US3787299A - Electrolytic condensation of carboxylic acids - Google Patents

Electrolytic condensation of carboxylic acids Download PDF

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Publication number
US3787299A
US3787299A US00126943A US3787299DA US3787299A US 3787299 A US3787299 A US 3787299A US 00126943 A US00126943 A US 00126943A US 3787299D A US3787299D A US 3787299DA US 3787299 A US3787299 A US 3787299A
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electrodes
percent
cell
current
acid
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H Nohe
F Beck
J Haufe
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BASF SE
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BASF SE
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    • 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
    • C25B3/29—Coupling reactions

Definitions

  • the Kolbe synthesis involves electrolysis in which large quantities of gas are evolved at both electrodes, 0.5 moles of hydrogen per Faraday at the cathode and approximately 1 mole of carbon dioxide per Faraday at the anode.
  • gas-filling effect a substantial proportion of the space between the electrodes isfilled with gas bubbles once a steady state has been reached (hereinafter referred to as gas-filling effect), and consequently a large portion of the crosssection' between the electrodes is not available for the conduction of current through the electrolyte and the cellpotential rises to high values.
  • the cited Belgian Patent also descloses a method of carrying out the Kolbe synthesisat low degrees of neutralization and at high current densities whilst maintaining low cell potentials.
  • This method involves the use of a cell having vibrating electrode pairs which are permeable to liquids, but such cells suffer from-the drawback that they are relatively complicated and do not lend themselves readily to use on an industrial scale.
  • the electrochemical condensation of carboxylic acids may be carried out in an industrially advantageous manner with good yields and no side reactions using a degree of neutralization of the carboxylic acid of less then 20 percent molar and preferably of less than 10 percent molar and a current density of more than 10 A/dm in a solvent and using electrodes which are impermeable to liquids, provided that the distance between the electrodes is from 0.1 to 2 mm and the electrolyte is caused to-flow through the space between the paired electrodes at a rate of from 0.05 to 2 m/sec.
  • the rate of flow of the electrolyte between the electrodes is primarily governed by the current density, the distance between the electrodes and the length of the gap between the electrodes.
  • the rates of flow at which the process may be best carried-out on an industrial scale range from 0.05 to 2 m/sec.
  • the range 0.1 to 0.17 m/sec is preferred.
  • the distance between the plane-parallel electrodes is advantageously from 0.1 to 2 mm. A distance of from 0.3 to 0.8 mm is preferred. This distance is defined by spacers in the form of insulator strips, for example strips made from polypropylene or polyester sheeting. The length of the gap through which the reaction mixture flows is determined by the size of the electrodes and is advantageously from 5 to cm.
  • Kolbe syntheses may be carried out on an industrial scale at atmospheric pressure with excellent yields and at high current densities, low potentials and high conversion rates, no trouble being caused by the gasfilling effect, and there is no need for the use of a flushing gas such as nitrogen or argon to remove the electrolytically evolved hydrogen and carbon dioxide.
  • a flushing gas such as nitrogen or argon
  • the process is applicable to all compounds susceptible to Kolbe synthesis.
  • Of particular interest is the synthesis of difunctional compounds from substituted but not a-substituted alkanoic acids, particularly those containing from 2' to 20 carbon atoms in the acid radical.
  • the starting carboxylic acids may carry substituents in the B-position or in a more remote position from the carboxyl group, such substituents being for example ester, acylamino, acyloxy, nitrilo, halo, aryl, alkyl or aralkyl groups or heterocyclic groups. Details of the range of application of the Kolbe synthesis are to be found, for example, in Russian Chemical Reviews, English translation, Vol. 29 (1960), pp. 161-180.
  • Examples of the use of the process of the invention are the synthesis of sebacic acid ester from adipic acid half-ester, of suberic acid ester from glutaric acid halfester, of thapsic acid ester (C from azaleic acid halfester, of 2,2-, 5,5'-tetramethyladipic acid ester from 2,2-dimethyl succinic acid half-ester, of N,N- diacetyldicamethylene diamine from e-acetylaminocaproic acid, of l,8-octanediol diformate from 5-formyloxyvaleric acid, of decamethylene dicyanide from e-cyanocaproic acid, of 1,20-dibromo-icosane from 11- bromoundecanoic acid and l,l-dichlorodecane from w-chlorocaproic acid.
  • C from azaleic acid halfester, of 2,2-, 5,5'-tetra
  • the concentration of the starting materials in the solvent is usually from 10 to 20 percent by weight.
