JPS5829739A - Preparation of glyoxylic acid - Google Patents

Abstract

PURPOSE:To obtain glyoxylic acid useful for a reaction with a phenol in high selectivity advantageously even in high conversion ratio of a raw material, by reacting an aqueous solution of glyoxal with chlorine as an oxidizing agent. CONSTITUTION:An aqueous solution of glyoxal is reacted with chlorine of a simple substance as an oxidizing agent, preferably under pressure and preferably in such a way that the concentration of hydrochloric acid prepared as a by- product in the aqueous solution is controlled at 1-15wt%, to give glyoxylic acid in high conversion ratio of >=90% and in high selectivity of >=80%. Since the reaction is controlled by regulating the feed speed of chlorine in this process, the reaction is controlled easily, and large-scale fixed devices are not required. This process can use raw materials with lower quality than nitric acid oxidation process, and the resultant reaction mixture can be used directly in a reaction with a phenol, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing glyoxylic acid by the oxidation method of glyoxal.

As a method for producing glyoxylic acid, the electrolytic reduction method of Scherer's acid has been known for a long time. There are many problems with the industrial production method, such as a decrease in selectivity and a decrease in current efficiency when the rate of use increases.

The nitric acid oxidation method is the most commonly used method for producing glyoxylic acid by oxidizing glyoxal. In this reaction, a funnel with a low conversion rate of glyoxal has good selectivity, but
When the rate of conversion is increased, Schereric acid is produced by sequential reactions, and the selectivity obtained for glyoxylic acid is dramatically reduced. For example, if the rate of change of glyol+f-ol is increased from yes to 90g, the glyoxylic acid selectivity will drop from 9011g to 70-.Also, in the nitric acid oxidation method, it will take some time for the added nitric acid to complete the reaction. The reaction proceeds with nitric acid accumulating in the system. The controllability of the reaction depending on the amount of nitric acid charged is poor. Moreover, if nitric acid oxidation is interrupted midway, the selectivity, especially H1, after restarting becomes extremely poor. Therefore, it is difficult to reduce the selectivity (after performing the first stage reaction at a reaction rate of 1 m, it is impossible to fine-tune the rate of change to the desired rate with additional nitric acid; Interruption/resumption due to technical inconvenience 411/0 Such inconvenience is observed not only in the y-reaction suspension solution, but also in the nitric acid oxidation of glyoxal aqueous solutions containing glyoxylic acid in general.

Furthermore, a method for producing glyoxylic acid by electrolytic oxidation of glyoxal is also known (Japanese Unexamined Patent Publication No. 79884/1984). This method increases the conversion rate to about 95% and maintains the selectivity of about 80%. Although this method solves to some extent the drawbacks of the nitric acid oxidation method, in which a high rate of change Ksi and high selectivity cannot be obtained, it is difficult to react at high concentrations and requires large fixed equipment.

In view of these problems of the conventional method, the present inventor has developed an oxidation method that can produce glyoxylic acid with high selectivity even when the conversion rate of glyoxal is high, has easy reaction control, and does not require large fixed equipment. We conducted a thorough study to find out. As a result, it has been found that by selecting chlorine as the oxidizing agent among the many oxidizing agents known in the world, the above objects can be achieved very satisfactorily, and the present invention has been completed. That is, the present invention is a method for producing glyoxylic acid, which is characterized in that an aqueous glyoxal solution and chlorine are mixed together several times.This reaction formula can be expressed as follows.

The oxidizing agent chlorine used in the present invention is simple chlorine,
It is produced in large quantities as a companion product to electrolytic soda, and it is available in large quantities in just one city. Elemental chlorine is an extremely effective oxidizing agent, and oxidizing glyoxal with chlorine is effective J)9.
Even at a high conversion rate of 091 or higher, glyoxylic acid can be obtained with a selectivity of 80 or higher.

Glyokizuru is obtained in the form of round O-water hydrated with overcharge, and can also be used in the form of overcharged 5~401!0 water SmO (commercially available glyokizuru) as well. Inferior glyokizuru water camellia case, for example, Dariokider water S wave containing a large amount of glyoxylic acid, which is a by-product in glyokizuru potion 1, is used to inject 4 nitric acid oxidation OS into Marubasha. The method of the present invention can be carried out by blowing chlorine into the glyoxal water, but it can be carried out by blowing chlorine into the glyoxal water. A 11ff reaction method can also be used, and either a batch method or a continuous method is possible. The reaction in this reactor can be controlled by adjusting the co-supply rate of chlorine), and by keeping the reaction temperature constant and finely adjusting the amount of oxidizing agent to achieve the desired rate of change, it is possible to oxidize nitric acid. This is much easier than in the case of The reaction is exothermic, and the reaction temperature is maintained by appropriate heat removal means such as water cooling. Although the liquid temperature is not fixed, it is usually between 0 and 100C, and the process will proceed satisfactorily even at temperatures below 11Kll, but at normal pressure.

