Patent GB-741446-A (GB)
Title: Improvements in or relating to cyclopentenyl phenols
Filed: 1953-06-23
Abstract: Resinous polymeric materials are made by reacting a phenol and a cyclopentadiene, or a polymer thereof which decomposes to form a cyclopentadiene, in the presence of a Friedel-Crafts catalyst, at a temperature above 200 DEG  C., the amount of catalyst being at least 1/2 per cent by weight of the phenol reacted.  Suitable catalysts include aluminium chloride, ferric chloride, antimony pentachloride, boron trifluoride, zinc chloride, titanium tetrachloride, hydrofluoric acid, sulphuric acid, phosphoric acid, phosphorus pentoxide, stannic chloride, bismuth chloride and tellurium di- and tetrachlorides.  Specified phenols are phenol itself; alkylated phenols such as the cresols and butyl resorcinols; substituted phenols such as the nitrophenols, aminophenols, halogenated phenols, halogenated nitrophenols, guaiacol, 2 : 3-dimethoxyphenol and 3 : 5-dimethoxyphenol and phenols containing more than one hydroxyl group such as catechol, resorcinol, pyrogallol and phloroglucinol.  In an example phenol is reacted with dicyclopentadiene in the presence of phosphoric acid at a temperature above 200 DEG  C. to give a resin.ALSO:The invention comprises cyclopentenyl phenols having two or three cyclopentenyl groups attached to a phenol residue, and comprises also a method for preparating cyclopentenyl phenols in general, by reacting a phenol with a cyclopentadiene, or a polymer thereof which decomposes to form a cyclopentadiene, in the presence of a Friedel-Crafts catalyst, preferably at a temperature between - 20 DEG  and 200 DEG  C.  By carrying out the reaction at 100 DEG  to 200 DEG  C. in the presence of less than 5 per cent by weight of catalyst the formation of an ortho-cyclopentanylphenol is favoured; reaction at 0 DEG  to 50 DEG  C. in the presence of 5 to 100 per cent of catalyst favours the formation of a paracyclopentenyl phenol, while reaction at 0 DEG  to 50 DEG  C. in the presence of less than 5 per cent of catalyst gives di- and tricyclopentenyl phenols as the major product.  Suitable catalysts include aluminium chloride, ferric chloride, antimony pentachloride, boron trifluoride, zinc chloride, titanium tetrachloride, hydrofluoric acid, sulphuric acid, phosphoric acid, phosphorus pentoxide, stannic chloride, bismuth chloride and tellurium di- and tetrachlorides.  Specified phenols which may be reacted comprise phenol itself; alkylated phenols such as the cresols and butyl resorcinols; substituted phenols such as the nitrophenols, aminophenols, halogenated phenols, halogenated nitrophenols, guaiacol, 2 : 3-dimethoxyphenol and 3 : 5-dimethoxyphenol and phenols containing more than one hydroxyl group such as catechol, resorcinol, pyrogallol and phloroglucinol.  The products may be hydrogenated in the presence of a catalyst to give the corresponding cyclopentyl phenols.  Para - (D 2 - cyclopentenyl)phenol may be converted to para - (D 1 - cyclopentenyl) phenol by isomerization in the presence of a catalyst such as palladium or sulphur.  In examples: (1) phenol is reacted with cyclopentadiene in the presence of a large amount of phosphoric acid at below 50 DEG  C. to give paracyclopentenylphenol, characterized by its paranitrophenylurethan derivative and a minor amount of di- and tri-cyclopentenylphenols; (2) phenol is reacted with cyclopentadiene at below 50 DEG  C. in the presence of a small percentage of phosphoric acid to give di- and tricyclopentenyl phenols with a minor amount of ortho- and para-cyclopentenyl phenol; (3) phenol is reacted with dicyclopentadiene in the presence of a small amount of phosphoric acid at a temperature of 150 DEG  to 170 DEG C. to give orthocyclopentenyl phenol, characterized by its para-nitrophenylurethan derivative, together with a mixture of di- and tri-cyclopentenylphenols and cyclopentanediphenols and polyphenols; (4) para-cresol is reacted with cyclopentadiene by the method of (1) to give 2-cyclopentenyl-para-cresol; and (5) guaiacol is reacted with cyclopentadiene by the method of (1) to give a cyclopentenyl substituted guaiacol.  In these examples the phenol may be replaced by an alkyl, alkoxy, nitro or chlorine substituted phenol or by a polyhydroxy phenol and the cyclopentadiene in example (1) may be replaced by methylcyclopentadiene or chlorocyclopentadiene to produce the corresponding substituted products.