US1544357A - Electrolytic process - Google Patents

Description

Patented June 30, 1925.

UNITED STATES CHARLES J. THATCHER, OF NEW YORK, N. Y.

ELECTROLYTIC rnocns's.

No Drawing.

To all whom it may concern:

Be it known that I, CHARLES J. THATCHER, a citizen of the United States, and a resident of New York, in the county of vNew York and State of New York, have invented certain new and useful Improvements in Electrolytic Processes, of which the following is a speeificatiom The invention relates to electrolytic processes; and its object isto prepare a plurality of products, particularly organic products, by one electrolysis.

By way of example, the novel process will be described as applied to the production of anthraquinone from anthracene and of benzidine from azoxybenzol or azobenzol. It is to be understood, however, that the process may be applied to the oxidation and reduction, by one electrolysis, of other compounds, either organic or inorganic, and which are either solid or liquid, and either insoluble or soluble in the electrolyte used.

provided the products resulting from the electrolysis can be substantially completely separated from the respective anolyte and catholyte after each operation or series of operations.

Apparatus suitable for thispurpose may consist of a single cell adapted to maintain effective separation of the anolyte and catholyte liquors, as by a diaphragm of the charactor, for example, set forth in my U. S. Iratters Patent No. 1,291,253. Or, as descrlbed U S. Letters Patent No.

' and shown'in my one, and

1,397,562, the apparatus may consist of a plurality of electrolytic cells connected preferably in series or series parallel, and having separated anode andcathode compartments. The cells should preferably be of a type providing for vigorous agitation of the electrolyte, and in whichthe agitation tends to maintain a homogenous mixture of suspended or dissolved substances to be o'xidized and reduced, and which might otherwise settle out at the bottom, r, other wa s. A suitable cell for this purpose is that s own and described in my U. S. Letters Patent No. 1,388,216.

The process itself will be described as adapted to the electrolytic oxidation of an acceptor, such as anthracene'to anthraquin- Y reduction of a difi'erent acceptor such as azoxybenzol to benzidine by one electrolysis. uch oxidation and reduction, producing two different products, I find can or float at the or causes concentration varlations 1n Application filed April 2, 1923! Serial No. 629,419.

be attained by the use of an electrolyte con-..

taining chromium ions both as anodic and cathodic catalysers, depolarizers or carriers of oxygen and hydrogen to the said acceptors. Other suitable depolariz ers or catalysers, such as vanadium, manganese, cerium or titanium ions, or combinations thereof; or other suitable ions possessing several different valencies or degrees of oxidation, may be utilized, and in concentrations suitable for or customary in electrolytes.

In the oxidation of anthracene and the reduction of azoxybenzol with an electrolyte containing chromium ions, electricity for the electrolysis is to be supplied in any well known manner to a suitable cell or cells (not shown); and the initial electrolyte, both as to the anode and cathode portions, may consist of an aqueous solution of sodium bichromate and sulphuric acid in the proportions of one pound of the former and two pounds of the latter to each gallon of solution, although other suitable portions may, of course, be used. At the initial stage of the process, the electrolysis is to be continued until substantially all of the sodium bichromate of the cathode portion of the electrolyte has been reduced to chromium sulphate. Or, as an alternative, the cell may be initially-supplied with an electrolyte containing chromium sulphate and sulphuric acid. such as spent chromium liquors resulting from oxidation of anthracene to anthraquinone. In suchease, the spent liquors will or may contain chromium sulphate, sodium sulphate and sulphuric acid in proportions substantially the same as those resulting from the electrolytic reductions of the sodium bichromate. and sulphuric acid solution hereinbefore specified. Electrolysis prior to the introduction of acceptors, for

oxidation and reduction, will then not be necessary.

With a catholyte which is substantially free from sodium bichromate and an anolyte consisting either of the specified solutions of sodium bichromate and sulphuric acid, or, chromium sulphate, sodium sulphate and sulphuric acid, there is added to the catholyte, azoxybenzol, as for example, in the proportion ofone-half to one pound thereof per gallon of eatholyte. To the anolyte,

there is added anthracene in the proportion,

for exam le, of one-half to one pound there of to eaci gallon of anolyte. Electrolysis" is then started, resumed or continued, ac-

companied preferably by a vigorous agitation of the anolyte and cathol te 1n such a way that the acceptors are we I distributed throughout the body of the electrolyte. Su1t-' able current density will be three to five reduced and substantially all of the anthracene is oxidized. In such an electrolysis, chromium ions act as a depolarizer or carrier of the hydrogen liberated at the cathode to the azoxybenzol, reducing it eventually to hydrazobenzol, which latter compound is converted into benzidine by the sulphuric acid present in the electrolyte. The end re-' sult is that all or substantially all of the azoxybenzol is converted into benzidine sulphate. which is insoluble in and may be separated from the catholyte, as by filtration. At the same time, the bichromate ions formed at the anode, under the conditions of the electrolysis, oxidize the anthracene suspended in the anolyte to anthraquinone, which is also insoluble in and may readily be separated from the anolyte, as by filtration.

