- Kinetics and mechanism of chlorine exchange between chloramine-T and secondary amines
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The kinetics and mechanisms of chlorine transfer from chloramine-T (CAT) to several amines are second order and independent of p-toluenesulfonamide concentration; thus, the reaction does not involve disproportionation of CAT to dichloramine-T. From the profile of pH versus rate, the following mechanisms were proposed: (1) reaction of the ionized species of CAT with the ionized amine (ionic mechanism) and (2) reaction of the un-ionized species of CAT with the un-ionized amine (nonionic mechanism). The second-order, pH- independent rate constants calculated for the ionic and nonionic mechanisms were 1.6 and 5 x 106 M-1 s-1, respectively. Although these two mechanisms are kinetically indistinguishable, the rate constant for the nonionic mechanism is of the same order of magnitude as those calculated for similar chlorination reactions involving nonionizable chloramines, such as N- chlorosuccinimide, N-chloroquinuclidine, and N-chloro-N- methylbenzenesulfonamide. The proposed mechanism for the chlorine exchange involves a molecule of water in a cyclic, six-membered transition state.
- Dannan,Crooks,Dittert,Hussain
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- STERIC FACTORS IN THE SHORT-RANGE SOLVATION OF SECONDARY AMINES
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Steric aspects of the short-range solvation of proton transfer complexes between 2,4-dinitrophenol and various secondary amines was studied in benzene-DMSO and benzene-dioxane mixed solvent systems.Diisopropylamine was hindered when compared with diethylamine, and 2,2,6,6-tetramethylpiperidine was hindered when compared with 2,6-dimethylpiperidine in forming the proton transfer complex.The smaller electron-donating solvent dimethylsulfoxide was capable of solvating the more hindered amines, but the the bulkier dioxane could only solvate diethylamine and dimethylpiperidine readily.Tetrahydropyran could solvate tetramethylpiperidine weakly, inferring that it did not solvate in precisely the same fashion as does dioxane.It is concluded that the solvation structure is sufficiently crowded as to be sensitive to small changes in the structures of the participants.
- Tayh, Jamal A.,Scott, Ronald M.
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- Transient Alkylaminium Radicals in n-Hexane. Condensed-Phase Ion-Molecule Reactions
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Time-resolved fluorescence detected magnetic resonance (FDMR) is used to observe alkylaminium radicals formed in n-hexane solutions by electron pulse radiolysis.The ease of observation of aminium radical FDMR signals increases with increasing alkyl substitution of the amine solutes.The results are discussed in terms of the ion-molecule reactions, such as proton transfer, which compete with electron-transfer processes, i. e., the electron transfer from solute molecules to n-hexane radical cations and geminate recombination.
- Werst, D. W.,Trifunac, A. D.
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- Effect of an Alumina Phase on the Reductive Amination of 2-Propanol to Monoisopropylamine over Ni/Al2O3
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Various single-phase aluminum oxides were prepared through the thermal decomposition of bayerite, boehmite, and gibbsite. Ni/γ-Al2O3 and Ni/δ-Al2O3 catalysts exhibited higher monoisopropylamine (MIPA) selectivity than the η-, θ-, and κ-Al2O3 supported Ni catalysts for the reductive amination of 2-propanol (IPA) in the presence of hydrogen and ammonia. FT-IR spectra after pyridine adsorption showed that a high number of Lewis acid sites could be correlated with enhancement in MIPA selectivity. Ni/η-Al2O3 and Ni/γ-Al2O3 catalysts exhibited the highest catalytic activity arising from differences in the metallic surface area. Both catalyst activity and selectivity with regards to reductive amination were strongly affected by the nature of the support.
