US2786022A

US2786022A - Electrolytic production of acetylene carboxylic acid

Info

Publication number: US2786022A
Application number: US442203A
Authority: US
Inventors: Wolf Viktor
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-07-20
Filing date: 1954-07-08
Publication date: 1957-03-19
Anticipated expiration: 1974-03-19

Description

United States Patent LELECTROLYTIC PRODUG'I ION ACETYLENE 4 CARBOXYLIC ACID ,Viktoi' Wolf; Hamburg,.Germany 'iNo Drawing. Application'July 8, 1954, :SerialNo. 442,203

' Claims priority, application Germany July 20,1953

2 Claims. 2 (Cl'i204-79) This invention relates to .theproduction Of-acetylene carboxylic acids.

Various. processes are already knownforthe production J of acetylene carboxylic acids.

..'Propiolic acid has, fortexample; :beenpreparedby con- ;yertingacetylene-with sodium into sodium acetylideaa'nd reactingtzthelatter with CO2 (U.'-S. .specificationwlslo. 2,205,885); alternatively acetylene sis cconverted FWlth chlorinewinto trichlorethylene, thesaid product isi'concompoundsby treatment with alkalimetalsand subsequent carbonisation :is 'mOf subordinate importance. .'(.Gilman, 'Haubin, J. Amer..Chem.Soc. 67 (1945);:1'420.) 1 Similarly, the action of carbon=dioxide onracetylene-di-Grig- A nard compounds. is. out of the gquestion for, synthesis .on -thetechnical scale (Ruggli,-Helv..-3 (1920.);559; G-rignard, Lapayre Faki, C. L187 (1928), 517). "ThGZCOH- ventional methodat the present time is :to removehydrogen halide from different halogenated succinic acidszor maleic;or fumeric acids. his true that by this. means a yield of 73-.88% is obtained, but the starting-materials are not readily available:- (Perkin, Simonsen; .lourniliChem.

(Soc- 9.1,(1907), 816; Abbott, Arnold,vThompson, Organic .SyntheseslS (-19 38), .3). It thereforehad to be considered tasxa technical advance-when Heilbron and:collaborators .(J. Chem-Soc. .1949, 604) were able-tooxidise-in sulphide ;solution, by means. of .chromic acid, butin-.(2-)-:'diol.-1.,'4

which is. today available on alargetechnical scale. .HOW- even, the yieldscould not. beincreased toimore than 23% .and .could ,only beobtained-by addition of "an vorganic solvent (acetone). According to the invention acetylene carboxylic acids. are obtained in good yield by'the electrolytic oxidation inacid solution of an acetylene alcohol with one or more primary hydroxyl groups, such assbutin- 2) -diol-1,4 or butin-( l )-ol-4 or propin-,(.1-) -ol=3. T he anode solution can be worked up in manner .known per =se, for'example by extractingwith anorganic solvenwdrying the extract and evaporating the solvent in vacuo. This process is of value from a technical point of view, not only on account of the cheap oxidising means, but also because it can be carried out with inexpensive anode material and with current densities of, for example, up to amps/elm? without the yields being appreciably reduced. By this means, it is possible to obtain a high transforma tion per unit of time with electrodes of small dimensions.

According to a preferred embodiment of the present invention, the temperature in the anode space during the oxidation process is kept below 50 C., more preferably below C., for which purpose external cooling may be necessary. When the temperature rises substantially above 2,786,022 Ph'teirtd Man 1 9, 1957 "-20C.,- for example to -40" C.,"the yield is lowered as compared withthe yieldswhich are obtainable by using "lower "temperatures. Whereas it is possible, for'example, 'underotherwise equal conditions to obtain a yield of 5 about7 2% 'ofacetylene dicarboxylic acidwhen'butin-(D- '-diol-1,4 is oxidised electrolytically to give the said acetylene dicarboxylic acid, using a temperature range of -about:8 9- C., theyield drops toabout 58% when the samebpteration is carried out without cooling and the "temperature-in the anode space rises to 30-40 C.'owing to spontaneousheating. This latteryield is still always substantially better than'theyield whichcan'be obtained according'tothe known processes. In the interest'of industrial' efficiency, however, it is expedient 'to determine 15 1..

particular case.

