrated most clearly by the commercial relevance of polysiloxanes (silicones). Organoboron-based materials such as π-conjugated organoborane polymers and BN-doped polycyclic aromatic hydrocarbons are currently attracting considerable attention. Surprisingly, poly(iminoborane)s (PIBs; [BRNR′]n), that is, the parent unsaturated BN polymers, which are formally isoelectronic to polyacetylene, have not been convincingly characterized thus far. Herein, we present the synthesis and comprehensive characterization of a linear oligo(iminoborane), which comprises a chain of 12–14 BN units on average. With our synthetic approach, unwanted side reactions that result in borazine formation are effectively suppressed. Supporting DFT and TD-DFT calculations provide deeper insight into the microstructure and the electronic structure of the oligomer.
- Ayhan, Ozan,Eckert, Thomas,Plamper, Felix A.,Helten, Holger
-
-
Read Online
- Silicoaluminophosphate molecular sieve DNL-6: Synthesis with a novel template, N,N″-dimethylethylenediamine, and its catalytic application
-
DNL-6, a silicoaluminophosphate (SAPO) molecular sieve with RHO topology, was hydrothermally synthesized using a new structure-directing agent (SDA), N,N′-dimethylethylenediamine. The obtained samples were characterized by X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption, which indicated that the synthesized DNL-6s have high crystallinity and relatively high Si content ranging from 20% to 35%. Solid-state magic-angle-spinning (MAS) nuclear magnetic resonance (13C, 29Si, 27Al, 31P, and 27Al multiple-quantum (MQ)) was conducted to investigate the status of the SDA and local atomic environment in the as-synthesized DNL-6. Thermal analysis revealed the presence of a large amount of amines in the DNL-6 crystals (about 4.4 SDAs per α-cage), which was the reason for the formation of DNL-6 with an ultrahigh Si content (36.4% Si per mole). Interestingly, DNL-6 exhibited excellent catalytic performance for methanol amination. More than 88% methanol conversion and 85% methylamine plus dimethylamine selectivity could be achieved due to the combined contribution of strong acid sites, suitable acid distribution, and narrow pore dimensions of DNL-6.
- Wu, Pengfei,Yang, Miao,Zhang, Wenna,Zeng, Shu,Gao, Mingbin,Xu, Shutao,Tian, Peng,Liu, Zhongmin
-
-
Read Online
- Selective Synthesis of Trimethylamine by Catalytic N-Methylation of Ammonia and Ammonium Chloride by utilizing Carbon Dioxide and Molecular Hydrogen
-
The synthesis of trimethylamine (TMA) through a multicomponent combination of ammonia with carbon dioxide and molecular hydrogen by using a homogeneous ruthenium catalyst was explored. The use of [Ru(triphos)(tmm)] [triphos: 1,1,1-tris(diphenylphosphinomethyl)ethane, tmm: trimethylene methane] together with aluminum trifluoromethanesulfonate as a co-catalyst resulted in high ammonia conversion and excellent selectivity for TMA in organic solvents. Aqueous solutions of ammonium chloride were methylated almost quantitatively to the corresponding hydrochloride salt (i.e., TMA·HCl) in a biphasic solvent system by using the same Ru complex without the need for any co-catalyst.
- Beydoun, Kassem,Thenert, Katharina,Streng, Emilia S.,Brosinski, Sandra,Leitner, Walter,Klankermayer, Jürgen
-
-
Read Online
- Enhanced catalytic reduction of N-nitrosodimethylamine over bimetallic Pd-Ni catalysts
-
Catalytic reduction of N-nitrosodimethylamine (NDMA) was investigated over γ-Al2O3 supported bimetallic Pd-Ni catalysts (3%(PdxNi1-x)). NDMA could be reduced to dimethylamine over 3%(Pd0.8Ni0.2) with a metal-loading-normalized pseudo-first-order rate constant of 836 ± 21 L gme-1 h-1. Characterization results showed that the reducibility of PdO (or NiO) was improved by addition of Ni (or Pd) in 3%(PdxNi1-x); Pd-Ni ensembles were formed in 3%(PdxNi1-x) and there was an electronic transfer from Pd to Ni; metal dispersion was affected by the formation of Pd-Ni ensembles and a volcano curve of metal dispersion via Pd/Ni ratio was observed. The activity profiles demonstrated that TOF had a significant positive relationship with metal dispersion of 3%(PdxNi1-x), indicating high metal dispersion favor NDMA reduction. NDMA reduction over 3%(Pd0.8Ni0.2) catalyst could be described by Langmuir-Hinshelwood model, reflecting an adsorption controlled reduction mechanism. The reduction mechanism of NDMA over 3%(Pd0.8Ni0.2) catalyst was proposed to be that H2 was activated by Pd, and H spillover from Pd to Ni/NiO reduced NDMA though N-N cleavage.
- Chen, Huan,Li, Ting,Jiang, Fang,Wang, Zhe
-
-
Read Online
- The nonenzymatic decomposition of guanidines and amidines
-
To establish the rates and mechanisms of decomposition of guanidine and amidine derivatives in aqueous solution and the rate enhancements produced by the corresponding enzymes, we examined their rates of reaction at elevated temperatures and used the Arrhenius equation to extrapolate the results to room temperature. The similar reactivities of methylguanidine and 1,1,3,3-tetramethylguanidine and their negative entropies of activation imply that their decomposition proceeds by hydrolysis rather than elimination. The influence of changing pH on the rate of decomposition is consistent with attack by hydroxide ion on the methylguanidinium ion (k2 = 5 × 10 -6 M-1 s-1 at 25 C) or with the kinetically equivalent attack by water on uncharged methylguanidine. At 25 C and pH 7, N-methylguanidine is several orders of magnitude more stable than acetamidine, urea, or acetamide. Under the same conditions, the enzymes arginase and agmatinase accelerate substrate hydrolysis 4 × 1014-fold and 6 × 1012-fold, respectively, by mechanisms that appear to involve metal-mediated water attack. Arginine deiminase accelerates substrate hydrolysis 6 × 1012-fold by a mechanism that (in contrast to the mechanisms employed by arginase and agmatinase) is believed to involve attack by an active-site cysteine residue.
- Lewis, Charles A.,Wolfenden, Richard
-
-
Read Online
- Investigating the Underappreciated Hydrolytic Instability of 1,8-Diazabicyclo[5.4.0]undec-7-ene and Related Unsaturated Nitrogenous Bases
-
The widespread use of amidine and guanidine bases in synthetic chemistry merits a thorough understanding of their chemical properties. The propensity of these reagents to hydrolyze under mild conditions and generate aminolactams and aminoureas, respectively, has not been adequately described previously. During the synthesis of uprifosbuvir (MK-3682), we became aware of this liability for 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) by observing the formation of an unexpected reaction impurity and traced the root cause to low levels of N-(3-aminopropyl)-?-caprolactam present in the commercial bottle. A controlled stability study over a period of two months at 25 °C demonstrated that, above a threshold water content, DBU steadily hydrolyzed over time. Rates of hydrolysis for DBU, 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and N,N,N′,N′-tetramethylguanidine (TMG) in organic, aqueous, and mixed solvent systems were then measured to gain a more general appreciation of what conditions to avoid in order to maintain their integrity. Our findings indicate that these bases are hydrolytically unstable in unbuffered and very basic solutions but become significantly more stable in buffered solutions at pH values below 11.6.
- Hyde, Alan M.,Calabria, Ralph,Arvary, Rebecca,Wang, Xiao,Klapars, Artis
-
-
Read Online
- Application of the WATR technique for water suppression in 1H NMR spectroscopy in determination of the kinetics of hydrolysis of neostigmine bromide in aqueous solution
-
Both ammonium chloride and guanidinium chloride were used to secure water suppression in 1H NMR spectra using the 'Water Attenuation by T2 Relaxation' (WATR) technique. The effect of phosphate buffer in the suppression was investigated over a range of pH values at 80 MHz. The spin-spin relaxation time of water protons at 80 MHz was found to reach a minimum at pH 7.3 in the presence of 0.1 M phosphate buffer and 1 M guanidinium chloride; these conditions were therefore chosen for subsequent use of the WATR technique in a study of the kinetics of hydrolysis of neostigmine bromide. The method was found to be very convenient for studies of the hydrolysis of this representative amide.
- Ferdous,Waigh
-
-
Read Online
- Standard enthalpies of formation of crystalline dimethylammoniumdimethyldithiocarbamate and of dimethyldithiocarbamate complexes of copper(II) and nickel(II). The mean Cu-S and Ni-S bond-dissociation enthalpies
-
The standard (p0 = 0.1 MPa) enthalpies of formation of crystalline dimethylammoniumdimethyldithiocarbamate and of the dimethyldithiocarbamate complexes of Ni(II) and Cu(II) were determined, at the temperature 298.15 K, by solution-reaction calorimetry.The enthalpy of "decomposition" of the dimethylammoniumdimethyldithiocarbamate salt and the enthalpies of sublimation of the metal complexes were measured by high-temperature microcalorimetry.From these values, the mean molar bond-dissociation enthalpies m>(M-S) were derived. .
- Silva, Manuel A. V. Ribeiro da,Reis, Ana M. M. V.,Faria, Rita I. M. C. P.
-
-
Read Online
- Reactions of Carbonyl Compounds in Basic Solutions. Part 27.1 Alkaline Hydrolysis of Bridged Benz[de]isoquinolin-1-ones: Torsionally Distorted Lactams
-
Rate coefficients have been measured for the alkaline hydrolysis of 2,3-ethanoxy- and 2,3-propanamino-2,3-dihydro-1H-benz[de]isoquinolin-1-ones? in 70% (v/v) dimethyl sulfoxide-water at several temperatures and of N,N-dimethyl-1-naphthamide in water: the relative rates of hydrolysis, activation parameters and other studies indicate the importance of the torsional distortion of the lactam nitrogen and steric 'bulk' factors in controlling reactivity.
- Bowden, Keith,Hiscocks, Simon P.
