MONOSUBSTITUTED BENZALDEHYDES 103the aldol condensation, followed by the condensation of formaldehydewith the acetaldehyde so formed (p. 101).OH" HCHOCH3CH=CHCHO + H2O ^—^ 2CH3CHO > C(CH2OH)4Aldehydes containing the grouping —C=C•CHO do not undergo dis-mutation when treated with alkali but are cleaved readily to yield thecorresponding acetylene and formic acid. Propiolaldehyde and phenyl-and methyl-propiolaldehydes are cleaved smoothly in the followingway.68NaOH -> RO^CH + HCO2Na (R=H, CH3,C6HS)Aromatic AldehydesThe formation of benzoic acid when benzaldehyde is treated withaqueous alkali was first observed by Liebig and Wohler.69Some yearslater Cannizzaro60recognized that benzyl alcohol is formed also. Laterstudies have shown that aromatic aldehydes which are not diortho-substituted generally react smoothly to give the corresponding snylcarbinols and aromatic acids in good yields. The usefulness of the reac-tion, which in the past has been employed largely as a route to the
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