The end result, of the electrolysis, therefore, is a catholyte containing chromium sulphate, sodium sulphate and sulphuric acid, and an anolyte which will be of substantially the same composition, if sufiicient anthracene has been used to reduce all the sodium bichromate originally present or formed by the electrolysis. It is desirable that this be done in order to have for the next operation or for the continuation of the same operation, an electrolyte which is substantially free from. sodium bichromate. If all t 1e sodium bichromate has not been used up in the oxidation of the anthracene, an ac ditional amount of anthracene may be oxidized with the resulting anolyte, by filtering ofi' 'the anthraquinone formed and using enough anthracene to reduce substantially all of the remaining sodium bichromate to chromium sulphate.

It will also be understood tion of the anthracene to anthraquinone by the bichro'mate electrolyte formed at the anode may be entirely effected. if desired,

subsequent to the electrolysis and outside the electrolytic apparatus, as by collecting an amount of the electrolyte containing suflicient bichromate to'oxidize chemically any desired amount of anthracene. This operation may be accomplished by well known methods and under well known conditions that the oxidain a suitable rat or other container (not shown) and extraneous to the electrolytic apparatus.

In either case, the anolyte, remaining from tration of the catholyte will have corrc-,.

spondingly diminished. For this reason, the liquors or the electrolysis should be reversed after each operation, that is to say the anolyte liquors should be used' as a catholyte liquor and the catholyte liquoras the anolyte liquor in the continuation of the operation or the succeeding electrolysis, whereby the concentrations in sulphuric acid will tend to be restored by the said 'migration ofSO ions.

The concentration of sulphuric acid in the catholyte will, moreover, be reduced during electrolysis, by the combination of sulphuric acid with the benzidine to form benzidine sulphate, as aforesaid. During the electrolysis, therefore, or after the separation of the benzidine sulphate fromthe catholyte,- a sufficient amount of sulphuric acid isto be added to the catholyte portion of the elec'- trolyte to replenish the amount of sulphuric acid removed in. combination as benzidine sulphate. After this has been done, the remaining catholyte is then to be used as the anolyte for. a continuation or the next operatlon of the process, as aforesaid.

Operating in cycles in this manner, the electrolyte will maintain substantially its initial concentration in chromium and sulphuric acid ions during any series of operations; and repeated reductions of azobenzol and repeated oxidations of 'anthracene can be effected each by one electrolysis, using the same electrolyte over and over againif desired. a It will be understood that azobenzol or other azo or azoxy derivatives or homologues may be so reduced, and that other compounds than anthracene may be so oxidized. It is not necessary, moreover, that the final product should be solid and substantially iusolublein the. resulting electrolyte, although that is desirable; for oxidation and reduction products, which can be separated by solvents immiscible in the electrolyte, or by other suitable means, may be produced by the novel process.

It will be understood that in using the word catalyser I intend toimply any ion or ions-which will either act catalytically or as a depolarizer and carrier of oxygen and which will be respectively oxidized or reduced with the formation of separable prodacts by the anodic and cathodic catalyser.

I am aware that separate oxidation and reduction, at different times, of certain compounds has been heretofore effected bymeans of electrolytes containing the same ion; but such oxidations and reductions have been carried out separately, with re sultant loss of oxygen or hydrogen in each reduction or oxidation. For a number of years it has been the aim of chemists to effect such an oxidation and a reduction by one electrolysis; but this result has first been achieved, so far as I am aware, only by the herein described invention.

I claim 1. The process of electrolytic oxidation of one product and electrolytic reduction of another product, which consists in electrolysing an electrolyte separated into an anolyte and catholyte and containing ions capable of acting as anodic and cathodic catalysers, introducing into the anolyte and catholyte liquors acceptors capable of being respectively oxidized and reduced thereby and of forming products separable therefrom. and separating the resulting products.

2. The process of electrolytic oxidation of one organic product and electrolytic reduction of another organic product, which consists in electrolysing an electrolyte separated into an anolyte and catholyte and containing ions capable of acting both as anodic and cathodic catalysers, introducing into the anolyte and catholyte liquors acceptors capable of being respectively oxidized and reduced therebyfand of .forming products separable therefrom, and separating the re-' s1 I l t i ng products.

:3. The process of electrolytic oxidation of one product and electrolytic reduction of another product. which consists in electrolysing an electrolyte separated into an anolyte and catholyte and containing ions capable of acting both as anodic and cathodic catalysers, subsequnetly adding to the anol \'te and catholyte liquors and While continuing the electrolysis acceptors capable of being respectively oxidized and reduced thereby and of forming products separable therefrom, and separating the resulting products.

4. The process of electrolytic oxidation of one product and electrolytic reduction of another product, which consists in e1ectrolysiug an aqueous solution of a chromium compound and sulphuric acid separated into an anolyte and catholyte, introducing into the anolyte and catholyte liquors acceptors capable of bemg respectively oxidized and reduced thereby and of forming products separable therefrom, and separating the resulting products.