-
-
Read Online
- One-pot synthesis of isoquinolinium salts by rhodium-catalyzed C-H bond activation: Application to the total synthesis of oxychelerythrine
-
It's worth its salt: The title reaction leads to the synthesis of highly substituted isoquinolinium salts (see scheme; Cp=Me5C 5). The reaction proceeds through a C-H activation and a subsequent annulation in the presence of a rhodium catalyst. The reaction mechanism is discussed as well as its application to the synthesis of the natural product oxychelerythrine.
- Jayakumar, Jayachandran,Parthasarathy, Kanniyappan,Cheng, Chien-Hong
-
-
Read Online
- Thiophene site activation: Synthesis and structures of Fischer carbene complexes with 3,3′- and 2,3′-bithienyl substituents
-
Deprotonation of the reactive α-thiophene ring positions of 3,3′-bithiophene and 2,3′-bithiophene afforded, after metalation with group 6 transition metal carbonyls and alkylation, a diverse range of mono- and biscarbene complexes. The bithienyl isomers differ in the number of active α-positions but representative examples of Fischer monocarbene complexes of all possible isomers were obtained. For 3,3′-bithienyl, the carbene fragment is in the electronically favoured C2-positions on the “inside” of the bithienyl and is structurally and electronically significantly different from the carbene substituent in the “outside” C5-positions. In the unsymmetrically substituted 2,3′-bithienyl scaffold, in addition to [M(CO)5{C(OEt)-2′-(2,3′-BT)}] and [M(CO)5{C(OEt)-5′-(2,3′-BT)}], a carbene moiety in the C5-position of the T2-thienyl ring, [M(CO)5{C(OEt)-5-(2,3′-BT)}], was also formed. In the same reaction mixture of the mono(ethoxycarbene) complexes, biscarbene complexes were obtained. In contrast, the major biscarbene complexes display the carbene fragments in the sterically favoured outside C5,C5′-positions. The unexpected formation of the 2,2′-bithienyl biscarbene complex, [{M(CO)5C(OEt)}2-5,5′-(2,2′-BT)] as well as the formation of the biscarbene complexes [{M(CO)5C(OEt)}2-2,5-(3,3′-BT)] and [{M(CO)5C(OEt)}2-2′,5′-(2,3′-BT)] with both carbene moieties on the same thiophene ring, were observed. By a modified method of synthesis, a mixed metal biscarbene complex of chromium and tungsten in the C2,C5-positions on the same thiophene ring could be isolated for both 3,3′-bithienyl and thiophene [{Ma/b(CO)5C(OEt)}2-2,5-(T/3,3′-BT)]. The formation of a monocarbene complex of 2,3′-bithienyl, [W(CO)5C(OEt)-5-(2,3′-BT){C(O)(OEt)}2-2′,5′] betrays the presence of an unstable triscarbene intermediate [{W(CO)5C(OEt)}3-5,2′,5′-(2,3′-BT)]. The molecular structures of most of the major isomers were confirmed by single crystal X-ray studies.
- Lamprecht, Zandria,Moeng, Mmushi M.,Liles, David C.,Lotz, Simon,Bezuidenhout, Daniela I.
-
-
Read Online
- Synthesis of Methylamines from Carbon Dioxide and Ammonia
-
Methylamines were synthesized from carbon dioxide, hydrogen and ammonia over Cu-Al2O3 catalysts, affording a distribution of monomethylamine : dimethylamine : trimethylamine of 1 : 0.23 : 0.07.
- Gredig, Silvia V.,Koeppel, Rene A.,Baiker, Alfons
-
-
Read Online
- A comparative study on the hydrolysis of acetic anhydride and N,N-dimethylformamide: Kinetic isotope effect, transition-state structure, polarity, and solvent effect
-
Recent studies have shown that general-base assisted catalysis is a viable mechanistic pathway for hydrolysis of smaller anhydrides. Therefore, it is the central purpose of the present work to compare and contrast the number of hydrogen atoms in-flight and stationary in the transition state structure of the base-catalyzed mechanisms of 2 hydrolytic reactions as well as determine if any solvent effects occur on the mechanisms. The present research focuses on the hydrolytic mechanisms of N,N-dimethylformamide (DMF) and acetic anhydride in alkali media of varying deuterium oxide mole fractions. Acetic anhydride has been included in this study to enable comparisons with DMF hydrolysis. Comparative studies may give synergistic insight into the detailed structural features of the activated complexes for both systems. Hydrolysis reactions in varying deuterium oxide mole fractions were conducted in concentrations of 2.0M, 2.5M, and 3.0M for DMF and 0.10M for acetic anhydride at 25°C. Studies in varying deuterium mole fractions allow for proton inventory analysis, which sheds light on the number and types of hydrogen atoms involved in the activated complex. For these systems, this type of study can distinguish between direct nucleophilic attack of the hydroxide ion on the carbonyl center and general-base catalysis by the hydroxide ion to facilitate a water molecule attacking the carbonyl center. The numerical data are used to discuss 3 possible mechanisms in the hydrolysis of DMF.
- Cooper, William C.,Chilukoorie, Abhinay,Polam, Suhesh,Scott, Dane,Wiseman, Floyd
-
-
Read Online
- Pushing the limits of energetic materials - The synthesis and characterization of dihydroxylammonium 5,5′-bistetrazole-1,1′- diolate
-
The safe preparation and characterization (XRD, NMR and vibrational spectroscopy, DSC, mass spectrometry, sensitivities) of a new explosive dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) that outperforms all other commonly used explosive materials is detailed. While much publicized high-performing explosives, such as octanitrocubane and CL-20, have been at the forefront of public awareness, this compound differs in that it is simple and cheap to prepare from commonly available chemicals. TKX-50 expands upon the newly exploited field of tetrazole oxide chemistry to produce a material that not only is easily prepared and exceedingly powerful, but also possesses the required thermal insensitivity, low toxicity, and safety of handling to replace the most commonly used military explosive, RDX (1,3,5-trinitro-1,3,5-triazacyclohexane). In addition, the crystal structures of the intermediates 5,5′-bistetrazole-1,1′-diol dihydrate, 5,5′-bistetrazole-1,1′-diol dimethanolate and dimethylammonium 5,5′-bistetrazole-1,1′-diolate were determined and presented.
- Fischer, Niko,Fischer, Dennis,Klapoetke, Thomas M.,Piercey, Davin G.,Stierstorfer, Joerg
-
-
Read Online
- Scanning electrochemical microscopy: Kinetics of chemical reactions following electron-transfer measured with the substrate-generation-tip-collection mode
-
The substrate-generation-tip-collection (SG-TC) mode of the scanning electrochemical microscope (SECM) is used as a new approach to investigate the kinetics of EC processes. Under the conditions of interest, a species O is generated at a macroscopic substrate (generator) electrode, with potential-step control, through the diffusion-limited electrolysis of a solution species R (E step). As O diffuses away from the generator, it undergoes a first order chemical reaction in solution (C step). A fraction of O is collected by electrolysis back to R at an externally biased ultramicroelectrode (UME), positioned directly over the substrate. This promotes the diffusional feedback of R to the substrate. Theory for the problem, relating the time-dependent tip current response to the rate constant for the C step and the tip-substrate electrode separation is developed numerically. Results of the calculations illustrate how the characteristic features of the tip current transients: peak current, peak time and post-half-peak time, depend on the kinetics of the C step and the inter-electrode separation. It is shown that both the kinetics and tip-substrate separation can be determined independently from a single transient by simply measuring the peak current and peak time. The theoretical results are validated experimentally through model studies of the oxidative deamination of N,N,-dimethyl-p-phenylenediamine (DMPPD) in aqueous solution at high pH. The effective second-order rate constant for the deamination step is in excellent agreement with values measured by alternative methods.
- Martin, Rachel D.,Unwin, Patrick R.
-
-
Read Online
- UV direct photolysis of N-nitrosodimethylamine (NDMA): Kinetic and product study
-
The ultraviolet (UV) direct photolysis of N-nitrosodimethylamine (NDMA) in aqueous solutions at pH 3 and 7 leads to dimethylamine, and nitrite and nitrate ions as the major degradation products. In addition, small amounts of formaldehyde, formic acid, and methylamine are formed. When the initial concentration of NDMA was 1 mM, only a 13% decrease in the total organic carbon (TOC) was measured at pH 7, whereas no significant change in the TOC was observed at pH 3. In the concentration range 0.01 - 1 mM NDMA, zero-order kinetics is obeyed, whereas first-order kinetics is followed at concentrations below 0.01 mM. The photolysis occurs much faster at pH 3 than at pH 7, which is explained by the difference in the quantum yields of the process at these two pH values. UV Direct photolysis is an efficient process for the removal of NDMA from contaminated waters, and electrical energy per order (EEO) values as low as 0.3 - 0.5 kWh/order/m3 were calculated for treatment of low concentrations of NDMA (0.001 mM).
- Stefan, Mihaela I.,Bolton, James R.
-
-
Read Online
- Determination of 18O Exchange Accompanying Basic Hydrolysis of p-Toluamide and N,N-Dimethyl-p-toluamide
-
The base-catalyzed hydrolysis and 18O-exchange rate constants for p-toluamide (IV) and N,N-dimethyl-p-toluamide (V) have been determined under pseudo-first-order conditions as a function of -> at T = 100 deg C, μ = 1.0 M.Both sets of rate constants are linearly dependent on ->, and therefore the ratio of kex/khyd for IV and V does not change as a function of ->.For IV and V the ratios are 3.5 +/- 0.2 and 0.11 +/- 0.007 respectively.The fact that V shows substantial exchange suggests that the original formulation of the Deslongchamps stereoelectronic theory needs to be reassessed with respect to the conformational equilibration of the anionic tetrahedral addition intermediate produced from N,N-dimethylbenzamide and OH-.
- Slebocka-Tilk, H.,Brown, R. S.
