DE2359863C3 - Process for the production of glyoxylic acid - Google Patents

Description

where R _{9 is} a divalent, saturated or unsaturated, straight-chain or branched aliphatic hydrocarbon radical and all of the radicals R ₁₀ , R ₁₁ and R _{12 have} less than a total of 40 carbon atoms, R ₁₃ , R ₁₄ , R ₁₅ and Rj _{6 are} one of the have the meanings given above for R ₁₀ , R ₁₁ and R ₁₂ , the possibility for two of these radicals to together form a single divalent radical, only for two radicals which come from the same nitrogen atom

IO

d) quaternary ammonium salts of the formula

contains, wherein R ₁₀ , R ₁₁ , R _{12 is} a saturated or unsaturated, straight-chain or branched, aliphatic hydrocarbon radical, two of these radicals may optionally together form a single saturated alkylene radical or an oxydialkylene radical, or a radical of the formula

- (CH ₂ ), - [0- (CH ₂ U-OH

where η = 2 or «3 and m = 1 to 10, where at least one of the radicals R ₁₀ , R ₁₁ and R _{12 is} an arylaliphatic radical of the formula

η
K ₉

where the number of carbon atoms of the radicals R ₁₃ , R ₁₄ , R ₁₅ and R _{1 is} as defined below and the presence of an arylaliphatic radical among the radicals R _13, R ₁₄ , R ₁₅ and R _{16 is} not necessary , R _{17 is} a divalent aliphatic or arylaliphatic hydrocarbon radical, the aliphatic chain or aliphatic chains of which can be interrupted by an oxygen atom *, the free va lences of the radical R _{n being carried} by aliphatic carbon atoms and the total number of carbon atoms in the radicals R. ₁₃ , R _14, R ₁₅ , R ₁₆ and R _{17 are} above 6 and below 40, R ₁₈ , R _19, R ₂₀ and R _{21 represent} a saturated or unsaturated straight-chain or branched aliphatic hydrocarbon radical, two of these radicals optionally together being a single saturated one Can form an alkylene radical or an oxydialkylene radical or a radical of the form

- (CH ₂ ) "- [O -

OH

with η = 2 or 3 and m = 1 to 10, where at least one of the symbols R ₁₈ , R ₁₉ , R ₂₀ and R _{2 is} a monovalent aromatic hydrocarbon radical that is either purely aromatic, aryl aliphatic or aromatic with linear or ver branched, saturated or unsaturated aliphatic radicals as substituents, and the entirety of the radicals R ₁₈ , R ₁₉ , R ₂₀ and R ₂ , more than 15 and less than 40 carbon atoms has R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ and R _{27 have} the same meanings as for R ₁₃ , R _u , R ₁₅ and R ₁₆ indicated; and R _{28 has} the same meaning as given for R ₁₇ ; and all of the radicals R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ and R _{28 have} more than 8 and fewer than 40 carbon atoms, y has the meaning of 1, 2 or 3, A " denotes the hydroxyl radical or represents an anion, so that AH ,, means an inorganic or organic sauna.

2. The method according to claim 1, characterized in that the adjuvant in the in Be desired concentration is soluble in water.

3. The method according to any one of claims 1 or 2, characterized in that the Ad juvans is selected from the group:

Tribenzylamine, bis (dimethylamino) diethyl

ether;

the hydroxides and halides of Di

methyl-benzyl-octadecylammonium;

the hydroxides and halides of Di

methyl-phenyl-dodecylammonium. Dimethyl

phenyl-hexadecylammonium;

the hydroxides and salts, in particular

the dihalides of 1.6-bis (triethylam

monio) hexane, 1,4-di (n-butyl) -1,4-diazonia

bicyclo [2.2.2] octane, 1,4 - di - (η - dodecyl)

1,4-diazonia-bicyclo [2.2.2] octane.

The present invention relates to a broader embodiment of the method of patent 22 40 75 < for the production of glyoxylic acid by cathodic! Reduction of an aqueous oxalic acid solution.

In patent 22 40 759 em is a process for the production of glyoxylic acid by cathodic reduction an aqueous oxalic acid solution which is free from strong mineral acid in an electrolysis device, a cathode, a cathode chamber, a cation exchange membrane designed as a separating diaphragm, having an anode chamber and an anode, the catholyte in a closed Circle is guided, where it circulates on the surface of the cathode and where it is at one end of the Cathode chamber is withdrawn and then reinserted at the other end of this same chamber, and the temperature of the catholyte is between 0 and 70 ° C, preferably between 5 and 35 ° C, described, which is characterized in that the catholyte 0.00005 to 1% of certain nitrogen-containing Contains additives. In particular, these nitrogenous adjuvants make it possible to:

to use commercially available oxalic acid for the production of glyoxylic acid without this having to be recrystallized several times,
To use oxalic acid of various origins without it being necessary to subject it to a special cleaning treatment or to take special precautions with regard to the type of device and the ions derived from it,

to reduce the hydrogen formation at the cathode during the electrolysis of oxalic acid, which enables better electrical yields to be obtained (a decrease in electrical yields corresponds to the formation of hydrogen).

