- Bifunctional Catalysis of the Dedeuteration of Methoxyacetone-1,1,3,3,3-d5
-
The dedeuteration of methoxyacetone-1,1,3,3,3-d5 is subject to bifunctional catalysis by 3-(dimethylamino)-propylamine (3DP) and (1R,2S,3R,4R)-3-((dimethylamino)methyl)-1,7,7-trimethyl-2-norbornamine (DTN).These catalysts act by using their primary amino groups to transform the ketone to an iminium ion and their tertiary amino groups to transfer a deuteron internally, changing the iminium ion to an enamine.Although analogous monofunctional bases favor exchange at the methyl position relative to exchange at the methylene position by factors up to 4-fold, bifunctional catalysis by the diamines used favors the methyl group by 11- to 15-fold.Exchange at the methylene group in the presence of DTN was strongly stereoselective.The pro-S deuteron was removed 12-20 times as rapidly as the pro-R deuteron.This is the result of the steric effect of the methoxy substituent.
- Hine, Jack,Sinha, Ashoke
-
-
Read Online
- Kinetics and mechanism of oxidation of 1-methoxy-2-propanol and 1-ethoxy-2-propanol by Ditelluratocuprate(III) in alkaline medium
-
The kinetics of oxidation of 1-methoxy-2-propanol and 1-ethoxy-2-propanol by ditelluratocuprate(III) (DTC) in alkaline liquids has been studied spectrophotometrically in the temperature range of 293.2-313.2 K. The reaction rate showed first order dependence in DTC and fractional order with respect to 1-methoxy-2-propanol or 1-ethoxy-2-propanol. It was found that the pseudo-first order rate constant kobs increased with an increase in concentration of OH- and a decrease in concentration of TeO4 2-. There is a negative salt effect. A plausible mechanism involving a pre-equilibrium of a adduct formation between the complex and 1-methoxy-2-propanol or 1-ethoxy-2-propanol was proposed. The rate equations derived from mechanism can explain all experimental observations. The activation parameters along with the rate constants of the rate-determining step were calculated. The kinetics of oxidation of 1-methoxy-2-propanol and 1-ethoxy-2-propanol by ditelluratocuprate(III) (DTC) in alkaline liquids has been studied spectrophotometrically in the temperature range of 293.2-313.2 K. The reaction rate showed first order dependence in DTC and fractional order with respect to 1-methoxy-2-propanol or 1-ethoxy-2-propanol. It was found that the pseudo-first order rate constant kobs increased with an increase in concentration of OH- and a decrease in concentration of TeO 42-. A plausible mechanism of reaction was proposed. The activation parameters along with the rate-determining step have been also calculated.
- Shan, Jinhuan,Liu, Yanping,Zhang, Jiying
-
-
Read Online
- Method for preparing methoxyacetone by using micro reaction device
-
The invention discloses a method for preparing methoxyacetone by using a microreaction device. The method comprises the following steps: mixing methanol with a basic catalyst to obtain a methanol solution; then pumping the methanol solution and epoxypropane into a micromixer in the microreaction device; sufficiently mixing and then introducing a mixed solution into a first microreactor in the microreaction device for reacting; after the reaction is ended, carrying out neutralizing and flash evaporation and concentration on a reaction solution to obtain 1-methoxy-2-propanol; pumping the 1-methoxy-2-propanol and an aqueous solution of sodium hypochlorite into a second microreactor in the microreaction device for reacting to obtain the methoxyacetone. According to the preparation method of the methoxyacetone, disclosed by the invention, the problems in the existing production can be overcome, the use of a complex catalyst is avoided, and the content of a byproduct is reduced; the production cost is low, the continuation degree of the process is high; the safety of the production process can be substantially improved; the quality of a product is improved.
- -
-
Paragraph 0028-0048
(2020/09/09)
-
- Regio- and chemoselective rearrangement of terminal epoxides into methyl alkyl and aryl ketones
-
The development of the highly active pincer-type rhodium catalyst 2 for the nucleophilic Meinwald rearrangement of functionalised terminal epoxides into methyl ketones under mild conditions is presented. An excellent regio- and chemoselectivity is obtained for the first time for aryl oxiranes.
- Tian, Yingying,Jürgens, Eva,Kunz, Doris
-
supporting information
p. 11340 - 11343
(2018/10/31)
-
- Method of synthesizing methoxyacetone through catalytic oxidation
-
The invention discloses a method of synthesizing methoxyacetone through catalytic oxidation. The method comprises the steps of mixing 1-methoxyl-2-propanol with sodium tungstate, tungstic acid and acetic acid, and raising temperature to 80-100 DEG C; adding hydrogen peroxide dropwise into the mixture, so as to obtain a reaction solution; naturally cooling the reaction solution to room temperature, and filtering and separating to obtain a filter cake and a filtrate; regulating pH of the filtrate to 6-7, transferring the filtrate into a rectifying tower and heating and rectifying, separating and purifying in a rectifying kettle to obtain a product methoxyacetone and residual liquid in the rectifying kettle; washing and drying the obtained filter cake to obtain tungstic acid; and mixing the residual liquid in the rectifying kettle and liquid caustic soda, raising temperature to dissolve and keeping warm, adding ethanol crystal, separating, and stoving to obtain the sodium tungstate. The catalyst is sodium tungstate that is low-cost, is easy to recycle, and causes low loss compared with other precious metal catalysts; in production, heavy metal contamination is prevented, fewer three wastes are generated, so that the method is environmentally friendly; and the conversion rate of 1-methoxyl-2-propanol reaches 93%, so that the method is suitable for industrial production.
