Question

Which of the following reactions would result in an ANTI- addition?

a. the addition of HCl
b. hydrogenation
c. the addition of mCPBA followed by H₃O⁺
d. the addition of OsO₄ followed by NaHSO₃

Answer 1

The reaction involving the addition of mCPBA followed by H₃O⁺ results in an ANTI addition, where substituents are added to opposite sides of a double bond.

Step-by-step explanation:

The reaction that would result in an ANTI addition is the addition of mCPBA followed by H₃O⁺. Anti addition occurs when two substituents are added to opposite sides of a double bond. The addition of mCPBA (meta-chloroperoxybenzoic acid) converts an alkene to an epoxide which, when followed by acidic hydrolysis (with H₃O⁺), results in a trans-diol, hence achieving the anti addition across the double bond.


In contrast, the addition of HCl and hydrogenation typically lead to syn additions, where the added groups end up on the same side of the former double bond. Lastly, the addition of OsO₄ followed by NaHSO₃ leads to a syn dihydroxylation, thus not an anti addition either.