Discoloration prevention of phenolic antioxidants

In a process of preparing phenolic antioxidants which comprises (1) reacting one mole of at least one phenolic reactant having the following structural formula:

• ##STR7## wherein R is selected from the group consisting of hydrogen, alkyl radicals having from 1 to 20 carbon atoms, cycloalkyl radicals having from 6 to 20 carbon atoms, and aralkyl radicals having from 6 to 20 carbon atoms, with (2) at least one tertiary olefin having from 4 to 9 carbon atoms at a temperature of from 50.degree. C. to 150.degree. C. in the presence of a catalyst;
• then (3) the catalyst is neutralized with an aqueous solution and (4) the reaction mixture is heated under vacuum to remove volatiles and filtered hot;
• the improvement is characterized in that (A) 0.01 to 5 percent by weight of at least one hydroxylamine selected from general formulae (I) and (II). ##STR8## wherein R.sub.1 and R.sub.2 are the same or different radicals selected from the group consisting of alkyl radicals of 1 to 18 carbon atoms;
• and R.sub.3, R.sub.4 and R.sub.5 are the same or different radicals selected from the group consisting of hydrogen and alkyl radicals of 1 to 8 carbon atoms;
• is added to the solution used to neutralize the catalyst and (B) prior to filtration 0.01 to 5 percent by weight of a substituted oxime of the structural formula (III):
• ##STR9## wherein R.sub.1 and R.sub.2 are defined as above is added to the reaction mixture together with an additional 0.01 to 5.0 percent by weight of at least one hydroxylamine selected from formulae (I) and (II);
• to yield a phenolic antioxidant with improved color and color stability.