JPH0730015B2 - Method for producing perpropionic acid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing perpropionic acid.

[Conventional technology]

In producing perpropionic acid by reacting hydrogen peroxide with propionic acid, it is generally known to use a suitable catalyst in order to shorten the reaction time. For example, sulfuric acid, hydrochloric acid, phosphoric acid and various sulfones. Acids, cation exchange resins, boric acid, etc. have been proposed. At the same time as research on catalysts, the above reaction is an equilibrium reaction accompanied by the formation of water,
Various methods for moving the equilibrium to the production system have been proposed.
The method conventionally proposed is described below.

(1) Propionic acid was reacted with hydrogen peroxide using 10 to 41 weight percent sulfuric acid aqueous solution as a catalyst, and then the generated propionic acid was extracted with a solvent such as benzene, and was generated by entrained water and reaction of hydrogen peroxide. A method in which water is removed by distillation and the concentrated aqueous solution of sulfuric acid is circulated to the reaction system (for example, JP-A-56-15263 and JP-A-56-45457).
issue).

(2) Hydrogen peroxide and propionic acid are reacted with each other in the presence of an acid catalyst such as several 10% sulfuric acid aqueous solution and alkylsulfonic acid in the presence of an inert organic solvent capable of forming a heterogeneous azeotropic mixture with water. In this case, water present in the reaction mixture is removed by distillation of a water / organic solvent azeotrope (for example, JP-A-54-160313).

(3) Instead of a strong acid catalyst such as sulfuric acid, a method of producing perpropionic acid in the same liquid phase using boric acid, boric acid oxide, arsenic oxide, an oxidation sensor or the like as a catalyst (for example, a special method) Kai-56-15263, JP-A-56-454
No. 57).

[Problems to be solved by the invention]

However, the method (1) requires a large amount of solvent and a large number of extraction stages in order to extract perpropionic acid from the reaction solution in high yield.

Further, since a considerable amount of sulfuric acid is transferred to the organic phase after extraction, it is necessary to wash the organic phase with water to remove sulfuric acid, and then to dry it by azeotropic distillation, which makes the operation complicated. Further, when general austenitic stainless steel is used, not only problems in corrosion resistance occur, but also the yield of perpropionic acid decreases, which is industrially difficult.

The method (2) above is an excellent method in terms of the yield of perpropionic acid based on hydrogen peroxide, since water in the reaction mixture is removed by azeotropic distillation with an organic solvent. Similarly, the reaction solution contains a strong acid such as sulfuric acid, and thus requires a large amount of energy for its removal. The use of perpropionic acid with the inclusion of strong acids leads to undesired side reactions, which reduces the yield of the desired product. For example, in the epoxidation reaction of olefin,
The epoxide formed is easily cleaved by the action of a strong acid catalyst and converted into a mixture of mono and diethyl.
Further, similarly to the above (1), it has a drawback that a high-grade corrosion resistant material is required.

In the above method (3), since a weak acid such as boric acid is used, it is not necessary to remove the catalyst from the reaction solution, and although the corrosion resistance of the apparatus is greatly improved, it is possible to remove water during the reaction. These processes for producing perpropionic acid using heterogeneous azeotropic distillation have the disadvantage that appreciable amounts of peroxide are adsorbed into the aqueous phase to be distilled. The amount of peroxide to be admitted depends on the type of azeotropic dehydration solvent used, but it is generally 4-10% of the charged hydrogen peroxide.
There is a problem that it can reach up to%.

[Means and Actions for Solving Problems]

The present inventors finally conducted the present invention as a result of various studies for solving the above problems.

That is, according to the present invention, hydrogen peroxide and propionic acid are reacted in the presence of a solvent and a catalyst capable of forming an inhomogeneous azeotrope with water, and then produced during the reaction with water introduced together with hydrogen peroxide. In the method for producing perpropionic acid by removing azeotropic water with azeotropic distillation, a method for producing perpropionic acid, characterized in that a part of propionic acid is continuously inserted from the top of the azeotropic distillation column. .