  • the preferred solvent is methanol.
  • Other useful solvents are water together with non-aqueous solvents such as lower alcohols, for example methanol, ethanol, isopropanol, or N,N-dialkylamides of lower alkanoic acids, in particular dimethyl formamide and dimethylacetamide, or mixtures of said solvents.
  • the degree of neutralization of the carboxylic acid used is less than 20 percent molar. We prefer to employ the carboxylic acid at a degree of neutralization of less than 10 percent molar, more preferably at from 2 to 5 percent molar.
  • Convenient bases for adjusting the degree of neutralization are sodium methylate and anhydrous sodium carbonate. Other useful bases are potassium methylate, sodium or potassium ethylate, potassium carbonate or amines of sufficient basicity, such as triethylamine, or alkanol amines such as dimethyl aminoethanol or morpholine.
  • Conversion rates based on the free carboxylic acid may be pushed up to very high values, for example to over 90 percent and, at very low degrees of neutralization, to over 95 percent.
  • Suitable electrodes are those having smooth surfaces.
  • suitable materials for the anode are platinum, platinium-rhodium, platinum-irridium, gold or gold-platinum.
  • these precious metals are applied as a thin layer, for example as a layer having a thickness of from 2 to 70p., to a conducting substrate, for example a substrate of aluminium, refined steel, titanium or graphite. by electroplating or ceramic processes or by rolling, soldering, welding or bonding by means of a conducting cement.
  • the material to be selected for the cathode is not critical and stainless steel or nickel may be advantageously used.
  • the current density may be kept high at a moderate cell potential despite the low degree of neutralization.
  • the process is generally carried out at current densities ranging from to 60 amps/dm and preferably from to 40 amps/dm To obtain such current densities, cell potentials of from 5 to 25 volts are generally necessary.
  • the temperature of the electrolyte during electrolysis is maintained in the range from 20 to C, preferably 40 to 55 C. 7
  • the process may be carried out batchwise or continuously.
  • use may be made, for example, of an electrolytic cell having a plurality of plane, plate-shaped electrodes in a bipolar series arrangement.
  • the electrodes have a slightly trapezoid shape such that they rest against the side walls of the trough to form a liquid-tight seal therewith.
  • they may be provided with a frame containing inlets and outlets for the solution and assembled in the manner of a filter press.
  • the current connections to the cell are to the end plates.
  • narrow insulating strips produced, for example, from plastics film such as polyester film, may be interposed between the plates in a direction parallel to the direction of flow.
  • the thickness of the strips is governed by the desired spacing of the electrodes and may be from 0.05 to 2 mm.
  • a gas escape is provided in the cover of the cell.
  • the reaction mixtures passes through an inlet, flows between the paired electrodes and leaves the cell through an outlet to be recirculated by a centrifugal pump, the circulating material being caused to pass through 'a heat exchanger and a flowmeter.
  • the cell is also equipped with an inlet for fresh reaction solution and an outlet for the partially converted mixture. There is no difficulty in observing the pH and temperature.
  • This arrangement is contained in a cell of glass.
  • the end electrodes are suitable connected to a source of direct current.
  • Narrow strips of from 0.2 to 0.7 mm thick polyester film are provided between the paired electrodes.
  • a gas escape is provided in the cover.
  • the reaction solution is pumped by a centrifugal pump through inlets to the central cavity of the electrode system, flows radially through the gap between the electrodes and is recycled via a cooler and a rotameter.
  • the pH and temperature of the circulated reaction mixture may be observed by means of a glass electrode and a thermometer.
  • electrodes of some other configuration may be used, such as pairs of electrodes consisting of ters and in the manufacture of special plastizizers or ester oils.
  • the electrolytic cell used is made up of three round discs of graphite having a diameter of 1 17 mm and a thickness of mm.
  • the discs have acentral bore of 30 mm diameter for the electrolyte feed.
  • the effective area is exactly twice 1 dm
  • the anode side is provided with a 40p. thick foil of platinum bonded thereto by a conducting epoxy cement, and the cathode side is provided by a sheet of refined steel 1 mm thick.
  • the ar-. rangement consists of two, series-connected cells. Four strips of 0.5 mm thick polypropylene are disposed radially between the electrodes to act as spacers.
  • the mixture is circulated through the cell and a heat exchanger and electrolysis is carried out using a current of 25 amps giving a current density of 25 Aldm
  • the temperature is maintained at 42 C by water cooling applied to the circulating mixture outside the cell.
