<span style="font-size:19.5pt;mso-bidi-font-size:13.5pt; font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">An unusual resistance to <img src='/image/spc_char/alpha.gif' border=0>-bromination by arylacetyl compound. Studies on bromination of 2-acetylbenzimidazoles and their subsequent reactions with sulphur nucleophiles - synthesis of novel β<span style="font-size:17.0pt; mso-bidi-font-size:11.0pt;font-family:HiddenHorzOCR;mso-hansi-font-family:"Times New Roman"; mso-bidi-font-family:HiddenHorzOCR;mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA">-ketosulphone <span style="font-size: 19.5pt;mso-bidi-font-size:13.5pt;font-family:"Times New Roman";mso-fareast-font-family: "Times New Roman";mso-ansi-language:EN-US;mso-fareast-language:EN-US; mso-bidi-language:AR-SA">derivtives of benzimidazoles.</span></span></span>

302-307<span style="font-size:14.0pt;mso-bidi-font-size:8.0pt; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Condensation of o -phenylenediamine with lactic acid under Phillips ' conditions gave the <span style="font-size:14.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">known 2- (-hydroxyethyl)benzimidazole 1 which on oxidation with acid dichromate furnishes 2-acetylbenzimidazole 2. Reaction of 2 with bromine in acetic acid at room temp. give a novel product 3 but not the expected 2-(-bromoacetyl benzimidazole 4. Rational explanation is offered for this anamolous behaviour of <b style="mso-bidi-font-weight: normal">2. Compound 2 on alkylation, give 1-alkyl derivatives which undergo smooth bromination with bromine in acetic acid to give the correspondig 1-alkyl-2- (-bromoacetyl) benzimidazoles. Reactions of latter with sulphur nucleophiles such as PhS-, ArSO2<span style="font-size:11.5pt; mso-bidi-font-size:5.5pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">-<span style="font-size:11.5pt; mso-bidi-font-size:5.5pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"=""> <span style="font-size:14.0pt;mso-bidi-font-size: 8.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">etc. , resulting in substitution of bromine, leading to novel -β<span style="font-size:14.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"=""> ketosulphone derivatives of benzimidazoles, are reported. Products have been characterised by IR , NMR (1H and 13C) and mass spectral data.