The present invention is the use of new nitrogen-containing adjuvants in the Production of glyoxylic acid by cathodic reduction of oxalic acid.

The invention therefore relates to a process for the production of glyoxylic acid by cathodic reduction of oxalic acid according to patent 22 40 759, which is characterized in that the catholyte 0.00005 up to 1% by weight of an adjuvant or an additive from the group of

a) tertiary amines of the formula

d) quaternary ammonium salts of the formula

2 /,

■ 24

■ 27

R,

contains, wherein R ₁₀ , R _n , R _{12 is} a saturated or unsaturated, straight-chain or branched, aliphatic hydrocarbon radical, where two of these radicals can optionally together form a single saturated alkyl radical or an oxydialkylene radical, or a radical of the formula

- (CH ₂ J ₁₁ - [O- (CH ₂ ) ^ OH

where π = 2 or 3 and m = 1 to 10, where at least one of the radicals R ₁₀ , R ₁₁ and R _{12 is} an arylaliphatic radical of the formula

C ₆ H ₅ R ₉

where R _{9 is} a divalent, saturated or unsaturated, straight-chain or branched aliphatic hydrocarbon radical and all of the radicals R ₁₀ , R _n and R _{12 have} less than a total of 40 carbon atoms, R ₁₃ , R ₁₄ , R ₁₅ and R _{16 are} one of the have the meanings given above for R ₁₀ , R ₁₁ and R ₁₂ , the possibility for two of these radicals to together form a single divalent radical exists only for two radicals which are carried by the same nitrogen atom; wherein the number of carbon atoms of the radicals R _u . R ₁₄ , R ₁₅ and R _{16 are} as defined below; and the presence of an araliphatic radical among the radicals R ₁₃ , R ₁₄ , R ₁₅ and R _{16 is} not necessary, R _{17 is} a divalent aliphatic or arylaliphatic hydrocarbon radical, the aliphatic chain or aliphatic chains of which can be interrupted by oxygen atoms, the free valences of the radical R _{17 are carried} by aliphatic carbon atoms and the total number of carbon atoms in the radicals R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ and R _{17 is} above 6 and below 40, R ₁₈ , R ₁₉ , R ₂₀ and R _{21 are} saturated or unsaturated, straight-chain or branched aliphatic hydrocarbon radical, where two of these radicals can optionally together form a single saturated alkylene radical or an oxydialkylene radical, or a radical of the formula

- (CH ₂ ) .- [O- (CH ₁ ).? = - OH

NO

12th

b) bitertiary amines of the formula

i 3

i 5

NR _n -N

c) quaternary ammonium salts of the formula

R.8

with η = 2 or 3 and m = 1 to 10, where at least one of the symbols R ₁₈ , R ₁₉ , R ₂₀ and R _{21 is} a monovalent aromatic hydrocarbon radical which is either purely aromatic, araliphatic or aromatic with linear or branched, saturated or unsaturated aliphatic radicals as substituents, and the totality of the radicals R ₁₈ , R ₁₉ , R ₂₀ and R _{21 has} more than 15 and less than 40 carbon atoms, R ₂₂ , R ₂₃ , Fl ₂₄ , R ₂₅ , R ₂₆ and R ₂₇ have the same meanings as given for R ₁₃ , R ₁₄ , R ₁₅ and R ₁₆ ; and R _{28 has} the same meaning as indicated _{for R 17;} and all of the radicals R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ and R _{28 have} more than 8 and less than 40 carbon atoms, y has the meaning of 1, 2 or 3, Α ' ^θ den Represents hydroxyl radical or an anion, so that AH _{y represents} an inorganic or organic acid.

The exact nature of A ^ye is not a characteristic of the invention and one can get such an anion through

replace another using conventional ion exchange techniques. As a possible meaning for Α * ^θ apart from a hydroxyl radical one can mention the nitrates, sulfates, phosphates, sulfonates, dicarbonates, oxalates, halides and especially the chlorides, bromides and iodides.

The adjuvants used in the present invention are mainly those which are soluble in water at the concentration contemplated; in particular, it is preferred to choose A ^{y &} so that this solubility is present.