  • the electrolytically generated hydrogen and carbon dioxide leave the cell via a brine-cooled reflux condenser.
  • the throughput through the two bipolar series-connected cells is maintained at 150 liters per hour, equivalent to a rate of flow in the cell of from 41 to 11 cm/sec (inlet and outlet rates of radial flow of material through the gap).
  • the potential across each cell is 15.4 volts at the commencement of electrolysis, 12.8 volts after 1 hour and 11.7 volts at the end of electrolysis.
  • the pH rises from an initial value of 5.4 to a final value of 9. After the passage of 132 percentof the theoretical amount of current (84 Ah) required for complete conversion of the monoester the reaction mixture, which is clear and colorless, is worked up by distillation.
  • the solvent is driven off in a rotary evaporator and the residue is diluted with hexane and washed with water and then freed from hexane in a rotary evaporator.
  • the residue weighing 232 g, is shaken with a little 8 percent sodium bicarbonate solution.
  • the final residue consists of 227 g of crude dimethyl sebacate.
  • EXAMPLE 2 Using the cell described in Example 1, 1,000 g of a mixture of-40 percent of mono(2-ethylhexyl) adipate in methanol neutralized with sodium methylate to a degree of neutralization of l0 percent molar are reacted at 40 C and a current density of 20 amps/dm the therate of flow of the reaction mixture in the cell of 55 to l5 cm/sec (inlet and outlet rates of radial flow through the gap between the electrodes). To avoid the rise of potential, which is characteristic of the electrolysis of this half-ester, the flow of current is stopped for 10 second' periods at intervals of 5 minutes. By this means the cell potential across each pair of electrodes is held virtually constant at 16.5 volts. If the current is not switched off periodically in this manner, the cell potential rises to about 30 volts due to the formation of a polymeric deposit on the anode.
  • Working up is effected by neutralizing the unreacted half-ester with aqueous 10 percent sodium hydroxide and distilling off the methanol, elutriating the sodium salt of the half-ester from the residue with water and subjecting the resiude to steam distillation at 20 mm of Hg and 130 C to remove further by-products.
  • the resulting product, bis-2-ethylhexyl sebacate, is confirmed by gas chromatography and the ester value.
  • the yield is 70.3 percent and the current efficiency 48.0 percent.
  • EXAMPLE 3 The cell consists .of a rectangular plate of refined steel measuring X 160 X 20 mm and having a groove cut near each of the short sides, which grooves serve as inlet and outlet for the reaction mixture'to be circulated as described in Example 1.
  • the anode is an aluminium plate of the same size, to which a 40;; thick foil of platnium has beenbonded by means of a conducting cement.
  • a frame having a thickness of 0.5 mm is interposed between the two plates to leave an effective electrode area of 0.5 dm
  • the assembly is held together by means of 12 screws.
  • the reactor is charged with a reaction mixture consisting of 220 g of methanol and 146 g of 5-formyloxyvaleric acid which has been neutralized to 5 percent molar with sodium methylate.
  • Electrolysis is carried out at a current of 12.5 g giving a current denisty of 25 amps/dm, at a temperature of 40 C and a theoretical current conversion of 119 percent.
  • the throughput is 60 liters per hour giving a rate of flow of reaction mixture between the electrodes of 67 cm/sec.
  • the cell potential adjusts itself to 12.3 volts and falls to 10.6 volts toward the end of electrolysis.
  • thepH rises from 6.0 to 8.6.
  • EXAMPLE 4 Using the arrangement described in Example 3, 300 g of a mixture of 40 percent by weight of 6- acetylaminocaproic acid in methanol neutralized to 5 percent molar with sodium methylate is reacted at 40 C, a current density of 25 amps/dm and a theoretical current conversion of percent.
  • the pumping rate is 36 1/hr giving a rate of flow of mixture between the electrodes of 40 cm/sec.
  • the cell potential rises from 16.3 to 22.0 volts and the pH from 6.6 to 7.1.
  • EXAMPLE 1 A solution of monomethyl glutarate having a degree of neutralization of 5 percent molar and produced by stirring 296 g of glutaric anhydride (2,60 moles) in a solution of 0.7 g (0.13 moles) of sodium methylate in 650 g of methanol for 1 hour at the boil, is electrolyzed for 400 minutes in the system described in Example 3 using a current of 12.5 amps giving a current density of 25 ampsldm at a temperature of 45 C. During this period the initial potential of 14.1 volts falls to 10.5 volts. The distance between the electrodes being 0.5 mm and the throughput 60 liters per hour, the rate of flow of the solution between the electrodes is 67 cm/sec.
  • Example 2 After working up as described in Example 1 there are obtained 9.1 g of unreacted monomethyl glutarate and 194.1 g of crude dimethyl suberate, which is found to contain 97.3 percent of dimethyl suberate when analyzed by gas chromatography. This is equivalent to a conversion rate of 97.6 percent, a yield of 77.7 percent and a current efficiency of 60.6 percent.

