Oxymercuration, and alkoxymercuration

The mechanisms for oxymercuration and alkoxymercuration are essentially identical the only difference is that water is the nucleophile in oxymercuration and an alcohol is the nucleophile in alkoxymercuration. Therefore, the product of oxymercuration-reduction is an alcohol, whereas the product of alkoxymercuration-reduction is an ether. 

Oxymercuration, alkoxymercuration, and the addition of Br2 and CI2 form cyclic intermediates. Oxymercuration and alkoxymercuration are followed by a reduction reaction. Reduction increases the number of C — H bonds or decreases the number of C — O, C—N, or C—X bonds (where X denotes a halogen). Hydroboration is followed by an oxidation reaction. Oxidation decreases the number of C—H bonds or increases the number of C—O, C—N, or C—X bonds (where, again, X denotes a halogen). 

I Review the mechanism of oxymercuration shown in Figure 7.4 (p. 225), and then i write the mechanism of the alkoxymercuration reaction of 1-methylcvclopentene with ethanol. Use curved arrows to show the electron flow in each step. 

A study of the intramolecular alkoxymercuration of ( )-5-arylpent-4-en-l-ols (70) has indicated that the regioselectivity is closely related to the Hammett constants of the para-substituents on the benzene ring. Large solvent effects on the regioselectivity were also observed (Scheme 17 and Tables 2 and 3). By contrast, the related oxymercuration of -methylstyrene is 100% a-sclcctivc. This comparison shows that the regioselectivity of the intermolecular reaction is controlled by electronic factors, whereas the cyclization is governed by a delicate balance of steric and electronic effects.65... 

Define each term, and give an example, (a) dimerization (d) stereospecific addition (g) Markovnikov addition (j) hydrogenation (m) heterogeneous catalysis (p) hydroxylation (s) hydroboration (v) oxymercuration-demercuration (y) alkoxymercuration-demercuration... 

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