The rate of collection of chlorine in the thermal reaction is relatively low, and it takes KJE time to complete 1JL conduction. The second way to shorten reaction time is reaction i++vi! For example, 80tl' with the selection of 5
Although it is possible to react at temperatures such as
e, the selectivity tends to decrease, so 1, for example, 10 to 5O
Moderate warm JI like t=! ) is the preferred reaction temperature.

An effective means for HIIiJ11oEKl during the reaction is pressurized reaction), and by reacting 5 liters of water with chlorine under pressure), the reaction rate can be increased without reducing the reaction performance. can be used.

For example, in Example 5, which will be described later, the snow pressure reaction took 58 hours, and the rate of change in glyokyl was 1.4 times, whereas in Example 4, which was slightly pressurized, it took s6 hours! In Example 7, which was pressurized at -4 gauge, a change rate of 9 s- or more was obtained in 14 hours, and the selectivity to glyoxylic acid was also high. ◇If the reaction pressure is further increased, the reaction rate is big)
, Place] 1 [Kyosi For example 5 kl/aj e or 1o4
/dG ll! However, it requires high-pressure equipment, which increases the heat removal load per unit. 2/, J3 is also low and hot at 01 hours 11JIKt (Example 9), Toma) does not require high pressure.

From the reaction formula shown above, it is clear that in the method of the present invention, water chloride is produced as a by-product, and since it is in water, it coexists as hydrochloric acid in the reaction system, and its OII degree increases as the reaction progresses. Wow. The reaction rate is also related to the degree of hydrochloric acid; for example, in the Ioc reaction, the hydrochloric acid concentration in the reaction system is 1 s to 15 V.
When it exceeds t-, it becomes uneven rapidly. Therefore, if the raw material concentration is adjusted so that the hydrochloric acid concentration reached by the hydrochloric acid by-produced in the reaction is 1 s to 15 or less Ke, even in normal pressure or slightly pressurized reactions, it is possible to reduce the amount of glyoxide in a reaction time of about 20 hours. Change rate from 90? 5 Ist (Example 1.
8). If the reaction pressure is further increased to 201Q/al G fi, the reaction time can be shortened to 9 to 10 hours (Example?).

Discover the unexpected fact that the reaction selectivity improves when the simultaneous KI [family glyoxal membership level is lowered and the hydrochloric acid concentration in the reaction system is suppressed (see Example 8 and 9 of 11111)0 Hydrochloric acid concentration in the reaction wave To keep the temperature below 11s-, it may be necessary to remove hydrochloric acid by means such as extraction, electrodialysis, ion-exchange resin layering, evaporation, etc.
The method based on mechanical modification of the raw material glyoxal is the simplest and has the highest practical value.

The hydrochloric acid concentration also affects the chlorine yield in the method of the present invention. That is, in the present invention, the yield relative to chlorine is 10@
OK noticed that it may be abnormally low due to @
In order to prevent this problem, we have carefully examined the oxidation reaction and found that when the concentration of hydrochloric acid is low, the following is produced: According to Shun Shion, the raw material glyoxal Km1 is the secondary oxidation rate of oxalic acid or formic acid.
), find out that the yield against chlorine is black. and,
It was discovered that this O2 reaction could be suppressed by ensuring the concentration of hydrochloric acid in the glyoxol aqueous container used for the reaction. There was no problem, and in the end a small amount of 0.0. *The initial concentration of hydrochloric acid can be maintained by adding Shun or other methods. The concentration of hydrochloric acid to be added is preferably 1 to 2 sachets. If the concentration of hydrochloric acid is high, the reaction rate will be affected as mentioned earlier, so it is best to maintain the concentration of hydrochloric acid in the glyoxal aqueous solution in the range of 1 to 159 G when reacting with chlorine. When adding hydrochloric acid as described in Example 10,
The yield of glyoxal based on the chlorine yield is improved, and 8
Wasteful hydrochloric acid by-products due to M reaction can be suppressed. the result,
When compared at the same level as glyoxal change 9596, the reached hydrochloric acid concentration f#i started from zero and remained at 12.8%, which is the same as in the nine case, but it reacts to the addition of 1 to 2 times of hydrochloric acid. There is no adverse effect on speed.