- Cho, Jun Hee,An, Sang Hee,Chang, Tae-Sun,Shin, Chae-Ho
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- Reductive amination of 2-propanol to monoisopropylamine over Ni/γ-Al2O3 catalysts
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Ni/γ-Al2O3 catalysts with different nickel loadings (4-27 wt%) were used for the synthesis of monoisopropylamine by the reductive amination of 2-propanol in the presence of hydrogen and ammonia. H2-chemisorption analysis i
- Cho, Jun Hee,Park, Jung-Hyun,Chang, Tae-Sun,Kim, Jin-Eok,Shin, Chae-Ho
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- Oxidative Detoxification of Sulfur-Containing Chemical Warfare Agents by Electrophilic Iodine
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Mild oxidation of sulfur-containing chemical warfare agents was performed in organic medium by electrophilic iodine reagents. Kinetic experiments on sulfur mustard (HD) showed rapid (t1/2 1/2 ~ 90 min). Higher donor number solvents, such as THF, DMF, or DMSO, showed slower rates with both iodine and NIS. The oxidation of the nerve agent O-ethyl-S-2-(N,N-diisopropylaminoethyl)methylphosphonothioate (VX) selectively to the nontoxic ethyl methylphosphonic acid product exhibited fast rates (t1/2 = 6 min) using NIS in DMSO solution. In all other solvents tested with VX, rates were slower (t1/2 ~ 30-70 min). Oxidation experiments under the same conditions with chloroethyl ethyl sulfide (HD simulant) and O,S-diethyl methylphosphonothioate (VX simulant) led to much faster reaction rates. These transformations are believed to proceed through electrophilic iodine attack on the sulfur moiety and display solvent dependency based on the agents' structural and chemical properties.
- Smolkin, Boris,Levi, Noam,Karton-Lifshin, Naama,Yehezkel, Lea,Zafrani, Yossi,Columbus, Ishay
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- Effect of the Ligand Structure on Chemical Vapor Deposition of WNxCy Thin Films from Tungsten Nitrido Complexes of the Type WN(NR2)3
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Tungsten nitrido complexes of the type WN(NR2)3 [NR2 = combinations of NMe2, NEt2, NiPr2, NnPr2, NiBu2, piperidine, and azepane] were synthesized as precursors for aerosol-assisted chemical vapor deposition of WNxCy thin films. The effects of the amido substituents on precursor volatility and decomposition were evaluated experimentally and computationally. Films deposited using WN(NMe2)(NiPr2)2 as a single-source precursor were assessed as diffusion barrier materials for Cu metallized integrated circuits in terms of growth rate, surface roughness, composition, and density. In diffusion barrier tests, Cu (100 nm)/WNxCy (5 nm)/Si samples prepared from WN(NMe2)(NiPr2)2 were annealed for 30 min at 500 °C and successfully blocked Cu penetration according to four-point probe, X-ray diffraction, scanning electron microscopy etch-pit test, and high-resolution transmission electron microscopy measurements.
- Koley, Arijit,O'Donohue, Christopher T.,Nolan, Michelle M.,McClain, K. Randall,Bonsu, Richard O.,Korotkov, Roman Y.,Anderson, Tim,McElwee-White, Lisa
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- Reductive amination of 2-propanol to monoisopropylamine over Co/γ-Al2O3 catalysts
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Co/γ-Al2O3 catalysts with 4-27 wt% cobalt loadings were prepared by incipient-wetness impregnation and used to catalyze the synthesis of monoisopropylamine by the reductive amination of 2-propanol in the presence of hydrogen and ammonia. The catalysts were characterized by X-ray diffraction, H2-temperature programmed reduction, N 2-sorption, and H2-chemisorption. 23 wt% Co loading resulted in the highest catalytic activity and a long-term stability of up to 100 h on stream. 2-Propanol conversion was related to the exposed metal surface area and the number of exposed cobalt atoms. In the absence of hydrogen, the catalyst was progressively deactivated; its initial activity and selectivity were completely recovered upon re-exposure to hydrogen. The deactivation was due to the formation of metal nitride caused by the strong adsorption of ammonia on the surface of the metal phase. Excess hydrogen hindered the phase transition to metal nitride, preventing deactivation.
- Cho, Jun Hee,Park, Jung Hyun,Chang, Tae-Sun,Seo, Gon,Shin, Chae-Ho
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- Zirconocene-Initiated Intramolecular Hydride Transfer in N -Isoalkyl-Substituted Propargylamines
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The unusual transformation of N -isoalkyl-substituted propargylamines into alkenylamines under the action of Cp 2 ZrCl 2 and organoaluminum compounds (Me 3 Al, EtAlCl 2) has been observed. The proposed mechanism, involving the N -isoalkyl-substituted propargylamine undergoing zirconocene-initiated intramolecular hydride transfer was supported by B3LYP/6-31G(d)/LanL2DZ calculations.
- Ramazanov, Ilfir R.,Kadikova, Rita N.,Saitova, Zukhra R.,Dzhemilev, Usein M.
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- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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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.
