. . "R12 is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms), a substituted or unsubstituted aryl group having 5 to 50 nucleus carbon atoms (preferably 5 to 10 nucleus carbon atoms), a substituted or unsubstituted cycloalkyl group having 3 to 20 nucleus carbon atoms (preferably 5 to 10 nucleus-carbon atoms), a substituted or unsubs" . .