Products from Electrophilic and Nucleophilic Substitution

Whilst arguably, the formaldehyde condensation reactions in the preceding section are, under acidic conditions, electrophilic in type, a considerably wider range of compounds result from the commercially available C4, Cg, and Cg alkylphenols with a variety of reactants in other electrophilic substitution reactions. Thus 2,6-di-tert-butylphenol condensed with formaldehyde in hydrochloric acid gives 3,5-di-tert-butyl-4-hydroxybenzyl chloride which can be utilised in an Arbuzov reaction with trialkylphosphites to afford the dialkyl phosphonate depicted (ref. 80). The diethyl ester (Irganox 1222, Ciba-Geigy Ltd.) in this series is a significant stabiliser for polyester fibres in the prevention of photo and oxidative deterioration. 

A related type of initial reaction has been employed in the thio series. For example, nonylphenol in toluene containing 4-toluenesulphonic acid and dodecylthiol upon treatment with aqueous formaldehyde and reaction at 135-140°C with azeotropic removal of water afforded a reaction product probably 

Bis-phenol monosulphides and disulphides resulting from the reaction of 4-alkylphenols writh sulphur monochloride and with sulphur dichloride are of importance in the form of their calcium, barium, magnesium salts as lubricating oil additives although their place has been partly displaced by the alkoxyphosphorodithioates. Thus 4-tert-nonylphenol and 4-tert-octylphenol, afford 2,2 -thiobis products (R = t-CgHig and t-CgHi repectively (ref. 82). 

2-tert-Butyl-4-methylphenol reacts similarly and the isomer 2-tert-butyl-5-methylphenol due to steric hindrance gives a 4,4 -thiobis final product (ref. 83) which is valuable as an antioxidant for polythene. 

The bisphenol from 4-tert-octylphenoi forms a nickel(ll) complex which has useful properties as a light stabiliser (ref.84). 

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