-
-
Read Online
- Effect of water during the quantitation of formate in photocatalytic studies on CO2 reduction in dimethylformamide
-
The effect of the water concentration on the quantitation of formate from dimethylformamide in the presence of electron-donating bases using ion chromatography is reported. This observation has important implications in the area of the photocatalytic reduction of CO2, where formate levels are often used to calculate catalyst turnover numbers.
- Paul, Avishek,Connolly, Damian,Schulz, Martin,Pryce, Mary T.,Vos, Johannes G.
-
-
Read Online
- Aminoborane polymers as precursors of C-N-B ceramic materials
-
Aminoborane polymers were prepared via condensation reactions between polyfunctional amines and either triethylborane or tris(dimethylamino)borane. The products were characterized by chemical and spectroscopic analyses. The thermal degradation of these ma
- Maya
-
-
Read Online
- Formic acid: A future bridge between the power and chemical industries
-
In the future hydrogen economy, formic acid is considered an efficient hydrogen storage molecule and a new C1 building block for the chemical industry. Formic acid could be used as a sustainable carbon monoxide source. In the present work efficient catalysts for the decomposition of formic acid and its derivatives to carbon monoxide have been found. The proposed catalysts are widely available zeolites, making the process feasible for industrial scale applications. Thus, formic acid and its derivatives could be seen as liquid and storable versions of carbon monoxide, which could be directly used in the existing chemical value chain.
- Supronowicz,Ignatyev,Lolli,Wolf,Zhao,Mleczko
-
-
Read Online
- Acid-catalysed chlorine transfer from N-chloramines to iodide ion: Experimental evidence for a predicted change in mechanism
-
Rate constants for acid catalysis of the reactions of N-chlorodimethylamine (1), N-chloro-2,2,2-trifluoroethylamine (2) and N,N-dichlorotaurine (3) with iodide ion were determined in H2O at 25°C and I = 0.5 (NaClO 4). The failure to detect significant catalysis by general acids of chlorine transfer from 1 to the nucleophile, together with the observed inverse solvent deuterium isotope effect on the hydronium ion-catalysed reaction (k H/kD = 0.37), indicates that this process occurs by protonation of 1 in a fast equilibrium step, followed by rate determining chlorine transfer to iodide ion. The appearance of general acid catalysis for the reactions of 2 and 3 shows that increasing the leaving group ability leads to a change to a concerted mechanism, which is suggested to be enforced by the absence of a significant lifetime of the protonated chloramine intermediate in the presence of iodide ion.
- Calvo, Paula,Crugeiras, Juan,Rios, Ana
-
-
Read Online
- REACTIONS OF ALLYLIC COMPOUNDS SUCH AS ALLYL ALCOHOLS, ALLYL ETHERS, AND ALLYLAMINES USING trans-Mo(N2)2(Ph2PCH2CH2PPh2)2
-
Double-bond migration of allylic alcohols and allylic alkyl ethers was catalytically effected with trans-Mo(N2)2(dpe)2(dpe=Ph2PCH2CH2PPh2).Decarbonylation occurred simultaneously in the case of allyl alcohol.Diallyl ether and allyl phenol ether gave the fragmentation products presumably through initial oxidative addition of the allyl-O bond.Allylamine was converted to N-propylideneallylamine and NH3.N,N-Dimethylallylamine was isomerized to N-trans-propenyldimethylamine, which was further transformed into 4-dimethylamino-1,3-hexadiene and dimethylamine on addition of oxygen.The catalytic allylation of methyl acetoacetate with allylic ethers and amines was achieved by use of trans-Mo(N2)2(dpe)2.
- Tatsumi, T.,Hashimoto, K.,Tominaga, H.,Mizuta, Y.,Hata, K.,et al.
-
-
Read Online
- Shape-selective synthesis of methylamines over the RRO zeolite Al-RUB-41
-
Aluminum was incorporated into the layered silicate RUB-39, which is transformed by calcination into RUB-41. This new zeolite with RRO topology contains 8- and 10-ring pores, and the acid sites in the aluminated material catalyze the synthesis of methylamines, in particular mono- and dimethylamine, by amination of methanol. Owing to the shape-selective catalytic properties of (H)Al-RUB-41, low selectivity to the thermodynamically favored trimethylamine product is obtained in comparison with results on RUB-39 or non-shape-selective materials. Both activity and selectivity are highest for RUB-41 catalysts with a high Si to Al ratio. Silylation reduces the number of unselective sites and results in a further suppression of trimethylamine formation. The introduction of acidity in the intact RUB-41 structure is supported by Al-MAS NMR and NH 3-TPD data. Additional characterization by XRD and SEM is provided.
- Tijsebaert, Bart,Yilmaz, Bilge,Mueller, Ulrich,Gies, Hermann,Zhang, Weiping,Bao, Xinhe,Xiao, Feng-Shou,Tatsumi, Takashi,De Vos, Dirk
-
-
Read Online
- Absence of stereoelectronic control in the hydrolysis of fully and partially N-alkylated cyclic amidinium ions
-
Deslongchamps' hypothesis of stereoelectronic control states that preferential cleavage of a tetrahedral intermediate occurs when a leaving group is antiperiplanar to two lone pairs. Yet substantial amounts of lactams were produced from hydrolysis of cyclic amidines, through cleavage of the exocyclic C-N bond that is antiperiplanar to only one lone pair and syn to the other. It may be that proton transfer catalyzes nitrogen inversion, leading to an intermediate with two antiperiplanar lone pairs, such that the product distribution is indeed consistent with stereoelectronic control. To exclude this possibility, three cyclic amidinium ions (1a,b,c) with methyl groups at both nitrogens were synthesized, and their hydrolysis products in NaOD/D2O were analyzed by NMR. Although stereoelectronic control favors ring opening to amino amide 3, substantial amounts (40-90%) of lactam 4 are again produced. To exclude the possibility that lactam formation is due to a steric effect, hydrolysis of a cyclic N,N′-dimethyl amidine (2) was also studied, and 26-35% lactam is still produced. These results cannot be rationalized by assuming reaction via a boat conformer, since the lone pair of the ring nitrogen does not become antiperiplanar even in the boat form. Thus stereoelectronic control is not operative in amidine hydrolysis.
- Perrin, Charles L.,Thoburn, John D.
-
-
Read Online
- Reduction of N-nitrosodimethylamine with granular iron and nickel-enhanced iron. 1. Pathways and kinetics
-
Laboratory batch and column tests were conducted to examine the reduction pathways and kinetics of N-nitrosodimethylamine (NDMA) by iron (Fe) and nickel-enhanced iron (Ni/Fe). A decrease in NDMA concentration and increases in dimethylamine (DMA) and ammonium were observed in both Fe and Ni/Fe columns. In the Fe column, the transformation process of NDMA appeared to follow pseudo-first-order kinetics with respect to NDMA, with an average half-life of 13±2 h. A small amount of nickel (0.25%) plated onto the iron greatly enhanced NDMA transformation rates. At early time the NDMA half-life in the Ni/Fe column was 2 min but as time progressed the half-life increased to 4 min, and departures from first-order kinetics were observed. The mass balances of carbon in DMA and nitrogen in DMA and ammonium improved over time and reached 100% and 90%, respectively, after NDMA had passed through the column for more than 50 pore volumes (PV). No 1,1-dimethylhydrazine, nitrous oxide, or methane were detected. Based on the electrochemical properties of NDMA, the transformation mechanism of NDMA with Fe and Ni/Fe is postulated to be catalytic hydrogenation, resulting in N-N bond breakdown to form DMA and ammonium as final products. Nickel, being a much stronger catalyst than Fe for catalytic hydrogenation, resulted in a much faster reduction rate of NDMA. Of several methods tested, flushing the Ni/Fe column with 0.01 N sulfuric acid proved to be the most effective in restoring the Ni/Fe activity. The rapid transformation rate on Ni/Fe and the formation of nontoxic products indicate that this material may be applicable for treating NDMA contaminated water, both in-situ and above ground. Laboratory batch and column tests were conducted to examine the reduction pathways and kinetics of N-nitrosodimethylamine (NDMA) by iron (Fe) and nickel-enhanced iron (Ni/Fe). A decrease in NDMA concentration and increases in dimethylamine (DMA) and ammonium were observed in both Fe and Ni/Fe columns. In the Fe column, the transformation process of NDMA appeared to follow pseudo-first-order kinetics with respect to NDMA, with an average half-life of 13±2 h. A small amount of nickel (0.25%) plated onto the iron greatly enhanced NDMA transformation rates. At early time the NDMA half-life in the Ni/Fe column was 2 min but as time progressed the half-life increased to 4 min, and departures from first-order kinetics were observed. The mass balances of carbon in DMA and nitrogen in DMA and ammonium improved over time and reached 100% and 90%, respectively, after NDMA had passed through the column for more than 50 pore volumes (PV). No 1,1-dimethylhydrazine, nitrous oxide, or methane were detected. Based on the electrochemical properties of NDMA, the transformation mechanism of NDMA with Fe and Ni/Fe is postulated to be catalytic hydrogenation, resulting in N-N bond breakdown to form DMA and ammonium as final products. Nickel, being a much stronger catalyst than Fe for catalytic hydrogenation, resulted in a much faster reduction rate of NDMA. Of several methods tested, flushing the Ni/Fe column with 0.01 N sulfuric acid proved to be the most effective in restoring the Ni/Fe activity. The rapid transformation rate on Ni/Fe and the formation of nontoxic products indicate that this material may be applicable for treating NDMA contaminated water, both in-situ and above ground.
- Odziemkowski,Gui,Gillham
-
-
Read Online
- An Unusual Suppression of Trimethylamine Formation in the High Temperature Alkylation of Ammonia with Methanol over (NH4)3PW12O40
-
A synthesis of methylamines from ammonia and methanol was studied by using mainly the title heteropoly catalyst.Although at low temperatures below ca. 750 K the three methylamines (MMA, DMA, and TMA) were formed as usual, at higher temperatures the formation of TMA was completely suppressed.This unusual product selectivity was explained by the strong adsorption of TMA to the catalyst.
