Write a series of equations showing how to prepare 1,1-dichloroethane from(a) Ethylene(b)...

Write a series of equations showing how to prepare 1,1-dichloroethane from

(a) Ethylene

(b) Vinyl chloride (H2C=CHCl)

(c) 1,1-Dibromoethane

Sample Solution (a) Reasoning backward, we recognize 1,1-dichloroethane as the product of addition of two molecules of hydrogen chloride to acetylene. Thus, the synthesis requires converting ethylene to acetylene as a key feature. As described in Section 9.7, this may be accomplished by conversion of ethylene to a vicinal dihalide, followed by double dehydrohalogenation. A suitable synthesis based on this analysis is as shown: