Condensation of methylcrotonic acid with 4-chloro-o-phenylenediamine in 4N HCl yielded 5-chloro-2(1-isobutenyl)benzimidazole and 7-chloro-4, 4-dimethyl-1,3,4,5-tetrahydro-2H-1,5-benzodiazepin-2-one. Methacrylic acid when condensed with o-phenylenediamine in 4N HCl yielded the already reported 3-methyl-1,2,4,5-tetrahydro-2H-1,5-benzodiazepin-2-one and 2(2-propenyl)beneimidazole. Condensation of methacrylic acid with 4-chloro-o-phenylenediamine in 4N HCl yielded 5-chloro-2 (2-propenyl)benzimidazole. The structures of all the purified compounds were confirmed with the help of mass and H-1 NMR spectral analysis.