Multifunctional ester-type additives for liquid hydrocarbyl or hydrocarbyloxy fuel

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS A polymeric ester was reacted with thiodipropionic acid in the presence of hydrocarbon solvent at elevated temperatures until water evolution ceased to be observed in a Dean-Stark trap.
The precise nature of the product is not known.
The solvent was then removed by stripping under reduced pressure.
Useful polymeric esters also include those made from dimer acids such as dimerized linoleic acid, dimerized oleic acid and the like, polypropyl succinic anhydrides or acids or other similar acid or acid-generating compositions.
Useful polymeric esters also include those made using other polyols or polyhydric alcohols such as trimethylolpropane or dipentaerythritol or tripentaerythritol or mixtures thereof as the polyol source, or tris(hydroxymethyl)aminomethane.
Typically the polyhydric alcohols include those containing 6 to about 30 carbon atoms and from about 3 to 6 hydroxyl groups.
Useful sulfur-ester generating species include 3,3'-thiodipropionic acid, dithiodipropionic acid, thiodibutanoic acid, similar sulfur-containing acids or anhydrides derived therefrom or mixtures of any, or all of the above or sulfur-containing similar acids containing aliphatic sulfur in the backbone of the acid.
The general scheme of the reaction may be described as follows: ##STR1## Alternatively (3), the sulfur acid, may be reacted directly with (1) the hydrocarbyl anhydride or acid and the reaction product thereof is thereafter reacted with (2) the polyol.
It is to be understood that (1), (2) and (3) may be simultaneously reacted if so desired.
Generally speaking, the polymeric ester is derived from an alkenyl succinic compound, i.
e.
, an alkenyl succinic anhydride or acid.
The alkenyl group can be polypropylene, polybutylene, polypentyl, oligomeric hexenyl, oligomeric oleyl, oligomeric decenes or mixtures of these or similar hydrocarbylene groups.
Preferred is isobutylene succinic anhydride having a molecular weight in the range of about 300 to 3,000, however, the alkenyl moiety may contain from 20 to about 36 carbon atoms or as many as 200 carbon atoms