77-78-1Relevant articles and documents
Synthesis method of quaternary ammonium salt
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Paragraph 0029; 0031; 0032, (2018/11/04)
The invention belongs to the technical field of preparation of chemicals and discloses a synthesis method of quaternary ammonium salt. The synthesis method comprises the following steps of: firstly reacting (CH3)2CO3 with H2SO4 to prepare (CH3)2SO4, then adding RN(CH3)2 to carry out quaternization reaction to prepare RN+(CH3)3O-SO2OCH3. The synthesis method disclosed by the invention has the advantages that generally, the one-pot reaction method is used and no solvent is used; by control of the feeding ratio, the reaction temperature and reaction substrate, the purity of the prepared quaternary ammonium salt is higher, and no residue of dimethyl sulfate and solvents is generated, so that the hazard of highly-toxic raw materials used in the traditional method to the environment and human isavoided; the synthesis method of the quaternary ammonium salt does not need reaction in the organic solvent, so that the production cost is reduced.
Understanding and control of dimethyl sulfate in a manufacturing process: Kinetic modeling of a fischer esterification catalyzed by H2SO 4
Guzowski Jr., John P.,Delaney, Edward J.,Humora, Michael J.,Irdam, Erwin,Kiesman, William F.,Kwok, Albert,Moran, Amy D.
body text, p. 232 - 239 (2012/06/18)
The formation and fate of monomethyl sulfate (MMS) and dimethyl sulfate (DMS) were studied by proton NMR for a sulfuric acid catalyzed esterification reaction in methanol. The kinetic rate constants for DMS and MMS were determined at 65 °C by fitting time-dependent experimental data to a model using DynoChem. In refluxing methanol, sulfuric acid was converted to monomethyl sulfate (MMS) in nearly quantitative yield within 45 min. Once formed, the MMS underwent a reversible esterification reaction to form DMS. Dimethylsulfate reacted with methanol to regenerate MMS and form dimethyl ether. A byproduct of the esterification reaction was water, which further consumed DMS through hydrolysis. On the basis of derived rate constants, in refluxing methanol, DMS would not be expected to exceed 4 ppm in the reaction mixture at equilibrium. In the presence of the carboxylic acid substrate, DMS was not detected in the reaction mixture. The reaction pathways of this system have been systematically investigated, and the results of this study will be presented.
A convergent approach to polycyclic aromatic hydrocarbons
Guignard, Raphael F.,Zard, Samir Z.
supporting information; experimental part, p. 12185 - 12187 (2011/12/15)
A new concise route to Polycyclic Aromatic Hydrocarbons (PAHs) through radical addition and cyclisation of xanthates is described. The Royal Society of Chemistry 2011.
Cu(II)-mediated methylthiolation of aryl C-H bonds with DMSO
Chu, Lingling,Yue, Xuyi,Qing, Feng-Ling
supporting information; scheme or table, p. 1644 - 1647 (2010/06/16)
(Figure Presented) An unprecedented Cu(II)-mediated methylthiolation of aryl C-H bonds under oxidative conditions that employs the widely available DMSO as the methylthiolation reagent is described. Various functional groups in the substrates were tolerat
Additives and products including oligoesters
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, (2008/06/13)
The present invention relates to oligoesters and their use or the creation of additives. Oligoester containing additives and/or oligoesters themselves may be used for formulating pharmaceutical preparations, cosmetics or personal care products such as shampoos and conditioners. These oligoesters are particularly useful for the creation of multi-purpose additives that can impart conditioning, long substantivity and/or UV protection. Individual oligoesters and oligoester mixtures are described.
Novel processes for the preparation of adenosine compounds and intermediates thereto
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, (2008/06/13)
Novel processes for the preparation of adenosine compounds and intermediates thereto. The adenosine compounds prepared by the present processes may be useful as cardiovascular agents, more particularly as antihypertensive and anti-ischemic agents, as cardioprotective agents which ameliorate ischemic injury or myocardial infarct size consequent to myocardial ischemia, and as an antilipolytic agents which reduce plasma lipid levels, serum triglyceride levels, and plasma cholesterol levels. The present processes may offer improved yields, purity, ease of preparation and/or isolation of intermediates and final product, and more industrially useful reaction conditions and workability.