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supporting information
(2022/01/04)
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- Electroactivated alkylation of amines with alcohols: Via both direct and indirect borrowing hydrogen mechanisms
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A green, efficient N-alkylation of amines with simple alcohols has been achieved in aqueous solution via an electrochemical version of the so-called "borrowing hydrogen methodology". Catalyzed by Ru on activated carbon cloth (Ru/ACC), the reaction works well with methanol, and with primary and secondary alcohols. Alkylation can be accomplished by either of two different electrocatalytic processes: (1) in an undivided cell, alcohol (present in excess) is oxidized at the Ru/ACC anode; the aldehyde or ketone product condenses with the amine; and the resulting imine is reduced at an ACC cathode, combining with protons released by the oxidation. This process consumes stoichiometric quantities of current. (2) In a membrane-divided cell, the current-activated Ru/ACC cathode effects direct C-H activation of the alcohol; the resulting carbonyl species, either free or still surface-adsorbed, condenses with amine to form imine and is reduced as in (1). These alcohol activation processes can alkylate primary and secondary aliphatic amines, as well as ammonia itself at 25-70 °C and ambient pressure.
- Appiagyei, Benjamin,Bhatia, Souful,Keeney, Gabriela L.,Dolmetsch, Troy,Jackson, James E.
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supporting information
p. 860 - 869
(2020/02/21)
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- Synthesis of Trialkylamines with Extreme Steric Hindrance and Their Decay by a Hofmann-like Elimination Reaction
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A number of amines with three bulky alkyl groups at the nitrogen, which surpass the steric crowding of triisopropylamine considerably, were prepared by using different synthetic methods. It turned out that treatment of N-chlorodialkylamines with organometallic compounds, for example, Grignard reagents, in the presence of a major excess of tetramethylenediamine offered the most effective access to the target compounds. The limits of this method were also tested. The trialkylamines underwent a dealkylation reaction, depending on the degree of steric stress, even at ambient temperature. Because olefins were formed in this transformation, it showed some similarity with the Hofmann elimination. However, the thermal decay of sterically overcrowded tertiary amines was not promoted by bases. Instead, this reaction was strongly accelerated by protic conditions and even by trace amounts of water. Reaction mechanisms, which were analyzed with the help of quantum chemical calculations, are suggested to explain the experimental results.
- Banert, Klaus,Hagedorn, Manfred,Heck, Manuel,Hertel, Raphael,Ihle, Andreas,Müller, Ioana,Pester, Tom,Shoker, Tharallah,Rablen, Paul R.
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p. 13630 - 13643
(2020/11/13)
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- Selective Synthesis of Secondary and Tertiary Amines by Reductive N-Alkylation of Nitriles and N-Alkylation of Amines and Ammonium Formate Catalyzed by Ruthenium Complex
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A new ruthenium catalytic system for the syntheses of secondary and tertiary amines via reductive N-alkylation of nitriles and N-alkylation of primary amines is proposed. Isomeric complexes 8 catalyze transfer hydrogenation and N-alkylation of nitriles in ethanol to give secondary amines. Unsymmetrical secondary amines can be produced by N-alkylation of primary amines with alcohols via the borrowing hydrogen methodology. Aliphatic amines were obtained with excellent yields, while only moderate conversions were observed for anilines. Based on kinetic and mechanistic studies, it is suggested that the rate determining step is the hydrogenation of intermediate imine to amine. Finally, ammonium formate was applied as the amination reagent for alcohols in the presence of ruthenium catalyst 8. Secondary amines were obtained from primary alcohols within 24 hours at 100 °C, and tertiary amines can be produced after prolonged heating. Secondary alcohols can only be converted to secondary amines with moderate yield. Based on mechanistic studies, the process is suggested to proceed through an ammonium alkoxy carbonate intermediate, where carbonate acts as an efficient leaving group.
- Alshakova, Iryna D.,Nikonov, Georgii I.
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p. 5370 - 5378
(2019/06/14)
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- Intramolecular alkene hydroamination and degradation of amidines: Divergent behavior of rare earth metal amidinate intermediates
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Direct N-H addition of amidines to alkenes is a highly valuable but challenging transformation that remains elusive. Now, the intramolecular hydroamidination of N-alkenylamidines is achieved by using a rare earth catalyst, which provides an efficient and atom-economical approach for substituted imidazolines and tetrahydropyrimidines. Moreover, a mild and efficient method for the catalytic degradation of amidines to give amines and nitriles is also developed. Additionally, amidine reconstruction followed by an intramolecular alkene hydroamidination strategy for the synthesis of substituted imidazolines and tetrahydropyrimidines from secondary enamines and inactive amidines has also been established, which may circumvent the need for some unavailable starting materials. The mechanistic studies prove that these reactions proceed via a key lanthanide amidinate intermediate that can undergo substrate- and amine-controlled chemodivergent transformations: intramolecular alkene insertion, nitrile extrusion, amidinate reconstruction, or a combination of the reactions. The results presented here not only demonstrate the synthetic potential and versatility of alkene hydroamidination with substrates, but also provide a good insight into the factors that promote or deter the hydroamidination of alkenes.