- -
-
Paragraph 0021-0025; 0027; 0030; 0033; 0036; 0039
(2017/12/29)
-
- Gas-Phase Reaction of Methyl n-Propyl Ether with OH, NO3, and Cl: Kinetics and Mechanism
-
Rate constants at room temperature (293 ± 2 K) and atmospheric pressure for the reaction of methyl n-propyl ether (MnPE), CH3OCH2CH2CH3, with OH and NO3 radicals and the Cl atom have been determined in a 100 L FEP-Teflon reaction chamber in conjunction with gas chromatography-flame ionization detector (GC-FID) as the detection technique. The obtained rate constants k (in units of cm3 molecule-1 s-1) are (9.91 ± 2.30) × 10-12, (1.67 ± 0.32) × 10-15, and (2.52 ± 0.14) × 10-10 for reactions with OH, NO3, and Cl, respectively. The products of these reactions were investigated by gas chromatography-mass spectrometry (GC-MS), and formation mechanisms are proposed for the observed reaction products. Atmospheric lifetimes of the studied ether, calculated from rate constants of the different reactions, reveal that the dominant loss process for MnPE is its reaction with OH, while in coastal areas and in the marine boundary layer, MnPE loss by Cl reaction is also important.
- Zhu, Jianqiang,Wang, Shuyan,Tsona, Narcisse T.,Jiang, Xiaotong,Wang, Yifeng,Ge, Maofa,Du, Lin
-
p. 6800 - 6809
(2017/09/23)
-
- Method for synthesizing methoxy acetone
-
The invention belongs to the technical field of chemistry and chemical engineering, and particularly relates to a method for synthesizing methoxy acetone.The method is a catalytic oxidation method, and 1-methoxy-2-propyl alcohol, chlorohydrocarbon, a nitroxide free radical, sodium bicarbonate and trichloroisocyanuric acid are used as a raw material, solvent, a catalyst, an acid-binding agent and an oxidizing agent respectively to conduct a catalytic oxidation reaction.The reaction product is filtered after the reaction is completed, filter liquor is concentrated to recover solvent, and methoxy acetone is obtained through distillation.The 100% conversion rate of 1-methoxy-2-propyl alcohol in the reaction process can be nearly realized, the purity of methoxy acetone can reach 99.5% or more, the reaction condition is mild, and the synthetic method has industrial production prospects.
- -
-
Paragraph 0011
(2017/04/03)
-
- Method for preparing methoxyacetone by oxidizing 1-methoxy-2-propanol with chlorine
-
The invention belongs to the technical field of chemistry and chemical engineering and particularly relates to a method for preparing methoxyacetone by oxidizing 1-methoxy-2-propanol with chlorine.In a catalytic oxidation reaction, 1-methoxy-2-propanol serves as a raw material, hydrochloric ether serves as a solvent, the catalytic oxidation reaction is generated under catalysis of nitroxide and carbonate with chlorine as an oxidant, filtering is conducted after reaction, and after the filter solution is concentrated and the solvent is recycled, the product is obtained through distillation.In the reaction process, the conversion rate of 1-methoxy-2-propanol can be almost 100%, the purity of the product can reach 99.5% or above, and reaction conditions are mild.
- -
-
Paragraph 0006; 0012-0013
(2017/04/03)
-
- Synthetic method for methoxyacetone
-
The invention belongs to the technical field of organic synthesis, and specifically relates to a synthetic method for methoxyacetone. The method comprises the following steps: subjecting propylene oxide and methanol to continuous reaction through a fixed-bed catalyst so as to obtain propylene glycol methyl ether; and mixing propylene glycol methyl ether with water, and carrying out continuous dehydrogenation reaction through the fixed-bed catalyst so as to obtain methoxyacetone. The synthetic method for methoxyacetone provided by the invention is scientific and reasonable, has simple process, is free of byproducts and contains less impurities.
- -
-
Paragraph 0042
(2016/10/24)
-
- Expanding Substrate Specificity of ω-Transaminase by Rational Remodeling of a Large Substrate-Binding Pocket
-
Production of structurally diverse chiral amines via biocatalytic transamination is challenged by severe steric interference in a small active site pocket of ω-transaminase (ω-TA). Herein, we demonstrated that structure-guided remodeling of a large pocket by a single point mutation, instead of excavating the small pocket, afforded desirable alleviation of the steric constraint without deteriorating parental activities toward native substrates. Molecular modeling suggested that the L57 residue of the ω-TA from Ochrobactrum anthropi acted as a latch that forced bulky substrates to undergo steric interference with the small pocket. Removal of the latch by a L57A substitution allowed relocation of the small pocket and dramatically improved activities toward various arylalkylamines and alkylamines (e.g., 1100-fold increase in kcat/KM for α-propylbenzylamine). This approach may provide a facile strategy to broaden the substrate specificity of ω-TAs.
