| 摘要 |
PROBLEM TO BE SOLVED: To obtain a new salicylic derivative useful as an electron acceptor providing a heat-sensitive medium rendering excellent storage stability to color- undeveloped parts and color-developed images after recording. SOLUTION: This new salicylic derivative, a compound of formula I (X1 and X2 are each H, a halogen, alkyl, alkoxy, etc.; M is H or a m-valent metal atom ; (n) is 1-4), for example, 3-(4'-carboxyphthalimido)salicylic acid, or its metal salt is obtained for example, by a reaction of an aminosalicylic derivative of formula II and trimellitic anhydride in the presence of a catalyst, such as an acid. A metal salt of a compound of formula I is obtained, for example, by treating one equivalent of a compound of formula I with 1-1.1 equivalent of hydroxide, carbonate or hydrogen-carbonate of an alkali metal in the presence of water. A compound of formula I or its metal salt is preferably used at a rate of 100-500 pts.wt. to 100 pts.wt. of a color developing compound of electron donor type. |
