Sodium hypochlorite (NaOCl)

Abstract

(A) Luka Gonsalvi and co-workers reported a highly efficient use of NaOCl in the Ru-catalysed oxidation of aliphatic ethers to esters. The selectivity of α-oxidation of ethers to esters via Ru-NaOCl can be dramatically improved by pH control, at high substrate/catalyst ratios using a stoichiometric amount of hypochlorite in biphasic media at room temperature.9 (Chemical Equation Presented) (B) A new practial method for the osmium-catalyzed dihydroxylation of olefins using bleach as the terminal oxidant is reported for the first time. Aromatic and aliphatic olefins yield the corresponding cis-1,2-diols in the presence of dihydroquinidine derivatives (Sharpless ligand) with good to excellent chemo- and enantioselectivities under optimized pH conditions. In the presence of a small excess of NaOCl as reoxidant fast dihydroxylation takes place even at 0°C. Under optimum reaction conditions it is possible to dihydroxylate terminal aliphatic and aromatic olefins as well as internal olefins. The low price of the oxidant and the simple handling of bleach make this dihydroxylation variant attractive for further applications.8 (Chemical Equation Presented) (C) Hopkins and Chisholm reported a useful method for the chlorination of benzene derivatives with cold aqueous NaOCl. The reaction gives good yields of monochloro derivatives when the orientation is favourable. Products chlorinated at the aromatic nucleus have been prepared in the present work from various substituted benzoic acids, arylacetic acids, aryloxyacetic acids and arylaldehydes, using sodium hypochlorite as the reagent. The results indicated that this method of halogenation is more widely applicable than previously supposed.2 (Table Presented) (D) A new catalytic route is reported for the epoxidation of simple olefins with NaOCl as oxygen source and manganese porphyrin complexes as catalyst. Among all the oxidants that are potentially donors of one oxygen atom, NaOCl has been shown to be a good reagent for efficient catalytic oxygenation reactions.1 Also, an easy method reported for epoxidation of olefins using bleach and either a stoichiometric or a catalytic amount of bromide has been developed. Without any transition-metal catalyst a variety of non-activated olefines gives epoxides in high yields and good selectivity at ambient conditions.3 (Chemical Equation Presented) (E) Selective ruthenium-catalyzed oxidation of 1,2:4,5-di-O-isopropylidene-β-D- fructopyranose and other alcohols was reported by Luca Gonsalvi et al. The asymmetric epoxidation catalyst 1,2:4,5-di-O-isopropylidene-β-D-erythro-2, 3-hexadiulo-2,3-pyranose 2 was obtained in high yield from 1,2:4,5-di-O- isopropylidene-β-D-fructopyranose 1 via a recyclable ruthenium-catalyzed hypochlorite oxidation protocol under biphasic conditions (MTBE/water) in the presence of an alkaline buffer (pH 9.5). Other secondary alcohols were also oxidized selectively to the corresponding ketones.11 (Chemical Equation Presented) (F) A series of new aliphatic 3-oxazolines was obtained in moderate to good yields via oxidation of the corresponding 1,3-oxazolidines by N-chlorination with sodium hypochlorite followed by elimination in basic medium. Some of the 3-oxazolines obtained present interesting properties in the field of fragrance chemistry.7 (Chemical Equation Presented) (G) Oxidation of aryl methyl sulfoxides with sodium hypochlorite catalyzed by (salen)Mn(III) complexes was reported by Chellamani and Harikengaram.12 (Chemical Equation Presented). © Georg Thieme Verlag Stuttgart.