- Han, Sang-Woo,Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
-
p. 2712 - 2720
(2015/09/01)
-
- A novel chimeric amine dehydrogenase shows altered substrate specificity compared to its parent enzymes
-
We created a novel chimeric amine dehydrogenase (AmDH) via domain shuffling of two parent AmDHs ('L- and F-AmDH'), which in turn had been generated from leucine and phenylalanine DH, respectively. Unlike the parent proteins, the chimeric AmDH ('cFL-AmDH') catalyzes the amination of acetophenone to (R)-methylbenzylamine and adamantylmethylketone to adamantylethylamine.
- Bommarius, Bettina R.,Schürmann, Martin,Bommarius, Andreas S.
-
p. 14953 - 14955
(2015/02/19)
-
- Efficient aerobic oxidation of secondary alcohols at ambient temperature with an ABNO/NOx catalyst system
-
New highly practical methods are presented for aerobic oxidation of secondary alcohols with a nitroxyl radical in combination with HNO3, NaNO2, or both as cocatalysts. Diverse nitroxyls are compared, including several novel bicyclic derivatives. Catalyst systems with the readily available nitroxyls, 9-azabicyclo[3.3.1]nonane-N-oxyl (ABNO) and 9-azabicyclo[3.3.1]nonan-3-one-N-oxyl (keto-ABNO), are optimized in acetic acid or acetonitrile as the solvent. The reactions are compatible with substrates bearing diverse functional groups and proceed efficiently under mild conditions at ambient pressure and temperature.
- Lauber, Markus B.,Stahl, Shannon S.
-
p. 2612 - 2616
(2013/11/19)
-
- Kinetics and mechanism of oxidation of 1-methoxy-2-propanol and 1-ethoxy-2-propanol by ditelluratoargentate(III) in alkaline medium
-
The kinetics of oxidation of 1-methoxy-2-propanol and 1-ethoxy-2-propanol by ditelluratoargentate(III) in alkaline liquids has been studied spectrophotometrically in the temperature range of 293.2 K-313.2 K. The reaction rate showed first order dependence in ditelluratoargentate(III) and fractional order with respect to 1-methoxy-2-propanol or 1-ethoxy-2-propanol. It was found that the pseudofirst order rate constant kobs increased with an increase in concentration of OH- and a decrease in concentration of H4TeO6 2-. There was a negative salt effect and no free radicals were detected. A plausible mechanism involving a two-electron transfer is proposed and the rate equations derived from the mechanism can explain all the experimental results. The rate equations derived from mechanism can explain all experimental observations. The activation parameters along with the rate constants of the rate-determining step were calculated.
- Shan, Jinhuan,Yin, Caihong,Liu, Lei,Liu, Yanping
-
body text
p. 5225 - 5227
(2012/10/18)
-
- ω-Transaminase-catalyzed kinetic resolution of chiral amines using l-threonine as an amino acceptor precursor
-
Kinetic resolution of chiral amines using l-threonine as a cosubstrate was demonstrated by a biocatalytic strategy in which (S)-selective ω-transaminase (ω-TA) was coupled with threonine deaminase (TD), eliminating the need to use an expensive keto acid as an amino acceptor. The coupled enzyme reaction enabled simultaneous production of enantiopure (R)-amine and l-homoalanine which are pharmaceutically important building blocks. To extend the versatility of this strategy to production of both enantiomers of chiral amines, (R)-selective ω-TA coupled with TD was employed to produce (S)-amine.
- Malik, M. Shaheer,Park, Eul-Soo,Shin, Jong-Shik
-
supporting information; experimental part
p. 2137 - 2140
(2012/09/25)
-
- Green and chemoselective oxidation of alcohols with hydrogen peroxide: A comparative study on Co(II) and Co(III) activity toward oxidation of alcohols
-
Two new cobalt (II) and cobalt (III) complexes of a terpyridine based ligand, (4′-(2-thienyl)-2,2′;6′,2″-terpyridine (L)), were synthesized. Each complex has two units of the tridentate ligand. The complexes were fully characterized by spectroscopic methods as well as CHN analysis. Moreover, their solid state structures were determined by single crystal X-ray diffraction. The cobaltous complex has the formula [Co(L) 2](NO3)2·2CH3OH·H 2O (1), whereas the cobaltic complex shows the formula [Co(L) 2](NO3)3·2CH3OH (2). Both complexes were tested as homogenous catalysts for the oxidation of a variety of aliphatic and aromatic alcohols utilizing aqueous hydrogen peroxide in water media. The Co(II) complex showed more activity in comparison with its isostructural Co(III) species. The results show that the aromatic alcohols were oxidized with higher conversions and selectivity compared to the aliphatic substrates, possibly due to their conjugation systems which thermodynamically stabilized the carbonyl products.
