US3200053A - Electrolytic reduction procedure for the production of diols - Google Patents

Description

United States Patent 3,200,053 ELECTROLYTIC REDUCTION PROCEDURE FOR THE PRODUCTION OF DIOLS William Lassiter Yost, Long Valley, N.J., assignor to Ciba Corporation, a corporation of Delaware N0 Drawing. Filed Dec. 11, 1961, Ser. No. 158,580 14 Claims. (Cl. 204-75) This is a continuation-in-part application of Serial No. 86,574, filed February 2, 1961, and now abandoned.

The present invention relates to an improved electrolytic reduction procedure for the preparation of diols.

It is known that upon cathodic reduction with simultaneous dimerization of ketones, such as aliphatic, aromatic or heterocyclic ketones, as well as mixed ketones, such as aliphatic-aromatic, aliphatic-heterocyclic or aromatic-heterocyclic ketones, diols are formed (Allen, Organic Elect-rode Processes, pages 61 to 67, Chapman & Hall, London, 1958). Resulting diols may have valuable properties of their own or can be used as intermediates in the preparation of other useful chemicals,

The electrolytic reduction methods of ketone compounds described in the prior art are performed by separating the catholyte solution containing the ketone and the cathode from the anolyte and the anode. Separation of the electrolytes and the electrodes is achieved by way of a semi-porous membrane, such as, for example, cellophane, porous porcelain (Alundum), sintered glass membrane and the like. Although adequate yields for the formation of diol compounds have been indicated in the literature for small laboratory runs, the electrolytic reduction to the desired diols of ketones, particularly of aromatic, aliphatic-aromatic, heterocyclic, aliphatic-heterocyclic and aromatic-heterocyclic ketones, as described in the prior art, i.e., by using a two-chamber system with separation of the cath-olyte from the anolyte by 21 diaphragm, has been found to be unsatisfactory whenever carried out on a larger scale. The product directly resulting from the electrolytic reduction is very crude and has to be subjected to several purification steps with a substantial loss of material. The yields of the purified diol, especially of a diol formed from a ketone containing a heterocyclic radical, are about to and clearly inadequate.

A possibility of improving the unsatisfactory yields from the two-chamber is a one-chamber electrolytic reduction procedure. Electrolytic one-chamber procedures .are known, particularly in the field of inorganic chemistry. In view of the fact that a reduction product is easily re-oxidized on the anode, the application of the one-chamber procedure in the field of organic chemistry is rather limited. Thus, in the electrolytic one-chamber procedures described in the prior art, re-oxidation of the desired reduction product at the anode cannot take place because the chemical structure of the resulting product prevents a reconversion into the starting material (for example, in its formation certain elements may have been added from or lost to the reaction medium), or the reoxidation is blocked by adding certain reagents which prevent a reconversion into the starting material, for example, a chemical reducing agent However, in the present procedure, which involves electrolytic reduction and simultaneous dimerization of ketones to form diol compounds, the possibility of omitting the diaphragm from the electrolysis chamber, is not suggested for obvious reasons. The reduction products, i.e., the diols, are easily re-oxidize-d into the starting materials, i.e., the ketones; thus, it had to be assumed that the resulting diol must be separated from the anode by a membrane, and that a two-chamber electrolytic reduction procedure had to be used. The addition of a chemical reducing ice reagent, which would prevent the oxidation of the resulting diol, to the electrolyte of a one-chamber electrolysis, is not suggested for the particular reason that 0t,]8-di01$ are labile compounds, which are susceptible to the action of many different chemicals (for example, they undergo rearrangement reactions and the like) and, therefore, may not be compatible with a chemical reducing reagent. Furthermore, such reducing reagent (added to prevent re-oxidation of a product) may actually reduce the ketone starting material to the alcohol without etfecting the desired dimerization, which occurs simultaneously in the two-chamber electrolytic reduction procedure of the prior art.

