Patent GB-598988-A (GB)
Title: Improvements in the manufacture of phenolic compounds
IPC: C07C37/50
Filed: 1945-07-30
Abstract: Catalysts for the conversion of non-aromatic monocyclic ketones to phenols consist of an absorptive alumina (preferably alumina a-monohydrate or g -alumina or mixtures thereof) containing a minor proportion (e.g., 1-10 per cent.) of an alkaline-earth metal or a compound thereof, preferably a compound of calcium or barium, though strontium and magnesium are also mentioned.  The absorptive alumina may be prepared by careful dehydration (e.g., to a water content of 7-12 per cent.) of a hydrated alumina, preferably alumina trihydrate crystallized from alkali aluminate solutions. The alkaline-earth metals are preferably incorporated in the form of their compounds, e.g., oxides, peroxides, nitrates, carbonates, silicates, aluminates or carboxylic acid salts (such as formates or oxalates), some of these compounds (e.g., silicates) remaining as such whilst some (e.g., nitrates) are decomposed to other compounds when heated.  The incorporation may be effected by impregnation of the alumina with an aqueous solution of the alkaline-earth metal compound, followed if desired, by heating, e.g., to convert nitrates to oxides.  The catalysts may be employed in any suitable form, e.g., granules, pellets or powders. The catalysts are easily regenerated when necessary, e.g., a catalyst consisting of alumina a-monohydrate and some g -alumina, with the addition of calcium, is regenerated by passing over it at about 700 DEG C. a mixture of equal quantities of air and nitrogen until all carbon present in it is burned. Specification 588,099, [Group IV], is referred to.ALSO:Phenolic compounds are manufactured by contacting the vapours of non-aromatic monocyclic ketones, containing six carbon atoms in the nucleus, a ketonic oxygen atom linked to one of the nuclear carbon atoms and two alkyl groups in the 5-position and one in the 3-position, with an adsorptive alumina containing a minor proportion (e.g. 1-10 per cent) of an alkaline-earth metal or a compound thereof at 400-700 DEG  C., preferably in the presence of steam.  Preferably the ketone contains at least one double hood in the nucleus but has a hydrogen atom attached directly to a saturated carbon atom adjacent to the carbonyl group, as in isophorone and its homologues.  The catalysts may be in any suitable form, e.g. granules, pellets or powder, and may consist of activated aluminas of the kinds described in Specification 588,099 with the addition of the alkaline-earth metals or compounds thereof, e.g. oxides, peroxides, nitrates, carbonates, silicates, aluminates or carboxylic acid salts (such as formates or oxalates) of calcium or barium (preferred) or of strontium, or mixtures thereof, some of these compounds (e.g. silicates) remaining as such whilst some (e.g. nitrates) are decomposed to other compounds when subjected to high temperatures.  The space velocity (gram-molecules of ketone per litre of catalyst per hour) may be from about 5 to about 100, preferably about 25-50 at temperatures of about 450-600 DEG  C.  The reaction may be effected at any suitable pressure and in a batch, intermittent or continuous manner.  In examples, isophorone is connected to phenols consisting mainly of 3 : 5-dimethylphenol by: (1) passing it at a space velocity of 25 with steam at 50 over a mixture of alumina a -monohydrate and some g -alumina with (and, for comparison, without) the addition of calcium, at about 500 DEG  C.; (2) substituting barium for calcium in the catalyst of (1); (3) doubling the space velocities in (1), the calcium being present as oxide), and working at about 550 DEG  C.; (4) using a catalyst containing a higher proportion of calcium, introduced in the form of nitrate, and working at about 525 DEG  C.; (5) using in (3) an activated alumina containing calcium, at 525 DEG  and at 550 DEG  C. (and, for comparison, an activated alumina containing sodium, at 525 DEG  C.); (6) passing the isophorone at a space velocity of 50 with steam at 150 over a catalyst consisting mainly of g -alumina with (and, for comparison, without) the addition of calcium, at 550 DEG  C.; (7) working as in (4) and repeatedly regenerating the catalyst by treatment with a mixture of equal quantities of air and nitrogen at 700 DEG  C.; (8) using calcium aluminate as catalyst in (1); (9) replacing the calcium in (7) by magnesium (as oxide).  In a further example, (10) dihydroisophorone is passed at a space velocity of 25 with steam at 100 over a catalyst consisting mainly of alumina a -monohydrate with the addition of calcium, at about 525-550 DEG  C. Additional starting materials specified are hydroxyisophorone (which likewise yields mainly 3 : 5-dimethylphenol), homoisophorones (which yield homologues thereof such as 3 : 5-diethylphenol), compounds in which the methyl groups of isophorone are replaced by other alkyl groups such as ethyl, n-propyl, isopropyl, n-butyl, isobutyl or amyl (which yield corresponding 3 : 5-dialkylphenols), and compounds further substituted in the nucleus by unsaturated side chains, hydroxy groups or halogen atoms.  The steam may be replaced by other inert gases or vapours, e.g. nitrogen.