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US4670112A Expired / Lapsed US ⏱️ 0.0 years remaining

Process for preparing p-amino phenols by electrolysis

Assignee: Farmaceutisk Laboratorium Ferring AS
•
Filing: 1985-11-21
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Granted: 1987-06-02
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Expires: 2005-11-21
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Abstract

Abstract PCT No. PCT/DK85/00108 Sec. 371 Date Mar. 20, 1986 Sec. 102(e) Date Mar. 20, 1986 PCT Filed Nov. 21, 1985 PCT Pub. No. WO86/03194 PCT Pub. Date Jun. 5, 1986.p-Amino phenols of the formula <IMAGE> (I) wherein R1 nd R2 are independently hydrogen, optionally substituted alkyl, halogen, COOH, SO3H or NO2, are produced by electrolytic reduction of p-phenylazophenols of the formula <IMAGE> (II) wherein R1 and R2 are as defined above, in an aqueous basic medium at a pH value at least equal to the pKa value of the p-phenylazophenol and at a temperature of at least 50 DEG C., preferably 70 DEG to 100 DEG C. The compounds (I) can hereby be produced without problems, in particular of an environmental nature, which are associated with the chemical reducing methods. The process is particularly useful for the preparation of the compound 5-aminosalicylic acid which is a valuable active component of certain medicaments for the treatment of colitis ulcerose and Crohn's disease.

Inventors

  • 👤 Henning Lund

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-06 17:53
CPC Classifications
C; C25; C25B; C25B3/00; C25B3/20; C25B3/25; C25B3/01; C25B3/07; C25B3/09; C25B3/11

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 94 words
A process for preparing p-amino phenols of the general formula ##STR5## wherein R 1 and R 2 are independently hydrogen, optionally substituted alkyl, halogen, COOH, SO 3 H or NO 2 , by electrolytic reduction of p-phenylazophenols of the formula ##STR6## wherein R 1 and R 2 are as defined above, in an aqueous medium, characterized by performing the electrolysis in a basic medium at a pH value at least equal to the pKa value of the p-phenylazophenol and at an elevated temperature of at least 50° C., preferably about 70° to 100° C.
Claim 2
Dependent Claim 94 words
A process for preparing p-amino phenols of the general formula ##STR5## wherein R 1 and R 2 are independently hydrogen, optionally substituted alkyl, halogen, COOH, SO 3 H or NO 2 , by electrolytic reduction of p-phenylazophenols of the formula ##STR6## wherein R 1 and R 2 are as defined above, in an aqueous medium, characterized by performing the electrolysis in a basic medium at a pH value at least equal to the pKa value of the p-phenylazophenol and at an elevated temperature of at least 50° C., preferably about 70° to 100° C.
Claim 3
Dependent Claim 15 words
A process according to claim 1, characterized in that the resulting compound is 5-aminosalicylic acid.
Claim 4
Dependent Claim 15 words
A process according to claim 1, characterized in that the resulting compound is p-amino phenol.
Claim 5
Dependent Claim 15 words
A process according to claim 1, characterized in that the resulting compound is 2-chloro-4-amino phenol.
Claim 6
Dependent Claim 12 words
A process according to claim 1, characterized in that pH exceeds 12.
Claim 7
Dependent Claim 35 words
A process according to claim 1, characterized in that the potential is between 0.1 and 0.7 V more negative than the halfwave potential of the compound which is being reduced, at the pH value used.

References Cited (Backward Citations)

US1542265A Cited
US1882758A Cited
US3645864A Cited
DE2256003A1 Cited
GB1421118A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1990-06-01 1990-12-01 1991-06-02 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1994-06-01 1994-12-01 1995-06-02 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1998-06-01 1998-12-01 1999-06-02 $7700.00 Window Closed / Lapsed

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