and observe 'the optimum reaction temperature in each Furthermore, it'has been found thatitis expedient not to's'elect-too high an alcohol concentration and preferably butin-(2) -diol-1,4 to form acetylenedicarboxylic acid, it

amounts to 'about72% of the theoretical, the yield with \an alcohol concentration of 10+1l% drops to about' 51%. The yieldof 51'% is substantially betterthan' th'atwhich canbe produced with the previously'kn'ov'vn processes, but -itisnevertheless in the interest of the industrial efficiency .30

tration in each particular case.

of thep'ro'cess' to determine the optimum a'lcohol concen- It is expedient toselect sulphuric acid'as the acid. The influence of the sulphuric acid concentration on the yield is not very pronounced. It is possible for the sulphuric acid concentration in the anode space to be-lowered to "about 1% without thereby substantially impairing the yield. On" the other hand, it is not desirable to raise the -sulphuric acid concentration beyond 30%, because the yield then begins to fall by a few percent.

When carrying out the process of the invention, it is only necessary to cover the anode space and provide it with a reflux condenser when the starting products or intermediate products or endproducts arereadily volatile. -It is'also not necessary to move the anode liquid with all acetylene alcohols.

than 70% acid is already obtained with current energypbut the yield drops gra-dually'when the current energyis more than It is expedient :to uselead dioxide anodes. It is also desirable to separate the anode and cathode chambers in a suitable manner.

The present process givescrude products int the form acids of high concentratiomwhich-are not or areonly slightly contaminated by by-products,gandc-which may he used as such or if desired may be further worked up into pure end products. In the case of acetylene dicarboxylic acid, a crude product which is 9195% pure is obtained in the form of a light-yellowish to light-brownish powder. The yields which are obtainable according to the present process are substantially higher, for example in the case of acetylene dicarboxylic acid, than the yields which can be produced by the prior known processes.

Example 1 In a rectangular electrolysis vessel, the anode chamber 18. separated from the cathode chamber by a clay plate as diaphragm. Plate glass sheets, fitted on by means of a 1 the electrolysis.

grease packing, serve to cover the electrode chambers.

V The plates are drilled above the cathode chamber to carry a reflux condenser through which extends the cable supplying current to a 8 x 16 cm. copper plate anode, while a second reflux condenser is arranged above the anode chamber, the stem of a mechanically operated agitator extending through a latter condenser. The two ends of an 8 x 10 mm. lead tube serving as anode also project through the cover of the anode chamber.

flat convolutions, i. e. with an effective surface of 1.0 dmi", in the anode liquid. 50 gm. of 96% propargyl alcohol and 550 gm. of sulphuric acid are disposed in the anode chamber, while the cathode chamber contains 15 sulphuric acid. Water is passed through the reflux condensers and the anode, so that a temperature of 8.5-9 C. is maintained in the anode chamber during the electrolysis. While constantly stirring, a current of 4.0 amps. with a terminal voltage of 3.2 volts is passed through for 26.9 hours, this corresponding-to 107.6 ampere hours=1l2.5% of the theoretical current energy.

'After a few minutes, the lead anode is covered with a distilled off from the boiling water bath. The residue is distilled under the vacuum of a water pump on an initially warm and then boiling water bath and produces 53.25

gm. of a light yellow clear liquid which contains 89.35% of propiolic acid, i. c. 47.6 gm. of a 160% acid 76.l% V of the theoretical. The current yield is 67.5%.

Example 2 In a rectangular electrolysis vessel, the anode chamber is separated from the cathode chamber by a clay plate as diaphragm. The cathode is a copper plate of 8 x 16 0111., which dips into approximately 15 sulphuric acid. The anode is a lead tube of 8 x 10 mm. which is coated by a dioxide layer and is immersed over a length of 63.5

cm.,'laid in flat convolutions, i. c. with an eflective surface of 1.0 dm. in the anode liquid. The anode cham- .ber contains 25 gm. of pure, butindiol, dissolved in 510 gm. of water, and 90 gm. of concentrated sulphuric acid. Water flows through the anode, so that a temperature of 89 C. is maintained in the anode chamber during the electrolysis. A current of 3.0 amps. with a terminal voltage of 3-4 volts is passed through for 26 hours and 36 -minutes, which corresponds to 79.75 ampere hours=1l0% of'the theoretical current energy. Towards the end of the electrolysis, the evolution of gaseous oxygen increases. The anode liquid is filtered, salted out by addition of .common salt and extracted for 8 hours with ether. The

extract is dried over calcium chloride, filtered off from the latter and the solvent distilled off in vacuo. There remain 25.75 gm. of a light brown powder with an acid content of 94.75%, i. c. 24.4 gm. of a 100% acid-=- 73.9% of the theoretical. The crude product melts at 169-174 C. with decomposition.