The following adjuvants can be mentioned in particular: tribenzylamine, (dimethylamino-ether, the hydroxides and salts, especially the halides of dimethyl-benzyl-dodecylammonium, Diethyl-benzyl-dodecylammonium, dimethyl-benzyl-tetradecylammonium, diethylbenzyl - tetradecylammonium, dimethyl - benzylhexadecylammonium, diethyl - benzyl - hexadecylammonium. Dimethyl - benzyl - octadecylammonium, diethyl - benzyl - octodecylammonium, dimethylbenzyl - eicosylammonium, diethyl - benzyl - eicosylammonium. Dimethyl-benzyl-docosylammonium, diethyl-benzyl-docosylammonium; the hydroxides and salts of dimethyl-phenyl-dodecylammonium, dimethyl-phenyl-hexadecylammonium; the hydroxides and salts, especially the dihalides of l, 6- (triethylammonium) -hexane, l.4-di- (n-butyl, 4-diazonia-bicyclo [2.2.2] octane, 1,4-Di- (n-dodecyl) -l, 4-diazonia-bicyclo [2.2.2] octane (see Examples 8 and 9).

The temperature of the catholyte is generally between 0 and 70 ° C, preferably between 5 and 35 ° C.

The main metals which the cathodes can form in the process of the present invention can be BH, cadmium, mercury and the amalgams as well as the alloys of these various Name metals, especially with silver, tin and antimony. The anode used in the invention Electrolysis cells consist in practice of an electrically conductive, electrochemical in the anolyte and material stable under the considered working conditions. As materials that are Suitable for the anode, metals and metalloids, such as platinum, can be platinized Titanium, graphite, lead and its alloys, especially with silver, antimony and tin, name.

The separating diaphragm of the anode and cathode chambers is preferably a cathion exchange membrane. The nature of the same is not a characteristic of the invention. So you can use all grained membranes, in particular, use the homogeneous membranes and the heterogeneous membranes. This Membranes can optionally be reinforced by an insert. To make electrolysis aisles longer To be able to perform duration, it is preferable to use membranes that are exposed to the action of the various constituents of the catholyte and the anolyte are stable and do not swell. As usable Membranes can be seen in particular in US Pat. No. 2,681,320 and in French Patents 15 68 994, 15 75 782, 15 78 019, 15 83 089, 15 85 187 and 20 40 950 described to name.

The permselectivity of the membranes used (measured as in the French patent 15 84 187) is preferably over 60%.

The catholyte used in the process according to the invention essentially contains water, oxalic acid, Glyoxylic acid, one or more adjuvants of one of the formulas I to IV, optionally a strong mineral acid such as sulfuric acid; however, it is preferred not to use such an acid.

At the beginning of the electrolysis, the catholyte can only hold oxalic acid without glyoxylic acid; also can the catholyte at the end of the electrolysis only glyoxyl

acid without oxalic acid. The concentrations of oxalic acid and glyoxylic acid can be constant be when you work continuously, or variable when you work discontinuously, or even during the initiation of a continuous process.

The concentration of oxalic acid is lower than the saturation for the one under consideration Temperature; in general this concentration is more than 2% by weight; this value concerns in particular the constant concentration when working continuously and the final concentration discontinuous work. The concentration of glyoxylic acid is generally 3 to 25% by weight, preferably 5 to 15% by weight, these values being in particular on the constant concentration of glyoxylic acid during a continuous operation and the final concentration of this acid refer to discontinuous work. As already stated above, the concentration of the Catholytes of adjuvant generally between 0.00005 and 1% by weight. This is preferably Concentration between 0.0001 and 0.5%; the usage this small amount has the advantage of removing the adjuvant from the produced To be able to omit glyoxylic acid, since this adjuvant then has practically no adverse effect exerts the qualities of this acid.

The catholyte can also, if appropriate, reaction by-products in small amounts, in general less than 1%.

An aqueous acidic solution is preferably used as the anolyte. The exact nature of this anolyte is not a characteristic of the invention, since the main purpose of the anolyte is to be electrical Ensure conductivity between the two electrodes. In general, aqueous ones are used Sulfuric acid and phosphoric acid solutions. The concentration of these solutions is generally between 0.1 and 5 mol 1, preferably between 0.5 and 2 minor.

The current density at the cathode is generally between 3 and 50 A dm ² , preferably between 10 and 35 A dm ² .

In the practice of the invention one can use any known electrolysis devices, for example those described in the above-mentioned patents and in particular in Belgian patent 7 57 106, use.

However, it is preferred to use electrolyzers with fixed electrodes, making the achievement of compact devices, in particular Filter press type devices made possible. The electrodes and the Separating diaphragm arranged in parallel planes.

In a likewise advantageous manner, the catholyte and the anolyte can be used in their respective Circulate chambers, which enables better results to be obtained.

Finally, separators or spacers can be placed between the electrodes and the separating diaphragm. for example, arrange tissue or grids.

The following examples serve to illustrate the invention.

The "commercially available" oxalic acid used in the examples is one according to that in the French patent 3,331,498 and techniques described in British Patent 11487/1915 Acid, whereby the various reactions carried out lead to an oxalic acid solution that is in vacuo dried and then vacuumed; it is an oxalic acid dihydrate with a degree of purity of about 99.2%.

