420-12-2Relevant articles and documents
Kinetic Studies of Cascade Reactions in High-Throughput Systems
Iron, David,Boelens, Hans F. M.,Westerhuis, Johan A.,Rothenberg, Gadi
, p. 6701 - 6707 (2003)
The application of robotic systems to the study of complex reaction kinetics is considered, using the cascade reaction A → B → C as a working example. Practical problems in calculating the rate constants k 1 and k2 for the reactions A → B and B → C from concentration measurements of CA, CB, or CC are discussed in the light of the symmetry and invertability of the rate equations. A D-optimal analysis is used to determine the points in time and the species that will give the best (i.e., most accurate) results. When exact data are used, the most robust solution results from measuring the pair of concentrations (CA, CC). The system's information function is computed using numeric methods. This function is then used to estimate the amount of information obtainable from a given cascade reaction at any given time. The theoretical findings are compared with experimental results from a set of two-stage cascade experiments monitored using UV-visible spectroscopy. Finally, the pros and cons of using a single reaction sample to estimate both k1 and k2 are discussed.
Preparation method of aliphatic mercaptan
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Paragraph 0053-0054; 0083-0084; 0097-0098, (2021/08/28)
The invention provides a novel method for preparing (CH3CH2) 2NCH2CH2SH, wherein alkali is added when (CH3CH2) 2NH is recovered, so that the content of impurities in the recovered (CH3CH2) 2NH is reduced, and particularly, the impurities which can influence the synthesis of (CH3CH2) 2NCH2CH2SH in the recovered (CH3CH2) 2NH are removed, so that the recovered (CH3CH2) 2NH can be reused in the production of (CH3CH2) 2NCH2CH2SH.
Preparation method of aliphatic mercaptan
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Paragraph 0030-0031; 0035-0036; 0039-0040; 0042-0043; ..., (2021/08/28)
The invention provides a novel method for preparing (CH3CH2) 2NCH2CH2SH, i.e., the reaction is carried out at a lower temperature, and the reaction is controllable by adopting a manner of dropwise adding materials, so that the safe production is realized.
Preparation process of ethane episulfide
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Paragraph 0021-0023, (2021/12/07)
The invention relates to a preparation process for synthesizing ethane episulfide from thiocyanate and ethylene carbonate, the preparation process comprises the following steps of: dissolving dried thiocyanate in a medium-polarity ketone solvent which is not easy to ionize, pressing ethylene carbonate into the ketone solution of thiocyanate through nitrogen, heating to react to generate a gas-phase product, condensing the gas-phase product to obtain ethane episulfide, filtering reaction liquid, recycling the liquid, and drying the solid so as to obtain the high-purity cyanate. The reaction belongs to homogeneous reaction, reactants are in full contact, and the process has the advantages of mild and controllable reaction, high reaction efficiency, low energy consumption, few side reactions, simple post-treatment and the like.
Taurine synthesis method (by machine translation)
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Paragraph 0036-0037; 0041-0042; 0045-0046; 0049-0050, (2020/07/15)
The invention provides a taurine synthesis method, and solves the problems of by-product accumulation, high temperature and high pressure in ammonia decomposition reaction, strong strong acid and strong base in acidification and the like in an addition reaction in a traditional taurine synthesis process. The method comprises the following steps: 1) carrying out cyclization reaction of sulfur solution and ethylene contact to obtain a solution of sulfur dissolved in carbon disulfide; 2) carrying out an addition reaction with ammonia or liquid ammonia contact to obtain an amino thiol; 3) carrying out an oxidation reaction in the presence of a catalyst to obtain the crude taurine. (by machine translation)
A process for preparing cyclic ethane
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Paragraph 0031; 0032; 0035; 0036, (2016/12/01)
The invention discloses a preparation process of ethylene sulfide. The preparation process comprises the following steps: heating potassium thiocyanate at a vacuum condition for dehydrating; continuously charging nitrogen to protect the reaction until a reaction system is at a micro-pressure; subsequently adding ethylene carbonate to perform a synthetic reaction; condensing to obtain liquid ethylene sulfide. The reaction system is also provided with an ethylene sulfide tail gas adsorbing device and an air drying device so as to prevent polymerization reaction of ethylene sulfide, so that the preparation process of ethylene sulfide is little in side reaction, high in reaction yield and small in environmental pollution.
