methyl shift or hydride shift

[AntonFreeman]

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TBR Ochem Part 1 page 228 #39,

The small amount of substitution product isolated was found to have both the OCH3 group and the CH3 group both on the same carbon. This can be explained in what way?

C. a hydride shift occurred.
D. A methyl shift occurred.

They could both move to form a more stable carbocation right? But how can you tell which one is being shifted?

 

[salim271]

TBR Ochem Part 1 page 228 #39,

The small amount of substitution product isolated was found to have both the OCH3 group and the CH3 group both on the same carbon. This can be explained in what way?

C. a hydride shift occurred.
D. A methyl shift occurred.

They could both move to form a more stable carbocation right? But how can you tell which one is being shifted?

How can it be a hydride shift? The product is a cyclopentane that either has a methyl substituent or an OCH3 substituent. The answer is in the question, its either methyl or OCH3, so the answer is methyl shift. A hydride shift doesnt occur here.

 

[AntonFreeman]

answer is hydride shift. I am little confused by the answer. It does not explain why it is hydride shift over methyl shift

 

[salim271]

Ah... i just reread the question, a small amount of side product had the methyl and OCH3 both on the same carbon. Only one product, one that has two substituents on it, and the only way that could happen would be carbocation formation ---> hydride shift from the carbon with methyl on it, then the OCl is added onto the new carbocation. So you get a product with both a methyl and OCl, and the other carbon has two hydrogens.

Feels kind of easy now that I looked at it twice, lol.