Question

The only alkene which gives primary alkyl halides on hydrogenations

Answer 1

HBr + (CH2CO)2NBr → Br2 + (CH2CO)2NH This mechanism is essentially the same as that for the free radical halogenation of alkanes, with NBS serving as a source of very low concentrations The acid catalyzed addition of water to an aldehyde is one such reaction and we studied it earlier. ... to the carbocation) are the same steps which occured in the SN1 hydrolysis (solvolysis in water) of an alkyl halide.

Answer 2

Explanation:

HBr   +   (CH2CO)2NBr   →   Br2   +   (CH2CO)2NH

This mechanism is essentially the same as that for the free radical halogenation of alkanes, with NBS serving as a source of very low concentrations of bromine. Unsymmetrical allylic radicals will react to give two regioisomers. Thus, 1-octene on bromination with NBS yields a mixture of 3-bromo-1-octene (ca. 18%) and 1-bromo-2-octene (82%) - both cis and trans isomers.

RCH2CH=CH2   +   (CH2CO)2NBr  →   RCHBrCH=CH2  +   RCH=CHCH2Br   +   (CH2CO)2N