- Zhang, Dexing,Liu, Ruiting,Zhou, Xigeng
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p. 5573 - 5581
(2018/11/20)
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- Dynamic Ureas with Fast and pH-Independent Hydrolytic Kinetics
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Low cost, high performance hydrolysable polymers are of great importance in biomedical applications and materials industries. While many applications require materials to have a degradation profile insensitive to external pH to achieve consistent release profiles under varying conditions, hydrolysable chemistry techniques developed so far have pH-dependent hydrolytic kinetics. This work reports the design and synthesis of a new type of hydrolysable polymer that has identical hydrolysis kinetics from pH 3 to 11. The unprecedented pH independent hydrolytic kinetics of the aryl ureas were shown to be related to the dynamic bond dissociation controlled hydrolysis mechanism; the resulting hindered poly(aryl urea) can be degraded with a hydrolysis half-life of 10 min in solution. More importantly, these fast degradable hindered aromatic polyureas can be easily prepared by addition polymerization from commercially available monomers and are resistant to hydrolysis in solid form for months under ambient storage conditions. The combined features of good stability in solid state and fast hydrolysis at various pH values is unprecedented in polyurea material, and will have implications for materials design and applications, such as sacrificial coatings and biomaterials.
- Cai, Kaimin,Ying, Hanze,Cheng, Jianjun
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supporting information
p. 7345 - 7348
(2018/06/11)
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- Steric Hindrance Underestimated: It is a Long, Long Way to Tri- tert-alkylamines
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Ten different processes (Methods A-J) were tested to prepare tertiary amines bearing bulky alkyl groups. In particular, SN1 alkylation of secondary amines with the help of 1-adamantyl triflate (Method D) and reaction of N-chlorodialkylamines with organometallic reagents (Method H), but also attack of the latter reagents at iminium salts, which were generated in situ by N-alkylation of imines (Method J), led to trialkylamines with unprecedented steric congestion. These products showed a restriction of the rotation about the C-N bond. Consequently, equilibration of rotamers was slow on the NMR time scale resulting in distinguishable sets of NMR data at room temperature. Furthermore, tertiary amines with bulky alkyl substituents underwent Hofmann-like elimination when heating in toluene to form an olefin and a secondary amine. Since the tendency to take part in this decay reaction correlated with the degree of steric hindrance around the nitrogen atom, Hofmann elimination at ambient temperature, which made the isolation of the tertiary amine difficult, was observed in special cases.
- Banert, Klaus,Heck, Manuel,Ihle, Andreas,Kronawitt, Julia,Pester, Tom,Shoker, Tharallah
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p. 5138 - 5148
(2018/05/17)
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- METHOD FOR PRODUCING N-ETHYL-DIISOPROPYLAMINE
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A process for preparing N-ethyldiisopropylamine by reacting acetaldehyde with diisopropylamine and hydrogen at elevated temperature and under pressure in the presence of a heterogeneous hydrogenation catalyst, the catalyst being a supported transition metal catalyst comprising Pd and/or Pt as catalytically active metal, wherein the diisopropylamine used has a purity of 58% to 94% by weight and impurities as follows: 3% to 20% by weight of water, 3% to 20% by weight of isopropanol, 0% to 2% by weight of others.
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Paragraph 0070-0076
(2017/01/26)
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- REACTIONS OF STANNYL CATIONS
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The present invention relates to a method of reducing, cleaving and/or coupling at least one C=O, C-O, C=C or C=N bond of a compound, using a reagent comprising a stannyl cation.
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Page/Page column 22; 23
(2018/01/17)
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- Ruthenium-catalyzed deaminative redistribution of primary and secondary amines
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A ruthenium-hydride complex, [Ru(H)(Cl)(CO)(PCy3)2], was found to be active in the highly selective redistribution of primary and secondary amines bearing an α-hydrogen atom. This new deaminative coupling of amines enables the highly selective synthesis of secondary amines from primary amines and of tertiary amines from secondary amines with the evolution of ammonia. A preliminary mechanistic view of this novel reaction based on catalytic experiments using NMR methods confirms the synthetic observations.
