C 2700 (OTTO) Cupric phosphate Cas 7798-23-4 - used as organic catalyst, fertilizer, emulsifier, corrosion inhibitor for phosphoric acid, metal protectant, and animal feed additive. C 2700 (OTTO) Cupric phosphate Cas 7798-23-4 -used as catalyst for org reactions, fertilizer; emulsifier; corrosion inhibitor for phosphoric acid; protectant for metal surfaces against oxidation.