Direct Introduction of Halogen and Cyano Groups

Methods for the Direct Introduction of Halogen and Cyano Groups 

The principal methods for direct preparation of halogenoacetylenes from the corresponding 1-alkynes are represented in the following equations [6]  

Alkynenitriles can be obtained from metallated acetylenes and the pseudo-halogen DON [114,115]  

The preparation of the extremely unstable (explosive) monohaloacetylenes HOCX by these methods has no practical importance. 

A useful variant of the sulfonyl chloride method is chlorination with N-chloro- 

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