Which of the following alkynes would give a single product under hydroboration-oxidation conditions?
A) 1-hexyne
B) 2-hexyne
C) 3-hexyne
D) A and B would each give a single product
E) A and C would each give a single product

Question

Quizplus · Accepted Answer

Under hydroboration-oxidation conditions, terminal alkynes (alkynes with a triple bond at the end of the carbon chain) give only one product which is an aldehyde. Therefore, 1-hexyne would give a single product. However, 2-hexyne and 3-hexyne are internal alkynes, and they have a triple bond within the carbon chain. Under hydroboration oxidation conditions, internal alkynes can give two products, a ketone or aldehyde, depending on the position of the triple bond. Therefore, 2-hexyne and 3-hexyne would not give a single product. Hence, only choice E, A and C would each give a single product, is correct.

Which of the Following Alkynes Would Give a Single Product