Patent GB-825599-A (GB)
Title: A process for the preparation of alkylated phenols
Filed: 1958-05-06
Abstract: 2,4,6-Trialkyl phenols are prepared by heating one or more compounds of the general formula <FORM:0825599/IV (b)/1> where R1 is alkyl, R1 is hydrogen or alkyl and R2 is <FORM:0825599/IV (b)/2> or -OCH2R3 (R3 being hydrogen or alkyl), and at least one R1 being hydrogen when R2 is -OCH2R3, in the presence of an alcohol and a base at above about 150 DEG  C. and below the temperature at which substantial decomposition occurs.  The preferred reactants are those where R1 and R3 are hydrogen or alkyl groups containing up to 6 carbon atoms and R1 a secondary or most preferably a tertiary alkyl group.  The alcohol used preferably contains 1-3 carbon atoms, e.g. methanol or isopropanol, and is present in excess, e.g. 10-50 mols. per mol. of reactant.  The basic compound may be any organic or inorganic base and is preferably present in quantities from 0.05 to 15 mols. per mol. of starting material.  The reaction is generally carried out at 175-250 DEG  C. at an autogeneously produced pressure in a reaction time of about 1 to 4 hours.  Hydrogenationdehydrogenation catalysts such as copper may be present in some instances, e.g. if it is desired to work at above 300 DEG  C.  The reactants may be a mixture containing 80-90% of the alkoxyalkyl phenol and 10-20% of the bis-phenolic alkane, such mixtures may be obtained by condensing phenols with aldehydes in the presence of alcohols.  When a bis-phenolic alkane reactant is used the product is homogeneous only when the alcohol used has the same number of carbon atoms and same configuration as the alkylene bridge, when they are different the product contains two different phenols, one having the 4-substituent derived from the alkylene bridge and the other from the alcohol.  In the examples in which sodium hydroxide or methoxide is used the following products are obtained: (1), (2) 2,6-di-tert.-butyl-p-cresol from 2,6 - di - tert. - butyl - 4 - methoxymethyl phenol; (3) 2,6-di-isopropyl-4-methyl phenol from 2,6 - di - isopropyl - 4 - ethoxymethyl phenol; (4) 2,4,6 - trimethyl phenol from 2,6-dimethyl - 4 - methoxymethyl phenol; (5) 2,6-di - tert. - butyl - 4 - ethyl phenol from 2,6 - di - tert. - butyl - 4 - (1 - ethoxyethyl) - phenol; (6) 2,6 - di - isopropyl - 4 - ethyl phenol from 2,6 - di - isopropyl - 4 - (1 - methoxyethyl) - phenol; (7) (1) is repeated in the presence of potassium carbonate, ethylene diamine and tetramethyl ammonium hydroxide; (8), (2) is repeated in the presence of copper; (9), (10) 2,6-di - tert. - butyl - p - cresol from 4,41 - methylene bis - (2,6 - di - tert. - butyl - phenol); (11) 4 - methyl - and 4 - isopropyl - 2,6 - di - tert. - butyl phenol from 4,41-methylene bis-(2,6-di-tert.-butyl phenol); (12) the same mixture as (11) from 2,2-bis-(4-hydroxy-3,5-di-tert.-butyl phenyl)-propane; (13) 2,6-di-isopropyl-p-cresol from 4,41 - methylene - bis - (2,6 - di - isopropyl - phenol); (14) 2,6-di-isopropyl-4-pentyl-phenol and 2,6 - di - isopropyl p - cresol from 4,41 - methylene - bis - (2,6 - di - isopropyl - phenol); (15) (9) is repeated in the presence of potassium carbonate, ethylene diamine and tetramethyl-ammonium hydroxide; (16) 2,4,6-trimethyl phenol and 2,4,6-trimethyl- and 2,6-dimethyl-4-isopropylphenol from 4,41-methylene bis-(2,6-dimethyl phenol).  Specification 814,278 is referred to.