JPH0730014B2 - Method for producing perpropionic acid - Google Patents

Description

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

More specifically, when hydrogen peroxide and propionic acid are reacted to produce perpropionic acid, water introduced together with hydrogen peroxide is coexisted in the presence of a solvent capable of forming a heterogeneous azeotrope with water. The present invention relates to a method for producing perpropionic acid, in which an acid catalyst is added and reacted after removing by boiling distillation, and water generated during the reaction is removed by azeotropic distillation.

[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 involving 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 a 10-40 weight percent sulfuric acid aqueous solution as a catalyst, and then the propionic acid formed was extracted with a solvent such as benzene and produced 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) A method of producing perpropionic acid in the same manner as in (2) using boric acid, boric oxide, arsenic oxide, selenium oxide, etc. as a catalyst instead of a strong acid catalyst such as sulfuric acid in the same manner as (2) (for example, JP-A-56-15263, JP-A-56-45457
issue).

[Problems to be solved by the invention]

However, the above 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 above method (2) 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.
Since a strong acid such as sulfuric acid is contained in the reaction liquid as in the above (1), a large amount of energy is required for this 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 an olefin, the produced epoxide 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 the corrosion resistance of the apparatus is greatly improved, but the production rate of perpropionic acid is increased. It is slower than when a strong acid catalyst such as sulfuric acid is used, so that the reaction takes a long time, and there is a problem that the yield is lowered due to thermal decomposition of perpropionic acid.

[Means and Actions for Solving Problems]

As a result of various studies to solve the above problems, the present inventors have found that the above problems can be solved by concentrating the hydrogen peroxide solution in advance, and finally completed the present invention. . That is, the present invention is a method for producing perpropionic acid by reacting aqueous hydrogen peroxide and propionic acid in the presence of a solvent capable of forming a heterogeneous azeotrope with water, which is introduced together with hydrogen peroxide. The water is removed by azeotropic distillation, an acid catalyst is then added to carry out the reaction, and the produced water is removed by azeotropic distillation.

The removal amount of water introduced together with hydrogen peroxide in the present invention is within the range represented by the following formula.

When 0 <χ ≦ 60 When 60 <χ χ: Hydrogen peroxide concentration (% by weight) Y: Weight of hydrogen peroxide water Z: Weight of water removed If the amount of dehydration is less than the above range, the thermal stability of perpropionic acid deteriorates, Decomposition loss increases.

The acid catalyst used in the present invention is boric acid or a combination of boric acid and phosphoric acid, and particularly when a stainless steel reactor is used,
It is desirable to use boric acid and phosphoric acid in combination as in the prior application of the present inventors (Japanese Patent Application No. 61-258392).

Commercially available orthoboric acid or metaboric acid can be used as the catalyst boric acid used in the present invention, and commercially available orthophosphoric acid can be used as the phosphoric 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 to allow the hydrogen peroxide to react efficiently and to avoid the risk of phase separation between hydrogen peroxide dehydrated in the reaction solution and an azeotropic dehydration solvent. Therefore, propionic acid / hydrogen peroxide = 2.0 to 5.0 (molar ratio) is 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 without any problems in ordinary epoxidation, ketone oxidation, aromatic ring opening reaction and the like.

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 In a 500 ml reactor made of Parex glass with a 10-stage Oldershaw distillation column equipped with a reflux condenser at the top of the column, 31.6 wt% hydrogen peroxide 81.6 g (0.84 mol), propionic acid 186.3 g
(2.52 mol), 1,2 dichloroethane 9 as azeotropic dehydration solvent
Charged 4g. The internal temperature of this reactor is 70 by an oil bath.
C., and heated to (internal pressure 200 mmHg).

In the condenser, only the condensed organic phase is refluxed to the distillation column,
On the other hand, the separated aqueous phase was designed to be continuously discharged.

60 minutes after the start of heating, 52.9 g of an aqueous phase was discharged. Then, 3.3 g (0.053 mol) of orthoboric acid was added as a catalyst, and the reaction was continued until the distilled water was completely discharged. The reaction time required 80 minutes. The reaction conditions and results are shown in Table 1.

Example-2 The procedure of Example-1 was repeated except that a 500 ml reactor made of SUS-316 was used. 60 minutes after the start of heating, 53.0 g of an aqueous phase was discharged. Next, as a catalyst, 3.3 g of orthoboric acid (0.05
3 mol) and 0.165 g (0.0017 mol) of phosphoric acid were added, and the reaction was continued until the distilled water was completely discharged. The reaction time required 80 minutes.
The reaction conditions and results are shown in Table 1.

Example 3 Instead of 1,2 dichloroethane as an azeotropic water solvent, 1,2
Using dichloropropane, internal pressure 170mmHg (internal temperature 70
The same procedure as in Example-1 was carried out except that the temperature was changed to 0 ° C). 50 minutes after the start of heating, 52.8 g of an aqueous phase was discharged. Next, 3.3 g (0.053 mol) of orthoboric acid was added as a catalyst,
The reaction was continued until the distilled water was completely discharged. The reaction time required 70 minutes. The reaction conditions and results are shown in Table 1.

Example-4 Performed in the same manner as in Example-1, and 4 minutes 39 minutes after the start of heating.
0.3 g of aqueous phase was discharged. Then orthoboric acid as catalyst
3.3 g (0.053 mol) was added and the reaction was continued until the distilled water was completely discharged. The reaction time required 120 minutes. The reaction conditions and results are shown in Table 1.

Comparative Example-1 The procedure of Example-1 was repeated except that 3.3 g of orthoboric acid was initially charged. The reaction was continued until the distilled water was completely discharged. The reaction time required 220 minutes. The reaction conditions and results are shown in Table 1.

Comparative Example-2 Performed in the same manner as in Example-1, 30 minutes after the start of heating
0.5 g of aqueous phase was discharged. Then orthoboric acid as catalyst
3.3 g (0.053 mol) was added and the reaction was continued until the distilled water was completely discharged. The reaction time required 160 minutes. The reaction conditions and results are shown in Table 1.

[Effect of the invention] As is apparent from the examples, the present invention drastically reduces the reaction time by dehydrating water previously introduced with hydrogen peroxide by azeotropic distillation and then carrying out the reaction by adding a catalyst. At the same time, the perpropionic acid can be produced in extremely high yield and can be safely operated. Therefore, its industrial utility value is great.

Claims (3)

[Claims] 1. A method for producing perpropionic acid by reacting aqueous hydrogen peroxide with propionic acid in the presence of a solvent capable of forming a heterogeneous azeotrope with water, which is introduced together with hydrogen peroxide. A method for producing perpropionic acid, which comprises removing water by azeotropic distillation, then adding an acid catalyst to carry out a reaction, and removing produced water by azeotropic distillation. 2. The method for producing perpropionic acid according to claim 1, wherein the weight of water introduced together with hydrogen peroxide and removed by azeotropic distillation is represented by the following formula. When 0 <χ ≦ 60 When 60 <χ χ: Hydrogen peroxide concentration (% by weight) Y: Hydrogen peroxide water weight Z: Water weight removed 3. The method for producing perpropionic acid according to claim 1, wherein the acid catalyst is boric acid or a combination of boric acid and phosphoric acid.