Selective heteroaromatic nitrogen base promoted chromium(VI) oxidation of isomeric pentanols in aqueous micellar media at room temperature

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• 作者：Pintu Sar^a ; Aniruddha Ghosh^a ; Susanta Malik^a ; Dhiman Ray^b ; Bijan Das^b ; Bidyut Saha^a ; ^{b_saha31@rediffmail.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Pentanol ; Chromium(VI) ; Valeraldehyde ; Metal-organic conjugate ; Surfactant
• 刊名：Journal of Industrial and Engineering Chemistry
• 出版年：2016
• 出版时间：25 October 2016
• 年：2016
• 卷：42
• 期：Complete
• 页码：53-62
• 全文大小：2010 K

文摘

Oxidation of the three isomeric pentanols by potassium dichromate in aqueous acidic medium was investigated spectrophotometrically at 25 °C. The oxidation leads to the formation of corresponding carbonyl products as identified by ¹H NMR measurement and other techniques. The effects of cationic (cetylpyridinium chloride, CPCl), anionic (sodium dodecylsulphate, NaDS) and nonionic surfactant (polyoxyethylene octyl phenyl ether, TX-100) on reaction kinetics were studied. Moreover the catalytic effect of surfactant in presence of three heteroaromatic nitrogen bases: 2-picolinic acid (2-PA), 2,2′-bipyridyl (2,2′-bipy) and 1,10-phenanthroline (1,10-phen) on the oxidation were also investigated. The value of the rate constant in promoted and unpromoted reaction has been found to be higher in NaDS than in TX-100 and CPCl micellar medium. Conductivity and tensiometry measurements were carried out to determine critical micellization concentration and free energy of micellization (ΔG_m°) of the used surfactant in presence of three pentanols. Among the different surfactant and promoter the combination of 2,2′-bipy and NaDS is efficient to exhibit ∼1000 fold rate enhancement for oxidation of 1-pentanol and it is ‘selective’ over the rest of two pentanols oxidation.