- Nasikin, Mohammad,Nakamura, Ryuichi,Niiyama, Hiroo
-
-
Read Online
- Proton-Coupled Reduction of an Iron Cyanide Complex to Methane and Ammonia
-
Nitrogenase enzymes mediate the six-electron reductive cleavage of cyanide to CH4and NH3. Herein we demonstrate for the first time the liberation of CH4and NH3from a well-defined iron cyanide coordination complex, [SiPiPr3]Fe(CN) (where [SiPiPr3] represents a tris(phosphine)silyl ligand), on exposure to proton and electron equivalents. [SiPiPr3]Fe(CN) additionally serves as a useful entry point to rare examples of terminally-bound Fe(CNH) and Fe(CNH2) species that, in accord with preliminary mechanistic studies, are plausible intermediates of the cyanide reductive protonation to generate CH4and NH3. Comparative studies with a related [SiPiPr3]Fe(CNMe2) complex suggests the possibility of multiple, competing mechanisms for cyanide activation and reduction.
- Rittle, Jonathan,Peters, Jonas C.
-
-
Read Online
- A new route to α-hetero β-enamino esters using a mild and convenient solvent-free process assisted by focused microwave irradiation
-
New α-hetero β-enamino esters 5 (X = NH, O, S) are obtained in good to excellent yields by transamination reactions from ethyl 3-dimethylamino acrylate 2(a-c) and various volatile amines 3(a-e) using solvent-free conditions assisted by focused microwave irradiation. Most of the α-hetero β-enamino ester derivatives 3 present a (E)s-cis/trans conformation.
- Dahmani, Zohra,Rahmouni, Mustapha,Brugidou, Richard,Bazureau, Jean Pierre,Hamelin, Jack
-
-
Read Online
- REACTIONS INVOLVING FLUORIDE ION. PART 21 . NUCLEOPHILIC SUBSTITUTION REACTIONS OF PERFLUOROCYCLOBUTENE OLIGOMERS
-
Reaction of perfluorocyclobutene oligomers, (1) - (4), with some simple nucleophiles gives products arising from SN2' displacement or vinylic substitution of fluorine, or a mixture of both processes.The reactivity of the dimers, (1) and (2), is much greater than that of acyclic analogues and this can be attributed to the ring strain present in these compounds.
- Chambers, Richard D.,Taylor, Graham
-
-
Read Online
- Adsorption and photocatalytic degradation of gas-phase UDMH under simulated sunlight by AgBr/TiO2/rGA
-
The degradation of UDMH has long been a concern for its harmful effects on humans and the environment. The current research on gas-phase UDMH treatment is limited and mainly focuses on ultraviolet light and high temperature environments, however the highly toxic substance NDMA is easily produced. In order to investigate the possibility of UDMH degradation in sunlight, AgBr/TiO2/rGA composites were prepared with the addition of different amounts of silver bromide. The highest UDMH conversion of AgBr/TiO2/rGA in humid air is 51%, much higher than the control group value of 24%, which can be ascribed to the synergy of adsorption and photocatalysis. The graphene and silver in AgBr/TiO2/rGA not only enhance the adsorption of light and UDMH, but also inhibit charge recombination and enhance electron-hole separation. More importantly, the temperature of the AgBr/TiO2/rGA composite was raised by the photothermal effect of graphene with promoted UDMH degradation efficiency. Furthermore, it is noted that NDMA was not detected in the optimal conditions.
- Ruomeng, Hou,Ying, Jia,Xiaomeng, Lv,Yuanzheng, Huang,Keke, Shen
-
-
Read Online
- Thermal Stability of Three Amines in Pressurized Water-Reactor Secondary Systems. Laboratory and Loop Experiments
-
Laboratory and loop tests have been carried out in order to investigate the thermal stability of the three amines, morpholine, AMP (aminomethylpropanol) and sarcosine in PWR secondary conditions.Laboratory experiments have been performed in a titanium autoclave at 300 deg C.The results pointed out high thermal decomposition rates of AMP and sarcosine.A decomposition mechanism is proposed for the 3 amines.Loop tests have been performed in order to compare steam cycle conditioning with ammonia, morpholine and AMP.The amine concentrations and the decomposition products such as acetate and formate have been followed around the secondary circuit of the ORION loop which reproduces the main physico-chemical characteristics of a PWR secondary circuit.These concentrations are reported together with the evolution of cationic conductivities.The influence of oxygen concentration on amine thermal stability has been observed.Results are expressed also in terms of decomposition rates and of relative volatility.KEY WORDS: Morpholine; aminomethylpropanol; sarcosine; thermal decomposition; PWR secondary water.
- Feron, Damien,Lambert, Irma
-
-
Read Online
- Scanning Electrochemical Microscopy. 9. Theory and Application of the Feedback Mode to the Measurement of Following Chemical Reaction Rates in Electrode Processes
-
The use of the scanning electrochemical microscope (SECM), in both the steady-state and chronoamperometric feedback modes, is proposed as a new method for measuring the kinetics of following chemical reactions in electrode processes.Particular attention is given to the ErCimechanistic case (first-order irreversible chemical step following reversible electron transfer).Theory for the problem, relating the SECM feedback current to the tip-substrate distance, tip electrode radius, and rate constant for the chemical step, is developed numerically by using the alternating-direction implicit finite-difference scheme.The theoretical results demonstrate that both the chronoamperometric and steady-state feedback modes are sensitive techniques for accurate kinetic determinations, and that homogeneous chemical rate constants in excess of 2 * 104 s-1 should be accessible to measurement with current SECM technology.The theoretical predictions are verified experimentally with the measurement of the rate of deamination, in aqueous basic solution (pH 10.2-12.4), of oxidized N,N-dimethyl-p-phenylenediamine, produced at a platinum electrode.
- Unwin, Patrick R.,Bard, Allen J.
-
-
Read Online
- Synthesis and Characterization of Tungsten Nitrido Amido Guanidinato Complexes as Precursors for Chemical Vapor Deposition of WNxCy Thin Films
-
Tungsten nitrido amido guanidinato complexes of the type WN(NR2)[(NR′)2C(NR2)]2 (R = Me, Et; R′ = iPr, Cy) were synthesized as precursors for aerosol-assisted chemical vapor deposition (AACVD) of WNxCy thin films. The reaction of tungsten nitrido amido complexes of the type WN(NR2)3 (R = Me, Et) with two equivalents of a carbodiimide R′N=C=NR′ (R′ = iPr, Cy) resulted in two insertions of a carbodiimide into W–N(amido) bonds, affording bis(guanidinato) amido nitrido tungsten complexes. These compounds were characterized by 14N NMR, indicating distinctive chemical shifts for each type of N-bound ligand. Crystallographic structure determination of WN(NMe2)[(NiPr)2C(NMe2)]2 showed the guanidinato ligands to be non-equivalent. The complex WN(NMe2)[(NiPr)2C(NMe2)]2 was demonstrated to serve as a precursor for AACVD of WNxCy thin films, resulting in featureless, X-ray amorphous thin films for growth temperatures 200–400 °C.
- Nolan, Michelle M.,Touchton, Alexander J.,Richey, Nathaniel E.,Ghiviriga, Ion,Rocca, James R.,Abboud, Khalil A.,McElwee-White, Lisa
-
-
Read Online
- Formal synthesis of cortistatins
-
A unified strategy toward the asymmetric facile construction of the [6.7.6.5]oxapentacyclic skeleton of cortistatins is reported, featuring intramolecular Diels-Alder (IMDA), oxidative dearomatization, and an oxy-Michael addition reaction.
- Fang, Lichao,Chen, Yuan,Huang, Jun,Liu, Lianzhu,Quan, Junmin,Li, Chuang-Chuang,Yang, Zhen
-
-
Read Online
- Reactions of Alkylnitrosoureas in Aqueous Solution
-
The acid- and base-catalyzed decompositions of N-methyl-, N,N'-dimethyl-, and N,N',N'-trimethyl-N-nitrosourea in aqueous solution have been studied.Below pH 2, the N-methyl compound undergoes both denitrosation and hydrolysis.The denitrosation yields methylurea and nitrous acid.The hydrolysis yields largely methylamine, nitrogen, and carbon dioxide.The acid-catalyzed denitrosation and hydrolysis of the trimethylnitrosourea are somewhat more rapid than the corresponding reactions of N-methyl-N-nitrosourea.The denitrosation of this compound yields trimethylurea and nitrous acid.The hydrolysis yields methanol, dimethylamine, nitrogen, and carbon dioxide.The solvent isotope effect, kH2O / kD2O = 1.3, and the absence of chloride ion catalysis suggest that the denitrosation reaction proceeds by a rate-determining proton transfer which is followed by the rapid loss of the nitroso group.The results for the hydrolysis reaction are compatible with a formulation in which a hydrate of the nitrosourea is protonated in a rate-determining step to form a tetrahedral intermediate which subsequently decomposes to yield methyldiazonium hydroxide and a carbamic acid derivative.The base-catalyzed reactions of the mono-, di-, and trimethylnitrosoureas are first order in hydroxide ion over a broad pH range.The hydrolysis of N-methyl-N-nitrosourea yields methanol and derivatives of carbamic acid.Salt effects on the reaction rate are negligible except for the influence of lithium ion.The rate constants for the hydrolysis of the mono- and dimethyl compounds depend upon the buffer concentration at pH 9.5.These constants reach limiting values.The rate constants for the hydrolysis of the trimethyl compound alsodepend upon the buffer concentration, but a limiting value is not achieved.The solvent isotope effect for the base-catalyzed reaction, the exchange reaction of water-18O with the carbonyl group of the urea, and the fact that N-methyl-N-nitrosourea is hydrolyzed about 2.2104 times more rapidly than N,N',N'-trimethyl-N-nitrosourea suggest that the hydrolysis occurs by a mechanism in which a tetrahedral intermediate is formed.Often, the formation of this intermediate is rate limiting.However, under certain conditions, its decomposition to methyldiazonium hydroxide and a carbamate anion which decompose to form methanol and the other products may be rate determining.
