The complete, detailed mechanism for alkoxymercuration part of the given reaction is to be drawn and the major product is to be predicted. Concept introduction: Oxymercuration-Reduction reaction is the addition of water to an alkene . In this reaction, an alkene is first treated with mercury (II) acetate, Hg(OAc) 2 , in a water-THF solution, and that is followed by reduction with sodium borohydride. The product of oxymercuration-reduction is the one expected from Markovnikov’s rule, that is, the OH group forms a bond to the carbon atom that can better stabilize a positive charge. Rearrangement does not take place with this reaction. In step 1 , the Hg atom is electron-deficient which is attacked by an electron-rich double bond in the alkene resulting in a three-membered mercurium ion intermediate. In step 2 , the solvent, water-THF, acts as a nucleophile to open the ring. In step 3 , the positively charged O atom is deprotonated. The reduction is then carried out when NaBH 4 is added, in which Hg , containing the substituent, is replaced by H . In alkoxymercuration-reduction, the solvent system used is ethanol-THF instead of water-THF. In the case of asymmetric alkene, alcohol attacks more highly substituted carbon to acquire more positive charge from Hg .

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Chapter 12, Problem 12.15P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for alkoxymercuration part of the given reaction is to be drawn and the major product is to be predicted.

Concept introduction:

Oxymercuration-Reduction reaction is the addition of water to an alkene. In this reaction, an alkene is first treated with mercury (II) acetate, Hg(OAc)2, in a water-THF solution, and that is followed by reduction with sodium borohydride. The product of oxymercuration-reduction is the one expected from Markovnikov’s rule, that is, the OH group forms a bond to the carbon atom that can better stabilize a positive charge. Rearrangement does not take place with this reaction.

In step 1, the Hg atom is electron-deficient which is attacked by an electron-rich double bond in the alkene resulting in a three-membered mercurium ion intermediate.

In step 2, the solvent, water-THF, acts as a nucleophile to open the ring.

In step 3, the positively charged O atom is deprotonated. The reduction is then carried out when NaBH4 is added, in which Hg, containing the substituent, is replaced by H. In alkoxymercuration-reduction, the solvent system used is ethanol-THF instead of water-THF.

In the case of asymmetric alkene, alcohol attacks more highly substituted carbon to acquire more positive charge from Hg.

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