The synthesis of isomeric thiobisphenols, di-(4-hydroxy-2-alk(en)ylphenyI)-sulphide and di-(2-hydroxy-4-alk(en)ylphenyI)sulphide from renewable phenolic lipid

摘要

Thiobisphenols may be prepared by the reaction of 3-pentadecylphenol (hydrogenated cardanol) or 3-undecylphenol (anagigantol) with sulfur dichloride. 3-Pentadecylphenol may be prepared by hydrogenation of cardanol obtained from Anacardium occidentale, while 3-undecylphenol may be prepared by catalytic decarboxylation of anagigantic acid obtained from Anacardium giganteum. These reactions afford a mixture of di-(4-hydroxy-2-alkylphenyl)sulphides and di-(2-hydroxy-4-alkylphenyl)sulphides, in which the former predominates. Suitable solvents include benzene, light petroleum, n-hexane, chloroform and acetonitrile. A catalyst selected from anhydrous aluminium chloride, iron and triphenylphosphine oxide may also be utilised. Thiobisphenols may also be prepared from cardanol and cardanol monoene using this process. The use of other 2-, 3- or 4-alkylphenols is also envisaged. The thio-bisphenols prepared by this process are useful as extreme pressure type additives in lubricating oils as an alternative to such materials prepared from t-octyl or 4-t-nonylphenols from fossil fuel petroleum resources.