- Kostera,Wyrzykiewicz,Pawlu?,Marciniec
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supporting information
p. 11552 - 11555
(2017/09/18)
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- Method for producing and phenoxyethylamine monoisopropylamine (MIPA)
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Method for producing ethylamines and monoisopropylamine (MIPA), in which bioethanol is reacted with ammonia in the presence of hydrogen and a heterogeneous catalyst to form ethylamines, wherein the bioethanol contains sulphur and/or sulphur-containing compounds of >= 0.1 ppm by weight (calculated S), and then in the presence of the same catalyst, isopropanol is reacted with ammonia in the presence of hydrogen to form MIPA.
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Paragraph 0113; 0121; 0122
(2016/12/26)
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- Transfer of 1-alkenyl groups between secondary amines. Relative stability and reactivity of enamines from popular organocatalysts
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Enamines from 3-methylbutanal and several Pro- and Phe-derived secondary amines were prepared in DMSO-d6, CD3CN, and CDCl 3. For the first time, the relative thermodynamic stabilities of these and other enamines were compared, and rapid exchanges of 1-alkenyl groups were demonstrated. Competition experiments showed that the most favored enamines (without significant steric inhibition of resonance) react more rapidly with electrophiles.
- Carneros, Hector,Sanchez, Dani,Vilarrasa, Jaume
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p. 2900 - 2903
(2014/06/23)
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- Development of a general non-noble metal catalyst for the benign amination of alcohols with amines and ammonia
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The N-alkylation of amines or ammonia with alcohols is a valuable route for the synthesis of N-alkyl amines. However, as a potentially clean and economic choice for N-alkyl amine synthesis, non-noble metal catalysts with high activity and good selectivity are rarely reported. Normally, they are severely limited due to low activity and poor generality. Herein, a simple NiCuFeOx catalyst was designed and prepared for the N-alkylation of ammonia or amines with alcohol or primary amines. N-alkyl amines with various structures were successfully synthesized in moderate to excellent yields in the absence of organic ligands and bases. Typically, primary amines could be efficiently transformed into secondary amines and N-heterocyclic compounds, and secondary amines could be N-alkylated to synthesize tertiary amines. Note that primary and secondary amines could be produced through a one-pot reaction of ammonia and alcohols. In addition to excellent catalytic performance, the catalyst itself possesses outstanding superiority, that is, it is air and moisture stable. Moreover, the magnetic property of this catalyst makes it easily separable from the reaction mixture and it could be recovered and reused for several runs without obvious deactivation. Copyright
- Cui, Xinjiang,Dai, Xingchao,Deng, Youquan,Shi, Feng
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supporting information
p. 3665 - 3675
(2013/03/29)
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- Aerobic oxidative N-dealkylation of tertiary amines in aqueous solution catalyzed by rhodium porphyrins
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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
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supporting information
p. 4214 - 4216
(2013/05/22)
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- Hindered ureas as masked isocyanates: Facile carbamoylation of nucleophiles under neutral conditions
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Bigger is better: Sterically hindered dialkyl ureas undergo nucleophilic substitution at dramatically faster rates than their less hindered counterparts (see scheme). Steric decompression upon the formation of an intermediate isocyanate can explain this c
- Hutchby, Marc,Houlden, Chris E.,Gair Ford,Tyler, Simon N. G.,Gagne, Michel R.,Lloyd-Jones, Guy C.,Booker-Milburn, Kevin I.
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supporting information; experimental part
p. 8721 - 8724
(2010/01/16)
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- Determination of basic strength of aliphatic amines through ion pair formation in some ionic liquid solutions
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(Chemical Equation Presented) To have an evaluation of the basic strength of aliphatic amines in ionic liquid solution, the stability constants relevant to the formation of amine/p-nitrophenol ion pairs were determined in different ionic liquids at 298 K.
- D'Anna, Francesca,Vitale, Paola,Noto, Renato
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experimental part
p. 6224 - 6230
(2009/12/08)
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- Hydrolysis rates of alkyl and aryl sulfinamides: evidence of general acid catalysis
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Sulfinamides are important in enantioselective synthesis, as rare post-translational modifications of proteins and as isosteres of the amide bond. Little is known about the rates of hydrolysis for aliphatic sulfinamides or the mechanism of hydrolysis. In this Letter, we show that sulfinamides hydrolyse by predominantly a non-specific acid/base catalysis with phosphate buffer but by varying the buffer concentration, it was possible to determine the hydrolysis rates of a range of sulfinamides with water through non-linear least squares regression.
