25006-32-0 AI3-27872 BRN 2947938 Leptophos OA Leptophos oxon Leptophos oxygen analog Leptophosoxon Leptophoxon PHOSPHONIC ACID, PHENYL-, 4-BROMO-2,5-DICHLOROPHENYL METHYL ESTER Phenylphosphonic acid 4-bromo-2,5-dichlorophenyl methyl ester Phosvel oxon Velsicol VCS O-analog