GB760040A - Improvements in or relating to method for preparing alkenyl substituted phenolic compounds - Google Patents

Abstract

A mixture of alkenylphenols containing at least 50 per cent by weight of monoalkenylphenols is prepared by reacting together a phenolic compound having at least one replaceable nuclear hydrogen atom and an acyclic conjugated diene in an amount such that there is at least a mol. of diene for each mol. of phenolic compound, and in the presence of a Friedel-Crafts catalyst comprising acids which are proton donors and have a room temperature acidity function (Ho), as determined by the use of Hammett indicators, of -4.0 to -7.5. For the determination of Ho values, see Hammett, Deyrup and Paul, J.A.C.S., 54, 2721-38 (1932), and Hammett and Paul, J.A.C.S., 56, 827-9 (1934). Sulphuric acid of 65 to 75 per cent concentration, mixtures of phosphoric and sulphuric acids, mixtures of phosphoric and polyphosphoric acids, and hydrofluoric acid have Ho values between -4.0 and -7.5. The product is mainly a mixture of monoalkenyl phenols with minor amounts of polyphenols, ethers, polyalkyphenols, and polymers. Specified phenols are phenol, cresols, catechol, resorcinol, butyl resorcinol pyrogallol, phloroglucinol, tert - butyl - catechol, beta - naphthol, nitro-phenols, aminophenols, halophenols, polyhalophenols, halogen substituted nitrophenols, guaiacol, 3:5- and 2:3-dimethoxyphenols, bis - (4 - hydroxyphenyl) - 2:2 - propane, 4:41 - dihydroxybenzophenone, bis - (4-hydr oxyphenyl) - 1 - ethane, and bis - (4- hydroxy - 2-methylphenyl) - 2:2 - propane. In the case of polynuclear phenols one alkenyl radical is attached to each phenolic nucleus. Specified acyclic conjugated dienes are butadiene-1:3, 2 - methyl - butadiene - 1:3, piperylene, 2:3 - dimethyl - butadiene - 1:3, 2 - or 4-methyl - pentadiene - 1:3, hexadiene - 1:3 or - 2:4, 2-neopentenyl-butadiene-1:3, 2-chloro-or bromo- or -iodo-butadiene-1:3, 2-chloro-or bromo- or iodo-3-methyl-butadiene-1:3, and 1-bromo- or -fluoro-2-methyl-butadiene-1:3. Preferred reactants are monohydric phenols and dienes free of tertiary double bonds (i.e. a double bond attached to a carbon atom which is bonded to 3 carbon atoms). The amount of catalyst used is preferably between about 5 and 50 per cent by weight of the phenol. An inert solvent such as hexane, heptane, toluene or xylene may be used in the reaction which is effected by mixing the reactants for 4 to 16 hours at the desired temperature, then removing the catalyst and recovering the products by fractional distillation. The reaction may also be carried out at sub- or super-atmospheric pressures. The products are used in the preparation of resins and polymers. In examples, phenol and butadiene-1:3 are reacted using various catalysts and conditions as described above to give products which are mainly ortho- and parabutenylphenol.