- Snyder, John K.,Stock, Leon M.
-
-
Read Online
- A Small Covalent Allosteric Inhibitor of Human Cytomegalovirus DNA Polymerase Subunit Interactions
-
Human cytomegalovirus DNA polymerase comprises a catalytic subunit, UL54, and an accessory subunit, UL44, the interaction of which may serve as a target for the development of new antiviral drugs. Using a high-throughput screen, we identified a small molecule, (5-((dimethylamino)methylene-3-(methylthio)-6,7-dihydrobenzo[c]thiophen-4(5H)-one), that selectively inhibits the interaction of UL44 with a UL54-derived peptide in a time-dependent manner, full-length UL54, and UL44-dependent long-chain DNA synthesis. A crystal structure of the compound bound to UL44 revealed a covalent reaction with lysine residue 60 and additional noncovalent interactions that cause steric conflicts that would prevent the UL44 connector loop from interacting with UL54. Analyses of the reaction of the compound with model substrates supported a resonance-stabilized conjugation mechanism, and substitution of the lysine reduced the ability of the compound to inhibit UL44-UL54 peptide interactions. This novel covalent inhibitor of polymerase subunit interactions may serve as a starting point for new, needed drugs to treat human cytomegalovirus infections.
- Chen, Han,Coseno, Molly,Ficarro, Scott B.,Mansueto, My Sam,Komazin-Meredith, Gloria,Boissel, Sandrine,Filman, David J.,Marto, Jarrod A.,Hogle, James M.,Coen, Donald M.
-
-
Read Online
- TiO2-reduced graphene oxide for the removal of gas-phase unsymmetrical dimethylhydrazine
-
Unsymmetrical dimethylhydrazine (UDMH) contaminated waste gas and related intermediates pose a great threat to human health. TiO2-reduced graphene oxide aerogel (rGA) samples with different graphene content levels were synthetized and characterized for the degradation of UDMH. The effects of GO content, humidity, and temperature were investigated under UV and VUV light, with highest UDMH conversion values of 68% and 95%, respectively. Compared with pure TiO2, the enhanced degradation activity of TiO2-rGA under UV light can be attributed to a synergetic effect between absorption and photocatalysis, while the high UDMH conversion under VUV light relies on photolysis and ozonation. The high oxygen-containing group content, rather than a high SSA, and electron trapping by graphene are key factors determining the outstanding performance of TiO2-rGA with 80 mg of GO. The prepared TiO2-graphene aerogels are promising for the degradation of gas-phase UDMH. This journal is
- Ruomeng, Hou,Ying, Jia,Yuanzheng, Huang,Keke, Shen,Huixin, Zhu
-
-
Read Online
- Absolute Rates of Recombination and Disproportination of Dimethylaminyl Radicals
-
The absolute rate constants for the recombination (kr) and disproportionation (kd) reactions of dimethylaminyl radicals were determined at room temperature with the very low pressure reactor (VLPR) technique.The obtained values were kr = (1.70 +/- 0.19) x 1E-12 cm3 molecule-1 s-1 and kd = (4.19 +/- 0.52) x 1E-12 cm3 molecule-1 s-1, and the ratio kd/kr was 2.32 +/- 0.26.The transition-state geometries for both recombination and disproportination reactions are loose, with the N...N bond length ca. 3.5 Angstroem and the N...H...C distance ca. 4.4 Angstroem.In the recombination TS, the four C-N...N bending modes are ca. 90 cm-1 and play a significant role in the formation of the N-N bond in tetramethylhydrazine.In the disproportionation TS, the two (in-plane and out-of-plane) vibrational modes of the metathetic hydrogen are ca. 110 cm-1 and are essential in the formation of the N-H bond in dimethylamine.
- Lazarou, Yannis G.,Papagiannakopoulos, Panos
-
-
Read Online
- Degradation of gaseous unsymmetrical dimethylhydrazine by vacuum ultraviolet coupled with MnO2
-
In this study, α-, β-, and δ-MnO2 were prepared by a uniform hydrothermal method and then coupled with vacuum ultraviolet (VUV) for the degradation of gaseous unsymmetrical dimethylhydrazine (UDMH). The performance in the removal of UDMH, by-product distribution and mechanism were systematically investigated. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, Field Emission Scanning Electron Microscopy (FE-SEM), Raman, thermogravimetry (TG), Fourier-transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) to investigate the factors affecting the catalytic activity. The results showed that O2 and H2O were essential for the removal of UDMH. Photooxidation and ozone catalytic oxidation contribute to the removal and mineralization of UDMH. The integrated process considerably improved the removal and mineralization of UDMH by ozone catalytic oxidation. More reactive oxygen species were generated in the integrated process. The catalytic activity of the prepared catalysts follows the order: δ-MnO2 > α-MnO2 > β-MnO2. δ-MnO2 displayed the highest removal rate of 100% and a CO2 concentration of 42 ppmv. The good performance of δ-MnO2 was mainly attributed to the large number of surface oxygen vacancies.
- Huang, Yuanzheng,Jia, Ying,Shen, Keke,Hou, Ruomeng,Zhang, Yongyong,Hou, Li'an
-
supporting information
p. 1194 - 1202
(2021/02/06)
-
- Electrochemical Reductive N-Methylation with CO2Enabled by a Molecular Catalyst
-
The development of benign methylation reactions utilizing CO2 as a one-carbon building block would enable a more sustainable chemical industry. Electrochemical CO2 reduction has been extensively studied, but its application for reductive methylation reactions remains out of the scope of current electrocatalysis. Here, we report the first electrochemical reductive N-methylation reaction with CO2 and demonstrate its compatibility with amines, hydroxylamines, and hydrazine. Catalyzed by cobalt phthalocyanine molecules supported on carbon nanotubes, the N-methylation reaction proceeds in aqueous media via the chemical condensation of an electrophilic carbon intermediate, proposed to be adsorbed or near-electrode formaldehyde formed from the four-electron reduction of CO2, with nucleophilic nitrogenous reactants and subsequent reduction. By comparing various amines, we discover that the nucleophilicity of the amine reactant is a descriptor for the C-N coupling efficacy. We extend the scope of the reaction to be compatible with cheap and abundant nitro-compounds by developing a cascade reduction process in which CO2 and nitro-compounds are reduced concurrently to yield N-methylamines with high monomethylation selectivity via the overall transfer of 12 electrons and 12 protons.
- Rooney, Conor L.,Wu, Yueshen,Tao, Zixu,Wang, Hailiang
-
supporting information
p. 19983 - 19991
(2021/12/01)
-
- Kinetics and mechanism of oxidation of metformin hydrochloride by hexamolybdocobaltate(III) in acidic medium
-
The oxidation of metformin hydrochloride by Anderson-Evans type hexamolybdocobaltate(III) anion was investigated under pseudo-first-order condition in acidic medium at 298 K. The rate of reaction is accelerated by increase in the concentration of H+ ion. The decrease in the reaction rate with increase in the concentration of the oxidant [H6CoMo6O24]3- anion and added molybdate ion kinetically indicate existence of the prior equilibria between various forms of the oxidant. In present study, the oxidant exists in monomers [H6CoMo6O24]3-anion, [H5CoMo5O20]2- anion and dimer [H4Co2Mo10O38]6- forms between the pH 2 and 1. The active oxidant species is [H5CoMo5O20]2-anion. Under experimental conditions, the reaction involves direct electron-transfer from metformin center to oxidant anion generating free radical in rate determining step. The fast hydrolysis of formed free radical in presence of second oxidant molecule leads to formation of carbonyl imino functional group in the oxidation product. The ionic strength and solvent polarity had no significant effect on the rate of reaction. FT-IR spectra of metformin and its oxidation product sample were recorded and analyzed. The FT-IR spectra show the change in frequency of the functional groups of oxidation product than that of the pure MET. The formation of oxidation product was confirmed by high performance liquid chromatography associated with electron impact mass spectroscopy (LC/EI-MS). Thermodynamic parameters are evaluated by temperature variation kinetic data and are in support of the proposed mechanism. The probable mechanism is proposed leading to complicated rate law as a result of involvement of prior equillibria between various forms of the oxidant.
- Sawant,Patil,Gokavi
-
-
- A comparative study on the coordination of diglycolamide isomers with Nd(iii): extraction, third phase formation, structure, and computational studies
-
A novel asymmetric diglycolamideN,N-dimethyl-N′,N′-dioctyl diglycolamide (LII) was synthesized. The Nd(iii) extraction behavior from HNO3and loading capability of the solution of LIIin 40/60 (v/v)%n-octanol/kerosene were studied. Analyses by the slope method, ESI-MS, and FT-IR indicated that, similar to the previously studied isomer ligandN,N′-dimethyl-N,N′-dioctyl diglycolamide (LI), 1?:?3 Nd(iii)/LIIcomplexes formed. Under the same experimental conditions, the distribution ratio and limiting organic concentration of LIItowards Nd(iii) were smaller than those of LI, but the critical aqueous concentration of LIIwas larger, which implies that LIIexhibited poorer extraction and loading capabilities towards Nd(iii) than LI, and LIIhas a tendency to be less likely to form the third phase. The quasi-relativistic density functional theory (DFT) calculation was performed to provide some explanations for the differences in their extraction behaviors. The electrostatic potential of the ligands indicated that the electron-donating ability of the amide O atoms in LIIdisplayed certain differences compared with LI. This inhomogeneity in LIIaffected the interaction between LIIand Nd(iii), as supported by QTAIM and bonding nature analysis, and it seemed to reflect in the extraction performance towards Nd(iii).
