Abstract: Derivatives of C-076 compounds are described in which the C-076 molecule, a series of macrolides, has the 23-hydroxy group thereof oxidized to the 23-keto group. The 23-keto compounds are prepared by selectively oxidizing the suitably protected 23-hydroxy compound using such oxidizing agents as pyridinium dichromate, chromic acid-dimethyl pyrazole, chromic acid, chromic acid-acetic acid, and the like. Alternatively, selective oxidation of the unprotected 23-hydroxy compound may be accomplished by placing the compound in soil. Further reaction of the oxidized C-076 compounds is also possible. The compounds thus produced have profound anthelmintic, insecticidal, ectoparasiticidal, and acaricidal activity. Compositions containing the described C-076 derivatives as the active ingredient thereof are also disclosed.

Abstract: Process for purification of crude pyromellitic acid dianhydride produced by vapor phase oxidation of 1,2,4,5-tetraalkylbenzene with an oxygen-containing gas, having a purity of more than about 95% pyromellitic acid dianhydride. In a first distillation stage, said crude pyromellitic acid dianhydride is distilled at pressure of less than about 310 Torr, and temperature of less than about 350.degree. C to distill overhead an impurities containing fraction amounting to less than about 20% of the crude introduced into the first stage, and provide a residue enriched in pyromellitic acid dianhydride. In a second distillation stage, the residue of the first stage is distilled at lower pressure and at temperature of less than about 325.degree. C to distill overhead the purified pyromellitic acid dianhydride, and provide an impurities containing residue of less than about 12% of the crude introduced into the first step.