GB325855A - Process for the propylation of ortho-and para-cresol - Google Patents

Abstract

325,855. Rheinische Kampfer-Fabrik Ges. Oct. 12, 1927, [Convention date]. Divided on 298,600. Propyl and isopropyl o- and p-cresols are produced by heating o- or p-cresol with propylene by splitting off water (such as propyl or isopropyl alcohol or ether) in presence of a solid dehydrating catalyst such as aluminium, thorium, or tungsten oxide or aluminium phosphate, alone or supported on carriers such as pumice, kieselguhr, silica gel, or active charcoal. Other suitable catalysts are bleaching earth, Florida, fuller's and silica earths, dried kaolins and brick clays, and the substances sold under the registered Trade Marks " Frankonit " and " Tonsil " (which are probably hydrosilicates of aluminium and magnesium), and mixtures of anv of these substances. The reaction may be effected in the liquid or vapour phase, and pressure such as 2-20 atmospheres may be employed, for instance in an autoclave. When the liquid phase is employed, the catalyst is distributed through the liquid by stirring. In an example o-cresol vapour and excess of propylene are passed at 250-350‹ over alumina, the condensed reaction product being fractionated to obtain the individual compounds, which include (a) " ortho-tnymol " (2-oxy-1-methyl-3-isopropylbenzene) boiling at 225-226‹ whose phenyl urethane melts at 159-160‹ C. ; (b) " alpha-metaisocymophenol " (2-oxy-1-methyl - 3 - isopropylbenzene) boiling at 231‹ C., whose benzoyl compound melts at 73‹ C.; (c) a small quantity of carvacrol which forms a phenyl-urethane of melting point 140‹ C.; these compounds being obtainable by forming and then saponifying the derivatives mentioned. A mixture of dipropyl o-cresols remains as a residue in the still. In another example p-cresol vapour and propylene are passed over thorium oxide alone or upon pumice, or of aluminium phosphate on active charcoal, or brick clay or fuller's earth in pieces, the product being fractionated to obtain " parathymol " (4-oxy-1-methyl-3-isopropyl-benzene), a small quantity of 4 - oxy - 1 - methyl-2-isopropylbenzene, and a residue in the still consisting of depropylated p-cresols. The Specification as open to inspection under Sect. 91 (3) (a) states that acids and anhydrides such as sulphuric, phosphoric and sulphonic acids and phosphoric anhydride and also anhydrous zinc and magnesium chlorides may be used as the catalyst. This subject-matter does not appear in the Specification as accepted.