| 摘要 |
Benzenemonocarboxylic acids having at least one unsubstituted position ortho to the carboxyl group, the optional substituents being phenyl, alkyl, alkoxy, nitro and halogen, are converted in the vapour phase to phenols at a temperature above the boiling or sublimation point of the acid and below that at which destructive carbonization occurs, in presence of oxygen or an oxygen-containing gas and a copper compound as catalyst. An anhydride, salt or ester of the acid may alternatively be used. In examples, benzoic acid was converted to phenol and phenyl benzoate. Specifications 763,738, 824,631, and U.S.A. Specifications Re-issue 24,848, 2,727,926 and 2,852,567 are referred to.ALSO:Catalysts for the conversion of carboxylic acids to phenols comprise a copper compound supported on, e.g., diatomaceous earth, pumice or Al2O3, especially corundum. Co2O3 and salts, oxides or hydrides of Mg, Na, K, Co, Li and Ba may be present, as well as transition metal compounds, e.g. of Zr, Ti, V, Cr, Mo, HF, Mn or the rare earth metals; Sc, Y, Zr, Th and U are also mentioned. The activating metals, as well as Cu, may be present as phosphates, sulphates, selenates, tellurates, carbonates, benzoates or phthalates, although oxides or hydroxides are preferred. Exemplified catalysts contain alpha-alumina supported Cu with Li or "didymium". Specifications 768,738 and 824,631 are referred to. |