In contrast to the teaching of the prior art and the accumulated knowledge, I have now found that diols from the electrolytic reduction and simultaneous dimerization of ketones or of mixtures of ketones are obtained in a greatly simplified manner, in satisfactory yields and in a pure state by carrying out the electrolytic reduction in the absence of a diaphragm, i.e., in a one-chamber electrolysis cell.

Certain advantages of such procedure over the prior art two-chamber electrolytic reduction of ketones are evident. For example, the absence of a diaphragm simplifies the construction of the electrolysis apparatus. Thus, the placement of a diaphragm becomes particularly cumbersome in scaled-up equipment, in which the semi-porous diaphragm has to be fastened tightly between the two chambers to prevent any mixing of the two electrolytes. In addition, the diols resulting from the reduction procedure tend to precipitate during the course of the reaction and clog the membrane, causing an increase of electrical resistance accompanied by a drop of current efiiciency (see: Allen, loc. cit., pages 31 to 33) and requiring costly replacements. Furthermore, in the onechamber procedure, the current may be alternated from time to time during the electrolysis; thus, clogging of the cathode by precipitating product can be prevented, and the electrodes can be cleaned during the reduction. After completion of the one-chamber electrolysis, the electrodes can be easily cleaned by simply reversing the current; in a two-chamber electrolysis they or the diaphragm have to be removed from the cell for cleaning purposes.

Furthermore, I have found that inithe absence of a diaphragm the yields of the pure diol are greatly enhanced over those obtained by way of the prior art twochamber electrolysis requiring a diaphragm. The desired diol product from the one-chamber electrolytic reduction of a ketone of this invention is much purer as compared with the diol from the prior art two-chamber procedure. Whereas the latter requires extensive purification involving several purification steps with a considerable loss of material, the diol from the one-chamber electrolytic reduction of a ketone according to my invention can be used without lengthy purification. It has been established that in a subsequent acidic pinacolone rearrangement of the diols used for the formation of pharmacologically useful compounds of the amphenouetype or, particularly the methopyrapone-type, the yields are unexpectedly and markedly higher whenever a very pure diol starting material is used; the pure diol resulting from the one-chamber electrolytic reduction of a ketone according to my invention is, therefore, particularly suited as the intermediate in the pinacolone-rearrangement.

The electrolytic reduction procedure for the preparation of diols from ketones or mixtures of ketones according to the present invention is carried out by subjecting the ketone starting material, e.g., the ketone or a mixture of ketones, in an electrolyte vehicle to electrolytic reduction in a one-chamber electrolysis cell.

Although the one-chamber electrolysis according to my invention may be carried out in water alone as the electrolyte, it is advantageously performed in a mixture of water and a non-retlucible, water-miscible, organic solvent. Such organic solvents are, for example, lower alkanols having one to four carbon atoms, e.g., methanol, ethanol, n-propanol, isopropanol or tertiary butanol, formamides, e.g., formamide, N,N-dimethylformamide and the like, lower alkanoic acids, e.g., acetic, propionic acid and the like, or any other analogous solvent. The preferred organic solvents have a rather high boiling point (above 75); water-miscible lower alkanols having three carbon atoms, especially isopropanol, as well as n-propanol, and water-miscible formamides, particularly N,N dimethylformamide, are suitable organic diluents, which fit these requirements. Preferred liquid conductive media are mixtures of water and one or several of the indicated solvents, particularly isopropanol, as well as n-propanol, N,N-dimethylformamide and the like. Any decrease of the electrolyte volume due to evaporation during the reaction may be offset by adding water.

In order to further enhance the conductivity of the electrolyte vehicle, an ionizable salt is advantageously added to the electrolyte. Such salts are preferably metal salts of organic carboxylic acids, such as alkali metal, e.g., sodium, potassium and the like, salts of lower alkanoic acids, e.g., formic, acetic, propionic acid and the like; alkali metal acetates, e.g., potassium acetate and the like, represent such ionizable salts.