The weight of propionic acid charged continuously in the present invention is 0.3 to 3.0 times the weight of water removed by azeotropic distillation.

If the amount of propionic acid charged is less than 0.3 times, the effect of preventing the peroxide in the water phase from being discriminated is not sufficient, and the amount charged is 3.0.
If the amount is more than doubled, the amount of the peroxide will be constant, so that it is not necessary to charge a larger amount.

The continuous charging of propionic acid in the present invention also means intermittent charging over most of the reaction time.

The catalyst used in the present invention is boric acid or a combination of boric acid and phosphoric acid. Especially when a stainless steel reactor is used, the present inventors have found that boric acid and phosphoric acid were used as in the previous application (Japanese Patent Application No. 61-258392). It is desirable to use together. The catalyst used in the present invention may be commercially available orthoboric acid or metaboric acid, and the phosphoric acid may be commercially available orthophosphoric acid. The addition amount of the catalyst is preferably 0.03 mol or more per mol of hydrogen peroxide. If it is less than 0.03 mol, the yield of perpropionic acid is lowered.

However, since the yield of perpropionic acid becomes almost constant when it is 1 mol or more, it is not necessary to add it in a larger amount.

Hydrogen peroxide and propionic acid used in the present invention may be used in the form of standard commercial products. Hydrogen peroxide, in particular, may be used in the form of a 30 to 60 weight percent commercially available aqueous solution. The molar ratio of hydrogen peroxide and propionic acid is not particularly limited, but in order to react hydrogen peroxide efficiently, propionic acid / hydrogen peroxide at the end of propionic acid charging = 2.0 to 5.0 (molar ratio). desirable.

As the solvent capable of forming an azeotrope used in the present invention, one which forms a heterogeneous azeotrope with water, has a large water content in the azeotropic composition, and has a low latent heat of vaporization is economically advantageous .
Examples of such a solvent include 1,2 dichloroethane, 1,2
Examples thereof include dichloropropane, benzene and cyclohexane.

The reaction temperature is preferably 50 to 80 ° C. When the reaction temperature is lower than 50 ° C., the production rate of perpropionic acid is slow, and when the reaction temperature exceeds 80 ° C., the decomposition loss of the produced perpropionic acid is large and the yield is reduced. The reaction pressure is usually 100 to 500 mmHg under reduced pressure which varies depending on the composition of the reaction system and the temperature selected.

The thus obtained perpropionic acid can be used for ordinary epoxidation, ketone oxidation, aromatic ring opening reaction and the like without any trouble.

The reaction and azeotropic distillation of the present invention can be carried out continuously or batchwise.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples.

Example 1 60% was added to a 500 ml reactor made of Piolex glass with a 10-stage Oldershaw distillation column equipped with a reflux condenser at the top of the column.
Hydrogen peroxide 47.6g (0.84mol), propionic acid 186.3g
(2.52 mol), orthoboric acid 3.3 g (0.053 mol) as a catalyst, and 1,2 dichloroethane 94 g as an azeotropic dehydration solvent were charged. The reactor was heated to an internal temperature of 70 ° C. (initial internal pressure of reaction: 200 mmHg) by an oil bath. The condenser at the top of the azeotropic distillation column was designed so that only the condensed organic phase was refluxed to the distillation column, while the separated aqueous phase was continuously discharged. The reaction continued for 2 hours until the distillation of the aqueous phase was completed. On the other hand, 100 g of propionic acid was continuously charged from the top of the azeotropic distillation column during this period. During this period, 35 g of an aqueous phase was discharged, and 0.009 mol of hydrogen peroxide and 0.001 mol of perpropionic acid were contained in this. This is 1.2% of the hydrogen peroxide used in the reaction. The reaction solution contained 0.788 mol of perpropionic acid. The reaction conditions and results are summarized in Table 1.

Example 2 The procedure of Example 1 was repeated, except that the amount of propionic acid charged from the top of the tower was 20 g. The reaction took 2 hours and 20 minutes. During this period, 35 g of an aqueous phase was discharged, which contained 0.012 mol of hydrogen peroxide and 0.002 mol of perpropionic acid.

