Part 8: MECHANISMS

Note that no other reagents are needed in order to complete any of these sequences, you should only be using what is there.

Part A:
i. Conversion of an aldehyde to an acetal : nucleophilic addition to a carbonyl followed by nucleophilic substitution of an alcohol:


In this scheme, the base, B:, could be C=O, R-OH or the conjugate base of the acid catalyst

ii. Nitration of benzene, an electrophilic aromatic substitution:


In this scheme, the base, B:, could be -OH or the conjugate base of the acid catalyst

iii. Grignard reaction of a carboxylic acid derivative, a nucleophilic substitution followed by a nucleophilic addition:

Part B:
i. The key issue is to focus on the new 5 membered ring formed adjacent to the ester by a double alkylation via the reaction of an alkyl bromide and an epoxide as the electrophile (note: it could also be drawn as reaction of the epoxide followed by reaction of the alkyl bromide).


In this scheme, the base, B-, was EtO-

ii This example combines electrophilic addition to an alkene that leads to a carbocation that is then involved in electrophilic aromatic substitution.


In this scheme, the base, B:, could be C=C, or the conjugate base of the acid catalyst

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