KR19980059281A - Method for preparing sorbic acid - Google Patents

Abstract

The present invention relates to a process for preparing sorbic acid, and more particularly, using a novel catalyst coated with a copper salt on a zeolite support in the process of preparing a polyester produced by the reaction of crotonaldehyde and ketene during solvinic acid production. The present invention relates to a method for producing a high yield of sorbinic acid economically by preparing an ester and solvinic acid or a derivative thereof.

Description

Method for preparing sorbic acid

The present invention relates to a process for preparing sorbic acid, and more particularly, using a novel catalyst coated with a copper salt on a zeolite support in the process of preparing a polyester produced by the reaction of crotonaldehyde and ketene during solvinic acid production. The present invention relates to a method for producing a high yield of sorbinic acid economically by preparing an ester and solvinic acid or a derivative thereof.

Solvate, sorbic acid or derivatives thereof are industrially very useful substances which have excellent antifungal properties and are harmless to the human body and are commonly used as food preservatives.

In general, a process for preparing sorbate, sorbic acid or a derivative thereof is to prepare polyester via beta-lactone, an intermediate produced by the reaction of ketene with crotonaldehyde, and solvate the produced polyester by various methods. Divided into acids or derivatives thereof to prepare and purify. However, in the polyester manufacturing step described above, most of the reaction catalysts have relatively disadvantageous industrial methods in terms of manufacturing or economics by using relatively expensive metal catalysts. In addition, the metal chloride catalyst [Japanese Patent Laid-Open No. 51-127019, Organic Reactions Harold E. Zaugg, Vol. 8, P340 (1954)], there are many industrial disadvantages in subsequent processes, and most metal fatty acid salts [British specification 883, 492 (1961), French Patent No. 1,309,051] are themselves powerful and There is a serious problem of having an unpleasant odor, which not only makes the worker uncomfortable at work, but also the bad odor of sorbic acid or a derivative thereof, which degrades the quality of the product.

In addition, as the catalyst used for the synthesis of polyester in the above process, metals or metal oxides thereof (JP-45-9368, 41-19687), metal chlorides and various metal fatty acid salts are used. It can be divided into a homogeneous phase or a non-uniform phase according to. In general, even when the non-uniform catalyst is made into a very fine powder and used in the reaction, there is a limit in increasing the reaction activity by widening the reaction surface area, which is an important influence factor in the reaction. Participation is advantageous in obtaining a high yield of polyester by increasing the absorption of ketene as compared with the case of using a non-uniform catalyst.

In general, when the polyester is synthesized in a state in which the catalyst is uniformly dissolved in the reaction solution, polyester of high quality and high yield is obtained (British Patent No. 1193137). However, when the catalyst is melted uniformly, since the amount of the catalyst used in the reaction is very small, it is impossible to recover the catalyst after the reaction. In addition, these remaining catalysts adversely affect the solvate decomposition reaction in the process of decomposing the polyester into sorbic acid, causing the whiteness of the sorbic acid to degrade and deteriorate the quality. As a result, the burden on the purification process to obtain high quality sorbic acid is increased, resulting in a vicious cycle in which the yield of sorbic acid is lowered due to the loss of some sorbic acid during purification.

In order to solve this problem, the present inventors have used a catalyst in which inorganic copper salts were applied to zeolite during the preparation of polyester in the process of preparing sorbinic acid, which is relatively much more expensive than metal chloride catalysts or metal fatty acid catalysts in terms of cost. It is inexpensive, easy to purchase and use, and can be recovered and reused, and the result of using the catalyst can be maintained economically and with high yield through the industrially very economical polyester manufacturing process, such that the yield of the catalyst can be maintained equal to that of the homogeneous catalyst. An attempt was made to develop a method for preparing an acid.

In other words, using a novel catalyst made by applying copper salt, an inorganic metal salt, to zeolite to react ketene with crotonaldehyde, the reaction is as effective as the catalyst that melts and reacts uniformly in the reaction solution compared to the existing catalysts. It is possible to obtain a high yield of sorbic acid even in terms of yield with little obstacle in the reaction. In addition, unlike fatty metal salts, not only does not cause discomfort to the worker at work, but also there is no deterioration factor of the product due to the fragrance, thus finding surprising facts having industrially advantageous advantages and completing the present invention.

Therefore, the present invention is to replace the catalyst used in the production of solvinic acid in the production of polyester with a new one to produce sorbinic acid in economical and high yield as well as mild and effective as compared to the conventional process or process. The purpose is to provide a new method.

The present invention is a method of producing polyester by reacting crotonaldehyde and ketene in the presence of a catalyst, and sorbic acid from the catalyst, wherein the catalyst is coated with an inorganic copper salt on a zeolite support. .

Hereinafter, a reaction process for preparing sorbic acid according to the method of the present invention is as follows.

Crotonaldehyde is added to the vessel, a zeolite catalyst coated with an inorganic metal salt such as a copper salt is added, and then ketene gas is added to react. At this time, the temperature of the reaction solution is maintained at 20 ~ 70 ℃, the viscosity of the reaction solution increases as the reaction proceeds, because the high viscosity polyester is produced. After completion of the reaction, unreacted crotonaldehyde is distilled off under reduced pressure to obtain polyester as an intermediate as a main product.

