| 摘要 |
A condensation product containing a free phenolic hydroxy group and obtainable by condensing dicyclopentadiene at a temperature not exceeding 150 DEG C. with a phenol, the nucleus of which is unsubstituted or is substituted by halogen atoms, or alkyl or alkoxy groups, at least one of the 2-, 4-, and 6-positions being unsubstituted, is used as an antioxidant for natural or synthetic rubber compositions (see Division C3). Preferably, one molecular proportion of phenol is condensed with one molecular proportion of dicyclopentadiene. Specified phenols include o-, m-, and p-cresol, 2.4-dimethyl phenol, p-chlorophenol, and mixtures thereof. The condensation is carried out under conditions such that the dicyclopentadiene does not polymerize. Preferably, a Friedel-Crafts catalyst such as boron trifluoride, or a complex containing boron trifluoride is present. If desired the desired product may be obtained in two stages, the first comprising condensation of the phenol with the dicyclopentadiene to form an ether, and the second comprising isomerisation of the ether to form the free phenolic condensation product. In an example, dicyclopentadiene is run dropwise into a solution of p-cresol in toluene containing as catalyst a complex of boron trifluoride and acetic acid. The temperature is raised to and maintained at 45 DEG C. for 4 hours. Water is added and the toluene layer is poured off, washed and dried. The toluene is driven off and the residue is distilled and fractionated. The compound 2-dicyclopentenyl-4-methyl-phenol is obtained. The compound p-tolyl dicyclopentenyl ether is also obtained. The ether compound is isomerised to form the phenolic compound by dissolving it in toluene and heating for 4 hours at 40 DEG C. in presence of a BF3 catalyst. Other examples are given. |
