Xn:Harmful;
106-36-5Relevant articles and documents
Substrate conformations set the rate of enzymatic acrylation by lipases
Syren, Per-Olof,Hult, Karl
, p. 802 - 810 (2010)
Acrylates represent a class of α,β-unsaturated compounds of high industrial importance. We investigated the influence of substrate conformations on the experimentally determined reaction rates of the enzyme-catalysed transacylation of methyl acrylate and derivatives by ab initio DFT B3LYP calculations and molecular dynamics simulations. The results supported a least-motion mechanism upon the sp2 to sp3 substrate transition to reach the transition state in the enzyme active site. This was in accordance with our hypothesis that acrylates form productive transition states from their low-energy s-sis/s-trans conformations. Apparent kcat values were measured for Candida antarctica lipase B (CALB), Humicola insolens cutlnase and Rhizomucor miehei lipase and were compared to results from computer simulations. More potent enzymes for acryltransfer, such as the CALB mutant V190A and acrylates with higher turnover numbers, showed elevated populations of productive transition states.
Reaction of Primary Alkyl Hydroperoxides with Sulphamoyl Chloride: Alkyl(sulphamoyl)peroxides. Peroxo Compounds, XVIII
Blaschette, Armand,Safari, Hassan
, p. 875 - 880 (1984)
The novel peroxides H2NSO2OOCH2R (1a: R=CH2CH3; 1b: R=CH2CH2CH3) are obtained by reaction of sulphamoyl chloride with the appropriate hydroperoxides in the presence of pyridine (temperature below -30 deg C, solvent diethyl ether).The solvent-free liquids 1 deflagrate at ca. 0 deg C.Hydrolysis or ammonolysis of 1 generates the hydroperoxide and sulphamic acid or sulphamide, respectively.Controlled thermolysis of 1 affords sulphamic acid and carbonyl compounds, i.e. propanal and n-propyl propanoate from 1a, butanal, 2-methylpropanal and n-butyl n-butyrate from 1b.These products suggest a nonradical cyclic decomposition path-way. - Keywords: Sulphamoyl chloride, reaction with n-alkyl hydroperoxides; n-Alkyl hydroperoxides, reaction with sulphamoyl chloride; Alkyl(sulphamoyl)peroxides, preparation and thermolysis
The role of functionalized phosphines in the hydrogenation of carboxylic acids in the presence of phosphine substituted hydrido ruthenium complexes
Salvini, Antonella,Frediani, Piero,Bianchi, Mario,Piacenti, Franco,Pistolesi, Leonardo,Rosi, Luca
, p. 218 - 228 (1999)
Hydrido ruthenium carbonyl complexes substituted by functionalized phosphines such as H4Ru4(CO)8[P(CH2OCOR) 3]4 have been synthesized and tested as catalysts in the hydrogenation of carboxylic acids. These complexes are more active than those reported previously, containing trialkyl- or triarylphosphines. On the basis of their behavior, their different activity has been explained in terms of an involvement of the phosphine ligand in the catalytic cycle. The ester group present in the phosphine P(CH2OCOR)3 is hydrogenated to produce an alcohol (RCH2OH) and a P(CH2OH) group which, in turn, reacts with the free acid present in solution to restore the P(CH2OCOR) group. This hypothesis has been confirmed by the reactivity of the possible intermediate H4Ru4(CO)8[P(CH2OH) 3]4 with acetic acid. Another support to this statement is the almost equal catalytic activity, displayed by H4Ru4(CO)8[P(CH2OCOR) 3]4 complexes, whatever the R group present, in the phosphine ligand, in the hydrogenation of carboxylic acids. These complexes, on the other hand, are less active than the corresponding tributylphosphine substituted ones in the hydrogenation of alkenes and ketones. Finally when the phosphine ligand is P(CH2CH2COOCH3)3 the ester group is not reduced and consequently the catalytic activity of this complex in the hydrogenation of carboxylic acids is very low.
Transesterification via Baeyer-Villiger oxidation utilizing potassium peroxydisulfate (K2S2O8) in acidic media
Zarrabi,Mahmoodi,Marvi
, p. 889 - 891 (2010)
Baeyer-Villiger oxidation of ketones with potassium peroxydisulfate (K 2S2O8) and sulfuric acid generates the anticipated esters or lactones. These products are transformed into new esters (or hydroxy esters) in the presence of alcohols via transesterification under Baeyer-Villiger reaction conditions in one pot. Springer-Verlag 2010.
Solvent-free oxidation of straight-chain aliphatic primary alcohols by polymer-grafted vanadium complexes
Chaudhary, Nikita,Haldar, Chanchal,Kachhap, Payal
, (2021)
Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6-tetramethyl-3,5-hepatanedione, 1,3-diphenyl-1,3-propanedione, and 1-phenyl-1,3-butanedione, respectively. Imidazole-modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer-supported complexes Ps-Im-[VIVO(tertacac)2] (4), Ps-Im-[VVO2(dipd)2] (5), and Ps-Im-[VIVO(phbd)2] (6) were applied for the solvent-free heterogenous oxidation of a series of straight-chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1-pentanol, 1-hexanol, and 1-heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.
