Di-substituted acetylenes

In detn of di substituted acetylenic compds, formation of ppts is observed only when using mercuric salts (chloride, sulfate or nitrate), but this reaction is not specific because some ethylenic compds and compds contg certain oxygen and nitrogen groups also give ppts. This method,however, can be used in conjunction with the Raman spectra method (Ref 8)... 

Polymethylacetylene can be doped by I2, but not by AsF5. Its conductivity in the doped state 36) is around 10-3 S cm 1. As might be expected, increasing content of mono- and di-substituted acetylenes in copolymers with acetylene gives increasing solubility at the expense of drastic reductions in the conductivity of both doped and undoped polymers. 

Costa, G., Polymerization of Mono- and Di-substituted Acetylenes , in Comprehensive Polymer Science, Pergamon Press, Oxford, 1989, Vol. 4, pp. 155-161. 

With diethyl(bipyridyl)nickel(II) and chlorohydrosilanes, the hydrosilyiation of di-substituted acetylenes undergoes dehydrogenative, stereoselective c -double silylation to give 1,2-bissilylalkenes, accompanied by normal hydrosilylated products ... 

The reaction of dialkylaluminum hydrides with mono- or di-substituted acetylenes provides the best route to alkenyldialkylaluminums . The hydroalumination of acetylene itself gives polymers Monohydroalumination of terminal acetylenes can be conducted either neat or in hydrocarbon solvents (< 50°C). The products are (E)-alkenylalanes as the result of a regio and stereoselective cis addition of Al—H to the C=C bond i- ... 

Hydration of mono- and di-substituted acetylenes can in many cases be effected by acid alone, particularly readily by sulfuric acid thus (/ -bromophenyl)prop-iolic acid in concentrated sulfuric acid gives (/ -bromobenzoyl)acetic acid quantitatively 80... 

CP2C0 catalyses the condensation of acetylene and mono-substituted acetylenes (but not di-substituted acetylenes) with nitriles at 150° to give 30-70% yields of substituted pyridines [WakatsuM Yamazaki Synthesis 26 1976], This synthesis has been applied successfully in a 2+2+2 cycloaddition reaction between di(trimethylsilyl)propargyl ether and acetonitrile to prepare a pyridine intermediate whieh was used to obtain pyridoxine (vitamin Be) [Greiger et al. Helv Chim Acta 67 1274 1984. ... 

R=R =Ph, C02Me R-CMCj, Ph Rl=Me, H) and R2C=CH (R2 Pr, Bu, hexyl) has been examined . a new synthesis of trisubstituted alkenes by the Pd(OAc)2/PPh3 catalysed arylation of mono- and di-substituted acetylenes is observed in the presence of formic acid and a tertiary amine . Cyclopropanation of olefins is catalysed by a number of complexes of late transition metals and the electronic effects of the metal provide the stereochemical and regiochemical control . 

Olefins of the type (177), which are readily prepared from the keten-anthracene adduct (176), undergo retro-Diels-Alder reactions to give high yields of mono- or di-substituted acetylenes. ... 

Mono- and di-substituted acetylenes react with Zr(CI)(H)(A -C5H8)2 by insertion into the zirconium-hydride bond. ... 

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