- Gao, Yang,He, Hui,Jiao, Caishan,Li, Chunhui,Liu, Sheng,Liu, Yaoyang,Liu, Zhibin,Zhang, Shaowen,Zhao, Chuang,Zhou, Yu
-
p. 27969 - 27977
(2021/09/15)
-
- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
-
The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
-
supporting information
(2022/01/04)
-
- Electrochemical Reduction of Carbamates and Carbamic Acids: Implications for Combined Carbon Capture and Electrochemical CO2 Recycling
-
Electrocatalytic reduction of CO2 to CO could represent the first step in solar-driven recycling of CO2 to fuels. While many reports focus on catalyst design or modification of additives such as Lewis or Bronsted acids, there is little focus on modification of the substrate, CO2 itself. Current carbon capture technology employs amines to capture CO2 as carbamates, suggesting that they may serve as a CO2 surrogate, streamlining carbon capture and recycling. Towards this, herein we explore the cyclic voltammetry of seven amines in the presence/absence of CO2. We show that on a glassy carbon electrode in acetonitrile (MeCN) up to -2.7 V vs Fc/Fc+ in tetrabutylammonium hexafluorophosphate (TBAPF6) electrolyte, the amines can only be reduced in the presence of CO2. The potential of the reduction is dependent on the amine identity as well as the protonation state of the resulting species, carbamate versus carbamic acid. Bulk electrolysis experiments indicate little or no reduction to CO and low Faradaic efficiency for formate. This suggests that these amines may be of use in subsequent studies with molecular electrocatalysts that take CO2 to CO and not formate.
- Bhattacharya, Moumita,Saouma, Caroline T.,Sebghati, Sepehr,Vercella, Yvensha Madeika
-
-
- Rational selection of co-catalysts for the deaminative hydrogenation of amides
-
The catalytic hydrogenation of amides is an atom economical method to synthesize amines. Previously, it was serendipitously discovered that the combination of a secondary amide co-catalyst with (iPrPNP)Fe(H)(CO) (iPrPNP = N[CH2CH2(PiPr2)]2-), results in a highly active base metal system for deaminative amide hydrogenation. Here, we use DFT to develop an improved co-catalyst for amide hydrogenation. Initially, we computationally evaluated the ability of a series of co-catalysts to accelerate the turnover-limiting proton transfer during C-N bond cleavage and poison the (iPrPNP)Fe(H)(CO) catalyst through a side reaction. TBD (triazabicyclodecene) was identified as the leading co-catalyst. It was experimentally confirmed that when TBD is combined with (iPrPNP)Fe(H)(CO) a remarkably active system for amide hydrogenation is generated. TBD also enhances the activity of other catalysts for amide hydrogenation and our results provide guidelines for the rational design of future co-catalysts.
- Artús Suàrez, Lluís,Jayarathne, Upul,Balcells, David,Bernskoetter, Wesley H.,Hazari, Nilay,Jaraiz, Martín,Nova, Ainara
-
p. 2225 - 2230
(2020/03/10)
-
- Too Short-Lived or Not Existing Species: N-Azidoamines Reinvestigated
-
Treatment of N-chlorodimethylamine with sodium azide in dichloromethane does not lead to N-azidodimethylamine, as thought for more than 50 years. Instead, surprisingly, (azidomethyl)dimethylamine is generated with good reproducibility. A plausible reaction mechanism to explain the formation of this product is presented. The reaction of lithium dibenzylhydrazide with tosyl azide does not result in the creation of an N-azidoamine, which can be detected by IR spectroscopy at ambient temperature, as it was claimed previously. Additional experiments with diazo group transfer to lithium hydrazides show that intermediate N-azidoamines are very short-lived or their formation is bypassed by direct generation of 1,1-diazenes via synchronous cleavage of two N-N bonds.
- Banert, Klaus,Pester, Tom
-
p. 4033 - 4039
(2019/04/10)
-
- Catalytic Hydrogenation of Carboxamides with a Bifunctional Cp Ru Catalyst Bearing an Imidazol-2-ylidene with a Protic Aminoethyl Side Chain
-
Synthesis of a Cp Ru complex bearing an NH 2 -functionalized N -heterocyclic carbene (C-N H) was achieved by treatment of CpRuBr(isoprene) with an equimolar amount of a silver complex, which was generated from Ag 2 O and 1-(2-aminoethyl)-3-methylimidazolium bromide, in CH 3 CN at room temperature. The new CpRuBr(C-N H) complex showed a higher catalytic performance than the related CpRuCl(P-N H) and CpRuCl(N-N H) complexes. In the reaction of N -arylcarboxamides, the amine products were obtained in satisfactory yields under mild temperature conditions.
- Ikariya, Takao,Kawano, Teruhiro,Kayaki, Yoshihito,Watari, Ryo
-
p. 2542 - 2547
(2019/06/08)
-
- A non-catalyst non-promoter under the conditions of amide derivatives of aromatic amine with transfers the amine reaction
-
The present invention discloses a non-catalyst under the condition of non-accelerator [...] amide derivatives of aromatic amine with transfers the amine reaction, yield of synthetic N - aryl amide derivatives. The method has a wide range of the substrate, its raw materials and cheap and easy to obtain acylation reagent, the reaction yield is high, one-step reaction, low cost, high reaction selectivity, simple operation and the like. Adopting this method can be gram scale can realize the high yield of the synthesis of drug molecules. Therefore, the method in the N - aryl amide derivatives of synthesis application field has very good application prospect. The method overcomes the existing technologies such as the reaction reagent toxicity is large, the need to use different type catalyst, synthesis method and the cost is high, more reaction steps, more byproducts and the like.
- -
-
Paragraph 0097; 0098; 0099; 0100-0102
(2019/03/28)
-
- Method for preparing formamide derivative by using catalyst-free transamination reaction
-
The invention discloses a method for synthesizing a formamide derivative by using a low-reactive catalyst-free and solvent-free tertiary amide and aliphatic amine transamination reaction, wherein thehigh-yield formamide derivative is obtained by directly using N,N-dimethylformamide (DMF) as a formyl source. According to the present invention, the method has advantages of inexpensive and easily available raw materials, inexpensive and easily available acylating reagent, high reaction yield, one-step reaction, low cost, high reaction selectivity, simple operation and the like, and can overcomethe defects of high toxicity of the reaction reagent, requirement of different types of catalysts, high cost, more reaction steps, more by-products and the like in the prior art.
- -
-
Paragraph 0014
(2019/02/13)
-
- Thermal behavior of ammonium dinitramide and amine nitrate mixtures
-
This paper focuses on the thermal behavior of mixtures of ammonium dinitramide (ADN) and amine nitrates. Because some mixtures of ADN and amine nitrate exhibit low melting points and high-energy content, they represent potential liquid propellants for spacecraft. This study focused on the melting behavior and thermal-decomposition mechanisms in the condensed phase of ADN/amine nitrate mixtures during heating. We measured the melting point and exothermal behavior during constant-rate heating using differential scanning calorimetry and performed thermogravimetry–differential thermal analysis–mass spectrometry (TG–DTA–MS) to analyze the thermal behavior and evolved gases of ADN/amine nitrate mixtures during simultaneous heating to investigate their reaction mechanisms. Results showed that the melting point of ADN was significantly lowered upon the addition of amine nitrate with relatively low molecular volume and low melting point. TG–DTA–MS results showed that the onset temperature of the thermal decomposition of ADN/amine nitrates was similar to that of pure ADN. Furthermore, during thermal decomposition in the condensed phase, ADN produced highly acidic products that promoted exothermic reactions, and we observed the nitration and nitrosation of amines from the dissociation of amine nitrates.
- Matsunaga, Hiroki,Katoh, Katsumi,Habu, Hiroto,Noda, Masaru,Miyake, Atsumi
-
p. 2677 - 2685
(2018/11/23)
-
- Ambient aqueous-phase synthesis of covalent organic frameworks for degradation of organic pollutants
-
The development of a mild, low cost and green synthetic route for covalent organic frameworks (COFs) is highly desirable in order to open the door for practical uses of this new family of crystalline porous solids. Herein, we report a general and facile strategy to prepare a series of microporous or mesoporous COFs by a β-ketoenamine based Michael addition-elimination reaction in aqueous systems at ambient temperature and pressure. This synthesis method not only produces highly crystalline and porous COFs, but also can be carried out with a high reaction rate (only 30 min), high yields (as high as 93%) and large-scale preparation (up to 5.0 g). Furthermore, an Fe(ii)-doped COF shows impressive performance in the oxidative degradation of organic pollutants in aqueous medium. This research thus provides a promising pathway to large-scale green preparation of COFs and their potential application in environmental remediation.
- Liu, Yaozu,Wang, Yujie,Li, Hui,Guan, Xinyu,Zhu, Liangkui,Xue, Ming,Yan, Yushan,Valtchev, Valentin,Qiu, Shilun,Fang, Qianrong
-
p. 10815 - 10820
(2019/12/03)
-
- Lewis Acid-Catalyzed Reductive Amination of Aldehydes and Ketones with N,N-Dimethylformamide as Dimethylamino Source, Reductant and Solvent
-
A practical zinc acetate dihydrate-catalyzed reductive amination of various carbonyl compounds with N,N-dimethylformamide (DMF) as dimethylamino (Me2N) source, reductant and solvent has been developed. This reaction shows broad substrate scope,
- Yang, Luo,Lin, Jie,Kang, Lei,Zhou, Wang,Ma, Da-You
-
supporting information
p. 485 - 490
(2018/01/15)
-
- Preparation method for 3-piperidyl acrylate
-
The invention relates to a preparation method for 3-piperidyl acrylate. According to the preparation method, 3-(N,N-dimethylamino)acrylate as shown in a formula I reacts with piperidine under the catalysis of acid to produce 3-piperidyl acrylate as shown in a formula II and dimethylamine. The preparation method for 3-piperidyl acrylate is low in cost, high in yield and suitable for industrial production.