- Piggott, Andrew M.,Karuso, Peter
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p. 7452 - 7455
(2008/03/13)
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- Photoactive materials applicable to imaging systems
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Organic photoprecursors of amines are provided for use in photosensitive imaging systems, finding particular application in the preparation of lithographic printing plates. Said photoprecursors generate free amines on exposure to long wavelength UV or visible radiation, have high solubility in organic solvents, and include photolabile 2-nitrobenzyl functional groups. Methods for the synthesis of the photoprecursors are described, and the use of the said photoprecursors for the production of printing plates using both positive working and negative working techniques are discussed.
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Page column 12
(2010/02/05)
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- Phenylureas. Part 2. Mechanism of the acid hydrolysis of phenylureas
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The mechanism of the hydrolytic decomposition of phenylureas in acid media is investigated. It includes, in part, knowledge already present in the literature. Over the investigated pH range the occurrence of a rate maximum in the pH curves due to the strongly reduced water activity at higher acid strengths is observed. An addition-elimination mechanism with rate-determining attack of water at the N-protonated substrate is proposed. The reversion of the substituent influence on the reaction rate with increasing acidity of the reaction medium points to a change of the hydrolytic decomposition mechanism in strongly acidic media.
- Laudien, Robert,Mitzner, Rolf
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p. 2230 - 2232
(2007/10/03)
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- Two new methodologies for the deoxygenation and reduction of nitrones based on the use of lithium and DTBB (cat.)
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A variety of nitrones undergo deoxygenation when treated with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) (10 mol%) in THF at room temperature to give the corresponding imines. The Li/DTBB system, when combined with nickel(II) chloride dihydrate allows the reduction of a series of nitrones to secondary amines. The use of the deuterium oxide-containing nickel(II) salt transforms the starting nitrones to deuterated secondary amines.
- Radivoy,Alonso,Yus
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p. 427 - 430
(2007/10/03)
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- 2,2-dideutero-5-aminolevulinic acid
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2,2-Dideutero-5-aminolevulinic acid or its salt, or a hydrate or a solvate thereof, preferably 2,2-dideutero-5-aminolevulinic acid hydrochloride, and a process for preparing 2,2-dideutero-5-aminolevulinic acid are provided. The 2,2-Dideutero-5-aminolevulinic acid provided by the present invention is useful as a contrast medium for MRI diagnosis.
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- Preparation of amines
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A process for preparing an amine by catalytic reaction of an olefin with ammonia or a primary or secondary amine by contacting a mixture of the reactants in a reactor at 200° to 400° C. and an elevated pressure up to 700 bar in the presence of a catalyst consisting essentially of an X-ray amorphous (non-crystalline) mesoporous catalyst, some of which may have a microporous non-crystalline content. The catalyst has the composition where Q is at least one of the trivalent elements aluminum, boron, chromium, iron or gallium, and M is at least one of the tetravalent elements silicon, titanium or germanium. The molar ratio of a:b is from 0.5:1 to 1000:1 and the molar ratio of c:b is from 0 to 2:1. As prepared and used in the process, this non-crystalline catalyst has a specific BET surface area of from 200 to 1000 m2 /g.
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- Kinetics and mechanism of tetrazole-catalyzed phosphoramidite alcoholysis
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Kinetics of the tetrazole-catalyzed reaction of diisopropyl N,N-diisopropylphosphoramidite (1b) with tert-butyl alcohol has been studied by 31P NMR spectroscopy in THF, and the results obtained have been compared to those observed for the possible partial reactions involved, viz. the formation of diisopropyl tetrazolylphosphite (2b) and its subsequent alcoholysis. The stoichiometry of the processes was first examined with dimethyl N,N-diisopropylphosphoramidite (1a) in MeCN. The tetrazole-promoted disappearance of 1b is as fast in the absence and in the presence of the alcohol: the alcoholysis of 1b is zero-order in the concentration of alcohol and second-order in the concentration of tetrazole. The reaction of 1b with tetrazole is independent of the concentration of the tetrazolide anion and second-order in that of tetrazole, while the reverse reaction, aminolysis of 2b is first-order in the concentration of the amine The alcoholysis of 2b is, in turn, first-order in the concentration of alcohol and second-order in that of tetrazole, but it also proceeds, although slowly, in the absence of tetrazole. The time-dependent product distribution of the alcoholysis of 1b shows intermediary accumulation of 2b, but at a lower level than could be predicted by applying the rate constants determined independently for the assumed partial reactions. Accordingly, tetrazole-catalyzed alcoholysis of 1b is shown to proceed at least mainly via 2b, but an additional pathway not involving 2b as an intermediate is proposed. Mechanisms of the partial reactions are discussed on the basis of the formal kinetics observed.
