Cleavage of a Tribromomethyl Ketone

Step 1 Hydroxide ion acts as a nucleophile and adds to the carbonyl group of 

Step 2 The carbon-oxygen double bond is restored by expelling the tribromomethide ion. 

Step 3 Proton transfer reactions convert the acid to carboxylate and tribromomethide ion to tribromomethane (bromoform). 

The methyl ketone shown in the example can enolize in only one direction and typifies the kind of reactant that can be converted to a carboxylic acid in synthetically acceptable yield by the haloform reaction. Methyl ketones of the type RCH2C(0)CH3 and R2CHC(0)CH3 undergo nonregioselective a halogenation to yield a mixture of products. 

Which of the following would be the most suitable starting material for the preparation of a carboxylic acid by the haloform reaction Give the structure of the carboxylic acid. 

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Acid-Catalyzed Enolization of an Aldehyde or Ketone in Aqueous Solution 899 Acid-Catalyzed Bromination of Acetone 901 Cleavage of a Tribromomethyl Ketone 903... 

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