5. The process of electrolytic oxidation of an oxidizable product and electrolytic reduction of a reducible product, which consists in electrolysing an aqueous solution of sodium bichromate and sulphuric acid sepaiaited into an anolyte and catholyte, introducing, after the substantial reduction ofthesodium bich'romate of the catholyte portion, into the anolyte and catholyte liquors acceptors capable of being respectively oxidized and reduced thereby and of forming products separable therefrom, and separating the resulting products.

(i. The process of electrolytic oxidation of an oxidizable product and electrolytic reduction of a reducible product, which consists in electrolysing an aqueous solution of' sodium bichromate and sulphuric acid in the proportion of one (1) pound of the former and two (2) pounds of the latter per gallon of solution, separated into an anolyte and catholyte, introducing, after the substantial reduction of the sodium bichromate ot' the catholyte portion, into the an olyte and catholyte liquors acceptors capable of being respectively oxidized and reduced thereby and of forming products separable therefrom, and separating the resulting products.

7. The process of electrolytic oxidation of an oxidizable product and electrolytic reduction of a reducible product, which consists in electrolysing an aqueous solution of sodium bichromate and sulphuric acid in the proportion of one (1) pound ofthe former and two (2) pounds of the latter per gallon of solution, separated into an anolyte and catholyte, and at a temperature of from to 90 C., introducing, after the substantial reduction of sodium bichromate of the catholyte portion, into the anolyte v and catholyte liquors acceptors capable of being respectively oxidized and. reduced thereby and of forming products separable therefrom, and separating the resulting products.

8. The process of electrolytic oxidation of one product and electrolytic reduction of another product, which consists in electrolysing an electrolyte separated into an anolyte and catholyte and containing ions capable of acting both as anodic and cathodic catalysers, introducing into the anolyte and catholyte liquors acceptors capable of being respectively oxidized and reduced thereby and of forming products separable therefrom, separating the resulting products, re plenishing ions depleted in the electrolysis, and repeating the operation.

9. The process of oxidation of anthracene to anthraquinone and reduction of benzol compounds to benzidine, which consists in electrolysing an electrolyte separated into an anolyte and catholyte and containing ions capable of acting both as anodic and cathodic catalysers, introducing anthracene into the anolyte and the benzol compound into the catholyte, and separating the resulting products therefrom.

10. The process of electrolytic oxidation of anthracene to anthraquinone and the electrolytic reduction of azoxybenzol to benzidine, which consists in electrolysing an aqueous solution of sodium bichromate and sulphuric acid, introducing anthracene into the anolyte and azoxybenzol into the catholyte, and separating theanthraquinone and benzidine sulphate from the respective liquors.

11. The process of electrolytic oxidation of anthracene to anthraquinone and electrolytic reduction of azoxybenzol to benzidine,

'WlllCll consists 1n electrolysmg an aqueous solution of sodium bichromate and sulphuric acid, introducing anthracenc into the anolyte and azoxybenzol into the catholyte, separating the anthraquinone and benzidine sulphate from the respective liquors, and replenishing the supply of sulphuric acid of the anolyte.

12. The process of electrolytic oxidation of one product and electrolytic reduction of another product, which consists in electrolysing an electrolyte separated into an anolyte and catholyte and containing ions capable of acting both as anodic and cathodic cataly'sers, introducing into the anolyte and catholyte liquors acceptors capable of being respectively oxidized and reduced thereby and of forming roducts separable therefrom, separating t e resulting products, and

repeating the operation with anolyte as catholyte and catholyte as anolyte.

13. Electrolytic oxidation and reduction process, with separated anolyte and catholyte and common 'catalyser ions, which in cludes the step of introducing therein acceptors capable of bein .respectively oxidized and reduced there y and of forming products separable therefrom.

14. A process of electrolysis for the production of two products, which consists in preparing an electrolyte containing ions capable of actin as anodic and cathodic catal'ysers, electro ysing so as to produce an anolyte and catholyte, adding thereto acceptors capable of being respectively oxidized and reduced thereby and of forming products separable therefrom, and separating the resulting products.

15. A process of electrolysis for the production of two organic products, which consist-s in preparing an electrolyte containing ions capable of acting both as anodic and cathodic catalysers, electrolysing so as to produce-an anolyte and catholyte, adding thereto acceptors capable of being respectively oxidized and reduced thereby and of formin products separable therefrom, and separating the resulting products.

16. A. process of electrolysis for the production of two products, which consists in preparing an electrolyte containing ions capable of acting both as anodic and cathodic catalysers, electrolysing so as to produce an anolyte and catholyte, adding thereto acceptors capable of being respectively oxidized and reduced thereby and of forming products separable therefrom, separating the resulting products, and using the anolyte as catholyte and the catholyte as anolyte in a subsequent operation.

17. The process of electrolytic oxidation" of anthracenc to anthraquinone and the electrolytic reduction of azoxybenzol to benzidine, which consists in electrolysing an aqueous solution of sodium bichromate and sulphuric acid, introducing anthracene into the anolyte and azoxybenzol into the catholyte, separating the anthraquinone and benzidine sulphate from the respective liquors, and using the anolyte as catholyte and the catholyte as anolyte in a subsequent operation.

Signed at New York in the county of New York and State of New York this 31st day of March, A. D. 1923.

CHARLES J. THATCI-I ER.