Method for producing polyisobutenylphenols

A process for preparing 2-alkylpolyisobutenylphenols and their Mannich adducts, by

• a) contacting at least one 2-alkylhydroxyaromatic compound with a catalytically active amount of a BF3 source which is capable of complex formation with the 2-alkylhydroxyaromatic compound, and alkylating with substantially monoethylenically unsaturated and substantially homopolymeric polyisobutenes having a number average molecular weight Mn of from 150 to 500000 and comprising at least 50 mol %, based on the total number of polyisobutene macromolecules, of terminal double bonds, wherein said BF3 source is at least one member selected from the group consisting of gaseous BF3;
• a BF3 complex with at least one of the 2-alkylhydroxyaromatic compounds of said a) contacting;
• a BF3 complex with a hydroxyaromatic compound which are substantially not alkylated under the reaction conditions of said a) contacting;
• and a mixture of BF3 with an alcohol which comprises less than 2 mol of alcohol per mol of BF3, and
• b) optionally, subjecting the 2-alkylpolyisobutenylphenols obtained in said a) contacting to an aminoalkylation wherein the alkylating is carried out in the absence of any BF3 complex of any of an aliphatic ether, a dicycloalkylether, tetrahydrofuran, a phenol, an arylalkyl ether or a BF3 complex with an aliphatic alcohol that comprises two or more mols of alcohol per mol of BF3.