Process for preparation of benzene dicarboxylic acids

US6355835B1 · kind B1 · utility

Assignee

• Chemintel (India) Private Limited · IN

Inventors

• Girendra Narain Kulsrestha · Dehradun, IN
• Mahendra Pratap Saxena · Dehradun, IN
• Ashok K. Gupta · Jülich, DE
• Satish Sharma
• Dinesh Prasad Bangwal
• Hari Bhagwan Goyal · Dehradun, IN
• Rameshwar Prasad · Sidhauli, IN
• Sanjib Mall · Jamkhed, IN
• Prakash D. Patel · Sayla, IN

Key dates

• Filing date: Dec 8, 1999
• Grant date: Mar 12, 2002
• Expiry date: Dec 8, 2019

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C51/43
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to a process for the preparation of benzene dicarboxylic acids by liquid phase oxidation of Xylene isomers using oxygen or air by oxidising in the presence of acetic acid as solvent, cobalt salt as catalyst and an initiator. The oxidation step is followed by flashing the said reaction mixture to remove volatile substances and cooling and filtering to get crude benzene di-carboxylic acid as a solid product and filtrate. The dicarboxylic acid solid product is recrystallised to get at least 99% pure benzene. The filtrate may be recycled.