The lead tube is immersed over a length of 63.5 cm., laid in 4 Example 3 e The operation is carried out as in- Example 2, but instead of the quantities of 25 gm. of pure butindiol, 510 gm. of water and gm. of concentrated sulphuric acid, as indicated in Example 2, there are now introduced 10 gm. of hexan-diine-(2.4)-diol-1,6 in 500 gm. of 3% su-lphuric acid. The apparatus is encased in black paper. A current of 1.0 amp.==0.01 amp./cm. current density is used. The current is passed through for 19.5 hours, which corresponds to 100% of the theoretical current energy. The anode liquid is extracted for 5 hours with ether. The material extracted is cooled with water, whereupon it becomes darker. The extract is washed twice with a little water. It isthen dried over calcium chloride, a low temperature being ensured by storing in a refrigerator. The red filtrate is mixed with 5 times the quantity of petroleum ether, decanted from the precipitated polymer and again diluted with petroleum ether to 5 times the volume. In the refrigerator, the acid crystalises into initially pure white crystals, which are discolourcd to greyish-red crystals in spite of cooling and darkness. The yield is 1.333 gm. of diacetylene dicarboxylic acid in the form of the dihydrate and in fact the crude yield has a content of 96.8% of dihydrate. The yield therefore corresponds to 1.29 gm. of 100% dihydrate: 8.15% of the theoretical.

The crystals darken at -100 C.. and decompose without explosion.

From the filtrate, there is obtained, after strong concentration and precipitation with petroleum ether, a further 0.531 gm. of a 91% dihydrate=0.483 gm. of

dihydrate=3.05% of the theoretical.

What I claim is:

1. A method of producing acetylene carboxylic acids, comprising the steps of subjecting an acetylene alcohol in a sulfuric acid solution containing a maximum of 30% sulfuric acid to electrolytic oxidation at a current density of up to 10 amps./dm. in an electrolytic cell'supplied with lead dioxide anodes and having separate anode and cathode compartments and at a temperature of below 20 C., the concentration of said acetylene alcohol in said acid solution being between 4-25%, thereby converting said acetylene alcohol to the corresponding acetylene car boxylic acid; and recovering said acetylene carboxylic acid.

2. method of producing acetylene carboxylic acids, comprising the steps of subjecting butin-(2)-diol-1,4 in

.a sulfpric acid solution containing a maximum of 30% Slllflll'lC acid to electrolytic oxidation at a current density of up to 10 amps./dm. in an electrolytic cell supplied with lead dioxide anodes and having separate anode and cathode compartments and at a temperature of below 20 C., the concentration of said butin-(2)-diol-1,4 in said acid solution being between 425%, thereby converting said butin-(2)-diol-1,4 to the corresponding acetylene carboxylic acid; and recovering said acetylene carboxylic acid.

References Cited in the file of this patent

Claims

1. METHOD OF PRODUCING ACETYLENE CARBOXYLIC ACIDS, COMPRISING THE STEPS OF SUBJECTING AN ACETYLENE ALCOHOL IN A SULFURIC ACID SOLUTION CONTAINING A MAXINUM OF 30% SULFURIC ACID TO ELECTROLYTIC OXIDATION AT A CURRENT DENSITY OF UP TO 10 AMPS./DM.2 IN AN ELECTROLYTIC CELL SUPPLIED WITH LEAD DIOXIDE ANODES AND HAVING SEPARATE ANODE AND CATHODE COMPARTMENTS AND AT A TEMPERATURE OF BELOW 20 C., THE CONCENTRATION OF SAID ACETYLENE ALCOHOL IN SAID ACID SOLUTION BEING BETWEEN 4-25%, THEREBY CONVERTING SAID ACETYLENE ALCOHOL TO THE CORRESPONDING ACETYLENE CARBOXYLIC ACID; AND RECOVERING SAID ACETYLENE CARBOXYLIC ACID.