- -
-
Paragraph 0019
(2018/03/24)
-
- Synthesis of Polysubstituted 3-Methylisoquinolines through the 6π-Electron Cyclization/Elimination of 1-Azatrienes derived from 1,1-Dimethylhydrazine
-
A convenient one pot microwave-assisted 6π-electron cyclization/aromatization approach toward 3-methylisoquinolines is reported. The starting 1-azatriene derivatives were prepared in situ by reaction of 2-propenylbenzaldehydes with 1,1-dimethylhydrazine, which exhibited superior performance when compared with other hydrazine derivatives. Minor amounts of the related 3,4-dihydro isoquinolines were formed concomitantly with the isoquinolines, and a mechanism for their generation was proposed. The reaction conditions were optimized, and its scope and limitations were explored. In general, the transformation proceeded in moderate to good yields.
- Vargas, Didier F.,Larghi, Enrique L.,Kaufman, Teodoro S.
-
p. 5605 - 5614
(2018/10/09)
-
- SAPO-34 synthesized with n-butylamine as a template and its catalytic application in the methanol amination reaction
-
SAPO-34 was synthesized with n-butylamine (BA) as a template for the first time. Crystallization temperature and initial Si amount were important factors leading to successful syntheses. Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures, though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature. Higher temperature (240 °C) can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation. The crystallization processes at 200 and 240 °C were investigated and compared. We used the aminothermal method to synthesize SAPO-34-BA at 240 °C and also found n-propylamine is a suitable template for the synthesis of SAPO-34. The SAPO-34-BA products were characterized by many techniques. SAPO-34-BA has good thermal stability, crystallinity and porosity. BA remained intact in the crystals with ~1.8 BA molecule per chabazite cage. The catalytic performance of SAPO-34 was tested in the methanol amination reaction, which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated, suggesting that this material is a good candidate for the synthesis of methylamines.
- Qiao, Yuyan,Wu, Pengfei,Xiang, Xiao,Yang, Miao,Wang, Quanyi,Tian, Peng,Liu, Zhongmin
-
p. 574 - 582
(2017/04/04)
-
- Preparation method of the formamide
-
The invention relates to a preparation method of methanamide. The method uses formamide or its derivative and amine (primary or secondary amine) as reactants, which are subjected to amidomethylation in the presence of a catalyst to prepare methanamide. The method is characterized in that solid acidic metal oxide or precious metal loaded acidic metal oxide is used as the catalyst and the reaction is carried out efficiently under mild conditions. The reaction process is as follows: mixing formamide with certain concentration or its derivatives with primary or secondary amine and a certain amount of catalyst, placing the mixture into pressure vessel without adding or additionally adding other solvent, sealing, stirring at a temperature no less than 60 DEG C, and reacting for no less than 0.5 h to obtain the reaction product methanamide. The method has the advantages of simple preparation of the catalyst, easy separation process of the catalyst and product, repeated usage of the catalyst, high controllability of the reaction process, and yield of the product formamide reaching more than 95%.
- -
-
Paragraph 0027-0034; 0043; 0043; 0044; 0047-0052
(2017/07/01)
-
- Efficient and selective hydrogenation of amides to alcohols and amines using a well-defined manganese-PNN pincer complex
-
Novel well-defined NNP and PNP manganese pincer complexes have been synthetized and fully characterized. The catalyst Mn-2 containing an imidazolyaminolphosphino ligand shows high activity and selectivity in the hydrogenation of a wide range of secondary and tertiary amides to the corresponding alcohols and amines, under relatively mild conditions. For the first time, more challenging substrates like primary aromatic amides including an actual herbicide can also be hydrogenated using this earth-abundant metal-based pincer catalyst.
- Papa, Veronica,Cabrero-Antonino, Jose R.,Alberico, Elisabetta,Spanneberg, Anke,Junge, Kathrin,Junge, Henrik,Beller, Matthias
-
p. 3576 - 3585
(2017/07/11)
-
- Benzimidazole compound and preparation method thereof
-
The invention discloses a benzimidazole compound and a preparation method thereof. The preparation method comprises the following steps: synthesizing various types of substituted benzimidazole through SN2 and cyclization reactions, that is, substituting fluorine atoms from corresponding o-fluoro aryl-N,N-dimethyl formamidine and primary amine through amine through a one-pot reaction, eliminating dimethylamine, and performing cyclizing, thereby obtaining a product. By adopting the method, no metal catalyst and/or toxic reagent is needed, the method has specific selectivity, and no isomer is generated in reaction products.
- -
-
Paragraph 0009
(2018/04/01)
-
- Compounds with cardiac myosin activating function and pharmaceutical composition containing the same for treating or preventing heart failure
-
The present invention relates to a compound having a cardiotonic activating function and a pharmaceutical composition containing the same. The composition comprising the compound according to the present invention is effective in preventing or treating heart failure. In addition, the compound is represented by chemical formula 2 or is pharmaceutically acceptable salt thereof.COPYRIGHT KIPO 2016
- -
-
Paragraph 1002; 1003; 1008; 1009
(2017/02/02)
-
- Iron-Catalyzed Hydrogenation of Amides to Alcohols and Amines
-
This article describes the iron-catalyzed hydrogenation of unactivated amides. Under the optimal conditions, a PNP-ligated Fe catalyst affords 25-300 turnovers of products derived from C-N bond cleavage. This reaction displays a broad substrate scope, including a variety of 2° and 3° amide substrates. The reaction progress of N,N-dimethylformamide hydrogenation has been monitored in situ using Raman spectroscopy. This technique enables direct comparison of the relative activity of the Fe-PNP catalyst to that of its Ru analogue. Under otherwise identical conditions, the Fe and Ru catalysts exhibit rates within a factor of 2.
- Rezayee, Nomaan M.,Samblanet, Danielle C.,Sanford, Melanie S.
-
p. 6377 - 6383
(2016/10/14)
-
- General method for nucleophilic aromatic substitution of aryl fluorides and chlorides with dimethylamine using hydroxide-assisted decomposition of N,N-dimethylforamide
-
A practical and convenient procedure for the nucleophilic aromatic substitution of aryl fluorides and chlorides with dimethylamine was developed using a hydroxide-assisted thermal decomposition of N,N-dimethylforamide. These conditions are tolerant of nitro, nitrile, aldehyde, ketone, and amide groups but will undergo acyl substitution to form amides for methyl esters and acyl chlorides. Isolated yields of the products range from 44% to 98%, with the majority being greater than 70% for 17 examples.
- Garcia, Juana,Sorrentino, Jacob,Diller, Emily J.,Chapman, Daniel,Woydziak, Zachary R.
-
supporting information
p. 475 - 481
(2016/04/05)
-
- Preparation of all N-coordinated zirconium amide amidinates and studies of their reactions with dioxygen and water
-
Zr(NR2)2[MeC(NiPr)2]2 (R = Me, 1; Et, 2) have been prepared through aminolysis and their reactions with O2 and water have been studied. Two major products from the reactions are the oxo dimer {(μ-O)Zr[MeC(NiPr)2]2}2 (3) and its insoluble polymer {(μ-O)Zr[MeC(NiPr)2]2}n (4). Over time the dimer 3 polymerizes to 4. Zr peroxo trimer {(μ-η2:η2-O2)Zr[MeC(NiPr)2]2}3 (5) was also observed from the reaction of 1 with O2 and its crystal structure is reported. DFT calculations show that the reaction of 1 with O2 follows a radical process, yielding the peroxo trimer 5. Mass spectrometric studies of the reactions of water in air with 1 and 2 show the formation of the oxo monomer (O=)Zr[MeC(NiPr)2]2 (6), oxo dimer {(μ-O)Zr[MeC(NiPr)2]2}2 (3), and the dihydroxy monomer (HO)2Zr[MeC(NiPr)2]2 (7). In addition, the cations {Zr(NR2)[MeC(NiPr)2]2}+ (R = Me, Et) were observed. 2 revealed an interesting dynamic NMR behavior. Variableerature (VT) NMR spectroscopy has been used to study the Bailar twist process in 2, giving activation parameters ΔH? = 10.9(1.1) kcal mol-1, ΔS? = -11(4) eu and ΔG?303 K = 14(2) kcal mol-1.
- Lamb, Adam C.,Wang, Zheng,Cook, Tabitha M.,Sharma, Bhavna,Chen, Shu-Jian,Lu, Zheng,Steren, Carlos A.,Lin, Zhenyang,Xue, Zi-Ling
-
-
- Kinetic and Mechanistic Aspects of Oxidation of Aminotriazole Formamidine by Cerium(IV) in Aqueous Perchloric and Sulfuric Acid Solutions: A Comparative Study
-
The kinetics of the oxidation of an aminotriazole formamidine derivative, N,N-dimethyl-N′-(4H-1,2,4-triazol-3-yl) formamidine (ATF) by cerium(IV) has been studied spectrophotometrically in aqueous perchloric and sulfuric acid solutions at constant ionic strength of 1.0 mol·dm-3. In both acids, the reaction shows first order kinetics with respect to [Ce(IV)], whereas the orders with respect to [ATF] are less than unity. The reaction exhibits negative fractional order kinetics with respect to [H+]. The rates of reaction are not significantly affected by variations of either ionic strength or relative permittivity of the reaction's media. Addition of cerium(III) product does not affect the rates. Plausible mechanistic schemes for the reactions have been proposed. In both cases, the final oxidation products were identified as aminotriazole, dimethyl amine and carbon dioxide. Under comparable experimental conditions, the oxidation rate in perchloric acid solution is about sixfold higher than that in sulfuric acid solution. The effect of temperature on the rates has also been studied and activation parameters have been evaluated and discussed. The rate laws associated with the reaction mechanisms are derived.
- Fawzy, Ahmed
-
p. 246 - 264
(2016/02/23)
-
- Towards a general ruthenium-catalyzed hydrogenation of secondary and tertiary amides to amines
-
A broad range of secondary and tertiary amides has been hydrogenated to the corresponding amines under mild conditions using an in situ catalyst generated by combining [Ru(acac)3], 1,1,1-tris(diphenylphosphinomethyl)ethane (Triphos) and Yb(OTf)3. The presence of the metal triflate allows to mitigate reaction conditions compared to previous reports thus improving yields and selectivities in the desired amines. The excellent isolated yields of two scale-up experiments corroborate the feasibility of the reaction protocol. Control experiments indicate that, after the initial reduction of the amide carbonyl group, the reaction proceeds through the reductive amination of the alcohol with the amine arising from collapse of the intermediate hemiaminal.
