The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 24, 1981
Filed:
Apr. 24, 1978
Michihiro Tsujimoto, Tachikawa, JP;
Tsutomu Nishizawa, Kamakura, JP;
Kiyoharu Hasegawa, Yokohama, JP;
Nobuyoshi Abe, Machida, JP;
Mitsui Toatsu Chemicals, Incorporated, Tokyo, JP;
Abstract
Novel chlorinated 4-methylphthalic acids or anhydrides of the general formula ##STR1## wherein n is an integer of 1, 2 or 3, with the proviso that when n is 1, the chlorine atom is positioned at 3- or 5-position and when n is 2, the chlorine atoms are positioned at 3- and 5-positions. The new compounds are produced by dissolving 4-methylphthalic anhydride in concentrated sulfuric acid or fuming sulfuric acid to form a solution, and reacting the solution with chlorine at room temperature preferably in the presence of a catalytic amount of iodine, thereby to yield a crude product containing a mixture of chlorinated 4-methylphthalic acids. By subjecting the mixture to a thermal dehydration treatment in an inactive organic solvent, each of the chlorinated compounds may be isolated as its corresponding anhydride in the form of crystals. These chlorinated 4-methylphthalic anhydrides are valuable as intermediates for the preparation of dyestuffs or pigments.