For example, esters formed by reaction of the maleic anhydride abducts with polyols such as pentaerythritol may be esterified further e.g. with carboxylic acids, anhydrides, acyl halides or anhydrides to introduce different ester groups, or with inorganic compounds e.g. acids such as boric acid, phosphoric acid, sulfonic acid or substituted acids of these types, to produce borated, phosphorylated