Alkynylide anions

Halogenoalkynes are also formed from alkynes and aqueous solutions of hypohalites. In these reactions, alkynylide anions are transient intermediates. The conversions give good results only when the acetylene has a low pK (e.g. aryl-feCH and ROCCsCH) or good solubility in water (e.g..HC-CCXCHj OH) [122], The hypohalite method of Strauss [123] has most applications in the synthesis of bromoacetylenes. 

The most utilized method for alkylation of alkynes is via alkynylide anions. Their reaction with electrophilic reagents provides access to both terminal and internal alkynes as well as to functionally substituted alkynes. The higher electronegativity of carbon in the sp-hybridization state imparts relatively greater acidity to acetylene and 1-alkynes (pATa 24-26), so that bases such as alkyllithiums, lithium dialkylamides. 

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