Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1987-09-02
1989-07-11
Niebling, John F.
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
20415794, 568361, 568362, 568364, 568403, B01J 1908, C07C 4529, C07C 4530
Patent
active
048469459
ABSTRACT:
Oxidation of alcohols to ketones using bromine suffers from a side reaction of comparable speed in which a bromide substituted product is formed. Additionally, the use of bromine as reagent is relatively unpleasant and it creates a major waste disposal problem.
The latter problem can be solved by generating bromine in situ by reaction between hydrogen peroxide and bromide ions or hydrogen bromide, but this inevitably increases the exposure of the alcohol to HBr/Br.sup.-. The selectivity of the process towards non-substituted oxidation depending upon the inherent deactivation or reactivity of the alcohol can be improved by irradiating the reactants with light of suitable frequency to generate bromine radicals in the mixture, and/or by controlling the rate of introduction of the hydrogen peroxide and controlling the extent to which mole ratio of HBr:alcohol is substoichiometric. Selectivity can also be improved by employing a two-phase reaction mixture, the alcohol being present to a considerable extent in the organic phase with HBr/Bromide being retained to a great extent in the aqueous phase.
It is particularly beneficial for the selective oxidation of alcohols that are substituted by adjacent electronegative groups, for example chloropropanols.
REFERENCES:
patent: 2674572 (1954-04-01), Gundel
patent: 3701722 (1972-10-01), Heckert
patent: 3985808 (1976-10-01), Gutieriez
Venkatasubramanian, N., et al., "The Mechanism of Oxidation of Alcohols by Bromine", Dept. of Chemistry, Vivekanada College, Mylapore, Madras-4, India, pp. 1171-1714.
Swain, C. Gardner, et al., "Use of Substituent Effects on Isotope Effects to Distinguish between Proton and Hydride Transfers, Pt. I. Mechanism of Oxidation of Alcohols by Bromine in Water", Oxidation of Alcohols by Bromine in Water, Apr. 20, 1961, vol. 83, pp. 1945-1950.
Deno, N. C., et al., "The Mechanism of Oxidation of Alcohols by Aqueous Bromine", Journal of the American Chemical Society, 89:14/Jul. 5, 1967, pp. 3355-3356.
Barker, I. R. L., et al., "The Oxidation of Cyclohexanol and Related Compounds with Bromine", J. Chem. Soc., 1964, pp. 3263-3267.
Jeff Martin
Routledge Vincent I.
Turner Philip J.
Hsing Ben C.
Interox Chemicals Limited
Niebling John F.
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