Examples of the phenyl lower alkyl group include phenylalkyl groups of which the alkyl moiety is a linear or branched alkyl group having 1 to 6 carbon atoms such as a benzyl group, 2-phenylethyl group, 1-phenylethyl group, 3-phenylpropyl group, 4-phenylbutyl group, 5-phenylpentyl group, 6-phenylhexyl group, 1,1-dimethyl-2-phenylethyl group, and 2-methyl-3-phenylpropyl group.