Effect of acetonitrile on stability of disperse phase of solutions of alkenylsuccinic anhydride in xylene

Abstract

This article reports on work directed toward accelerating the alkenylsuccinic anhydride (ASA) solution cleanup operation by the use of acetonitrile. ASA is an intermediate in the production of the widely used ashless succinimide additives for motor oils. The byproducts that are formed in ASA production, finely dispersed tarry precipitates with a complex composition, contaminate the end product. The stability of the dispersed system in a solution of the ASA in xylene (1:1) was evaluated from the rate at which the tarry products settled out, with and without the addition of acetonitrile, as determined by measurements of the height of the column of clarified liquid as a function of the settling time. The results indicate that acetonitrile, which is highly polar, reduces the stability of the dispersed phase in the ASA solution by a factor of 1.5-2. It is recommended that the quantity of acetonitrile added to the ASA solution should not be greater than 12% by weight, since with larger amounts, the ASA forms a new phase because of its limited solubility in the mixture of xylene and acetonitrile. Acetonitrile does not require any additional equipment, and it does not give any difficulty in the subsequent operation of stripping themore » solvent from the purified ASA, as the acetonitrile has low boiling point (81.6/sup 0/C) and has a good solubility in xylene.« less