An electrolyte vehicle, which is particularly suitable in the one-chamber electrolysis of this invention, is the mixture of isopropanol, water and potassium acetate. The components of such mixture may, of course, be replaced by their equivalents; for example, n-propanol or N,N-dimethylformamide may be substituted for the isopropanol, and potassium acetate may be replaced by sodium acetate.

The electrolysis as such is carried out according to known methods. The cathode, on which reduction occurs, may be any suitable metal cathode, such as tin, nickel, lead, copper, cadmium, zinc, iron, stainless steel, mercury and the like, and is placed in the electrolyte together with a suitable anode, e.g., nickel, lead, platinum anode and the like.

The electrolysis is preferably carried out at a constant current density; the latter is determined by (a) the size of the electrodes, (b) the type of equipment used, and (c) the possibility of side reactions, such as undesired gas evolution and the like. A practical current density lies in the range of from about 0.01 amp/cm. to about 0.1 amp./cm. particularly from 0.02 to 0.04 amp./cm. Although the electrolytic reduction of the ketone may take place at room temperature, it is preferably performed at an elevated temperature, ranging from about 40 C. to about 80 C., preferably from about 60 C. to about 70 C.

The starting materials used in the electrolytic reduction procedure of this invention are ketones, such as aliphatic ketones, for example, lower alkanones, e.g., acetone, methyl ethyl ketone, diethyl ketone and the like, lower alkyl lower alkenyl ketones, e.g., ethyl vinyl ketone and the like, cycloaliphatic ketones, e.g., di-cyclopentyl ketone, cyclohexyl cyclopentyl ketone, di-cyclohexyl ketone and the like, aliphatic cyclo-aliphatic ketones, such as cycloalkyl lower alkyl ketones, e.g., cyclopentyl methyl ketone, cyclohexyl ethyl ketone (hexahydropropiophenone) and the like, aliphatic cycloaliphaticaliphatic ketones, for example, cyclopentylmethyl methyl ketone, Z-cyclohexylethyl ethyl ketone and the like, or any other ketone of aliphatic or cycloaliphatic nature.

Preferred ketones used as the starting materials in the electrolytic procedure of this invention are more particularly aliphatic carbocyclic aryl ketones, particularly lower alkyl monocyclic carbocyclic aryl ketones, such as lower alkyl phenyl ketones, in which the phenyl portion may be unsubstituted or substituted by an aliphatic hydrocarbon group, such as lower alkyl, e.g., methyl, ethyl, isopropyl, tertiary butyl, and the like, or by a functional group, for example, hydroxyl, etherified hydroxyl, primarily lower alkoyxy, e.g., methoxy, ethoxy, isopropyloxy, n-butyloxy and the like, as well as lower alkenyloxy, e.g., allyloxy, 2-butenyloxy and the like, cycloalkyl-lower alkoxy, e.g., cyclopentylmethoxy, 2-cyclohexylethoxy and the like, or any other'etherified hydroxyl, esterified hydroxyl, particularly halogeno, e.g., fluoro, chloro, bromo and the like, halogeno-lower alkyl, e.g., trifiuoromethyl and the like, or more especially by amino, such as primary amino, secondary amino, for example, N-lower alkyl-amino, e.g., N-methylamino, N-ethylamino, N- isopropylamino and the like, tertiary amino, such as N,N- di-lower alkyl-amino, e.g., N,N-dimethylamino, N-ethyl- N-methyl-amino, N,N-diethylamino and the like, or N- acyl-amino, for example, N-lower alkanoyl-amino, e.g., N-acetyl-amino, N-propionylamino and the like, or any other N-acyl-arnino group, for example, N-nicotinoylamino and the like. These ketones may be represented by lower alkyl phenyl ketones, e.g., methyl phenyl ketone (acetophenone), ethyl phenyl ketone (propiophenone) and the like, (lower alkoxy)-phenyl lower alkyl ketones e.g., 4-methoxy-phenyl methyl ketone (4-methoxy-acetophenone), 4-ethoxy-phenyl ethyl ketone (4-ethoxy-propiophenone) and the like, (halogeno)-phenyl lower alkyl ketone, e.g., 4-chloro-phenyl methyl ketone (4-chloroacetophenone), 4-bromo-phenyl ethyl ketone (4-bromopropiophenone) and the like, or more especially, (amino)-phenyl lower alkyl ketones, such as lower alkyl (primary amino)-phenyl ketones, e.g., 4-amino-phenyl methyl ketone (4-amino-acetophenone or 4-acetyl-aniline), 4-amino-phenyl ethyl ketone (4-amino-propiophenone or 4-propionylaniline) and the like, lower alkyl (secondary amino)-phenyl ketones, for example, lower alkyl (N-lower alkyl-amino)-phenyl ketone, e.g., methyl 4-N-methylamino-phenyl ketone (4 N methylaminoacetophenone) and the like, lower alkyl (tertiary amino)- phenyl ketones, such as (lLN-di-lower alkyl-amino)- phenyl lower alkyl ketones, e.g., 4-N,N-dimethylaminophenyl methyl ketone (4-N,N-di-methyl-amino-acetophenone) and the like, (N-acyl-amino)-phenyl lower alkyl ketones, such as (N-lower alkanoyl-amino)-phenyl lower alkyl ketones, e.g., 4-N-acetylamino-phenyl methyl ketone (4-N-acetylamino-acetophcnone), ethyl 4-N-propionyl-amino-phenyl ketone (4-N-propionylamino propiophenone) and the like, as well as methyl 4-N-nicotinoylamino-phenyl ketone (4-N-nicotinoylamino-acetophenone) and the like, or any other aliphatic aryl ketone.

