Patent GB-944136-A (GB)
Title: Preparation of alkenyl succinic anhydrides
IPC: C08F8/46
Filed: 1962-06-25
Abstract: An alkenyl succinic anhydride is produced by reacting a polyolefine, formed from a C2 to C4 olefine, and having an average molecular weight in the range 200 to 2000, with maleic anhydride at a temperature in excess of 400 DEG F. and under a pressure less than the vapour pressure of liquid maleic anhydride at said temperature, and converting any maleic acid impurity in the reaction system to readily filterable fumaric acid by reducing the reaction temperature to 380 to 350 DEG F. for a period of time sufficient to isomerize substantially completely the maleic acid to fumaric acid. Polyisobutenyl succinic anhydride is produced by reacting polyisobutene with maleic anhydride, the mol ratio of maleic anhydride to polyisobutene being 0.3 to 2.  Maleic anhydride is continuously distilled from the reactor and is collected in an overhead condenser and may be pumped back to the reactor. When the desired extent of the reaction is reached or when the maleic acid content (formed by maleic anhydride reacting with any moisture present) of the maleic anhydride has reached a critical level, all the maleic anhydride collected overhead is pumped into the reactor, the temperature of which is reduced to 380 to 350 DEG F., to isomerize the maleic acid to fumaric acid, this taking 1 1/2 to 3 hours. Any remaining maleic anhydride is stripped off and the stripped reaction mixture is diluted with neutral hydrocarbon oil and heated at 190 to 210 DEG F. and then filtered, the filtrate consisting of pure polyisobutenylsuccinic anhydride, being collected. When commercial maleic anhydride is used containing 0.1 to 2% by weight of maleic acid or when the maleic anhydride used is that obtained from a previous operating cycle and contains 2 to 3% by weight of maleic acid, and also in other cases, the isomerization step may be carried out first i.e. before the heating in excess of 400 DEG F.  More than one receiver for the distallation and recycle of excess maleic anhydride may be used.ALSO:An alkenyl-substituted anhydride of succinic acid is prepared by reacting a polyolefine, formed from a C2 to C4 olefine, and having an average molecular weight in the range 200 to 2,000, with maleic anhydride at a temperature in excess of 400 DEG F. and under a pressure less than the vapour pressure of liquid maleic anhydride at said temperature, and converting any maleic acid impurity in the reaction system to readily filterable fumaric acid by reducing the reaction temperature to 380 to 350 DEG F. for a period of time sufficient to isomerize substantially completely the maleic acid to fumaric acid. Polyisobutenyl succinic anhydride is produced by reacting polyisobutene with maleic anhydride, the mol ratio of maleic anhydride to polyisobutene being 0.3 to 2. Maleic anhydride is continuously distilled from the reactor and is collected in an overhead condenser and may be pumped back to the reactor.  When the desired extent of the reaction is reached or when the maleic acid content (formed by maleic anhydride reacting with any moisture present) of the maleic anhydride has reached a critical level, all the maleic anhydride collected overhead is pumped into the reactor, the temperature of which is reduced to 380 to 350 DEG F., to isomerize the maleic acid to fumaric acid, this taking 1 1/2 to 3 hours. Any remaining maleic anhydride is stripped off and the stripped reaction mixture is diluted with neutral hydrocarbon oil and heated at 190 to 210 DEG F. and then filtered, the filtrate consisting of pure polyisobutenylsuccinic anhydride, being collected. If commercial maleic anhydride, which may contain 0.1 to 2% by weight of maleic acid, is used, the isomerization reaction may be carried out first, before the heating in excess of 400 DEG F.  Similarly the isomerization may be carried out first in other cases and also when the maleic anhydride used is that obtained from a previous operating cycle and contains 2 to 3% by weight of maleic acid. More than one receiver for the distillation and recycle of excess maleic anhydride may be used.