Acid-catalyzed α-halogenation of ketones

α-Halogenation (acidic): 4,4-dimethyl-2-pentanone (a methyl ketone) with Br2; MeOH gives 1-bromo-4,4-dimethylpentan-2-one (the α-halo ketone). 89% yield.

α-Halogenation (acidic): 2-methylcyclohexanone (a six-membered cyclic ketone) with SO2Cl2; CCl4 gives 2-chloro-2-methylcyclohexan-1-one (the α-halo ketone).

α-Halogenation (acidic): cyclohexanone (a six-membered cyclic ketone) with Cl2, H2O gives 2-chlorocyclohexanone (the α-halo ketone).

α-Halogenation (acidic): benzylmalonic acid (a carboxylic acid) with Br2; CH3CH2OCH2CH3 gives 2-benzyl-2-bromopropanedioic acid (the α-halo acid).

α-Halogenation (acidic): 3-methyl-2-butanone (a methyl ketone) with Br2, CH3OH; 0-10 °C gives 1-bromo-3-methylbutan-2-one (the α-halo ketone).

α-Halogenation (acidic): p-bromoacetophenone (an aryl ketone) with Br2; AcOH gives 4-bromophenacyl bromide (the α-halo ketone).

α-Halogenation (acidic): acetone (a methyl ketone) with Br2; AcOH, H2O gives bromoacetone (the α-halo ketone).

α-Halogenation (acidic): 1,3-diphenyl-2-propanone (a dialkyl ketone) with Br2, AcOH gives 1,3-dibromo-1,3-diphenylpropan-2-one (the α-halo ketone).

α-Halogenation (acidic): diethyl malonate (a malonate ester) with Br2, hν; CCl4, Δ gives diethyl bromomalonate (the α-halo ester).

α-Halogenation (acidic): phenylacetone (a methyl ketone) with Br2; benzene gives 1-bromo-1-phenylpropan-2-one (the α-halo ketone).

α-Halogenation (acidic): 1-(3-fluoro-4-(methylsulfonyl)phenyl)propan-2-one (a methyl ketone) with Br2; dioxane (solvent) gives the α-halo ketone. 85% yield.

α-Halogenation (acidic): pinacolone (a methyl ketone) with 2 equiv Br2, MeOH gives 1,1-dibromo-3,3-dimethyl-2-butanone (the α-halo ketone). 75% yield.

α-Halogenation (acidic): acetone (a methyl ketone) with Br2; AcOH gives bromoacetone (the α-halo ketone). 92% yield.