| abstract |
Definitions: in the following Formulae I, II and IV, R1 represents hydrogen, alkyl of 1 to 4 carbon atoms, or a nontoxic cation, while each of R2, R3, R4, R5, and R6 symbolizes hydrogen, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, carboxy, carbalkoxy of 1 to 4 carbon atoms, trihalomethyl, halogen, nitro or cyano. |