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US3884776A Expired / Lapsed US ⏱️ 0.0 years remaining

Preparation of hydroquinone

Assignee: EIDP Inc
•
Filing: 1973-05-15
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Granted: 1975-05-20
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Expires: 1993-05-15
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Abstract

Abstract An economical process for producing hydroquinone in a single electrolytic cell comprises anodizing benzene dispersed in an aqueous anolyte in one half cell to produce a quinone-rich benzene phase while catholyzing quinone-rich benzene dispersed in aqueous catholyte of the other half cell to produce a benzene phase depleted in quinone and an aqueous catholyte containing hydroquinone, transferring quinone-rich benzene phase from the anolyte to the catholyte, transferring the benzene phase depleted in quinone from the catholyte to the anolyte and recovering hydroquinone from the catholyte by crystallization. Preferably, the dispersions of benzene phases in the anolyte and the catholyte are flowed at high velocity along the anode and the cathode having expanded electrically active surface. Catholysis can be accelerated in the presence of a selected redox couple such as Cr 2-Cr 3.

Inventors

  • 👤 Frederick Andrew Keidel

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-28 23:29
CPC Classifications
C; C25; C25B; C25B3/00; C25B3/01; C25B3/03; C25B11/00; C25B11/02; C25B11/036; C25B3/07; C25B9/00; C25B9/70; C25B9/73; C25B9/75; C25B9/77

