Substituted acylating agents and their production

Polybutenyl substituted succinic acylating agents are formed by reacting (a) an acidic reactant represented by the general formulaR - CO - CH = CH - CO - R′ wherein R and R′ are independently -OH, -O-lower alkyl, a halogen atom, or taken together are a single oxygen atom, with (b) a polymer composed mainly or entirely of polyisobutene, at least 50% of the polyisobutene content of the polymer having an end group represented by the formula The mole ratio of acidic reactant : polymer is at least 1 : 1; and the reaction mixture is maintained under superatmospheric pressure during at least a substantial portion of the reaction period. The reaction rate is high, the yields of desired product are high, and despite the fact that superatmospheric pressures and elevated temperatures are used, the process forms only small amounts of tars or resinous co-products, even when employing as much as a 20% or more molar excess of maleic anhydride. Any unreacted acidic reactant such as maleic anhydride, maleic acid, fumaric acid, etc. can be, and preferably is, recovered from the reaction mixture, and thus is available for use either as recycle to the process or for other uses. Inasmuch as chlorine is not used in the process, the expense and difficulties associated with handling chlorine on a plant scale are eliminated, and the product is less corrosive than corresponding products formed by use of chlorine.