Other Acetylenes

The extension of the reaction with ketoximes to vinylacetylene could lead to the preparation of 2- or 3-vinylpyrroles. However, the products, obtained upon heating (60°C-80°C) ketoximes and vinylacetylene, represent a mixture of acetylenic and allenic ethers (in up to 50% total yield) (Schane 1.123) [292]. 

SCHEME 1.121 Assembly of 3-acyl-5-unsubstitutedpyrrole from 0-2-(acyl)vinyl ketoxime. r2 

SCHEME 1.122 Synthesis of functionalized pyrroles from ketoximes and ethyl propiolate or dimethylacetylenedicarboxylate. 

SCHEME 1.123 Reaction of ketoximes with vinylacetylene in the KOH/DMSO system. 

SCHEME 1.124 Reaction of ketoximes with diacetylene in the KOH/DMSO/HjO system. 

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The proton of terminal acetylenes is acidic (pKa= 25), thus they can be deprotonated to give acetylide anions which can undergo substitution reactions with alkyl halides, carbonyls, epoxides, etc. to give other acetylenes. 

To extend the study of the apparent decomposition recombination reaction, and specifically to determine if the carbon atoms exchange with other atoms in other acetylene molecules, tests using carbon isotopes were conducted. A mixture of 50% regular acetylene, C2H2, and 50% heavy acetylene. 

The U.S. Department of Commerce estimates total production of about 163,000 t in 1990. Other estimates based on demand data indicate that it was as high as 175,000 t. With demand and supply in balance, it is estimated that in 1997 the demand will be 185,000 t. The distribution in product demand is projected to be the following 1,4-butanediol and other acetylenic chemicals (45%), vinyl chloride monomer (45%), acetylene black (5%), and industrial use (5%). 

With other acetylenes steric factors may be operative which render the selective reduction somewhat difficult. In the aldosterone intermediates (53) and (54), for instance, selective hydrogenation is obtained only with the 14 -acetylenic ether " (hydroxyl group effect). 

The triple bond in pyrazole derivatives gives, as do other acetylene derivatives, typical addition reactions. 

Ono and coworkers have devised a new acetylene eqidvalent for the Diels-Alder reacdon namely, l-phenylsulfony-2-nitrQethylene is a very reacdve dienophile, and the radicM eliminadon from the adduct gives the Diels-Alder adduct of acetylene, as exemplified in Eq. 7.113. " " Other acetylene eqidvMents are summarized in a review. 

Isanic) and Other Acetylenic Acids. J. Chem. Soc. [London] 1953, 1785. 

See other acetylenic compounds, aldehydes, glass incidents, polymerisation INCIDENTS... 

See METAL ACETYLIDES See other ACETYLENIC COMPOUNDS, ORGANIC ACIDS... 

See Other ACETYLENIC compounds, endothermic compounds, organic AZIDES... 

See other acetylenic compounds See related organic acids... 

Octakis(trifluorophosphine)dirhodium See Octakis(trifluorophosphine)dirhodium Acetylenic esters See other acetylenic compounds... 

See other acetylenic compounds, endothermic compounds, high-nitrogen compounds, organic azides... 

See Other ACETYLENIC COMPOUNDS, CATALYTIC IMPURITY INCIDENTS... 

Brandsma, 1971, 7, 182 It decomposes explosively above 85°C. See Other ACETYLENIC COMPOUNDS... 

See 2,4-Hexadiynylene chloroformate also Dimethylformamide See other acetylenic compounds, acyl halides... 

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