Examples 1 to 9

A number of attempts are made to reduce oxalic acid; these different attempts differ in the nature of the adjuvant used. The electrolytic cell in which this Experiments are carried out has the following characteristics:

The two electrodes are rectangular lead plates.

The usable surface of these electrodes is 0.8 dm ² .

The cathion exchange membrane is of the heterogeneous type: crosslinked sulfonated styrene-divinylbenzene copolymer, dispersed in a material reinforced by an insert in the form of a fabric made of polyvinyl chloride.

Permselectivity, measured in 0.6 m-KCL: 77.5%.

Substitution resistance, measured in 0.6 m-KCL; 7 ohms cm ² .

Distance between electrodes and membrane: 3 mm.

Table 1

Two pumps ensure the circulation de; Catholyte and the anolyte in the corresponding Chambers of the cell.

The circles in which the anolyte and catholyte circulate each have an expansion vessel which is equipped with feed and discharge lines.

A heat exchanger is also provided in the circuit of the catholyte.

ίο The electrolysis conditions are as follows:
Current density: 25 A / dm ² .
Voltage: about 5.25V.
Temperature: 25 ° C.

Circulation speed of the electrolytes around the electrodes: 1 m / sec.

Catholyte introduced at the beginning: 21 an 8 weight percent aqueous oxalic acid solution (commercially available oxalic acid).
This solution is continuously electrolyzed.

After one hour, 25 j is added to the catholyte; commercial oxalic acid and then 25 pounds of this acid every half hour.

During this entire period of time, the hydrogen escaping as a gas is caught in one Water trough and tracks the electricity yield, which corresponds to this hydrogen gas development. When If this yield reaches a value of 6 to 12%, this is added to the catholyte in each experiment special adjuvant too. The volume of hydrogen generated is measured in response to the addition of the adjuvant following hour and calculates the corresponding current yield. The results obtained with the various following adjuvants are listed in the tables below:

Example type of adjuvant

N-TCH ₂ -C ₆ H ₅ J ₃

Duration of
electrolysis
before addition
of the adjuvant

2 h 15 min

(CH ₃ ) ₂ N-f CH ₂ ) ₂ -O- (CH ₂ ) ₂ -N (CH ₃ ) ₂ 2h 20 min

CH ₃

CH ₂ -QH ₅

CH ₃ -N *

h 48 mn 12

Current concentration Mean current yield of the adjuvant yield (in%) (in%) ent- in mM / 1 in in to the
speaking of the catho- addition of the
H, production lytes of adjuvant follow hourly at the time of its addition
the encore
of the adjuvant

8 1 1.5

8.4 5 5.1

1 3.2

CH ₃ C ₆ H ₅

CH ₃ -Ν® Ι ^θ

Q ₂ H ₂₅

CH ₃ C ₆ H ₅

CH ₃ -N * ΟΗ ^Θ

te den TabeHra brafentel the abbreviation mM Mfllnnol

3h 20mn 6

2.8

3.9

3h 20mn 8.9

4.7

709819/308

Table 2

23 59 8t> 3

Example ArI of the adjuvant

CH ₃ Q ₁ H ₅

CH ₃ -Ν® OH

Duration of the current Concentration Middle Slrom

Eleklrolysc Stroin bulge of the adjuvant bulge (in%)

before addition (in%) ent- in niM / 1 in in the on the

of the adjuvant speaking of the your catho- addition of the

H, -production lytes with adjuvant (blgen-

at the time of its addition the hour

the encore

des Ad j u viiii s

45 mn 6.4

2.6

(C ₂ H ₅ J ₃ N- (CH ₂ J ₆ -N (C ₂ H ₅ J ₃ 2 Br®

CH ₂ -CH ₂ UC ₄ H ₉ -N-CH ₂ -CH ₂ -N-Ii-C ₄ Ii,

CH ₂ -CH ₂

21 ©

CH2

nC ,, H "- N-CH ₃ -CH ₂ -N

2ΙΘ

CH ₂ -CH ₂

DC ₁₂ H ₂₅

2h 18 mn 9.5

3 h 17 mn 7.2

6.5

1.5

U

Claims (1)

Patent claims: 1. Process for the production of glyoxylic acid by cathodic reduction of oxalic acid according to Patent 22 40 759, characterized in that that the catholyte 0.00005 to 1% of an adjuvant or an additive from the group of a) tertiary amines of the formula ¹⁰ \ NO 1.2 b) bitertiary amines of the formula 13, R, 15th NR ₁₇ -N R ,. ^V 14 Rl 6 c) quaternary ammonium seeds of the form! R ₁ , - Ν®— R " ■ 20 R22 R25 R ₂₃ -NR ₂₈ -NR ₂₆ ,
R24 R27 2 /, A '