- Nemati Kharat, Ali,Bakhoda, Abolghasem,Tamaddoni Jahromi, Bahareh
-
scheme or table
p. 2768 - 2775
(2011/12/13)
-
- Structure-reactivity relationship for alcohol oxidations via hydride transfer to a carbocationic oxidizing agent
-
Second-order rate constants were determined for the oxidation of 27 alcohols (R1R2CHOH) by a carbocationic oxidizing agent, 9-phenylxanthylium ion, in acetontrile at 60°C. Alcohols include open-chain alkyl, cycloalkyl, and unsaturated alcohols. Kinetic isotope effects for the reaction of 1-phenylethanol were determined at three H/D positions of the alcohol (KIEα-D=3.9, KIEβ-D3=1.03, KIE OD=1.10). These KIE results are consistent with those we previously reported for the 2-propanol reaction, suggesting that these reactions follow a hydride-proton sequential transfer mechanism that involves a rate-limiting formation of the α-hydroxy carbocation intermediate. Structure-reactivity relationship for alcohol oxidations was deeply discussed on the basis of the observed structural effects on the formation of the carbocationic transition state (Cδ+-OH). Efficiencies of alcohol oxidations are largely dependent upon the alcohol structures. Steric hindrance effect and ring strain relief effect win over the electronic effect in determining the rates of the oxidations of open-chain alkyl and cycloalkyl alcohols. Unhindered secondary alkyl alcohols would be selectively oxidized in the presence of primary and hindered secondary alkyl alcohols. Strained C7-C11 cycloalkyl alcohols react faster than cyclohexyl alcohol, whereas the strained C5 and C12 alcohols react slower. Aromatic alcohols would be efficiently and selectively oxidized in the presence of aliphatic alcohols of comparable steric requirements. This structure-reactivity relationship for alcohol oxidations via hydride-transfer mechanism is hoped to provide a useful guidance for the selective oxidation of certain alcohol functional groups in organic synthesis. Copyright
- Lu, Yun,Bradshaw, Joshua,Zhao, Yu,Kuester, William,Kabotso, Daniel
-
p. 1172 - 1178
(2013/01/12)
-
- Enzymatic racemization of amines catalyzed by enantiocomplementary ω-Transaminases
-
A strategy for the biocatalytic racemization of primary α-chiral amines was developed by employing a pair of stereocomplementary PLP-dependent ω-transaminases. The interconversion of amine enantiomers proceeded through reversible transamination by a prochiral ketone intermediate, either catalyzed by a pair of stereocomplementary ω-transaminases or by a single enzyme possessing low stereoselectivity. To tune the system, the type and concentration of a nonchiral amino acceptor proved to be crucial. Finally, racemization could be achieved by the cross-transamination of two different amines without a requirement for an external amino acceptor. Several synthetically and industrially important amines could be enzymatically racemized under mild reaction conditions. ω-Transaminases play ping-pong: A biocatalytic protocol for the 'clean' racemization of α-chiral prim-amines was developed by an equilibrium-controlled deamination/amination sequence catalyzed by a pair of (R)- and (S)-ω-transaminases (see scheme).
- Koszelewski, Dominik,Grischek, Barbara,Glueck, Silvia M.,Kroutil, Wolfgang,Faber, Kurt
-
experimental part
p. 378 - 383
(2011/03/21)
-
- Deracemisation of α-chiral primary amines by a one-pot, two-step cascade reaction catalysed by ω-transaminases
-
Racemic a-chiral primary amines were deracemised to optically pure amines in up to >99 % conversion and >99 % ee within 48 h. The deracemisation was a result of a stereoinver- sion of one amine enantiomer; the formal stereoinversion was achieved by a one-pot, two-step procedure: in the first step, kinetic resolution of the chiral racemic amine was performed by employing a -transaminase to yield an intermediate ketone and the remaining optically pure amine; in the second step, the ketone intermediate was stereoselectively transformed into the amine by employing alanine as the amine donor and a -transaminase displaying opposite stereopref- erence than the -transaminase in the first step. In the second step, lactate dehydrogenase was used to remove the side product pyruvate to shift the unfavourable reaction equilibrium to the product side. Depending on the order of the en- antiocomplementary enzymes employed in the cascade, the (R), as well as the (S), enantiomer was accessible.
