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Kinetic Studies on the Selective Oxidation of Benzyl Alcohols in Organic Medium under Phase Transfer Catalysis

1Department of Chemistry, N. S. S. College, Manjeri, Malappuram, Kerala - 676122, India

2Department of Chemistry, University of Calicut, Kerala - 673635, India

Received: 16 Mar 2014; Revised: 18 May 2014; Accepted: 18 May 2014; Available online: 27 Jul 2014; Published: 30 Aug 2014.
Editor(s): Istadi Istadi
Open Access Copyright (c) 2014 by Authors, Published by BCREC Group
Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
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Abstract
Kinetic studies on the oxidation of benzyl alcohol and substituted benzyl alcohols in benzene as the reaction medium have been studied by using potassium dichromate under phase transfer catalysis (PTC). The phase transfer catalysts (PT catalysts) used were tetrabutylammonium bromide (TBAB) and tetrabutylphosphonium bromide (TBPB).  Benzyl alcohols were selectively oxidised to corresponding benzaldehydes in good yield (above 90%).  The order of reactivity among the studied benzyl alcohols is p - OCH3 > p - CH3 > - H > p - Cl.  Plots of log k2 versus Hammett's substituent constant (s) has been found to be curve shaped and this suggests that there should be a continuous change in transition state with changes in substituent present in the substrate from electron donating to electron withdrawing. A suitable mechanism has been suggested in which the rate determining step involves both C - H bond cleavage and C - O bond formations in concerted manner.  © 2014 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)
Keywords: Benzyl alcohols; Kinetics; Phase transfer catalysis; Phase transferred monochromate; Selective oxidation

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  1. Wiberg, K. B. (1965). Oxidation in Organic Chemistry. Academic Press, London and New York
  2. Lee, D. G. (1980). Oxidation of Organic Compounds by Permanganate ion and Hexavalent Chromium , Open Court: La Salle
  3. Bijudas, K., Radhakrishnan Nair, T.D. (2004). Selective oxidation of benzyl alcohol with monochromate in non – polar solvents. Indian Journal of Chemistry. 43A: 1216-1218
  4. Basheer, M.K., Joseph, J., Nair, T.D.R. (2007). Catalysis by onium salts on the monochromate oxidation of benzhydrols in non polar media – A kinetic study. Indian Journal of Chemistry. 46A: 273-275
  5. Bijudas, K., Radhakrishnan Nair, T.D. (2014). Kinetics and mechanism of the selective oxidation of primary aliphatic alcohols under phase transfer catalysis. Current Chemistry Letters. 3(2): 109-114, doi: 10.5267/j.ccl.2013.12.001
  6. Pletcher, D., Tait, S.J.D. (1979). A procedure for the oxidation of alcohols to aldehydes based on phase transfer catalysis. Journal of the Chemical Society, Perkin Transactions 2. 6: 788-791
  7. Pletcher, D., Tait, S.J.D. (1978). The oxidation of alcohols and aromatic hydrocarbons by dichromate in two phase systems. Tetrahedron Letters. 18: 1601-1602
  8. Perrin, D.D., Armarego, W.L., Perrin, D.R. (1966). Purification of organic compounds, Oxford: Pergamon Press
  9. Starks, C.M., Liotta, C.L. (1978). Phase Transfer Catalysis, Principles and Techniques, Academic Press: New York
  10. Exner, O. (1964). On the enthalpy- entropy relationship. Collection of Czechoslovak Chemical Communications. 29: 1094 -1113
  11. Exner, O. (1964). Concerning the isokinetic relationship. Nature, 201: 488-490, doi: 10.1038/201488b0
  12. Woodword, R.B., Hoffmann, H. (1969). The conservation of orbital symmetry. Angewandte Chemie International Edition in English. 8: 781-932
  13. Banerji, K.K. (2013). Structure-reactivity correlation in the oxidation of substituted benzyl alcohols by imidazolium flourochromate. European Chemical Bulletin. 2(10): 816-824
  14. Banerji, K.K. (1988). Oxidation of substituted benzyl alcohols by pyridinium fluorochromate: a kinetic study. Journal of Organic Chemistry. 53: 2154-2159
  15. Beattie, J.K., Haight, G.P.Jr. (1972). Chromium (IV) oxidation of inorganic substrates. Progress in Inorganic Chemistry: Inorganic reaction mechanism: Part II, 17: 93-145
  16. Wiberg, K.B., Schafer, H. (1969). Chromic acid oxidation of isopropyl alcohol. Preoxidation equilibria. Journal of American Chemical Society. 91: 927- 932
  17. Bordwell, F.G. (1974). How common are base-initiated, concerted 1,2 eliminations. Accounts of Chemical Research. 5: 374 – 384
  18. Littler, J.S. (1971). Oxidation of olefins, alcohols, glycerols and other organic compounds, by inorganic oxidants such as chromium(VI), manganese(VII), iodine(VII), lead(IV), vanadium(V) and halogens, considered in the light of the selection rules for electrocyclic reactions. Tetrahedron. 27: 81-91

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