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Vinyl ethyne

Example 6.4. By-product formation in ethyne dimerization. Dimerization of ethyne (acetylene) to vinyl ethyne (vinyl acetylene)... [Pg.140]

Ethyne is the starting point for the manufacture of a wide range of chemicals, amongst which the most important are acrylonitrile, vinyl chloride, vinyl acetate, ethanal, ethanoic acid, tri- and perchloro-ethylene, neoprene and polyvinyl alcohol. Processes such as vinylation, ethinylation, carbonylation, oligomerization and Reppe processes offer the possibility of producing various organic chemicals cheaply. Used in oxy-acetylene welding. [Pg.169]

CH2 CH C CH. Colourless gas with a sweet odour b.p. 5°C. Manufactured by the controlled low-temperature telomerization of ethyne in the presence of an aqueous solution of CuCI and NH Cl. Reduced by hydrogen to butadiene and, finally, butane. Reacts with water in the presence of HgSO to give methyl vinyl ketone. Forms salts. Forms 2-chloro-butadiene (chloroprene) with hydrochloric acid and certain metallic chlorides. [Pg.266]

The original Sonogashira reaction uses copper(l) iodide as a co-catalyst, which converts the alkyne in situ into a copper acetylide. In a subsequent transmeta-lation reaction, the copper is replaced by the palladium complex. The reaction mechanism, with respect to the catalytic cycle, largely corresponds to the Heck reaction.Besides the usual aryl and vinyl halides, i.e. bromides and iodides, trifluoromethanesulfonates (triflates) may be employed. The Sonogashira reaction is well-suited for the synthesis of unsymmetrical bis-2xy ethynes, e.g. 23, which can be prepared as outlined in the following scheme, in a one-pot reaction by applying the so-called sila-Sonogashira reaction ... [Pg.158]

Diphenylmethyl vinyl ether has also been prepared from benzhydrol and acetylene (ethyne) under high-pressure conditions.3 In the described method, which is an adaptation of the procedure ofWeinstock and Boekelheide,4 improved yields of the alkene are obtained by using more convenient experimental conditions. [Pg.6]

Vitamin B12 catalyzed also the dechlorination of tetrachloroethene (PCE) to tri-chloroethene (TCE) and 1,2-dichloroethene (DCE) in the presence of dithiothreitol or Ti(III) citrate [137-141], but zero-valent metals have also been used as bulk electron donors [142, 143]. With vitamin B12, carbon mass recoveries were 81-84% for PCE reduction and 89% for TCE reduction cis-l,2-DCE, ethene, and ethyne were the main products [138, 139]. Using Ni(II) humic acid complexes, TCE reduction was more rapid, leading to ethane and ethene as the primary products [144, 145]. Angst, Schwarzenbach and colleagues [140, 141] have shown that the corrinoid-catalyzed dechlorinations of the DCE isomers and vinyl chloride (VC) to ethene and ethyne were pH-dependent, and showed the reactivity order 1,1-DCE>VC> trans-DCE>cis-DCE. Similar results have been obtained by Lesage and colleagues [146]. Dror and Schlautmann [147, 148] have demonstrated the importance of specific core metals and their solubility for the reactivity of a porphyrin complex. [Pg.530]

Despite the undeniable synthetic value of the benzannulation reaction of aryl and alkenyl Fischer carbene complexes, the details of its mechanism at the molecular level remain to be ascertained. Indeed, although a relatively large number of theoretical studies have been directed to the study of the molecular and electronic structure of Fischer carbene complexes [22], few studies have been devoted to the analysis of the reaction mechanisms of processes involving this kind of complexes [23-30]. The aim of this work is to present a summary of our theoretical research on the reaction mechanism of the Dotz reaction between ethyne and vinyl-substituted hydroxycarbene species to yield p-hydroxyphenol. [Pg.271]

Strong bases readily eliminate thiol from vinylic sulfides. 1,2-Bis(alkyl- or arylthio)ethynes for example, react with two equivalents of BuLi or alkali amide to give metallated alkyl- or arylthioacetylenes and thiolates [24] ... [Pg.162]

Ethynes are industrially used as a starting material for polymers, e.g. vinyl flooring, plastic piping. Teflon and acrylics. Polymers are large molecules, which are prepared hy linking many small monomers. Polyvinyl chloride, also commonly known as PVC, is a polymer produced from the polymerization of vinyl chloride. [Pg.110]

Gold(III) was identified as the most active catalyst for that process in 1985, when Hutchings recognized that the efficiency in catalyzing the hydrochlorination of ethyne to vinyl chloride (a very important industrial process that previously used mercury salts as catalysts) correlated with the standard reduction potential of the supported metal cation. That meant that the metal could be found as a transient species in the reaction [10]. [Pg.446]

Alkynes, unlike alkenes, are not hydrated readily in aqueous acid unless a mercuric salt is present as a catalyst. Also, the products that are isolated are either aldehydes or ketones instead of alcohols. Even though the addition of one molecule of water to ethyne probably gives ethenol (vinyl alcohol) initially, this compound is unstable relative to its structural isomer (ethanal) and rapidly rearranges ... [Pg.383]

At 60 °C, bicyclic titanacyclopentene complex 179 rearranges to 2-vinyl-substituted titanacyclobutene complex 180 in indeterminate yield (Equation 91) <1993CB1541>. This transformation proceeds by bis(trimethylsilyl)ethyne extrusion, rearrangement of the residual coordinated cyclopropene to vinylalkylidene, and [2+2] cycloaddition to reincorporate alkyne. [Pg.609]


See other pages where Vinyl ethyne is mentioned: [Pg.140]    [Pg.141]    [Pg.255]    [Pg.154]    [Pg.155]    [Pg.140]    [Pg.141]    [Pg.255]    [Pg.154]    [Pg.155]    [Pg.169]    [Pg.169]    [Pg.419]    [Pg.420]    [Pg.420]    [Pg.420]    [Pg.420]    [Pg.421]    [Pg.200]    [Pg.291]    [Pg.291]    [Pg.292]    [Pg.293]    [Pg.68]    [Pg.123]    [Pg.40]    [Pg.291]    [Pg.451]    [Pg.158]    [Pg.431]    [Pg.45]    [Pg.667]    [Pg.2090]    [Pg.582]   
See also in sourсe #XX -- [ Pg.140 ]

See also in sourсe #XX -- [ Pg.154 ]




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