C(O)OR17 in which R17 is hydrogen, alkyl containing from 1 to 7 carbons or alkenyl having 3-7 carbon atoms, aryl or heteroaryl, particularly pyridyl, phenyl, tolyl, ethylphenyl, butylphenyl, halophenyl, alkenyl containing 3 to 7 carbons and having formula Cn H.sub.(2n-1) ; or