- Koszelewski, Dominik,Clay, Dorina,Rozzell, David,Kroutil, Wolfgang
-
experimental part
p. 2289 - 2292
(2009/08/09)
-
- TEMPO/HCl/NaNO2 catalyst: A transition-metal-free approach to efficient aerobic oxidation of alcohols to aldehydes and ketones under mild conditions
-
Hydrochloric acid, a very inexpensive and readily available inorganic acid, has been found to cooperate exquisitely with NaNO2/TEMPO in catalyzing the molecular-oxygen-driven oxidation of a broad range of alcohol substrates to the corresponding aldehydes and ketones. This transition-metal- free catalytic oxidative conversion is novel and represents an interesting alternative route to the corresponding carbonyl compounds to the metal-catalyzed aerobic oxidation of alcohols.The reaction is highly selective with respect to the desired product when carried out at room temperature in air at atmospheric pressure. Notably, the use of very inexpensive NaNO2 and HCl in combination with TEMPO for this highly selective aerobic oxidation of alcohols in air at ambient temperaturemakes the reaction operationally and economically very attractive. The results of mechanistic studies, performed with the aid of electrospray ionization mass spectrometry (ESI-MS), are presented and discussed. TEMPO, TEMPOH, and TEMPO+ were observed in the redox cycle by means of ESI-MS. On the basis of these observations, a mechanism is proposed that may provide an insight into the newly developed aerobic alcohol oxidation.
- Wang, Xinliang,Liu, Renhua,Jin, Yu,Liang, Xinmiao
-
supporting information; experimental part
p. 2679 - 2685
(2009/04/10)
-
- Kinetics and mechanism of oxidation of aliphatic alcohols by [bis(trifluoroacetoxy)iodo]benzene
-
The oxidation of some aliphatic alcohols by [bis(trifluoroacetoxy)iodo] benzene (TFAIB) in aqueous acetic acid solution leads to the formation of the corresponding carbonyl compounds. The reaction is first order in TFAIB and a Michaelis-Menten kinetics is obtained with respect to the alcohols. The reaction shows a first order dependence on hydrogen ions. The oxidation of [1,1- 2H2]ethanol and [2-2H]propan-2-ol exhibits the presence of a substantial primary kinetic isotope effect at 298 K (k H/kD = 3.64 and 3.89 respectively). The rate of disproportionation of the intermediate is susceptible to both polar and steric effects of the substituents. A suitable mechanism has also been proposed.
- Banerji, Jayshree,Sharma, Pradeep K.,Banerji, Kalyan K.
-
body text
p. 1213 - 1217
(2009/03/11)
-
- Kinetics and mechanism of oxidation of alcohols by butyltriphenylphosphonium dichromate
-
Butyltriphenylphosphonium dichromate (BTPPD) oxidizes aliphatic alcohols to the corresponding carbonyl compounds. The reaction is first order in BTPPD. The reaction exhibits a second order dependence each on the alcohol and hydrogen ions. The oxidation of deuteriated ethanol and 2-propanol indicates the presence of a substantial primary kinetic isotope effect. The reaction has been studied in nineteen organic solvents and the solvent effect was analyzed using multiparametric equations. It is observed that the cation-solvating power plays a major role in the reaction. The rate of oxidation shows excellent correlation with the polar and steric substituent constants. Suitable mechanisms have been proposed.
- Kothari, Anita,Kothari, Seema,Banerji, Kalyan K.
-
p. 2039 - 2043
(2007/10/03)
-
- Kinetics and mechanism of the oxidation of alcohols by tetrapropylammonium perruthenate
-
2-Propanol is oxidized by tetrapropylammonium perruthenate (TPAP) in a reaction that is second order in TPAP and first order in 2-propanol. One of the products, believed to be ruthenium dioxide, is an effective catalyst for the reaction, making it an autocatalytic process. The rate of oxidation is relatively insensitive to the presence of substituents. Primary kinetic deuterium isotope effects are observed when either the hydroxyl or the α hydrogen is replaced by deuterium. The only product obtained from the oxidation of cyclobutanol is cyclobutanone, indicating that the reaction is a two-electron process. Tetrahydrofuran is oxidized at a rate that is several orders of magnitude slower than that observed for 2-propanol, suggesting that the reaction of TPAP with alcohols may be initiated by formation of perruthenate esters. A tentative mechanism consistent with these observations is proposed.
- Chandler, W. David,Wang, Zhao,Lee, Donald G.
-
p. 1212 - 1221
(2007/10/03)
-
- Unusual reversal of regioselectivity in antibody-mediated aldol additions with unsymmetrical methyl ketones
-
A catalytic regio- and enantioselective aldol reaction of various unsymmetrical methyl ketones with para-nitrobenzaldehyde has been developed using aldolase antibodies as the catalysts. It has been found that the sense and level of regioselectivity for the reactions catalysed by antibody 38C2 and 33F12 are highly dependent on the structure of both the donor and the acceptor but in contrast, antibodies 84G3 and 93F3 catalyse the exclusive formation of the linear regioisomer independent of the structure of the reactants examined. The level of enantiocontrol is very high for most reactions. Both linear aldol enantiomers could be accessed through aldol or retro-aldol reactions using the same antibody. Theoretical studies on regioisomeric α- and β-heteroatom substituted enamines derived from unsymmetrical ketones suggest that most of the linear aldol products formed in the presence of antibodies 84G3 and 93F3 must be formed from intermediate enamines which are not the thermodynamically most favourable.
