Question

5 multiple choice 2 points when an alkene is subjected to treatment with $hg(oac)_2$ in alcohol followed by reaction with $nabh_4$, what new class of compound is formed? syn diol alkane ether epoxide previous ne

Explanation:

This reaction is alkoxymercuration - demercuration. In the first step, \(Hg(OAc)_2\) (mercury (II) acetate) reacts with the alkene in alcohol. The alkene acts as a nucleophile and attacks the \(Hg^{2 + }\) center. The alcohol (\(ROH\), where \(R\) is an alkyl group) then adds to the more substituted carbon of the alkene - mercury intermediate. In the second step, \(NaBH_4\) (sodium borohydride) replaces the \(Hg\) - containing group with a hydrogen atom. The general reaction for alkoxymercuration - demercuration of an alkene \(R_1R_2C = CR_3R_4\) with alcohol \(ROH\) is:

$$R_1R_2C = CR_3R_4+Hg(OAc)_2 + ROH ightarrow R_1R_2C(OR) - CHR_3R_4HgOAc$$

$$R_1R_2C(OR) - CHR_3R_4HgOAc+NaBH_4 ightarrow R_1R_2C(OR) - CHR_3R_4H+Hg + NaOAc$$

The product \(R_1R_2C(OR) - CHR_3R_4H\) is an ether (\(R - O - R'\), where \(R'\) is part of the original alkene structure).

• A syn - diol is formed by the syn - hydroxylation of alkenes (e.g., using \(OsO_4\) followed by \(NaHSO_3\)).
• An alkane would be formed if the alkene were fully hydrogenated (e.g., using \(H_2/Pt\)).
• An epoxide is formed by the reaction of an alkene with a per - oxyacid (e.g., \(m - CPBA\)).

Answer:

C. ether