Replacement of halogen via intermediates

Hydrocarbons are formed on hydrolysis of Grignard compounds by water or hydroxyl-containing substances 438 

Mobile chlorine attached to a heterocycle often reacts also with hydrazine and decomposition of the resulting hydrazine derivative by aqueous copper sulfate solution gives a product in which the original halogen has been replaced by hydrogen.441 

A route involving reaction with / -toluenesulfonohydrazide and decomposition of that product with alkali has been described by Albert and Roger.442 

Finally, aliphatically bound iodine may be replaced in a circuitous route in which reaction with thiourea gives a thiouronium salt that is cleaved reductiv-ely when shaken with Raney nickel.443 

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