- Maggiotti,Bahmanyar,Reiter,Resmini,Houk,Gouverneur
-
p. 619 - 632
(2007/10/03)
-
- Erbium(III) triflate: A valuable catalyst for the rearrangement of epoxides to aldehydes and ketones
-
Rearrangement of epoxides is performed with erbium triflate as catalyst. In contrast to most proposed catalysts for this re-action, erbium triflate works well with both aromatic and aliphatic epoxides.
- Procopio, Antonio,Dalpozzo, Renato,De Nino, Antonio,Nardi, Monica,Sindona, Giovanni,Tagarelli, Antonio
-
p. 2633 - 2635
(2007/10/03)
-
- Method for preparing chiral diphosphines
-
The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
- -
-
-
- Methoxyacetone preparation
-
A process for making methoxyacetone is disclosed. The process comprises oxidizing 1-methoxy-2-propanol in the liquid phase using aqueous hydrogen peroxide and a Group 8-10 transition metal catalyst. The process gives high alcohol conversions (>95%) and good selectivities (>80%) to methoxyacetone using mild conditions, simple equipment, and readily available reagents.
- -
-
-
- Kinetic and Mechanism of the Oxidation of Aliphatic Alcohols by Benzyltrimethylammonium chlorobromate
-
Oxidation of fourteen aliphatic alcohols by benzyltrimethylammonium chlorobromate (BTMACB) in aqueous acetic acid leads to the formation of the corresponding carbonyl compounds. The reaction is first order each in BTMACB and the alcohol. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of benzyltrimethylammonium chloride or potassium bromide on the reaction rate. The proposed reactive oxidizing species is chlorobromate ion. The oxidation of [1,1-2]ethanol and [2-]propan-2-ol exhibited a substantial kinetic isotope effect. The effect of solvent composition indicated that the rate increases with an increase in the polarity of the solvent. The reaction is subject to both the polar and steric effects of the substituents. A mechanism involving transfer of a hydride ion from the alcohol to the oxidant has been proposed.
- Anjana,Sharma, Pradeep K.,Banerji, Kalyan K.
-
p. 739 - 750
(2007/10/03)
-
- Kinetics and mechanism of oxidation of aliphatic alcohols by oxo(salen) manganese(V) complexes
-
The oxidation of aliphatic alcohols by substituted oxo(salen)manganese(V) (H2salen = N,N'- Bissalicylideneethylenediamine) complexes, in acetonitrile, leads to the formation of the corresponding carbonyl compounds. The reaction is first order each in alcohol and Mn(V) complex. The oxidation of [1,1-2H2]ethanol and [2-2H]propan-2-ol exhibits substantial kinetic isotope effects. The rate of oxidation of twelve alcohols by four Mn(V) complexes have been determined. The oxidation is susceptible to both the polar and steric effects of the substituent in the alcohol molecule. The reaction constants are negative. The rate of reduction of the substituted Mn(V) complexes shows an excellent correlation in terms of Hammett equation with positive reaction constants. The reactivity-selectivity principle (RSP) is obeyed in this reaction. The validity of RSP is verified by Exner's mathematical procedure. Suitable mechanisms have been discussed.
- Bansal,Sharma,Banerji
-
p. 654 - 659
(2007/10/03)
-
- Kinetics and mechanism of the oxidation of aliphatic alcohols by quinolinium fluorochromate
-
The oxidation of some aliphatic alcohols by quinolinium fluorochromate (QFC) in dimethyl sulfoxide leads to the formation of corresponding carbonyl compounds. The reaction is first order with respect to QFC. The reaction exhibited Michaelis-Menten type kinetics with respect to the alcohol. The reaction is catalyzed by hydrogen ions. The hydrogen-ion dependence has the form: kobs = a+b[H+]. The oxidation of [1,1-2H2]ethanol (MeCD2OH) exhibits a substantial primary kinetic isotope effect. The reaction has been studied in nineteen different organic solvents. The solvent effect was analyzed using Taft's and Swain's multiparametric equations. The rate of disproportionation of the complex is susceptible to both polar and steric effects of the substituents. A suitable mechanism has been proposed.
- Choudhary,Sharma,Banerji
-
p. 469 - 475
(2007/10/03)
-
- Kinetics of the gas-phase reactions of NO3 radicals with a series of alcohols, glycol ethers, ethers and chloroalkenes
-
Using a relative rate method, rate constants have been measured for the gas-phase reactions of the NO3 radical with methacrolein, a series of ethers, glycol ethers, alcohols and chloroalkenes at 298 ± 2 K and atmospheric pressure of air. The rate constants determined (in units of 10-16 cm3 molecule-1 s-1) were: methacrolein, 33 ± 10; diethyl ether, 31 ± 10; di-n-propyl ether, 49 ± 16; diisopropyl ether, 40 ± 13; ethyl tert-butyl ether, 45 ± 14; 1-methoxypropan-2-ol, ≤15 ± 5; 2-butoxyethanol, ≤31 ± 11; propan-1-ol, ≤21 ± 8; propan-2-ol, ≤17 ± 6; butan-1-ol, ≤27 ± 10; butan-2-ol, ≤25 ± 8; heptan-4-ol, ≤60 ± 20; cis-1,2-dichloroethene, 1.3 ± 1.3; 1,1-dichloroethene, 18-6+9; trichloroethene, 3.6-1.5+2.0; tetrachloroethene, -2.0+3.0. Carbonyl products of the alcohol reactions arising after H-atom abstraction at the carbon atom to which the -OH group is attached were observed, and rate constants for this reaction pathway obtained. Significant discrepancies with the literature concern propan-2-ol, ethyl tert-butyl ether and 3-chloropropene, with our relative rate constants for these compounds being factors of ca. 2, ca. 2, and ca. 8 lower, respectively, than previously reported absolute rate constant determinations.
