物理化学学报 >> 2008, Vol. 24 >> Issue (05): 810-816.doi: 10.1016/S1872-1508(08)60036-4

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硫酸溶液中胶束催化Ce(IV)氧化D-甘露糖

KABIR-UD-DIN; ALI Mohd. Sajid; KHAN Zaheer   

  1. Chemistry Department, Aligarh Muslim University, Aligarh 202002, UP, India; Chemistry Department, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
  • 收稿日期:2007-09-12 修回日期:2008-02-25 发布日期:2008-05-05
  • 通讯作者: KABIR-UD-DIN E-mail:kabir7@rediffmail.com

Micelle Catalyzed Oxidation of D-Mannose by Cerium(IV) in Sulfuric Acid

KABIR-UD-DIN; ALI Mohd. Sajid; KHAN Zaheer   

  1. Chemistry Department, Aligarh Muslim University, Aligarh 202002, UP, India; Chemistry Department, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
  • Received:2007-09-12 Revised:2008-02-25 Published:2008-05-05
  • Contact: KABIR-UD-DIN E-mail:kabir7@rediffmail.com

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摘要： Kinetics of D-mannose oxidation by cerium (IV) was studied in a sulfuric acid medium at 40 ℃ both in absence and presence of ionic micelles. In both cases, the rate of the reaction was first-order in D-mannose and in cerium (IV), which decreased with increasing [H2SO4]. This suggested that the redox reaction followed the same mechanism. The reaction proceeded through formation of an intermediate complex, which was proved by kinetic method. The complex underwent slow unimolecular decomposition to a free radical that reacted with cerium (IV) to afford the product. The catalytic role of cationic cetyltrimethylammonium bromide (CTAB) micelles was best explained by the Menger-Portnoy model. The study of the effect of CTAB also indicated that a negatively charged species was reactive form of cerium (IV). From the kinetic data, micelle-cerium (IV) binding and rate constants in micellar medium were evaluated. The anionic micelle of sodiumdodecyl sulfate plays no catalytic role. The oxidation has the rate expression:
-d[Ce(IV)]=k1Kc1[D-mannose][Ce(IV)]dt
Different activation parameters for micelle catalyzed and uncatalyzed paths were also calculated and discussed.

关键词: Kinetics, D-Mannose, Cerium(IV), Cationic micelles, Anionic micelles

Abstract: Kinetics of D-mannose oxidation by cerium (IV) was studied in a sulfuric acid medium at 40 ℃ both in absence and presence of ionic micelles. In both cases, the rate of the reaction was first-order in D-mannose and in cerium (IV), which decreased with increasing [H2SO4]. This suggested that the redox reaction followed the same mechanism. The reaction proceeded through formation of an intermediate complex, which was proved by kinetic method. The complex underwent slow unimolecular decomposition to a free radical that reacted with cerium (IV) to afford the product. The catalytic role of cationic cetyltrimethylammonium bromide (CTAB) micelles was best explained by the Menger-Portnoy model. The study of the effect of CTAB also indicated that a negatively charged species was reactive form of cerium (IV). From the kinetic data, micelle-cerium (IV) binding and rate constants in micellar medium were evaluated. The anionic micelle of sodiumdodecyl sulfate plays no catalytic role. The oxidation has the rate expression:
-d[Ce(IV)]=k1Kc1[D-mannose][Ce(IV)]dt
Different activation parameters for micelle catalyzed and uncatalyzed paths were also calculated and discussed.

Key words: Kinetics, D-Mannose, Cerium(IV), Cationic micelles, Anionic micelles