Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1996-03-26
1998-01-06
Ivy, C. Warren
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568420, C07C 4527
Patent
active
057057052
DESCRIPTION:
BRIEF SUMMARY
This is the US National Stage Application of PCT/GB94/02080 filed Sep. 26, 1994 now WO95/09139 published Apr. 6, 1995.
This invention concerns a process for the oxidation of alkylaromatic compounds. More specifically, this invention concerns a catalysed process for the oxidation of alkylaromatic compounds with peroxygen compounds.
The oxidation of alkylaromatic compounds is a desirable reaction in organic chemistry because it permits the conversion of a readily available organic substrate having only limited reactivity into a compound including more reactive functional groups and hence having greater reactivity. Oxidation of alkylaromatic compounds commonly involves the oxidation of an alkyl hydrogen which requires the use of a relatively strong oxidant. It is therefore readily apparent that such an oxidant can often readily be employed for the oxidation of other more easily oxidised functional groups such as alcohols.
Many systems have been proposed for carrying out the oxidation of alkylaromatic compounds, including the use of transition metal oxides such as manganese dioxide, potassium permanganate and chromium oxide, and other oxidants such as organic peracids and air or gaseous oxygen. One particularly desirable oxidant that has been employed comprises an aqueous solution of hydrogen peroxide. In order to successfully employ hydrogen peroxide in the oxidation of alkylaromatic compounds it is often necessary to employ some other component such as a catalyst, for example, cobalt species, or a co-reagent, such as hydrogen bromide. However, it remains desirable to identify alternative and further oxidation systems for the oxidation of alkylaromatic compounds.
The oxidation of an alkylaromatic can be regarded as proceeding via a number of stages i.e. alkyl.fwdarw.alcohol.fwdarw.carbonyl compound.fwdarw.carboxyl compound (if appropriate). In addition, the presence of additional reagents may lead to the formation of other compounds, for example mono- and/or di-brominated species in the case of a bromide co-reagent. These compounds can sometimes be easily oxidised and/or hydrolysed to produce alcohols, carbonyl or carboxyl compounds. It will be recognised that once an alcohol or carbonyl compound, especially an aldehyde has been formed, the oxidising conditions can often result in this compound being further oxidised. For this reason, it is often difficult to halt the oxidation at one of the intermediate oxidation products, and on account of this, such intermediate compounds can command a premium price. It would therefore be desirable to identify an oxidation system for alkylaromatic compounds that was effective at producing such intermediate products and/or which produced compounds that could be conveniently converted to such intermediate compounds.
It is an object of the present invention to provide an alternative and further system for the oxidation of alkylaromatic compounds.
It is a further objective of at least some embodiments of the present invention to provide a process for the oxidation of alkylaromatic compounds that is effective at producing intermediate oxidation products and/or which produces compounds that can be conveniently converted to such intermediate compounds.
According to the present invention, there is provided a catalysed process for the oxidation of alkylaromatic compounds with a peroxygen compound in a reaction medium, characterised in that the catalyst comprises a source of cerium (III) or (IV), the reaction medium comprises a source of bromide ions and a solvent selected from the group consisting of carboxylic acids and anhydrides, and the alkylaromatic compound comprises an alkyl hydrogen atom, and optionally a hydroxyl group, bonded to the carbon alpha to the aromatic ring.
According to a second aspect of the present invention, there is provided a process for the selective oxidation of methylaromatic compounds to aldehydes with a peroxygen compound in a reaction medium, characterised in that the catalyst comprises a source of cerium (III) or (IV), and the reaction medium compris
REFERENCES:
Ma, Jianwei et al; "Controlled oxidation of toluene to oxygen-containing compounds"; (J. Shiyou Huagong; 21(4), 228-31 (1992).
Yazu Kazumasa et al; Chemical Abstracts;vol. 112;219165x (J. Chem. Soc., Japan, (1), 92-96 (1990).
Auty Kevin
Brown Scott William
Ivy C. Warren
Padmanabhan Sreeni
Solvay Interox Limited
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