1-Methylethylene oxide when treated with an excess of HBr produces:

1-Methylethylene Oxide When Treated with Excess HBr

In this question, we are analyzing the reaction of 1-methylethylene oxide (an epoxide) with an excess of HBr. The epoxide undergoes nucleophilic attack by the bromide ion, breaking the three-membered ring and leading to the formation of a bromo-alcohol. Since the reaction involves excess HBr, the resulting product will have two bromine atoms attached to the carbon chain.

Analysis of the Options:

• Option a: The structure shows a bromine attached to a methyl group, which could be part of the product of an epoxide ring opening.
• Option b: This structure shows a carbon chain with two bromines attached to different carbons. This could be the correct answer since it indicates a dibromination at two adjacent carbons after the epoxide ring is opened.
• Option c: The structure here shows a bromo compound with a double bond, which seems less likely in this case since the reaction should lead to the formation of a saturated alcohol or alkyl bromide.
• Option d: This shows an epoxide ring with two bromines attached to the ring, which is also possible as part of the mechanism, but it's not the expected final product.

From this analysis, Option b seems the most likely as the correct answer for the product of 1-methylethylene oxide when treated with excess HBr.