Method for the preparation of meta dihydroxybenzenes

• US 4,009,212 A
• Filed: 08/07/1975
• Issued: 02/22/1977
• Est. Priority Date: 02/21/1973
• Status: Expired due to Term

• Current Assignee: INDSPEC Chemical Corporation (Occidental Petroleum Corporation)
• Original Assignee: Koppers Co Inc (Persimmon PLC)
• Inventors: Leston, Gerd
• Primary Examiner(s): Thomas, Jr., James O.
• Assistant Examiner(s): Lone, W. B.
• Application Number:
  US05/602,767
• Time in Patent Office: 565 Days
• Field of Search: 260/628, 260/621 R, 260/625
• US Class Current: 568/769
• CPC Class Codes: C07C 37/04 by substitution of SO3H groups or a derivative thereof
• CPC Class Codes: C07C 39/08 Dihydroxy benzenes; Alkylated derivatives thereof

Abstract

A process for the preparation of dihydroxybenzenes whereby there are obtained primarily meta isomers of the dihydroxybenzenes includes the steps of: preparing a mixture of sulfonic acid isomers by sulfonation-isomerization of an hydroxybenzene having the formula: ##STR1## in which R and R'"'"' are selected from the group consisting of hydrogen and an alkyl radical having at most 4 carbon atoms per molecule, the total carbon atoms in radicals R and R'"'"' being at most 4; subjecting the so-produced sulfonic acids to selective hydrolyzation in aqueous medium at a temperature between about 100° and 150° C., the monohydroxy benzene being recovered by the said selective hydrolyzation in an enriched concentration that makes it readily recoverable by recycle in the process or other separation methods, and unhydrolyzed sulfonic acid remaining in the said aqueous medium; caustically fusing the said unhydrolyzed sulfonic acid, and liberating by acidification the desired dihydroxybenzene.

Claims

1. A process for the preparation of dihydroxybenzenes wherein the hydroxyl radicals are in meta position to each other, the said process comprising:

A. heating in the presence of sulfuric acid and at a temperature between 25° and

120°

C. a hydroxybenzene having the formula ##STR3## in which R and R'"'"' are each selected from the group consisting of hydrogen and an alkyl radical having inclusively from one to four carbon atoms in the alkyl chain, the total number of carbon atoms in radicals R and R'"'"' being at most four, thereby forming a mixture of sulfonic acid isomers;

B. isomerizing the said mixture in the presence of sulfuric acid at a temperature of between 130° and

200°

C to obtain an isomeric mixture containing the isomer wherein the sulfonic acid group is meta with respect to the hydroxyl group;

C. selectively hydrolyzing in an aqueous medium at a temperature between about 100° and

150°

C. in the said mixture those sulfonic acid isomers in which the sulfonic acid group is in a position other than meta with respect to the hydroxyl group to produce thereby the selected hydroxybenzene of step A;

D. caustically fusing the unhydrolyzed meta sulfonic acid remaining in the aqueous medium; and

E. acidifying the resultant salt of the meta dihydroxybenzene to liberate the desired meta dihydroxybenzene.

2. The process of claim 1 in which the hydroxybenzene is phenol.

3. The process of claim 1 in which the hydroxybenzene is a mixture of cresol isomers including meta-cresol.

4. The process of claim 1 in which the hydroxybenzene is substantially meta-cresol.

5. The process of claim 1 in which the hydroxybenzene is xylenol.