By the haloform reaction

The methyl ketone shown in the example can enohze in only one direction and typifies the kind of reactant that can be converted to a carboxylic acid in synthetically accept able yield by the haloform reaction When C 3 of a methyl ketone bears enolizable hydro O... 

Methyl ketones 1, as well as acetaldehyde, are cleaved into a carboxylate anion 2 and a trihalomethane 3 (a haloform) by the Haloform reaction The respective halogen can be chlorine, bromine or iodine. 

To retain a side-chain substituent, selective methods of oxidation are required. For example, 4-methylbenzoic acid can be prepared from l-(4-methylphenyl)-ethanone by the haloform reaction (Section 17-2B) ... 

Dihydropyridines substituted at the 3- and/or 4-positions undergo selective acylation with trichloroacetic anhydride to give 5-trichloroacetyl-l,4-dihydropyridines 136, which are easily converted by the haloform reaction to esters 137 (Scheme 37) <1998TL9275, 2002T8099, 2003TL4711>. Hydrogenation, over platinum oxide, of... 

Since methyl ketones are convertible into acids by the haloform reaction, the present sequence provides a means of lengthening the chain by three carbon atoms. 

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. 

In contrast, base-promoted halogenation tends to occur on the less substituted a carbon atom. For example, base-promoted iodination of methyl alkyl ketones leads initially to the iodomethyl alkyl ketone. Further reaction leads to the a,a-diiodo-, then to the a,a,a-triiodoketone, and then to iodoform and a carboxylate ion by the haloform reaction (Figure 7.10). 

The preparation of 1- (IAS) and 2-anthracenesulfonates (2AS) was described elsewhere (16). The preparation of 1- (lAC) and 2-anthracenecarboxylates (2AC) was carried out by the haloform reaction of corresponding acetyl-anthracenes. 9-Anthracenecarboxylate (9AC) was used as commercially available. ... 

EXPERIMENT 34 Hypochlorite Oxidation of Methyl Ketones by the Haloform Reaction 403... 

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