Other ketones which are used as the especially preferred starting materials in the process of this invention. are aliphatic heterocyclic ketones, particularly lower alkyl pyridyl ketones (lower alkanoyl-pyridines), e.g., methyl Z-pyridyl ketone (2-acetyl-pyridine), methyl 3-pyridyl ketone (3-acetyl-pyridine), ethyl 3-pyridyl ketone (3- propionyl-pyridine), methyl 4-pyridyl ketone (4-acetyl pyridine) and the like, or any other aliphatic heterocyclic aryl ketone, in which the heterocyclic aryl represents other heterocyclic aryl groups, such as pyrimidyl and the like, or any other analogous group.

Additional ketones useful as starting materials in the electrolytic procedure for the preparation of diols according to this invention, are di-carbocyclic aryl ketones, such as di-monocyclic carbocyclic aryl ketones (benzophenones), in which the phenyl groups are unsubstituted or substituted as shown hereinbefore, e.g., diphenyl ketone (benzophenone), 4-amino-phenyl phenyl ketone (4- arnino-benzophenone) and the like, di-heterocyclic aryl ketones, particularly di-monocyclic heterocyclic aryl ketones, such as dipyridyl ketones, e.g., di-3-pyridyl ketone, 3-pyridyl 4-pyridy1 ketone, di-4-pyridyl ketone and the like, or monocyclic carbocyclic aryl monocyclic heterocyclic aryl ketones, such as phenyl pyridyl ketones, in which phenyl may be unsubstituted or substituted as shown hereinbefore, e.g., phenyl 3-pyridyl ketone (3- benzoyl-pyridine), 4-chloro-phenyl 4-pyridyl ketone [4- (4-chloro-benzoyl)-pyridine], 4-amino-phenyl 3-pyridyl ketone [3-(4-aminobenzoyl)-pyridine] and the like.