In addition, when using glyokizil containing formic acid and sulfur as impurities as a raw material, when chlorine oxidation begins even if the concentration of hydrochloric acid is low, approximately 80'vo of carbon dioxide, an inert component, is present in the exhaust gas at the initial stage of the reaction. 'l-, and therefore the amount of exhaust gas removed in order to sustain the reaction pressure and the accompanying chlorine pollution were large. However, when the reaction was carried out with an initial concentration of Carbon dioxide in the initial exhaust gas is S
Ovol % or less, the loss of chlorine is also very small.

In this way, it is sufficient to add hydrochloric acid to bring the initial temperature to 1-11 degrees. Adding hydrochloric acid to above l)
When the reaction has a high rate of change, the reaction rate becomes slower once the Km chain degree becomes high. 1M) The reaction acid lII becomes worse, ■)
This is preferable for reasons such as wasting hydrochloric acid. Glyoxylic acid is used for reactions with phenolic steel, for example, but pressurized glyoxylic acid is produced by nitric acid oxidation. Removal, separation and purification are necessary.

Glyoxylic acid obtained in the present invention is obtained as water** mixed with hydrochloric acid as a by-product, but there is no problem@) It can be used in Kikou 1iK.

Of course, it depends on the purpose! According to NK, ion exchange resin Asahiho, electrodialysis, Ann extraction, etc.
#& can also be used @The degree of glyoxylic acid obtained is firstly glyoxal water IFIII
! However, in the case of nitric acid oxidation, the stone is further diluted by the water accompanying the nitric acid. Chlorine is advantageous in that it does not involve water. To obtain a high-concentration glyoxyl aqueous solution which is difficult to directly measure as the concentration of the reaction solution, the reaction solution obtained in the present invention may be concentrated using known techniques as required.

The present invention will be explained below with reference to Examples. - in the example is IPI
Example 1 Glyoxal S, OS Chronic and Glyoxylic Acid 0.4
Glycocontaining # dF f -ol aqueous solution containing 511 111850
．． Chlorine gas was blown into 2f at 15 to 111r for 19 hours to obtain a water-soluble t19stsr containing 5.08fkb glyoxylic acid, 0.54 mounds of glyoxal, and 7.24 mounds of hydrochloric acid.

The conversion rate of glyoxal was 92.8%, and the selectivity of glyoxylic acid was 8s, 4-.

Example 2 Glyoxal 14.0011 and Glyoxylic Acid 1
．． Glyokizil aqueous solution containing 15-@8295fK15
Glyoxyl Shun 9 by blowing chlorine gas for 1 s at ~20C
2? li, glyoxal 5.43 and hydrochloric acid 10.
Aqueous solution containing 57-? The rate of change of the 12.7 F lift pressure is 57.55 k.

The selectivity of glyoxylic acid was 88.4% Example 3 Glyoxal! 10411i and glyoxylic acid 2
．． Glyoxal water containing 68 steamed rice $ 111850.
Blowing chlorine gas at 0PK15G for 46 hours, glyoxylic acid 14.4.-, glyoxal 14. A reaction solution 2114.52 containing IS- and 14.19 s of hydrochloric acid was obtained.

At this time, it changes to 5.81 moles of glyoxal at t! 2.4-glyoxylic acid was obtained, and the result was 90%.

Example 4 Glyoxal 14.2- and glyoxylic acid 0.
Glyokizur water containing 4G- $11H4os, 1rK
Blow in chlorine gas with an ear for 24 hours, glyoxyl 8
．． 02Is1 glyoxal 4.07%, and hydrochloric acid 9
．． The reaction containing 65- @ 2400.9f was pumped up. At this time, the change rate of glyoxal was 53,9-, the selectivity of glyoxylic acid was 84.4%, and fI-0. If the chlorine injection was restarted, the interruption would be completed. Without a doubt, we were able to obtain a higher rate of change. That is, from the beginning! 2,40.
After 48 hours, the glyoxal concentration was 4.64.
%, decreased by 245%, 047%, reaching a change rate of 9511. What is the concentration of glyoxylic acid during this time? , 2?
11, 10.04%, jO, 51%], hydrochloric acid is also 11
．． 4'lk + 12.856116, increased with Ofun.

Example 5 Glyoxal aqueous solution 2250.6f containing glyoxal 13.01111 and glyoxylic acid 5,18-
Reaction f/g 2594.4f containing glyoxal 0.945kb glyoxyl 14,02- and hydrochloric acid 14,02- by bubbling chlorine with SaC at normal pressure for 58 hours.
Obtained 0 What is the rate of change in glyoxal at this moment? 1.4-
The glyoxylic acid selectivity was 7S 456, and the yield based on the glyoxyl compound (total number of moles of glyoxal and glyoxylic acid in the W material) was 74.9.

