The compounds have the structure IN WHICH R is a lower alkyl or phenyl radical, R1 is a branched or straight-chain lower alkyl radical, and R2 is a branched or straight-chain...http://www.google.com/patents/US3878210?utm_source=gb-gplus-sharePatent US3878210 - Pyridazinothionophosphoric (-phosphonic) acid estersAdvanced Patent SearchPublication numberUS3878210 APublication typeGrantPublication dat