US3663381A - Electrochemical conversion of phenol to hydroquinone - Google Patents

Electrochemical conversion of phenol to hydroquinone Download PDF

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US3663381A
US3663381A US26924A US3663381DA US3663381A US 3663381 A US3663381 A US 3663381A US 26924 A US26924 A US 26924A US 3663381D A US3663381D A US 3663381DA US 3663381 A US3663381 A US 3663381A
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hydroquinone
phenol
percent
lead
anode
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Frank H Covitz
Robert V Carrubba
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Union Carbide Corp
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Union Carbide Corp
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Assigned to MORGAN GUARANTY TRUST COMPANY OF NEW YORK, AND MORGAN BANK ( DELAWARE ) AS COLLATERAL ( AGENTS ) SEE RECORD FOR THE REMAINING ASSIGNEES. reassignment MORGAN GUARANTY TRUST COMPANY OF NEW YORK, AND MORGAN BANK ( DELAWARE ) AS COLLATERAL ( AGENTS ) SEE RECORD FOR THE REMAINING ASSIGNEES. MORTGAGE (SEE DOCUMENT FOR DETAILS). Assignors: STP CORPORATION, A CORP. OF DE.,, UNION CARBIDE AGRICULTURAL PRODUCTS CO., INC., A CORP. OF PA.,, UNION CARBIDE CORPORATION, A CORP.,, UNION CARBIDE EUROPE S.A., A SWISS CORP.
Assigned to UNION CARBIDE CORPORATION, reassignment UNION CARBIDE CORPORATION, RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: MORGAN BANK (DELAWARE) AS COLLATERAL AGENT
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
    • C07C37/06—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by conversion of non-aromatic six-membered rings or of such rings formed in situ into aromatic six-membered rings, e.g. by dehydrogenation
    • C07C37/07—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by conversion of non-aromatic six-membered rings or of such rings formed in situ into aromatic six-membered rings, e.g. by dehydrogenation with simultaneous reduction of C=O group in that ring
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
    • C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
    • C07C37/70—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment
    • C07C37/74—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C39/00—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring
    • C07C39/02—Compounds having at least one hydroxy or O-metal group bound to a carbon atom of a six-membered aromatic ring monocyclic with no unsaturation outside the aromatic ring
    • C07C39/08—Dihydroxy benzenes; Alkylated derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/01—Products
    • C25B3/07—Oxygen containing compounds
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/23—Oxidation

