Patent ID: 7189875

Claim:
An alkylated diphenylamine of the general formula: wherein R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of hydrogen, oligomers of isobutylene, and oligomers of propylene, provided that at least one of R 1 , R 2 , R 3 , and R 4 is not hydrogen, prepared by a process comprising adding to a diphenylamine a mixture of oligomers of isobutylene or a mixture of oligomers of propylene in which said mixtures comprise highly reactive fractions, as well as fractions having lesser reactivity, in the presence of an acidic clay catalyst at a temperature low enough to prevent substantial deactivation of the catalyst until the addition is complete and then increasing the temperature to increase the alkylation rate of the less reactive fractions to yield a product that comprises 0.1 to 1% diphenylamine, <10% tert-butyl diphenylamine, <10% di-tert-butyl diphenylamine, <10% mono-octyl diphenylamine, >20% dodecyl diphenylamine, >15% hexadecyl diphenylamine, <10% eicosenyl diphenylamine, <7% tetracosenyl diphenylamine, <4% octacosenyl diphenylamine and <2% polyisobutyl diphenylamine.