This is 1.7% of hydrogen peroxide used in the reaction. The reaction conditions and results are summarized in Table 1.

Example 3 As an azeotropic dehydration solvent, 94 g of 1,2 dichloropropane was used instead of 1,2 dichloroethane, and the initial internal pressure of the reaction was 170 mmHg.
Example 1 was repeated except that the internal temperature was 70 ° C. The reaction time required 1 hour and 40 minutes, during which 35 g of the aqueous phase was discharged. In this, 0.020 mol of hydrogen peroxide and 0.003 mol of perpropionic acid were contained. This corresponds to 2.7% of hydrogen peroxide used in the reaction. The reaction conditions and results are summarized in Table 1.

Example 4 A procedure similar to that of Example 1 was carried out except that a 500 ml reactor made of SUS-316 was used as a reactor and 3.3 g (0.053 mol) of orthoboric acid and 0.165 g (0.0017 mol) of phosphoric acid were added as catalysts. did. The reaction takes 2 hours, during which 35 g of the aqueous phase is discharged, and 0.010 mol of hydrogen peroxide, perpropionic acid
It contained 0.001 mol.

This is 1.3% of the hydrogen peroxide used in the reaction. The reaction conditions and results are summarized in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that 286.3 g (3.87 mol) of propionic acid was charged all at once and the initial internal pressure of the reaction was 140 mmHg (internal temperature 70 ° C.). The reaction time required 1 hour and 50 minutes, during which 35 g of the aqueous phase was discharged. In this, 0.045 mol of hydrogen peroxide and 0.005 mol of perpropionic acid were contained. This corresponds to 6.0% of hydrogen peroxide used in the reaction.
The reaction conditions and results are summarized in Table 1.

Comparative Example 2 The procedure of Example 1 was repeated, except that the amount of propionic acid charged from the top of the tower was 6 g. The reaction took 2 hours, during which 35 g of the aqueous phase was discharged, containing 0.033 mol of hydrogen peroxide and 0.003 mol of perpropionic acid.

This is 4.5% of the hydrogen peroxide used in the reaction. The reaction conditions and results are summarized in Table 1.

Comparative Example 3 286.3 g (3.87 mol) of propionic acid was charged all at once, 94 g of 1,2 dichloropropane was used as the azeotropic dehydration solvent instead of 1,2 dichloroethane, and the initial internal pressure of the reaction was 110 mmHg (internal temperature). Example 1 was repeated except that the temperature was 70 ° C. The reaction time required 1 hour 30 minutes, during which 35 g of the aqueous phase was discharged. In this, 0.092 mol hydrogen peroxide, perpropionic acid
It contained 0.010 mol. This is 12.1% of the hydrogen peroxide used in the reaction. The reaction conditions and results are summarized in Table 1.

[Effects of the Invention] As is apparent from the examples, the present invention provides a pertinent peroxidation in the aqueous phase by a simple method of continuously charging propionic acid from the top of an azeotropic distillation column. Material loss can be greatly reduced, and as a result, especially hydrogen peroxide is effectively used for the reaction, and the yield of perpropionic acid is improved, so that its industrial utility value is great.

Claims (3)

[Claims] 1. A method of reacting hydrogen peroxide with propionic acid in the presence of a solvent and a catalyst capable of forming an inhomogeneous azeotrope with water, and then forming during the reaction with water introduced together with hydrogen peroxide. A method for producing perpropionic acid in which a portion of propionic acid is continuously charged from the top of an azeotropic distillation column in the method for producing perpropionic acid by removing azeotropic water with azeotropic distillation. 2. The method for producing perpropionic acid according to claim 1, wherein the catalyst is boric acid or a combination of boric acid and phosphoric acid. 3. The method for producing perpropionic acid according to claim 1, wherein the weight of propionic acid charged continuously is 0.3 to 3.0 times the weight of the water removed by azeotropic distillation.