Instead of one single ketone, a mixture of two different ketones may be used in the one-chamber electrolytic reduction procedure of this invention. For example, the mixture of an aliphatic carbocyclic aryl ketone, such as a lower alkyl monocyclic carbocyclic aryl ketone, e.g., 4-chloro-phenyl methyl ketone (4-chloro-acetophenone) and the like, and an aliphatic heterocyclic aryl ketone, such as a lower alkyl monocyclic aryl ketone, e.g., methyl 3-pyridyl ketone (3-acetyl-pyridine) and the like, when treated according to the procedure of this invention, yields a mixture of diols, from which a mixed asymmetric diol, such as an a-monocyclic carbocyclic aryl p-monocyclic heterocyclic aryl-lower alkane-a,,B-diol, e.g., 2-(4- chloro-phenyl)-3-(3-pyridyl)-2,3-butanediol and the like, can be isolated.

The process of this invention is especially useful for the preparation of u,fi-bis-pyridyl-lower alkan-u,,B-diols, particularly of 2,3-bis-(3-pyridyl)-2,3-butanediol,'by electrolytic reduction of a lower a'lkanoyl-pyridine, particularly of 3-acetyl-pyridine; such procedure comprises subjecting the lower alkanoyl-pyridine, especially 3-acetyl-pyn'dine, to electrolytic reduction in a one-chamber electrolysis cell, using as the electrolyte water or preferably a mixture of water and a non-reducible, water-miscible, organic solvent, such as a lower alkanol, e.g., isopropanol and the like, or a formamide, e.g., N,N-dimethylformamide and the like, which'preferably contains an ionizable salt, such as an alkali metal salt of a lower alkanoic acid, e.g., sodium acetate, potassium acetate and the like, to enhance the conductivity of the medium. Electrolyte vehicles, electrodes, particularly the cathodes, and current densities used in such preferred procedure are those described and specified hereinbefore.

Diols prepared according to the present procedure show adrenal inhibiting effects, but are more especially useful as starting materials in pinacolone rearrangements (treatment with a strong acid, e.g., hydrochloric, polyphosphoric, sulphuric acid and the like) to ketones, or in double dehydration procedures with simultaneous cyclization to indenes, which ketones and indenes show outstanding adrenal inhibiting efiects, and can be used either as therapeutic or as diagnostic agents. Particularly outstanding adrenal inhibiting etfects are, for example, those of 3,3-bis (4-amino-phenyl)-butane-2-one (amphenone B), 1,2-bis-(3-pyridyl)-2-methyl propan-l-one (methopyrapone) and the like, which may be prepared by pinacolone rearrangement from 2,3-bis-(4-amino-phenyl)-2,3-butanediol, 2,3-bis-(3-pyridyl)-2,3-butanediol and the like, respectively, as well as those shown by 6-chloro-2-(3-pyridyl)-indene and the like, which may be obtained, for example, by double dehydration and simultaneous cyclization of 2-(4-chloro-phenyl)-3-(3-pyridyl)-2,3-butanediol and the like, in the presence of a stronge acid, e.g., hydrochloric acid and the like. As has been mentioned previously, the pinacolone rearrangement to form these ketones occurs most readily and with high yields, if a pure and uniform diol is used as the starting material.

In the process of this invention such starting materials are preferably used which lead to final products mentioned as preferred products.

The following examples are intended to illustrate the invention and are not to be construed as being limitations thereon. Temperatures are given in degrees Centigrade.

Example 1 A solution of 24.23 g. of 3-acetyl-pyridine and 30 g. of potassium acetate in 100 ml. of N,N-dirnethylformamide and 45 ml. of water forms the electrolyte; the latter is placed into the one-chamber electrolysis cell. A tin electrode with a surface of 100- cm. (previously cleaned with nitric acid) is used as the cathode, and a nickel electrode of 12 cm. surface is placed into the electrolyte as the anode. A current, kept between 4.1 and 4.4 amps, is passed through the solution, while a solution temperature of from 67 to 69 is maintained. A total of 18 ml. of water is added in portions during the electrolysis in order to hold the liquid level constant. After minutes, a precipitate forms; the electrolysis is interrupted after 11.9 ampere-hours have passed.