- Cabrero-Antonino, Jose R.,Alberico, Elisabetta,Junge, Kathrin,Junge, Henrik,Beller, Matthias
-
p. 3432 - 3442
(2016/05/19)
-
- Catalytic hydrogenation of functionalized amides under basic and neutral conditions
-
A new, base-free high turnover number (TON) catalyst for hydrogenation of simple and functionalized amides is prepared by reacting [Ru(η3-C3H5)(Ph2P(CH2)2NH2)2]BF4 and BH4- under hydrogen. The hydrogenation proceeds with C-N cleavage to form the corresponding amine and alcohol. The base-free and base-promoted hydrogenations tolerate alcohols, amines, aromatic bromides, chlorides and fluorides, ethers, certain olefins, and N-heterocyclic rings. The reaction was used to deprotect the amine groups in certain acetyl amides to form, for example, an N-heterocyclic amine containing an aryl bromide. The base-free system also selectively hydrogenates N-acyloxazolidinones without epimerization at the α-position, and reduced β-lactams to form the corresponding amino alcohols.
- John, Jeremy M.,Loorthuraja, Rasu,Antoniuk, Evan,Bergens, Steven H.
-
p. 1181 - 1186
(2015/02/19)
-
- METHOD FOR PREPARING DIALKYL CARBONATE
-
Disclosed is a method for preparing a dialkyl carbonate, in which a dialkyl carbonate such as dimethyl carbonate is economically prepared in an environmentally-friendly manner at a higher yield while reducing generation of a by-product. The method for preparing the dialkyl carbonate includes reacting urea, an alkyl carbamate having 1 to 3 carbon atoms, or a mixture thereof with a monovalent alcohol having 1 to 3 carbon atoms in the presence of a room temperature ionic liquid and a catalyst including a salt of a transition metal or a rare earth metal.
- -
-
Paragraph 0095; 0102
(2014/03/24)
-
- METHOD FOR PREPARING DIALKYL CARBONATE
-
Disclosed is a method for preparing a dialkyl carbonate, in which a dialkyl carbonate such as dimethyl carbonate is economically prepared in an environmentally-friendly manner at a higher yield while reducing generation of a by-product. The method for preparing the dialkyl carbonate includes reacting urea, an alkyl carbamate having 1 to 3 carbon atoms, or a mixture thereof with a monovalent alcohol having 1 to 3 carbon atoms in the presence of a room temperature ionic liquid and a catalyst including a salt of a transition metal or a rare earth metal.
- -
-
Paragraph 0103; 0110
(2014/03/24)
-
- Tungsten nitrido complexes as precursors for low temperature chemical vapor deposition of WNxCy films as diffusion barriers for Cu metallization
-
Tungsten nitrido complexes of the form WN(NR2)3 [R = combinations of Me, Et, iPr, nPr] have been synthesized as precursors for the chemical vapor deposition of WNxCy, a material of interest for diffusion barriers in Cu-metallized integrated circuits. These precursors bear a fully nitrogen coordinated ligand environment and a nitrido moiety (Wi - N) designed to minimize the temperature required for film deposition. Mass spectrometry and solid state thermolysis of the precursors generated common fragments by loss of free dialkylamines from monomeric and dimeric tungsten species. DFT calculations on WN(NMe 2)3 indicated the lowest gas phase energy pathway for loss of HNMe2 to be β-H transfer following formation of a nitrido bridged dimer. Amorphous films of WNxCy were grown from WN(NMe2)3 as a single source precursor at temperatures ranging from 125 to 650 C using aerosol-assisted chemical vapor deposition (AACVD) with pyridine as the solvent. Films with stoichiometry approaching W2NC were grown between 150 and 450 C, and films grown at 150 C were highly smooth, with a RMS roughness of 0.5 nm. In diffusion barrier tests, 30 nm of film withstood Cu penetration when annealed at 500 C for 30 min.
- McClain, K. Randall,O'Donohue, Christopher,Koley, Arijit,Bonsu, Richard O.,Abboud, Khalil A.,Revelli, Joseph C.,Anderson, Timothy J.,McElwee-White, Lisa
-
supporting information
p. 1650 - 1662
(2014/02/14)
-
- Oxidant-free conversion of cyclic amines to lactams and H2 using water as the oxygen atom source
-
Direct conversion of cyclic amines to lactams utilizing water as the only reagent is catalyzed by pincer complex 2. In contrast to previously known methods of amine-to-amide conversion, this reaction occurs in the absence of oxidants and is accompanied by liberation of H2, with water serving as a source of oxygen atom. Formation of a cyclic hemiaminal intermediate plays a key role in enabling such reactivity. This represents an unprecedented, conceptually new type of amide formation reaction directly from amines and water under oxidant-free conditions.
- Khusnutdinova, Julia R.,Ben-David, Yehoshoa,Milstein, David
-
supporting information
p. 2998 - 3001
(2014/03/21)
-
- Exploratory process development and kilogram-scale synthesis of a novel oxazolidinone antibacterial candidate
-
A concise, environmentally benign, and cost-effective route was developed for the large-scale preparation of 1, a novel oxazolidinone antibacterial candidate. The key intermediate 2-(1-(2-fluoro-4-nitrophenyl)-1H-pyrazol-4-yl) pyridine 7 was prepared with high purity by mild deamination of the regioisomeric mixture 21. The mixture was prepared from a nucleophilic SNAr reaction by selective C-N coupling of the secondary amine functionality of 4-(pyridin-2-yl)-1H-pyrazol-3-amine 14 with 1,2-difluoro-4-nitrobenzene 10 in optimized conditions with the primary amine group remaining intact. The gaseous nitrogen release rate and reaction mixture temperature of the deamination step can be well controlled by altering the feeding manner, thereby providing safety guarantees. The optimized synthetic strategy of 1 with an overall yield of 27.6%, including seven sequential transformations by only five solid-liquid isolations, significantly improved the product separation workup. The strategy bypassed time-consuming and laborious procedures for any intermediate involved as well as for the final API. This study presents a process enabling the rapid delivery of a multikilogram quantity of API with high purity.
- Yang, Tao,Chen, Jia-Xiang,Fu, Yiwei,Chen, Kaixiao,He, Jinyun,Ye, Weiwei,Sang, Zitai,Luo, Youfu
-
p. 511 - 519
(2014/05/06)
-
- Kinetic and mechanistic investigations on the oxidation of N'-heteroaryl unsymmetrical formamidines by permanganate in aqueous alkaline medium
-
Kinetic studies on the oxidation of two substituted azinyl formamidines (Azn-Fs), namely N,N-dimethyl-N'-(pyrimidin-2-yl) formamidine (Pym-F) and N,N-dimethyl-N'-(pyridin-2-yl) formamidine (Py-F), by alkaline permanganate have been performed by spectrophotometry. The spectroscopic and kinetic evidence reveals the formation of 1:1 intermediate complexes between the oxidant and substrates. The influence of pH on the oxidation rates indicated that the reactions are base-catalyzed. The reactions show identical kinetics, being first order each in [MnO4 -]0 and [Azn-F] 0, but with a fractional first-order dependence on [OH-]. The effect of temperature on the reaction rate has been studied. Increasing ionic strength has no significant effect on the rate. The final oxidation products of Pym-F and Py-F were identified as 2-aminopyrimidine and 2-aminopyridine, respectively, in addition to dimethyl amine and carbon dioxide. Under comparable experimental conditions, the oxidation rate of Py-F is higher than that of Pym-F. A reaction mechanism adequately describing the observed kinetic behavior is proposed, and the reaction constants involved in the different steps of the mechanism have been evaluated. The activation parameters with respect to the rate-limiting step of the reactions, along with thermodynamic quantities, are presented and discussed.
- Fawzy, Ahmed,Shaaban, Mohamed R.
-
p. 379 - 386
(2014/05/20)
-
- CATALYSTS AND PROCESSES FOR THE HYDROGENATION OF AMIDES
-
There is provided a process for the reduction of one or more amide moieties in a compound comprising contacting the compound with hydrogen gas and a transition metal catalyst in the presence or absence of a base under conditions for the reduction an amide bond. The presently described processes can be performed at low catalyst loading using relatively mild temperature and pressures, and optionally, in the presence or absence of a base or high catalyst loadings using low temperatures and pressures and high loadings of base to effect dynamic kinetic resolution of achiral amides.
- -
-
Paragraph 0262; 0263
(2014/06/24)
-
- Reactions of zirconium amide amidinates with dioxygen. Observation of an unusual peroxo intermediate in the formation of oxo compounds
-
Reaction of d0 Zr(NMe2)2[MeC(N iPr)2]2 (1) with O2 at -30°C gives three Zr containing products: a peroxo trimer {(μ-η2: η2-O2)Zr[MeC(NiPr)2] 2}3 (2), an oxo dimer {(μ-O)Zr[MeC(N iPr)2]2}2 (3), and an oxo polymer {(μ-O)Zr[MeC(NiPr)2]2}n (4). 2 is a rarely observed peroxo complex from the reaction of a d0 complex with O2. This journal is the Partner Organisations 2014.
- Lamb, Adam C.,Lu, Zheng,Xue, Zi-Ling
-
supporting information
p. 10517 - 10520
(2014/12/10)
-
- Aerobic oxidative N-dealkylation of tertiary amines in aqueous solution catalyzed by rhodium porphyrins
-
Aerobic oxidative N-dealkylation of a variety of aliphatic tertiary amines and anilines catalyzed by rhodium(iii) tetra (p-sulfonatophenyl) porphyrin ((TSPP)RhIII) is achieved in aqueous solution using dioxygen as the sole oxidant.
- Ling, Zhen,Yun, Lin,Liu, Lianghui,Wu, Bing,Fu, Xuefeng
-
supporting information
p. 4214 - 4216
(2013/05/22)
-