α-aminoboronic acids prepared by novel synthetic methods
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, (2008/06/13)
The present invention relates to a novel class of α-aminoboronic acids of Formula (V), which are useful as intermediates in synthetic processes for inhibitors of the serine proteases, leukocyte elastase, pancreatic elastase, cathepsin G, and chymotrypsin. More specifically, the α-aminoboronic acids are useful as intermediates for the synthesis of Hepatitis C Virus (HCV) protease inhibitors. This invention also generally relates to novel methods for the preparation of α-aminoboronic acids.
Kinetics and mechanism of oxidation of dimethylsulfoxide by N-halosulfonamides in water-methanol and water-acetic acid media
Thimme Gowda,Nambiar,D'Souza
, p. 403 - 406 (2007/10/03)
Kinetics of oxidation of dimethylsulfoxide (DMSO) by N-halosulfonamides (chloramine-B, chloramine-T, dichloramine-B and dichloramine-T) have been studied in 1 : 1 (v/v) water-methanol and water-acetic acid media in the presence of perchloric acid. The rates show first order kinetics in [oxidant], fractional to first order in [DMSO] and zero order in [H+]. Variation in ionic strength of the reaction medium or addition of the reduced products of oxidants has no significant effect on the rates of oxidations. But the rates decrease with decrease in dielectric constant of the reaction medium by increasing the methanol or acetic acid composition of the solvent. Two-pathway as well as Michaelis-Menten type mechanisms have been considered to explain the observed results. The activation parameters have also been computed.
Uptake of methanol vapor in sulfuric acid solutions
Kane, Scan M.,Leu, Ming-Taun
, p. 1411 - 1415 (2007/10/03)
The uptake of gas-phase methanol by liquid sulfuric acid has been investigated over the composition range of 40-85 wt% H2SO4 and the temperature range of 210-235 K. Laboratory studies were performed with a flow-tube reactor coupled to an electron-impact ionization mass spectrometer to detect trace gases. While reversible uptake was the primary mechanism at low acid concentrations, an irreversible reaction between methanol and sulfuric acid at low temperatures, forming methyl hydrogen sulfate and dimethyl sulfate, was observed at all concentrations. At compositions >65 wt% H2SO4, more than 90% of uptake was found to be reactive. On the basis of the uptake data and the calculated liquid-phase diffusion coefficients, the product of the effective Henry's law constant (H*) and the square root of the overall liquid-phase reaction rate (k1) was calculated as a function of acid concentration and temperature. The results suggest that the reaction with sulfuric acid forming methyl hydrogen sulfate and dimethyl sulfate is the dominant loss mechanism of methanol and that the oxidation of methanol is only a minor source of hydroxyl radicals in the upper troposphere.
Ester compounds
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, (2008/06/13)
An ester compound represented by the formula: wherein R is a hydrogen atom, a C1-C3 alkyl group unsubstituted or substituted with one or more halogen atoms, an allyl group unsubstituted or substituted with one or more halogen atoms, or a propargyl group unsubstituted or substituted with one or more halogen atoms; and X is a hydrogen atom, a halogen atom, a C1-C3 alkyl group unsubstituted or substituted with one or more halogen atoms, a C2-C3 alkenyl group unsubstituted or substituted with one or more halogen atoms, a C2-C3 alkynyl group unsubstituted or substituted with one or more halogen atoms, a C1-C3 alkoxy group unsubstituted or substituted with one or more halogen atoms, a C1-C3 alkylthio group unsubstituted or substituted with one or more halogen atoms, or a C1-C3 alkoxymethyl group containing a C1-C3 alkoxy group unsubstituted or substituted with one or more halogen atoms, has an excellent pest-controlling effect.