- Chew, Andrew A.,Atkinson, Roger,Aschmann, Sara M.
-
p. 1083 - 1089
(2007/10/03)
-
- Kinetics and Mechanism of the Oxidation of Secondary Alcohols by Hexamethylenetetramine-Bromine
-
Oxidation of secondary alcohols by hexamethylenetetramine-bromine (HABR) in acetic acid leads to the formation of the corresponding ketones. The reaction is first order with respect to HABR. Michaelis-Menten type kinetics were observed with respect to alcohols. The oxidation of benzhydrol-α-d exhibited a substantial kinetic isotope effect (kH/kD = 3.16 at 298 K). The reaction was subjected to both polar and steric effects of the substituents. A mechanism involving transfer of a hydride ion from the alcohol to the oxidant has been proposed.
- Bohra, Anupama,Sharma, Pradeep K.,Banerji, Kalyan K.
-
p. 784 - 787
(2007/10/03)
-
- Kinetics and mechanism of oxidation of secondary alcohols by bis(2,2'-bipyridyl)copper(II) permanganate
-
The oxidation of secondary alcohols by bis(2,2'-bipyridyl) copper(II) permanganate (BBCP) in aqueous acetic acid leads to the formation of corresponding ketones. The reaction is first order with respect to BBCP and the alcohols. The reaction rates have been determined at different temperatures and the activation parameters have also been calculated. The reaction rate increases with increase in the concentration of H+ ions. The oxidation of benzhydrol-α-d exhibits a substantial kinetic isotope effect (kH/kD = 5.34). With increase in the amount of acetic acid in the solvent mixture of acetic acid and water, the rate increases. Addition of 2,2'-bipyridine and acrylonitrile has no effect on the rate. Suitable mechanism has been proposed.
- Grover, Anjali,Varshney, Seema,Banerji, Kalyan K.
-
p. 206 - 209
(2007/10/03)
-
- Kinetics and Mechanism of the Oxidation of Secondary Alcohols by Pyridinium Hydrobromide Perbromide
-
The oxidation of secondary alcohols by pyridinium hydrobromide perbromide (PHPB) in aqueous acetic acid leads to the formation of the corresponding ketones. The reaction is first order with respect to PHPB and the alcohols. The reaction rates have been determined at different temperatures and the activation parameters calculated. The oxidation of benzhydrol-α-d exhibited a substantial kinetic isotope effect (kH/kD = 4.83). With an increase in the amount of acetic acid in the solvent mixture of acetic acid and water, the rate increases. Addition of pyridinium hydrobromide and acrylonitrile has no effect on the rate. Suitable mechanisms have been proposed.
- Devi, Jai,Kothari, Seema,Banerji, Kalyan K.
-
p. 243 - 246
(2007/10/03)
-
- Reaction of Methoxyoxirane with Inorganic Phosphate and Reflections on SN2-Reactivity
-
In the context of the chemistry of potentially prebiological natural products it would be imported to know whether, from a chemical point of view, glycoaldehyde phosphate could be considered as a potentially prebiological natural material.In this connection, the reaction of rac. methoxyoxirane with inorganic phosphate in aqueous solution was checked: it does not produce glycoaldehyde phosphate but the 1-phosphate of 1-methoxy-1,2-ethanediol instead.In this context, earlier reflections on the question of how electronegative substituents influence SN2-reactivity are recorded. methoxyoxirane, glycolaldehyde phosphate, SN2-reactivity, nitrogen-inversion
- Pitsch, S.,Eschenmoser, A.