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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)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US00126943A 1970-03-28 1971-03-22 Electrolytic condensation of carboxylic acids Expired - Lifetime US3787299A (en)

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DE2014985A DE2014985C3 (de) 1970-03-28 1970-03-28 Verfahren zur elektrolytischen Kondensation von Carbonsäuren

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AT (1) AT304465B (enrdf_load_stackoverflow)
BE (1) BE764885A (enrdf_load_stackoverflow)
CH (1) CH564098A5 (enrdf_load_stackoverflow)
DE (1) DE2014985C3 (enrdf_load_stackoverflow)
FR (1) FR2085018A5 (enrdf_load_stackoverflow)
GB (1) GB1337763A (enrdf_load_stackoverflow)
NL (1) NL7104124A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3879271A (en) * 1972-10-04 1975-04-22 Basf Ag Production of diesters of dicarboxylic acids by electrochemical condensation of monoesters of dicarboxylic acids
US3896011A (en) * 1973-01-31 1975-07-22 Asahi Chemical Ind Process for the preparation of sebacic acid
US3941666A (en) * 1973-07-20 1976-03-02 Hoechst Aktiengesellschaft Process for the preparation of N-(α-alkoxyethyl)-carboxylic acid amides
FR2298615A1 (fr) * 1975-01-21 1976-08-20 Basf Ag Cellule electrochimique a electrodes bipolaires
US5021131A (en) * 1990-05-17 1991-06-04 E. I. Du Pont De Nemours And Company Optically pure 1,4-diols
US20090048441A1 (en) * 2005-06-22 2009-02-19 Manne Satyanarayana Reddy Process for the Preparation of Ezetimibe
WO2016170075A1 (de) * 2015-04-24 2016-10-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur elektrochemischen umwandlung von fettsäuren und anlage zur durchführung des verfahrens
WO2017116358A1 (en) 2015-12-28 2017-07-06 Oran Ismail Method and apparatus for determination of fatty acid markers using electrical impedance measurement
CN111850596A (zh) * 2020-07-13 2020-10-30 万华化学集团股份有限公司 一种电化学合成癸二酸酯类化合物的连续生产方法
US11512401B2 (en) 2019-01-14 2022-11-29 Gridthink Inc. Process for short chain alkane synthesis while maintaining faradaic efficiency