- Nurminen, Erkki J.,Mattinen, Jorma K.,Loennberg, Harri
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p. 1621 - 1628
(2007/10/03)
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- Leukotriene B4 synthesis inhibitors
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This invention relates to a compound of the formula: STR1 or a pharmaceutically acceptable salt thereof wherein X is oxygen, sulfur, --CH=CH--, or --CH=N--; wherein R1 is --CO2 R2 or tetrazole; wherein R2 is hydrogen, alkyl of 1 to 6 carbons or a pharmaceutically acceptable cation; wherein R is an alkyl of from 1 to 20 carbons, --(CH2)p CF3 or --(CH2)q R3 wherein R3 is alkoxy, phenoxy or alkoxy substituted phenoxy wherein the alkoxy group has from 1 to 8 carbons; wherein p and q are integers from 0 to 20; wherein n is 0 or 1; and wherein m is 0, 1, 2, or 3.
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- Synthesis of [35S]phosphorothionate insecticides: The example of [35S]fenthion
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A general method for the synthesis of [35S]phosphorothionates is proposed, based on the example of [35S]fenthion. This consists of reacting molecular 35S with the corresponding phosphites which are easily prepared from commercial precursors.
- Dias,Mornet,Kotoujansky
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- Structure-activity considerations in kinetics and mechanism of chlorine exchange between chloramine-T and secondary amines
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To study the mechanism of N-chlorination of secondary amines by chloramine-T, the kinetics of the reactions of some aromatic-substituted analogues of N-chlorobenzenesulfonamide with various secondary amines were determined. The importance of amine basicity and reactivity of the N-Cl bond of the N-chlorobenzenesulfonamide was also assessed. The results indicate that a mechanism involving the un-ionized species of both reactants (i.e., a molecular mechanism), rather than an ionic mechanism, is operating and that the reaction most likely proceeds via a six-membered-ring transition state that incorporates a water molecule.
- Dannan,Hussain,Crooks,Dittert
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p. 657 - 660
(2007/10/02)
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- ELECTROCHEMICAL REDUCTIVE AMINATION. I. AMINATION OF ALIPHATIC KETONES BY PRIMARY AMINES
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The reductive amination of aliphatic ketones in aqueous solutions of primary amines was realized by an electrochemical method.The best yields of the secondary amines were obtained at lead and cadmium cathodes in an aqueous electrolytic solution at pH 11-12.Elongation and branching in the carbon chain of the radicals both of the ketone and of the primary amine lead to a reduction in the yield of the secondary amine.The yield of the secondary amine is mainly determined by the rate of the chemical reaction leading to the formation of the azomethine compound, preceding the electrochemical reduction stage.
- Smirnov, Yu. D.,Tomilov, A. P.
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- Chlorination of ortho-chlorophenol
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The polychlorophenols, e.g., 2,6-dichlorophenol (a known agrochemical intermediate), are effectively prepared by chlorinating ortho-chlorophenol with gaseous chlorine, optionally in the presence of other chlorophenols, characteristically in the molten state, and in the presence of a catalytically effective amount of a primary, secondary or tertiary amine.
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- ON THE DIRECT METALATION OF ISOPRENE
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Isoprene has been metalated in tetrahydrofuran with an excess of sterically hindered potassium dialkylamides, prepared by combining equimolar amounts of the corresponding lithium amide and potassium tert-butoxide.Subsequent reaction with oxirane, alkyl bromides, and pivaldehyde gave the expected coupling products in reasonable yields.Coupling with (CH3)2CHCH2CH=O and (CH3)2C=CHCH=O afforded the bark beetle pheromones (+/-)-ipsenol and (+/-)-ipsdienol in low yields.
- Klusener, P. A. A.,Tip, L.,Brandsma, L.
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p. 2041 - 2064
(2007/10/02)
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- Protonation Dynamics of 2(μ-CO)(μ-C=CH2) and Decomposition Processes for 2(μ-CO)(μ-C=CH2)H(+) in the Gas Phase
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The proton affinity (PA) and site of protonation of 2(μ-CO)(μ-C=H2) (2), as well as the decomposition processes for 2(μ-CO)(μ-C=CH2)H(+) (7), are studied in the gas phase by using Fourier transform mass spectrometry (FTMS).The
- Jacobson, D. B.
