A new phthalide derivative useful as a colorless chromogenic material has the following formula:
wherein A is
R is an alkyl group having 1 to 4 carbon atoms or a propylene group which may form jullolidine ring together with the adjacent benzene ring, and n is 0 or an integer of 1 to 4 when
A is
but
m is an integer of 1 to 3 when A is
一种可用作无色变色材料的新
邻苯二甲酸酯衍
生物具有下式: 其中 A 是 R 是具有 1 至 4 个碳原子的烷基或
丙烯基,可与邻近的苯环一起形成鸦胆子环,当 A 是 R 时,n 是 0 或 1 至 4 的整数,但当 A 是 R 时,m 是 1 至 3 的整数。