Question

The stable hemiacetals is/are (A) CC1(O)CCCCC1 (B) OC1CCCCO1 (C) \(\mathrm{Br}_{3} \mathrm{C} \quad \mathrm{OCH}_{3}\) (D)

Short answer

The stable hemiacetal is (A) with the structure CC1(O)CCCCC1, as it meets the criteria of having an -OH group, an -OR group, and two other groups in a six-membered ring.

Step-by-step solution

Structure of molecule (A)

For molecule (A), the SMILES notation is CC1(O)CCCCC1. This tells us that the molecule has a six-membered ring with an oxygen atom in the ring, and a methyl group attached to one of the carbons. The structure meets the criteria for being a stable hemiacetal since it has an -OH group, an -OR group, and two other groups in a six-membered ring.

Structure of molecule (B)

For molecule (B), the SMILES notation is OC1CCCCO1. The molecule has a five-membered ring with two oxygen atoms in the ring. This structure does not meet the criteria for being a hemiacetal as no carbon atom in the ring has an -OH group and an -OR group within the same ring.

Structure of molecule (C)

For molecule (C), the formula is \(\mathrm{Br}_{3} \mathrm{C} \quad \mathrm{OCH}_{3}\). This molecule does not have a ring structure and therefore cannot be a stable hemiacetal.

Conclusion

Among the given molecules, only molecule (A) meets the criteria for being a stable hemiacetal. Therefore, the correct answer is (A).