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p. 1626 - 1634
(2007/10/02)
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- Chlorination of phenolic compounds
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The chlorophenols, e.g., 2,4,6-trichlorophenol, are efficiently prepared by chlorinating an ortho-/para-substituted phenolic compound with gaseous chlorine, whether in molten state or in a solvent reaction medium, in the presence of a catalytically effective amount of a primary, secondary or tertiary amine.
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- Selective chlorination of phenols
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Phenolic compounds and mixtures thereof, e.g., admixture of 2,4-dichlorophenol and 2,6-dichlorophenol, are selectively chlorinated at a position ortho to a hydroxyl function thereof, by reacting such phenolic compound with gaseous chlorine, in a molten reaction medium, in the presence of a catalytically effective amount of a primary, secondary or tertiary amine.
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- Preparation and reactions of an alkylzinc enolate
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The preparation, characterization, and reactivity of ethylzinc enolate 3 are reported. Enolate 3 is less reactive than the corresponding lithium enolate but undergoes many of the same reactions. The unprecedented protonation of 3 by secondary amines is reported. The metal exchange reaction used to prepare 3 is not a general method for the preparation of other alkylzinc enolates.
- Hansen, Marvin M.,Bartlett, Paul A.,Heathcock, Clayton H.
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p. 2069 - 2074
(2008/10/08)
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- N,N-DIALKYLCARBAMATO COMPLEXES OF TITANIUM(III) AND VANADIUM(III)
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N,N-Dialkylcarbamato complexes of titanium(III) and vanadium(III) have been prepared by the reaction of MCl3 with CO2 and HNiPr2 in a saturated hydrocarbon or by the exchange reaction 1/2 M2(O2CNiPr2)6 + 3 HNEt2 1/n n + 3 HNiPr2.The equilibrium M2(O2CNR2)6 + O2CNR2(-) (-) has been observed in solution (M = Ti, V; R = Et, iPr) and some of the anionic complexes have been isolated.The crystal and molecular structure of the titanium(III) derivative NH2iPr2iPr2)7> has been solved by X-ray diffraction methods.Crystal Data: C55H114N8O14Ti2; MW = 1207.3; monoclinic; space group P21/a; a= 23.741(9); b= 22.730(7); c= 13.359(6) Angstroem; β= 99.06(4) deg; U= 7119(5) Angstroem3; Z= 4; Dc = 1.126 g cm-3; Cu-Kα(λ=1.54178 Angstroem); μ(Cu-Kα)= 23.79 cm-1; F(000)= 2624; R= 0.0805.In the dimeric carbamato-bridged anion, the titanium is hexacoordinated in a distorted pseudo-octahedral geometry.
- Dell'Amico, Daniela Belli,Calderazzo, Fausto,Giurlani, Ugo,Pelizzi, Giancarlo
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p. 609 - 612
(2007/10/02)
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- BESTIMMUNG DER IONENPAAR-BASIZITAT VON LITHIUM- UND KALIUMAMIDEN
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Ion pair basicities of lithio and potassio salts of some secondary amines were determined by equilibration with benzyl compounds.With these bases it is possible to span a range of about 19 pK-units from pK = 27 up to 46.The structural dependence of thermodynamic as well as kinetic basicity is discussed.Some new effective amide bases for preparative purposes are recommended.For the first time the pK-value of toluene has been determined by direct equilibration.It amounts to 40.7 in tetrahydrofuran.
- Ahlbrecht, Hubertus,Schneider, Gunther
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p. 4729 - 4742
(2007/10/02)
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- REACTION MONITORING IN SUPERCRITICAL FLUIDS BY FLOW INJECTION ANALYSIS WITH FOURIER TRANSFORM INFRARED SPECTROMETRIC DETECTION.
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The advantages of direct reaction monitoring using supercritical fluids as solvents in conjunction with Fourier transform infrared spectrometry (FTIR) are illustrated. A capillary system was used in the 'flow-injection analysis' mode for the study of the decomposition of allyldiisopropylamine oxide. The solvation effects of supercritical carbon dioxide were monitored as a function of solvent density.
- Olesik,French,Novotny
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p. 2256 - 2258
(2007/10/02)
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- 7-Oxabicycloheptane prostaglandin intermediates and method for preparing same
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Optically active 7-oxabicyclopheptane prostaglandin intermediates are provided having the general structure STR1 wherein one of R1 and R2 is STR2 and the other is hydrogen. A method for preparing the above intermediates is also provided.
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