Highly efficient use of NaOCI in the Ru-catalysed oxidation of aliphatic ethers to esters
Gonsalvi, Luca,Arends, Isabel W.C.E.,Sheldon, Roger A.
, p. 202 - 203 (2002)
The selectivity of α-oxidation of ethers to esters via RuNaOCI can be dramatically improved by pH control, at high substrate to catalyst ratios using a stoichiometric amount of hypochlorite in biphasic media at room temperature.
Laboratory studies of the OH-initiated photooxidation of di-n-propyl ether
Sempeles, John,Andino, Jean M.
, p. 703 - 711 (2000)
The OH-initiated photooxidation of di-n-propyl ether was investigated in this study. Di-n-propyl ether was mixed with nitric oxide and a hydroxyl radical precursor and irradiated using UV black lamps in a glass environmental chamber. Mass spectrometry was used as the primary analytical technique to monitor the reactants and products. FTIR spectroscopy was used to monitor formaldehyde. The products observed were propyl formate, acetaldehyde, propionaldehyde, and propyl propionate, with molar yields relative to di-n-propyl ether concentration loss of 0.61±0.044, 0.60±0.057, 0.15±0.062, and 0.043±0.015, respectively. Errors represent ±2σ. Nitrates could not be quantified because of a lack of commercially available standards. However, evidence exists for nitrate formation from the photooxidation of di-n-propyl ether. Formaldehyde concentrations were negligible. Mechanism predictions were performed on the di-n-propyl ether/OH system using the Carter kinetic software. Propyl formate and acetaldehyde yields were reasonably predicted (under 11.7% error). However, propionaldehyde and propyl propionate yields were vastly underpredicted, and examination of the experimental data suggested secondary production of both propionaldehyde and propyl propionate. Reactions were proposed for the photolysis and OH-initiated photooxidation of a primary nitrate product (1-propoxy propyl nitrate) that resulted in the formation of propionaldehyde and propyl propionate. Basic semiempirical computational chemistry calculations at the UHF/PM3 level of theory were performed using Hyperchem to investigate pathways for the secondary formation of propionaldehyde in particular.
Formation of Ketone Ions Upon the Loss of CH2O from Ionized Esters
Lin, Thomas,Hudson, Charles E.,McAdoo, David J.
, p. 2 - 3 (1985)
Unimolecular and collision-induced decomposition of the products of CH2O loss from propyl propanoate and butyl butanoate demonstrate that the respective products are the 3-pentanone and 4-heptanone ions.
Oxidation of Alcohols and Ethers Using Sodium Bromate-Hydrobromic Acid System
Kajigaeshi, Shoji,Nakagawa, Takashi,Nagasaki, Noritaka,Yamasaki, Hiromochi,Fujisaki, Shizuo
, p. 747 - 750 (1986)
Reaction of primary alcohols or simple ethers, α,ω-diols or cyclic ethers, and secondary alcohols with sodium bromate in the presence of catalytic amount of hydrobromic acid under mild conditions gave dimeric esters, lactones, and ketones in fairly good yields, respectively.
Gas-phase, catalytic hydrodeoxygenation of propanoic acid, over supported group VIII noble metals: Metal and support effects
Lugo-José, Yuliana K.,Monnier, John R.,Williams, Christopher T.
, p. 410 - 418 (2014)
The catalytic, gas-phase hydrodeoxygenation (HDO) of propanoic acid (PAc) over supported group VIII noble metals (M = Pd, Pt, Rh, Ru, Ni) was studied at 1 atm and 200-400 C. The activity and selectivity as a function of the reaction temperature was investigated. The reaction activity based on the TOF follows the order: Pd > Ru > Pt > Rh > Ni. The reaction over Pd, Pt and Rh catalysts proceeds mainly via decarbonylation (DCN) and decarboxylation (DCX) pathways at each reaction temperature. For Ru and Ni catalysts, while decarbonylation and decarboxylation pathways were predominant at lower temperatures (e.g., 200-250 C), at higher temperatures (>300 C) the formation of diethyl ketone was observed. Additionally, the kinetics of Pd over different supports (carbon, SiO2 and TiO2) were examined. The activity based on the TOF decreases in the following order: Pd/SiO2 > Pd/TiO2 > Pd/C. The reaction orders in acid and H2 were found to be approximately 0.5 and zero, respectively, regardless of the support. The apparent activation energies studied in a temperature range of 200-240 C, were 16.7 ± 0.6, 19.3 ± 1.6 and 11.7 ± 0.7 kcal/mole for Pd/C, Pd/TiO2 and Pd/SiO2 catalysts, respectively. The selectivity for Pd/C and Pd/SiO2 indicated mainly decarbonylation/decarboxylation and hydrogenation reaction pathways. In contrast, Pd/TiO2 at low temperatures (200 C) could generate decarbonylation and esterification products.
Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
, p. 803 - 808 (2021/07/20)
Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
