Propynes carbon-alkene reactions

Acetylene is the most widely used alkyne. Alkynes undergo the same reactions as alkenes. Because a triple bond coimects the two carbon atoms, addition of an atom initially forms a double bond. The addition of a second atom converts the double bond into a single bond. For example, hydrogenation of propyne to propane is represented as ... 

The methods for the synthesis of alkynes have been extensively reviewed in the past 20 years two books, which deal particularly with the preparative aspects of alkyne chemistry, have been published. Except for the syntheses of acetylene and propyne, which are prepared in technical processes from carbides, from methane by oxidation, or by electric arc processes, all carbon-carbon triple bonds must be generated by an elimination reaction. Again, as in the synthesis of alkenes, the most important is the de-hydrohalogenation. 

Directed Pauson-Khand reactions , giving only one of two possible regioisomers, occur when the carbon chain of the alkene is attached to a nitrogen or sulphur atom. Thus treatment of the propyne-dicobalthexaarbonyl complex with the thioether 491 gave solely the cyclopentenone 492. ... 

Strategy Addition polymers, whether they are synthesized from alkenes or alkynes, form via a free-radical reaction in which one pair of pi electrons in the carbon-carbon multiple bond of a monomer molecule is used to form carbon-carbon single bonds to other monomer molecules. Draw the structural formula of propyne such that the triple bond can be opened up to form single bonds between consecutive monomer units. 

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