Definitions

  • ABSTRACT The electrochemical conversion of phenol to hydroquinone has been improved by a combination of steps directed to effect removal of by-products and conversion of p-benzoquinone to hydroquinone as part of the process for the recovery of the hydroquinone product. These steps include first reducing residual p-benzoquinone to hydroquinone, followed by removal of tars and color bodies, vacuum distillation to condense the volume of the electrolyzed reaction mixture, and finally crystallizing the hydroquinone product out of the condensed distillation residue.
  • the electrochemical oxidation of phenol to produce hydroquinone has been shown to be feasible by controlling such variables as the weight per cent of phenol, the weight percent of electrolyte used, the temperature of the electrolysis, the pH of the aqueous solution, the voltage used, the current density used, and the control of the per cent conversion of phenol to hydroquinone.
  • the electrochemical oxidation of phenol to hydroquinone is characterized by the formation of a plurality of products some desirable, some undesirable. If this reaction were ideal only quinone would be produced at the anode and all of this would then be reduced to hydroquinone at the cathode.
  • a possible sequence of reactions leading to tars consists in the reaction of p-benzoquinone with phenol in the presence of hydrogen ion to product phenoxy hydroquinone, the reaction of p-benzoquinone with water to produce hydroxy hydroquinone and the reaction H 1 l l henol OH i II lit) a i II on of p-benzoquinone with hydroquinone to producehydroxy phenoxy hydroquinone.
  • llydroquinonc IIO-Q-O- a electrolyzing an aqueous solution containing from about 0.5 to 4 percent by weight of phenol and about 1 to 5 percent by weight of sulfuric acid at a temperature of about 25 to 100 C., a pH of less than about 4, an anode d.c. potential of at least about +0.9 volts in reference to a saturated calomel electrode, a cathode d.c. potential more negative than +0.4 volts in reference to a saturated calomel electrode, and a current density of at least 4 amperes per square decimeter until up to about percent by weight of the phenol has been electrolyzed to hydroquinone; and,
  • the isolation of hydroquinone product can be improved by the steps of:
  • step (c) treating the electrolyzed aqueous solution from step (a) with sufficient reducing agent to convert p-benzoquinone to hydroquinone;
  • Conventional vacuum distillation equipment can be used for the stripping operation used for concentrating the electrolyzed aqueous solution after the reduction and tar removal and color body removal steps have been carried out.
  • the temperature range used for the stripping operation has a critical upper limit in that temperatures above 65 result in decomposition of the hydroquinone product as evinced by the formation of additional color bodies. While the lower temperature limit of 45 is not narrowly critical, temperatures below this point brings the stripping operation to a point where economic factors become a consideration due to the higher vacuum needed.
  • the pressure range is critical in that it corresponds to pressures at which the temperature range is feasible.
  • the electrolyzed aqueous solution could be concentrated to as 'low a volume as onetenth that of the original volume because the distillate consists mainly of water and phenol and results in an increase in the acid concentration of the stripped residue containing the hydroquinone product to about 10 times that of the feed stream. Since sulfuric acid is commonly used as the electrolyte both because of its effectiveness and low cost, this would mean the effective sulfuric acid concentration increases to about 30 percent. Since concentrated sulfuric acid is notoriously reactive towards organic compounds, it was completely unexpected that no decomposition of the hydroquinone resulted in the recovery process. This fortuitous discovery not only permits the recycle of sulfuric acid but the presence of the sulfuric acid after this concentration step aids in the crystallization of the hydroquinone product from the distillation residue by a salting out effect.
  • the hydroquinone which crystallizes out can then be recovered from the aqueous acid supernatant solution by any technique well known in the chemical art such as filtration centrifugation and the like.
  • the temperature of crystallization is not narrowly critical. For example, ambient room temperature is most convenient although temperatures from about -20 C. shorten the time required for crystallization.
  • sulfur dioxide as the reducing agent in step (c) of the improved process delineated above, although other reducing agents can be used if desired, e.g., nascent hydrogen which can be generated in situ by adding a metal, higher in the electrochemical series than hydrogen, to the acidic effluent from the electrolysis cell.
  • suitable metals include zinc, tin, iron and the like.
  • a further modification consists in effecting reduction electrolytically at the cathode of a divided cell instead of by the use of a reducing agent.
  • a unique advantage in the use of sulfur dioxide lies in the fact that it is converted to sulfuric acid in the reduction process and thus forms more of this useful electrolyte instead of a foreign substance or contaminant.
  • the preferred method for removal of residual tars and color bodies entails the use of an adsorbent grade of activated charcoal. It has been found convenient to utilize this adsorbent in the form of a column allowing the clectrolyzed aqueous solution to either drip through by gravity or perculate through.
  • Other adsorbents which can be used for this step include: activated alumina, molecular seives and the like.
  • a particularly preferred decolorizing agent is activated cocoanut charcoal having a high surface area, used in the form of a powder or granules in the range of about 40 to 200 mesh.
  • a continuous operation in which a feed of 3 percent phenol and 3 percent sulfuric acid is fed as an aqueous solution to the electrolysis cell at a rate sufficient to afford a phenol conversion of about 50 percent by weight.
  • Other preferred conditions include a current density of about 20-40 amperes per square decimeter, an electrolysis temperature of about 50-60 C. and the use of an expanded lead anode preanodized in 30 percent aqueous sulfuric acid and a cathode of aluminum, amalgamated lead or Monel metal (Trademark of the International Nickel Co., Inc. for a wrought nickel-copper alloy containing approximately twothirds nickel and one-third copper).
  • the stripping operation affords an overhead distillate consisting of phenol and water which is available for recycle to the electrolysis cells. It is particularly preferred to employ a series of electrolysis cells connected in series, in place of a single electrolysis cell, starting with undivided cells and finishing with divided cells.
  • Hydroquinone and p-benzoquinone were analyzed for in aqueous solutions by known polarographic techniques recognized in the art.
  • One ml. samples were withdrawn from the electrolysis cell and transferred to a 25 ml. volumetric flask and the liquid meniscus brought to the fiducial mark with a 0.2 molar pH 7 aqueous phosphate buffer.
  • a polarogram of each solution was obtained and the diffusion limiting currents for hydroquinone and p-benzoquinone were determined. These data were compared with a calibration curve prepared from standard hydroquinone and p-benzoquinone solutions.
