Mechanism of Pd(II) and Hg(II) co-catalyzed oxidation of d-mannose and maltose by acidic solution of N-bromoacetamide

✍ Scribed by Ashok Kumar Singh; Vineeta Singh; Shahla Rahmani; Ajaya Kumar Singh; Bharat Singh

• Book ID: 104422218
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 182 KB
• Volume: 197
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(02)00590-3

✦ Synopsis

The kinetics of the homogeneously Pd(II) catalyzed oxidation of d-mannose (Man) and maltose (Mal) by N-bromoacetamide (NBA) in perchloric acid medium, using mercuric acetate as scavenger for Br -ions as well as co-catalyst, have been studied in the temperature range 35-50 • C. The reactions exhibit first-order kinetics at low concentrations of sugars (Man and Mal) and NBA, tending to zero-order at high sugar and NBA concentrations. The oxidation rate is directly proportional to [Pd(II)], while inverse fractional order in each of [H + ], [Cl -] and [acetamide] was found. A positive effect on the rate of the reaction was observed on successive addition of [Hg(OAc) 2 ], whereas change in ionic strength (µ) of the medium has no effect on the reaction velocity. Formic acid and arabinonic acid (for both reducing sugars, i.e. Man and Mal) were identified as main oxidation products of reactions. The various activation parameters have also been evaluated. A plausible mechanism from the results of kinetic studies, reaction stoichiometry and product analysis is proposed.