The electrolyte is diluted with ml. of water, cooled to 8 for 64 hours and filtered. The solid material is Washed with four portions of water (30 ml. each) and dried at 100 under reduced pressure for sixteen hours to yield 12.65 g. of pure 2,3-bis-(3-pyridyl)-2,3-butanediol, M.P. 218-225".

Example 2 In the procedure of Example 1, the tin cathode is replaced by a nickel cathode while using a nickel anode of 36 cm. otherwise, the electrolysis is carried out as shown in Example 1.

After cooling to -8 for sixteen hours, the reaction mixture is filtered, the precipitate is washed with four 30 ml. portions of water and dried at 70 under reduced pressure for sixteen hours. 13.9 g. of the desired 2,3- bis-(3-pyridyl)-2,3-butanediol is recovered, M.P. 224- 230.

' Example 3 A solution of 36.3 g. of 3-acetyl-pyridine and 30 g. of potassium acetate in 62.5 ml. of deionized water and 82.5 ml. of isopropanol is placed into a one-chamber electrolytic cell equipped with a cylindrical nickel cathode having a surface of 100 crn. and a smaller cylindrical nickel anode placed concentrically within the circular cathode and having a surface of 36 cm. The reduction is car- 'ried out at a temperature of 62 and at a current density of 0.03 amp/cm? of cathode. The reduction is complete after six hours; a total of 29.4 g. of pure 2,3-bis-(3- pyridyl)-2,3-butane-diol is isolated by diluting the resulting solution with 100 ml. of water, letting stand for sixteen hours at room temperature and working up as shown in Example 1.

Example 4 A solution of 5030 g. of 3-acetyl-pyridine and 6290 g. of potassium acetate in a mixture of 15200 ml. of isopropanol and 15200 ml. of deionized water is subjected to electrolytic reduction using a rectangular nickel cathode of 7000 cm. surface and a nickel anode of 2000 cm. surface; the reaction is carried out at 62 and 0.04 amp/cm? of cathode and is completed after nine hours. A total of 3240 g. of pure 2,3-bis-(3-pyridyl)-2,3-butanediol is recovered by diluting the resulting solution with 20,000 ml. of water and working up according to the procedure described in Example 3.

Example 5 A mixture of 66.6 g. of 3-acetyl-pyridine and 82.5 g. of potassium acetate in 200 ml. of deionized water and 200 ml. of isopropanol are placed into a rectangular cell using identical, flat nickel electrodes, each having 100 cm. surface. They are connected to the power supply through a reversing switch, so that the roles of the cathode and the anode can be exchanged without interrupting the reaction. The electrolysis is carried out at 62 and 0.04 amp/cm. of electrode for eight hours and twenty minutes, reversing the direction of the current fiow every thirty minutes. The 2,3-bis-(3-pyridyl)-2,3-butanediol is isolated by diluting the resulting solution With 275 ml. of water and working up according to the procedure described in Example 3; yield: 43.5 g. of pure product.

Other lower alkanoyl-pyridines, such as, for example, 3-propionyl-pyridine, 4-acetyl-pyridine and the like, or other analogous ketones, particularly aliphatic aromatic ketones, particularly lower alkyl phenyl ketones, e.g., 4-chloro-acetophenone, 4-arnino-acetophenone, and the like, or mixtures of ketones, e.g., a mixture of 3-acetylpyridine and 4-chloro-aceto-phenone and the like, or any other analogous ketone or ketone mixture mentioned hereinbefore, may be used as the'starting materials in the above-described electrolysis procedure, which yields the desired diols, such as for example, 3,4-bis-(3-pyridyl)-3, 4-hexandiol, 2,3 -bis- 4-pyridyl -2,3-butanediol, 2,3-di- 4- chloro-phenyl -2,3-butanediol, 2,3-di- 4-amino-phenyl 2,3-butanediol, 2-(4-chlorophenyl)-3-(3-pyridyl)-2,3-butanediol and the like.

