MCAT Organic Chemistry Question 84: Answer and Explanation
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Question: 84
9. In a hemiacetal, the central carbon is bound to:
- A. –OH, –OR, –H and –R.
- B. –H, –OR, –OR, and –R.
- C. –OH, –OR, –R, and –R.
- D. –OR, –OR, –R, and –R.
Correct Answer: A
Explanation:
A hemiacetal is a molecule in which one equivalent alcohol has been added to a carbonyl (–OR) and the carbonyl oxygen has been protonated (–OH). Otherwise, there is the same alkyl group (–R) and hydrogen atom (–H) as the parent aldehyde. Choice (B) describes an acetal, choice (C) a hemiketal, and choice (D) a ketal.