Example 6 Glyoxal 11.851% and Glyoxylic Acid 6
．． Glyoxal aqueous solution containing 12-11 Kk0.2 4
Chlorine was bubbled with black OC under pressure of G for 54 hours to obtain reaction 92BS4.8f containing glyoxal 0.7011b glyoxylic acid 14.1i5- and hydrochloric acid 14.2011. What is the rate of change in glyoxal during Jin? 1.111. The glyoxyl selectivity was 71.7%, and the yield relative to the glyoxyl compound was 77.6%.
Guri #*f- containing 1G and 11i of water [K2. o1q/-
・Blow chlorine with sOC under the pressure of G for 14 hours. ll, glyoxylic acid L2.41, steamed rice and hydrochloric acid, 1,. Reaction solution containing 4.44-995.4
I got 2.0 The glyoxark change rate at this time is 91.51
1. The glyoxylic acid selectivity was 111,411°, and the yield based on the glyoxyl compound was 79.5-.

Example 8 Glyoxal! , 11- and glyoxylic acid 5.6
Glyoxal water 1111!22B4.1t containing 0t
Glyoxal 05416 by blowing chlorine at 50C for 21 hours under the pressure of K O, 2 gas director G. glyoxylic acid 1
1.2? - and hydrochloric acid 12.48- reaction *2sz
Get x, 1t. At this time, the change rate of Gri1kizar is 95
The 15ks glyoxylic acid selectivity was 84.5%, and the yield to glyoxylic compound was 857%.

Example! Glyoxylic acid 9.52% and glyoxylic acid 3.4%
Glyoxal water solution containing 6-*848.9f11c2
．． 0 wheel, under pressure of 4 G, blowing chlorine at SOC for 10 hours, glyoxylic acid 0.65'fk1 glyoxylic acid 1
Reaction solution 97 containing 1.459 I and 12.47 pieces of hydrochloric acid
5.4f was obtained. What is the glyoxal change rate at this time? 2
, 211, the glyoxylic acid selectivity was 11,511 gI, and the yield to glyoxyl compound was 85.8-69.

Example 10 Glyoxylic acid 9.141s% Glyoxylic acid 1.9
Glyoxal water containing 3- and hydrochloric acid 1.0011 @
Under the pressure of il @ 48.0 f K 2.01#/af・G, chlorine was cooked in 30 Ll' for 8 hours, and glyoxal 0.4411. The reaction involving 10.54 glyoxylic acid and 12.18 glyoxylic acid and 12.18 glyoxylic acid was pumped up at 969.4 t.At this time, the glyoxal conversion rate was 94.7%, the glyoxylic acid selectivity was 87.1%, and the glyoxylic acid selectivity was 87.1%, with respect to the glyoxyl compound. The yield is @5. It was an O-sac. The change rate up to 6 hours in the middle is 90
．． ! 9 with a selectivity of 89.25i. The amount of glyoxylic acid absorbed relative to the amount of absorbed chlorine determined from the increment of hydrochloric acid before and after the O reaction was 182.1%.

For comparison, almost the same KSO as the initial Minato fO-
r, When reacted with chlorine under a pressure of 2.01 ap/d, the increase in hydrochloric acid concentration for 1 reaction time showed a similar trend at about 2 hours, and at 10 hours 11 the glyoxal change rate, [ Both values of 1118 degrees were almost the same as those above. The yield relative to chlorine was 80.0-), and there was an adverse effect at the early stage of the reaction due to the low concentration of hydrochloric acid.

In the case of 1.5% and 2 g/I immediately after initial hydrochloric acid, the chlorine collection was 85.411 and 82.491, respectively.

Comparative Examples Glyoxal 17.8411 and Glyoxylic Acid 1
0. Glyoxal aqueous solution containing s O* 1s o o
, o tKa 516@1IJ742.4 t 40C
It was added dropwise over 4 hours at 40C' and further aged for 6 hours to give 17.44% glyoxylic acid and 1% glyoxal.
A reaction solution 2052.1f containing 10% was obtained. Glyoxal conversion rate 91.6-, glyoxylic acid selectivity 4i
It was 5.116.

Original agent Kaoru Furutani

Claims (1)

[Claims] 1. A method for producing glyoxylic acid, which comprises reacting 5ill of glyoxal water with chlorine. 2. The production method according to claim 1, wherein the reaction is carried out under pressure. 3 The reaction is at a hydrochloric acid concentration of 1 to 11 in the glyokizuru water S case.
- The manufacturing method according to claim 1, which is carried out under the following conditions.