Example 6 An electrolyte consisting of 24.2 g. of 3-acetyl-pyridine and 30 g. of potassium acetate in 72.5 ml. of n-propanol and 78.5 ml. of water is subjected to the one-chamber electrolytic reduction procedure described in Example 1, using a nickel cathode having a surface of 100 cm. and a current density of 0.04 amp/cm. The reduction is complete after three hours, and, after dilution of the resulting solution with 100 ml. of water, the pure 2,3-bis- (3-pyridyl)-2,3-butanediol is recovered according to the procedure described in Example 3; yield: 15.3 g.

What is claimed is:

1. Process for the preparation of diols from ketones, which comprises subjecting the ketone starting material to electrolytic reduction in a one-chamber electrolysis cell, using as the electrolyte vehicle the mixture of a nonreducible, water-miscible organic solvent, water and an ionizable metal salt of an organic carboxylic acid and a current density of from about 0.01 amp/cm. to about 0.1 amp./cm.

2. Process according to claim 1, which comprises using a water-miscible lower alkanol having three carbon atoms as the non-reducible, water-miscible organic solvent.

3. Process according to claim 1, which comprises using a water-miscible formamide as the non-reducible, watermiscible organic solvent.

4. Process according to claim 1, which comprises using an alkali metal salt of a lower alkanoic acid as the ionizable metal salt of an organic carboxylic acid.

5. Process according to claim 1, which comprises using a mixture of isopropanol, water and potassium acetate as the electrolyte vehicle.

6. Process according to claim 1, which comprises using a mixture of N,N-dimethylformamide, water and potassium acetate as the electrolyte vehicle.

7. Process according to claim 1, which comprises using a lower alkyl pyridyl ketone as the ketone starting material.

8. Process according to claim 1 which comprises using 3acetyl-pyridine as the ketone starting material.

9. Process for the preparation of 2,3-bis-(pyridyl)-2,3- butanediol from 3-acetyl-pyridine, which comprises subjecting 3-acetyl-pyridine to electrolytic reduction in a onecharnber electrolysis cell, using as the electrolyte vehicle the mixture of a non-reducible, water-miscible organic solvent, water and an ionizable metal salt of an organic carboxylic acid, and a current density of from about 0.01 amp/cm. to about 0.1 amp./cm.

10. Process according to claim 9, which comprises using a water-miscible lower alkanol having three carbon atoms as the non-reducible, water-miscible organic solvent.

11. Process according to claim 9, which comprises using a formamide as the non-reducible, water-miscible organic solvent.

12. Process according to claim 9, which comprises using an alkali metal salt of a lower alkanoic acid as the ionizable metal salt of an organic carboxylic acid.

13. Process according'to claim 9, which comprises using a mixture of isopropanol, Water and potassium, acetate as the electrolyte vehicle.

14. Process according to claim 9, which comprises using a mixture of N,N-dimethylformamide, water and potassium acetate as the electrolyte vehicle.

References Cited by the Examiner UNITED STATES PATENTS 2,420,954 5/47 Isham 204-76 2,507,973 5/50 Hefti a a1. 204-77 2,867,569 l/59 Kronenthal 204-72 2,981,667 4/61 Foreman et al. 20477 FOREIGN PATENTS 447,323 3/48 Canada.

WINSTON A. DOUGLAS, Primary Examiner.

MURRAY TILLMAN, Examiner.

Claims (1)

1. PROCESS FOR THE PREPARATION OF DIOLS AND KETONES, WHICH COMPRISES SUBJECTING THE KETONE STARTING MATERIAL TO ELECTROLYTIC REDUCTION IN A ONE-CHAMBER ELECTROLYSIS CELL, USING AS THE ELECTROLYTE VEHICLE THE MIXTURE OF A NONREDUCIBLE, WATER-MISCIBLE ORGANIC SOLVENT, WATER AND AN IONIZABLE METAL SALT OF AN ORGANIC CARBOXYLIC ACID AND A CURRENT DENSITY OF FROM ABOUT 0.01 AMP./CM.2 TO ABOUT 0.1 AMP./CM.2.