alkene major and minor products (markovnikov)

[INH]

Which of the following would yield more than one major organic product upon reaction with HCl in the absence of peroxides?

choice a: 2-hexene
choice b: 2-methyl-1-hexene
Correct answer: choice a


This question has revealed a flaw in my understanding of the Markovnikov rule, specifically for substituted alkenes..... I know that 2 hexene will react with HCl to form 2-chlorohexane (minor product) and 3-chlorohexane (major product). However, the answer key says that 2-methyl-1-hexene will only produce 2-chloro-2-methylhexane. I thought that 2-methyl-1-hexene would have a minor and major product just like 2-hexene, but apparently it does not.

Thanks for the help!😀

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[J777]

For choice A yields two disubstituted products in (2-chlorohexane and 3-chlorohexane) in roughly equal amounts. Since Markovnikov says that the more substituted product will be formed, and both products are disubsituted, there is more than one major product.

Choice B only yields one major product, the trisubstituted 2-chloro-2-methylhexane. No other major organic product will be formed in appreciable amounts because there are no other ways to make a trisubstituted alkyl halide. Hope that helps

 

[INH]

Got it. So if the molecule had a structure, which had offered more than one possible trisubstituted product, then a major/minor product ratio would have resulted- thanks!