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2680713A (en) * 1953-03-16 1954-06-08 Du Pont Process for preparing diesters of unsaturated alpha, omega-dicarboxylic acids by electrolysis
DE1802865A1 (de) * 1967-11-11 1970-09-17 Basf Ag Verfahren zur elektrolytischen Kondensation von Carbonsaeuren
US3582484A (en) * 1968-02-28 1971-06-01 Ici Ltd Continuous production of diesters

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2680713A (en) * 1953-03-16 1954-06-08 Du Pont Process for preparing diesters of unsaturated alpha, omega-dicarboxylic acids by electrolysis
DE1802865A1 (de) * 1967-11-11 1970-09-17 Basf Ag Verfahren zur elektrolytischen Kondensation von Carbonsaeuren
US3652430A (en) * 1967-11-11 1972-03-28 Basf Ag Electrolytic condensation of carboxylic acids
US3582484A (en) * 1968-02-28 1971-06-01 Ici Ltd Continuous production of diesters

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Eberson, Electrolysis of Some Cyanocarboxylic Acids, J. of Organic Chem., Vol. 27, No. 7, July 1962, pp. 2,329 2,331 *
Glasstone & Hickling, The Mechanisms of Kolbe Synthesis & Other Reactions, The Electrochemical Society, Vol. 75, May 1939, pp. 333 350. *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3879271A (en) * 1972-10-04 1975-04-22 Basf Ag Production of diesters of dicarboxylic acids by electrochemical condensation of monoesters of dicarboxylic acids
US3896011A (en) * 1973-01-31 1975-07-22 Asahi Chemical Ind Process for the preparation of sebacic acid
US3941666A (en) * 1973-07-20 1976-03-02 Hoechst Aktiengesellschaft Process for the preparation of N-(α-alkoxyethyl)-carboxylic acid amides
FR2298615A1 (fr) * 1975-01-21 1976-08-20 Basf Ag Cellule electrochimique a electrodes bipolaires
US4048047A (en) * 1975-01-21 1977-09-13 Basf Aktiengesellschaft Electrochemical cell with bipolar electrodes
US5021131A (en) * 1990-05-17 1991-06-04 E. I. Du Pont De Nemours And Company Optically pure 1,4-diols
US20090048441A1 (en) * 2005-06-22 2009-02-19 Manne Satyanarayana Reddy Process for the Preparation of Ezetimibe
US8013150B2 (en) * 2005-06-22 2011-09-06 Msn Laboratories Ltd. Process for the preparation of ezetimibe
WO2016170075A1 (de) * 2015-04-24 2016-10-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur elektrochemischen umwandlung von fettsäuren und anlage zur durchführung des verfahrens
WO2017116358A1 (en) 2015-12-28 2017-07-06 Oran Ismail Method and apparatus for determination of fatty acid markers using electrical impedance measurement
US11512401B2 (en) 2019-01-14 2022-11-29 Gridthink Inc. Process for short chain alkane synthesis while maintaining faradaic efficiency
CN111850596A (zh) * 2020-07-13 2020-10-30 万华化学集团股份有限公司 一种电化学合成癸二酸酯类化合物的连续生产方法
CN111850596B (zh) * 2020-07-13 2021-04-20 万华化学(四川)有限公司 一种电化学合成癸二酸酯类化合物的连续生产方法

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GB1337763A (en) 1973-11-21
DE2014985A1 (de) 1971-10-14
BE764885A (fr) 1971-09-27
DE2014985B2 (de) 1977-10-20
FR2085018A5 (enrdf_load_stackoverflow) 1971-12-17
NL7104124A (enrdf_load_stackoverflow) 1971-09-30
DE2014985C3 (de) 1978-06-08
CH564098A5 (enrdf_load_stackoverflow) 1975-07-15
AT304465B (de) 1973-01-10

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