Claims Analysis

Total Claims: 12
Claim 1
Independent Claim 230 words
THE PROCESS FOR PREPARING HYDROQUINONE FROM BENZENE IN A SINGLE ELECTROLYTIC CELL HAVING AN ANODE AND A CATHODE SEPARATED BY AN ION-PERMEABLE MEMBRANE WHICH COMPRISES A. ANOLYZING A DISPERSION OF BENZENE PHASE IN AQUEOUS A. ANOLYTE AT THE ANODE ELECTRODE, THEREBY PRODUCING BENZENE ENRICHED WITH QUINONE WHILE B. SIMULTANEOUSLY CATHOLYZING A DISPERSION IN AQUEOUS CATHOLYTE OF BENZENE PHASE ENRICHED WITH QUINONE AT THE CATHODE ELECTRODE, THEREBY PRODUCING A BENZENE PHASE OF LOWERED QUINONE CONTENT AND AQUEOUS CATHOLYTE PHASE ENRICHED WITH HYDROQUINONE, C. SEPARATING THE BENZENE PHASE ENRICHED WITH QUINONE FROM THE AQUEOUS ANOLYTE AND DISPERSING IT IN THE AQUEOUS CATHOLYTE, D. SEPARATING THE BENZENE PHASE OF LOWERED QUINONE CONTENT FROM THE AQUEOUS CATHOLYTE PHASE AND DISPERSING IT IN THE AQUEOUS ANOLYTE, AND E. RECOVERING HYDROQUINONE FROM AN AQUEOUS PHASE, WHEREIN THE AQUEOUS CATHOLYTE CONTAINS AT LEAST ONE MEMBER OF A REDOX COUPLE, WHICH CAN BE CONVERTED FROM THE REDUCED TO THE OXIDIZED FORM AT A STANDARD POTENTIAL AT LEAST AS POSITIVE AS 0.7 VOLTS, IN AN AMOUNT SUFFICIENT TO ACCELERATE THE REDUCTION OF QUINONE TO HYDROQUINONE, THE COUPLE COMPRISING AN OXIDIZED AN A REDUCED FORM WHEREIN A. BOTH THE OXIDIZED AND REDUCED FORMS ARE SOLUBLE IN THE CATHOLYTE, B. THE OXIDIZED FORM IS ELECTROCHEMICALLY REDUCIBLE TO ITS REDUCED FORM, AND C. THE REDUCED FORM IS CAPABLE OF CHEMICALLY REDUCING QUINONE TO HYDROQUINONE AND THEREBY BE CONVERTED TO THE OXIDIZED FORM.
Claim 2
Dependent Claim 230 words
THE PROCESS FOR PREPARING HYDROQUINONE FROM BENZENE IN A SINGLE ELECTROLYTIC CELL HAVING AN ANODE AND A CATHODE SEPARATED BY AN ION-PERMEABLE MEMBRANE WHICH COMPRISES A. ANOLYZING A DISPERSION OF BENZENE PHASE IN AQUEOUS A. ANOLYTE AT THE ANODE ELECTRODE, THEREBY PRODUCING BENZENE ENRICHED WITH QUINONE WHILE B. SIMULTANEOUSLY CATHOLYZING A DISPERSION IN AQUEOUS CATHOLYTE OF BENZENE PHASE ENRICHED WITH QUINONE AT THE CATHODE ELECTRODE, THEREBY PRODUCING A BENZENE PHASE OF LOWERED QUINONE CONTENT AND AQUEOUS CATHOLYTE PHASE ENRICHED WITH HYDROQUINONE, C. SEPARATING THE BENZENE PHASE ENRICHED WITH QUINONE FROM THE AQUEOUS ANOLYTE AND DISPERSING IT IN THE AQUEOUS CATHOLYTE, D. SEPARATING THE BENZENE PHASE OF LOWERED QUINONE CONTENT FROM THE AQUEOUS CATHOLYTE PHASE AND DISPERSING IT IN THE AQUEOUS ANOLYTE, AND E. RECOVERING HYDROQUINONE FROM AN AQUEOUS PHASE, WHEREIN THE AQUEOUS CATHOLYTE CONTAINS AT LEAST ONE MEMBER OF A REDOX COUPLE, WHICH CAN BE CONVERTED FROM THE REDUCED TO THE OXIDIZED FORM AT A STANDARD POTENTIAL AT LEAST AS POSITIVE AS 0.7 VOLTS, IN AN AMOUNT SUFFICIENT TO ACCELERATE THE REDUCTION OF QUINONE TO HYDROQUINONE, THE COUPLE COMPRISING AN OXIDIZED AN A REDUCED FORM WHEREIN A. BOTH THE OXIDIZED AND REDUCED FORMS ARE SOLUBLE IN THE CATHOLYTE, B. THE OXIDIZED FORM IS ELECTROCHEMICALLY REDUCIBLE TO ITS REDUCED FORM, AND C. THE REDUCED FORM IS CAPABLE OF CHEMICALLY REDUCING QUINONE TO HYDROQUINONE AND THEREBY BE CONVERTED TO THE OXIDIZED FORM.
Claim 3
Dependent Claim 24 words
A process of claim 1 wherein at least one of steps (A) and (B) is carried out with a flowing dispersion at the electrode.
Claim 4
Dependent Claim 23 words
A process of claim 1 wherein at least one of the step (A) and step (B) electrodes has an expanded electrically active surface.
Claim 5
Dependent Claim 22 words
A process of claim 1 wherein the benzene phase of step (D) is extracted with water before its dispersion in the anolyte.
Claim 6
Dependent Claim 34 words
A process of claim 3 wherein the expanded electrically active surface has a multiplicity of projections disposed such that they are pointed in a direction perpendicular to the flow of dispersion along the electrode.
Claim 7
Dependent Claim 17 words
A process of claim 1 wherein both the anolyte and catholyte dispersions flow past the respective electrodes.
Claim 8
Dependent Claim 13 words
A process of claim 6 wherein the electrodes have expanded electrically active surfaces.
Claim 9
Dependent Claim 16 words
A process of claim 7 wherein the redox couple is the Cr 2 -Cr 3 system.
Claim 10
Dependent Claim 44 words
A process of claim 6 wherein the benzene phase enriched with quinone is continuously separated from the anolyte and is dispersed in the catholyte, and the benzene phase of lowered quinone content is continuously separated from the catholyte and is dispersed in the anolyte.
Claim 11
Dependent Claim 24 words
A process of claim 9 wherein the benzene phase of lowered quinone content is continuously extracted with water before its dispersion in the anolyte.
Claim 12
Dependent Claim 16 words
A process of claim 10 wherein the redox couple is the Cr 2 -Cr 3 system.

References Cited (Backward Citations)

US1322580A Cited
US3423300A Cited
US3721615A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-05-19 1978-11-18 1979-05-20 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-05-19 1982-11-18 1983-05-20 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-05-19 1986-11-18 1987-05-20 $7700.00 Window Closed / Lapsed

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