  • calibration curves consisted of a plot of diffusion limiting current in microamperes versus concentration in moles or grams.
  • the phenol content of aqueous solutions was determined by vapor phase chromoiography. Test samples were treated with excess sulfur dioxide and extracted with an equal volume of amixture of 98 percent toluene and 2 percent dichlorobenzene. (as an internal standard) in a thermostat at 530 C. A small sample of the toluene phase was injected into the vapor phase chromotography apparatus operating with a 2 meter column containing 10 percent solid polyethylene oxide deposited on a Teflon (Trademark for polytetrafluoroethylene) support at 1 C.
  • Acids were determined by non-aqueous titration of 1 ml. samples from the electrolysis cell (diluted with 25 ml. of isopropyl alcohol) with about 0.1N standardized tetramethylammonium hydroxide in methanol. An automatic titrator with an external derivative and logarithmic response transducer was used to generate end-point peaks.
  • Orsat analysis was used to determine C0 ,CO, and 0 with H, determinations by difference.
  • a continuous electrolysis reactor cell was constructed consisting of a circular lead anode and circular lead cathode separated by an insulating collar or cell spacer 1.6 centimeters thick of polypropylene having an inlet and outlet means for delivery and removal of the reactants to and from the electrolysis cell.
  • the cell also is fitted with a thermocouple well and a connection to the reference electrode of a polarographic apparatus.
  • the effective electrode area of both the anode and the cathode was 25 centimeters sq.
  • the lead electrode surfaces prior to the actual electrolysis experiments were first scoured with 400 mesh silicon carbide sandpaper, polished with crocus cloth and then washed with water. These lead electrodes were then pressed to a fiat polished surface between chrome plated steel plates.
  • the electrodes were weighed prior to cell assembly. For better reproduceability from run to run a standard preconditioning of the electrodes was carried out consisting of pre-electrolyzing them by electrolyzing a 3 percent sulfuric acid solution for 30 minutes at a current density of 40 amperes per sq. dec. with 10 amperes passing through the cell. After this preconditioning a standard aqueous feed composition consisting of 3 percent phenol, 3 percent sulfuric acid (wt./vol. per cent) was fed into the electrolysis cell maintained at a temperature of 50 C. at a feed rate of 4.95 ml. per minute. The effluent from the cell was obtained by overflow and thus the withdrawal rate was the same as the feed rate of 4.95 ml. per minute.
  • the recovery system is best described by referring to the FIGURE where the overflow from the cell is shown in a flow diagram as passing into the SO, reactor 1 which is simultaneously saturated with S0 from tank 2 through a flow meter 3.
  • the S0; reactor 1 also has an overflow takeoff level which maintains a constant level in the S0 reactor 1 and leads the overflow into a charcoal column 4 which is standard chromatagraphic glass column 0.5 inches in diameter and 18 inches high filled to a level of 16 inches with 40 mesh adsorbent grade charcoal.
  • the charcoal column 4 is equipped with a level overflow drain 6 and is connected to a level controller 8 through a sensor 10.
  • the purified and reduced effluent is removed through the bottom of charcoal column 4 by means of line 12 which leads to flow rate valve 14 and thence to solenoid valve 16.
  • the solenoid valve 16 is activated or deactivated by level controller 8.
  • level controller 8 When the solenoid valve 16 is opened the treated effluent passes into a stripping column 18 which is heated through steam passing through valve 20 into jacket 22. Steam is drained from jacket 22 through drain 24.
  • the distillate taken off at the top of stripping column 18 through line 26 passes to a condenser 28.
  • the condensate consisting mainly of water and unreacted phenol is stored in overhead holding tank 30 which in turn is connected to traps and a vacuum source through line 32.
  • the bottoms emerging from the stripping column 18 through line 34 into tank 36 contained mainly the product hydroquinone and concentrated aqueous sulfuric acid.
  • the level in tank 36 is controlled through sensor 38 connected to level controller 40 which in turn activates solenoid valve 42.
  • the temperature of the bottoms in tank 36 is measured by thermocouple 44 which is connected to temperature controller 46. Temperature controller 46 activates the steam control valve 20.
  • the product removed from tank 36 passes through recycle pump 48 and then either to bottoms holding tank 50 or back to the stripping column 18 through line 52.
  • the bottoms holding tank 50 is connected to the vacuum source and traps through line 54.
  • hydroquinone was produced at a rate of 0.0301 moles per hour (3.25 grams per hour) and pbenzoquinone at a rate of 0.0101 moles per hour (1.07 grams per hour). This represents a ratio of hydroquinone to pbenzoquinone of 3.0.
  • the electrical efficiency for this experiment was 43 percent and the chemical efficiency 85 percent.
  • the recovery operating conditions used included an input rate into the S0 reactor 1 of 4.95 ml. of electrolysis cell overflow per minute with an $0 flow rate into SO reactor 1 of 5.0 ml. per minute at standard temperature and pressure.
  • the pot temperature in stripping column 18 was maintained at 50 C. while the pot pressure in stripping column 18 was maintained at about 90 mm of mercury Hg.
  • the overhead to bottoms ratio in stripping column 18 was about 8.0.
  • the bottoms takeoff rate was about 0.62 ml. per minute.
  • the product in the bottoms holding tank 15 was placed in a crystallization container at about 0 C. in which an 80 percent recovery of hydroquinone was effected at a crystallization rate of about 3.48 grams per hour.
  • the distillate obtained as the overhead fraction from stripping column 18 which collected in overhead holding tank 30 and which consists mainly of water and phenol can be recycled to the electrolysis cell if desired with sufficient phenol and sulfuric acid to make up the original charge.
  • aqueous solution containing from about 0.5 to 4 percent by weight of phenol and about I to 5 percent of sulfuric acid at a temperature of about 25 to C., a pH of less than about 4, an anode d.c. potential of at least about 0.9 volts in reference to a saturated calomel electrode, a cathode d.c. potential more negative than about 0.4 volts in references to a saturated calomel electrode, and a current density of at least 4 amperes per sq. dec. until up to about 50 percent by weight of the phenol has been electrolyzed to hydroquinone and b. recovering the hydroquinone from the aqueous solution, the improvement which consists essentially of carrying out in order the steps of:
  • step (c) treating the electrolyzed aqueous solution from step (a) with a sufficient reducing agent to convert p-benzoquinone to hydroquinone;
  • Electrodes are preconditioned by pre-electrolyzing at 10 amperes, a current density of 40 amperes per square decimeter, and room temperature in a 3 percent aqueous sulfuric acid solution.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
US26924A 1970-04-09 1970-04-09 Electrochemical conversion of phenol to hydroquinone Expired - Lifetime US3663381A (en)

