1. Field of the Invention
This invention is directed to an improved method for preparing alkenyl-substituted succinic anhydrides.
Alkenyl-substituted succinic anhydrides are valuable intermediates for the production of products which have a wide range of uses. For example, the acids and the anhydrides are useful as rust inhibiting agents in mineral and synthetic lubricating oils and in paint and other protective coating compositions. The reaction products of alkenylsuccinic anhydrides with amines results in the production of alkenyl-substituted succinamic acids and succinimides and provides products which have valuable friction modifying and detergent-dispersant properties for lubricating oil compositions.
The alkenylation of maleic anhydride to produce an alkenyl-substituted succinic anhydride particularly with the higher molecular weight olefin polymers is a relatively slow, inefficient process. The art describes many processes for improving the reaction between an olefin polymer and maleic anhydride. One such process involves halogenating the olefin polymer prior to reacting with it maleic anhydride. Many processes for improving this reaction are based on the use of a catalyst promoter. Thus, processes have been proposed which involve the use of a halogenated organic or inorganic catalyst such as a chlorinated or brominated organic or inorganic compound. Another type of promoted process involves the use of a free radical initiator in the process.
2. Description of the Prior Art
U.S. Pat. No. 3,231,587 discloses a process for reacting an aliphatic polymer of a lower metal olefin and maleic anhydride by contacting the reactants at a temperature of above about 140.degree. C. in the presence of about 1 mole of chlorine for each mole of maleic anhydride.
U.S. Pat. No. 3,927,041 discloses a method for preparing an alkenylsuccinic anhydride by reacting a viscous polybutene with an unsaturated aliphatic dicarboxylic acid anhydride in the presence of 1,3-dibromo-5,5-dialkyl-substituted hydantoin.