-
p. 2383 - 2396
(2007/10/02)
-
- Lifetimes of Oxocarbenium Ions in Aqueous Solution from Common Ion Inhibition of the Solvolysis of α-Azido Ethers by Added Azide Ion
-
Rate constants for hydration of the oxocarbenium ions derived from a series of carbonyl compounds have been determined from common ion inhibition of the solvolysis of the corresponding α-azido ethers by trapping of the oxocarbenium ion intermediate with added azide ion, assuming kaz = 5E9 M-1s-1: acetophenone, kHOH = 5E7; acetone, 1E9; 4-methoxybutanone, 2E9; methoxyacetone, 4E9; benzaldehyde, 2E9; propionaldehyde, 2E10 s-1.Substitution on the reacting carbon atom affects log kHOH 0.4 as much as log Keq.Resonance effects are much larger than polareffects of substituents on kHOH, compared with Keq; this represents imbalance in the expression of these effects in the transition state.Use of these substituent effects to estimate the lifetime of glycosyl and methoxymethyl oxocarbenium ions gives values of kHOH ca. 1E12 s-1 for the glycosyl cation and 1E12-1E15 s-1 for the methoxymethyl cation.It is concluded that the glycosyl cation has a short but significant lifetime in aqueous solution and that there is little or no barrier for hydration of the methoxymethyl cation.The effects of substituents on the rate constants for addition to oxocarbenium ions are smaller than those for addition to the corresponding carbonyl compounds.The decrease in reactivity toward water of protonated acetone compared with the corresponding oxocarbenium ion by ca. 1E5 suggests that the proton occupies an intermediate position between the carbonyl group and water.The dependence of log kROH on pKROH for the addition of alcohols to oxocarbenium ions derived from derivatives of butanone and propionaldehyde in aqueous alcohol mixtures follows slopes of 0.5 and 0.1, respectively.
- Amyes, Tina L.,Jencks, William P.
-
p. 7888 - 7900
(2007/10/02)
-
- Kinetics and Mechanism of Oxidation of Alcohols by Ceric Ammonium Nitrate
-
The main product of the oxidation of secondary alcohol by ceric ammonium nitrate is the corresponding ketone.The reaction is of first-order with respect to the oxidant but exhibit a Michaelis-Menten type kinetics with respect to the alcohol.The formation constants of the alcohol-CeIV complex and its thermodynamic parameters have been calculated.The rate of decomposition of the complex and the activation parameters have also been evaluated.The rates of decomposition of the complex correlate with Taft's ?* values with a low negative reaction constant.The oxidation induced polymerisation of acrylonitrile.The retardation of rate with increasing acidity has been explained on the formation of kinetically inactive protonated alcohol.The protonated constants for the various alcohol have been calculated.The presence of a small primary kinetic isotope effect, kH/kD = 2.3, confirms that the rate-determining step involves a C-H bond rupture in a non-symmetrical transition state.
- Mathur, Dwarka, L.,Agarwal, Anupma,Banerji, Kalyan K.
-
p. 519 - 522
(2007/10/02)
-
- Kinetics and Mechanism of the Oxidation of Alcohols by N-Bromoacetamide in Alkaline Solution
-
The kinetics of the oxidation of seven secondary alcohols by N-bromoacetamide has been studied in alkaline solution.The main product of the oxidation is the corresponding ketone.The reaction is first order with respect to the oxidant and alcohol.The oxidation of benzhydrol-α-d indicates the absence of a primary kinetic isotope effect.The rate decreases with the increase in the concentration of hydroxide ion.Addition of acetamide decreases the reaction rate.The rates were determined at four different temperatures, and the activation parameters were evaluated.Theactivation enthalpies and entropies of the oxidation of the seven alcohols are linearly related.Hypobromite ion has been postulated as the reactive oxidizing species.A mechanism involving rate-determining nucleophilic attack of hypobromite ion on the alcohol molecule has been proposed.
- Negi, Suresh C.,Banerji, Kalyan K.
-
p. 3329 - 3332
(2007/10/02)
-
- Synthesis of 1-Substituted-2,3,4,9-tetrahydro-(2-oxopropyl)-1H-pyridoindoles and their Base-catalyzed Rearrangements to N-ethyl>acetamides
-
The condensation of 1H-indole-3-ethanamines, 1, with 2,4-pentanediones, 2, gave enamines 3.Acid catalyzed ring closure of 3 gave 1-(1-substituted-2,3,4,9-tetrahydro-1-(2-oxopropyl)-1H-pyridoindoles 4.Subsequent N-acetylation yielded 5 which sequentially produced 2,3-disubstituted indoles 6 and 7 resulting from C-N bond cleavage after treatment with sodium alkoxide in ethanol.Controlled catalytic hydrogenation of the latter gave saturated derivatives 8 and 9.
- Bobowski, George
-
p. 267 - 272
(2007/10/02)
-
- Process for preparing propylene glycol monoalkyl ethers and alkoxyacetones
-
Propylene glycol monoalkyl ethers and alkoxyacetones are formed by contacting a mixture of carbon monoxide and hydrogen and (a) acetaldehyde or (b) an acetal and an alcohol, with a catalyst comprising a cobalt-containing compound and at least one tin- or germanium-containing promoter.
- -
-
-
- Manufacture of aliphatic hydroxycarbonyl compounds etherified with aliphatic groups
-
Aliphatic hydroxycarbonyl compounds etherified with aliphatic groups are prepared by oxidizing hydroxyalcohols in the presence of a metal catalyst which consists of one or more layers, each of a particular weight and each containing particles of a particular size, the catalyst bed also having a particular total thickness, and the catalyst components used being silver and copper, with or without added copper/tin/phosphorus or silver alone. The etherified hydroxyaldehydes and hydroxyketones obtainable by the process of the invention are valuable starting materials for the preparation of dyes, pesticides, plastics and scents.
- -
-
-