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JP (1) JPS5136255B1 (enExample)
BE (1) BE765476A (enExample)
CA (1) CA926809A (enExample)
DE (1) DE2117750C3 (enExample)
FR (1) FR2089395A5 (enExample)
GB (1) GB1329483A (enExample)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4035253A (en) * 1976-06-01 1977-07-12 Eastman Kodak Company Electrolytic oxidation of phenol at lead-thallium anodes
US4624758A (en) * 1986-01-06 1986-11-25 The Dow Chemical Company Electrocatalytic method for producing dihydroxybenzophenones
US4624759A (en) * 1986-01-06 1986-11-25 The Dow Chemical Company Electrolytic method for producing quinone methides
US4689124A (en) * 1985-09-13 1987-08-25 The Dow Chemical Company Flow-through electrolytic cell

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN119332257B (zh) * 2024-10-29 2025-09-26 华东理工大学 一种电解苯酚制备高浓度对苯二酚的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2130151A (en) * 1933-12-16 1938-09-13 Palfreeman Herbert Production of quinone and hydroquinone
US2135368A (en) * 1934-10-10 1938-11-01 Vagenius Nels Harold Method of preparing quinone
US3509031A (en) * 1968-08-28 1970-04-28 Union Carbide Corp Electrochemical oxidation of phenol

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3708744A (en) * 1971-08-18 1973-01-02 Westinghouse Electric Corp Regulating and filtering transformer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2130151A (en) * 1933-12-16 1938-09-13 Palfreeman Herbert Production of quinone and hydroquinone
US2135368A (en) * 1934-10-10 1938-11-01 Vagenius Nels Harold Method of preparing quinone
US3509031A (en) * 1968-08-28 1970-04-28 Union Carbide Corp Electrochemical oxidation of phenol

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Laboratory Practice of Organic Chem. by Robertson pp 77, 78 pub by Macmillan Co., New York 1939 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4035253A (en) * 1976-06-01 1977-07-12 Eastman Kodak Company Electrolytic oxidation of phenol at lead-thallium anodes
US4689124A (en) * 1985-09-13 1987-08-25 The Dow Chemical Company Flow-through electrolytic cell
US4624758A (en) * 1986-01-06 1986-11-25 The Dow Chemical Company Electrocatalytic method for producing dihydroxybenzophenones
US4624759A (en) * 1986-01-06 1986-11-25 The Dow Chemical Company Electrolytic method for producing quinone methides

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GB1329483A (en) 1973-09-12
DE2117750A1 (enExample) 1971-10-28
CA926809A (en) 1973-05-22
JPS5136255B1 (enExample) 1976-10-07
DE2117750B2 (de) 1975-02-13
DE2117750C3 (de) 1975-09-25
FR2089395A5 (enExample) 1972-01-07
BE765476A (fr) 1971-10-08

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