Atom economical synthesis of di- and trithiocarbonates by the lithium: Tert -butoxide catalyzed addition of carbon disulfide to epoxides and thiiranes
Diebler,Spannenberg,Werner
supporting information, p. 7480 - 7489 (2016/08/16)
Alkali metal alkoxides were studied as catalysts for the addition of CS2 to epoxides. A screening of several commercially available alkoxides revealed lithium tert-butoxide as an active and selective catalyst for this reaction. The influence of different reaction parameters as well as the substrate scope under optimized reaction conditions has been studied. Terminal and highly substituted epoxides as well as thiiranes were converted. In total 28 products were prepared and isolated in yields up to 95%. Notably, the reactions were performed under mild conditions without additional solvents. The regio- and stereoselectivity of the reaction has been studied e.g. by converting (R)-styrene and (R)-propylene oxide. Moreover, the test reaction was monitored by 13C NMR and a plausible mechanism for the conversion of terminal and internal epoxides is given. This proposal is in agreement with the observed regio- and stereoselectivity of the reaction.
Polyfunctional thiirane compounds
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, (2008/06/13)
Describes novel polyfunctional thiiranes. Also described are polymerizable compositions comprising such novel polyfunctional thiiranes, and polymerizates, e.g., optical lenses, prepared therefrom. The described polymerizates may have a refractive index of at least 1.6, and an Abbe number of at least 27.
Thermal degradation processes in polysulfide copolymers investigated by direct pyrolysis mass spectrometry and flash pyrolysis - Gas chromatography/mass spectrometry
Sundarrajan,Surianarayanan,Srinivasan,Kishore
, p. 3331 - 3337 (2007/10/03)
This is the first report on the analysis of random block polysulfide copolymers containing different amounts of repeating units in the copolymer backbone, which has been studied by direct pyrolysis mass spectrometry (DPMS) and by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The homopolymers such as poly(ethylene sulfide) (PES), poly(styrene sulfide) (PSS), and two random copolymers, viz., poly(ethylene sulfidex-co-styrene sulfidey) [copolymer I (x = y = 0.5) and copolymer II (x = 0.74, y = 0.26)] were investigated by both DPMS and Py-GC/MS (except copolymer II) techniques. In the case of copolymer I, the thermal degradation products of SE1, SE2, S2, and S2E (S = styrene sulfide, E = ethylene sulfide) were detected in DPMS, whereas the formation of SE1 and SE2 were observed by Py-GC/MS technique. However, for copolymer II, SE3 was also found along with SE1, SE2, S2, and S2E in DPMS. The formation of additional product (SE3) observed in copolymer II could be due to an increase in the block length formed during copolymerization. Further, a comparative study on thermal degradation of PES, poly(ethylene disulfide) (PEDS), and poly(ethylene tetrasulfide) (PETS) were investigated by Py-GC/MS. The pyrolysis products detected by both DPMS and Py-GC/MS indicates that the thermal decomposition of these polymers yield cyclic sulfides through an intramolecular exchange or by backbiting processes. The linear products with thiol and vinyl groups were also observed by Py-GC/MS along with the cyclic products via carbon hydrogen transfer reaction.
Gas Phase Thermolysis of Pyrazolines. 5. Electronic Structure and Gas Phase Thermolysis of Tetrazole Derivatives Studied by Photoelectron Spectroscopy
Awadallah, Adel,Kowski, Klaus,Rademacher, Paul
, p. 113 - 122 (2007/10/03)
The photoelectron spectra of substituted tetrazoles 1-3, 1,4-dihydro-5H-tetrazol-5-ones 4-9, and 1,4-dihydro-5H-tetrazole-5-thiones 10-15 have been recorded. Based on PM3 and some ab initio calculations, the ionization potentials have been assigned to molecular orbitals. Gas-phase thermolyses of 1-15 have been studied by real-time gas analysis controlled by photoelectron spectroscopy. Compounds 1 and 2 lose formaldehyde and thioformaldehyde, respectively, leaving unsubstituted tetrazole (16), which decomposes mainly through extrusion of a nitrogen molecule and formation of cyanamide. Thiirane is split off from 3, and the remaining molecule decomposes into smaller products. Compounds 4-9 are cleaved by [3+2] cycloreversion to isocyanates and azides. Some of the unsymmetrically substituted compounds exhibit a marked selectivity in this reaction. For thiones 10-15 [3+2] cycloreversion is the main way of decomposition affording isothiocyanates and azides. In addition, the sulfur atom can split off and dimerize or abstract hydrogen atoms to form hydrogen sulfide. Some products like thiirene, formaldehyde, thioformaldehyde and acetaldehyde are generated solely from substituent. Photoelectron spectroscopy proved to be an excellent method for such thermolysis studies.