In order to increase the reaction surface area of inorganic metals when reacting gaseous reactants under inorganic metal catalysts, adsorption of inorganic metals on various supports to increase reactivity yields a high yield of products, which are well known in the field of lower alkylamine production. to be.

The present invention applies the same principle to the present invention by dissolving a small amount of metal ion salt used as a catalyst in a suitable solvent and then adsorbed evenly to an excess of zeolite support, and then dried well and used as a catalyst, thereby having a reaction of a non-uniform catalyst. Increasing the surface area to the maximum to increase the reaction activity, it is possible to recover and reuse the homogeneous catalyst can be recovered after the reaction is impossible. In particular, in the present invention, since the catalyst is naturally recovered and reused, the residual catalyst adversely affects the decomposition reaction when the polyester is decomposed into sorbic acid, thereby lowering the whiteness of sorbic acid and increasing the burden on the purification process. The problem causing the degradation is fundamentally solved.

Zeolite used as a support in the present invention is represented by the following formula (1).

here,

N is the balance value of cation M,

W is the number of water molecules per lattice of zeolite units,

X and Y represent the total number of tetrahedera per unit lattice.

In addition, the zeolite used in the reaction as a support in the present invention can be used in any kind and examples that can be used specifically as follows. Chabazite, mordenite, erionite, faujasite, clinoptilolite, zeolite A, zeolite X, zeolite Y, zeolite omega, ZSM -5, ZSM-11 and the like are used after coating copper salts through cation exchange in zeolite lattice.

In general, transition metal ions such as copper ions, zinc ions, cadmium ions, nickel ions, and silver ions are easily applied by ion exchange reactions with cations of zeolites and are reduced by flowing hydrogen while applying heat after ion exchange reactions. It is used as a catalyst after performing.

According to the present invention, when looking at the amount of the copper salt applied to the zeolite in the catalyst as described above, the amount of the copper salt to the zeolite as a support can be applied to the zeolite within the range of 0.5 to 20% by weight, and as a better condition 1 to 10% by weight of copper salt is applied to the zeolite and used for the reaction. At this time, as the copper metal ion source to be applied, one selected from monovalent or divalent copper halide salts, copper hydroxide, copper nitrate salts or hydrates thereof and copper equivalents or hydrates thereof is used.

If the coating amount of the copper salt is less than 0.5% by weight, the amount of the catalyst applied to the support is large, making it difficult to stir, and if it exceeds 20% by weight, the reaction activity is lowered and the production yield is lowered.

According to the present invention, the amount of catalyst usually used in the synthesis of polyesters as intermediates in the production of sorbic acid is 0.1 to 5% by weight, based on the weight of only the copper metal salt (coated on the support zeolite) based on the amount of crotonaldehyde used. More preferably, the weight of the copper metal salt alone is 0.5 to 2% by weight based on the amount of crotonaldehyde used.

At this time, the atmosphere of the zeolite used as the support may be any kind of zeolite such as acidic, neutral, basic zeolite, and acid-neutral zeolite may be used as a better condition.

On the other hand, according to the present invention, the reaction temperature of the reaction solution using the catalyst is generally 20 to 70 ℃, it is more advantageous to perform the reaction at a temperature of 40 to 60 ℃ more suitably. If the temperature is too high, the ketene is partially decomposed to lower the yield. If the temperature is too low, the reaction rate is slow and the utilization rate of the ketene is decreased.

As such, if the polyester obtained using the catalyst according to the present invention is purified by a known solvate purification method, it is possible to obtain a high-quality white solid, solvate or sorbate. As such a method for purifying sorbic acid, generally, a method of pyrolyzing polyester after vacuum distillation or recrystallizing low-quality sorbic acid obtained by acid decomposition with hydrochloric acid or sulfuric acid under vacuum distillation or an aqueous solvent is used.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

Crotonaldehyde (112.15 g) was added to the flask, and a catalyst (10 g) coated with 5% by weight of copper sulfate was added to ZSM-5, followed by vigorous stirring. The gaseous ketene (33.6 g) is injected into the reaction while the temperature of the reaction solution is maintained at 40 to 60 ° C. After completion of the reaction, the catalyst is filtered off, and the filtrate is distilled under reduced pressure to remove unreacted crotonaldehyde to obtain polyester (89.6 g, 100% yield).

Concentrated hydrochloric acid is acid-decomposed in the obtained polyester, vacuum distilled (JP-A-54-163516), washed with cold toluene (20 g) and dried to obtain sorbic acid (76.16 g, 85% total yield) as white crystals. Melting | fusing point of the obtained sorbic acid is 135 degreeC.

Example 2

After adding crotonaldehyde (112.15 g) to the flask, a catalyst (10 g) coated with 5% by weight of copper sulfate was added to ZSM-11, followed by vigorous stirring. The gaseous ketene (33.6 g) is injected into the reaction while the temperature of the reaction solution is maintained at 40 to 60 ° C. After completion of the reaction, the catalyst is filtered off, and the filtrate is distilled under reduced pressure to remove unreacted crotonaldehyde to obtain polyester (89.6 g, 100% yield).

Example 3

After adding crotonaldehyde (112.15 g) to the flask, a catalyst (10 g) coated with 5% by weight of copper sulfate was added to zeolite A, followed by vigorous stirring. The gaseous ketene (33.6 g) is injected into the reaction while the temperature of the reaction solution is maintained at 40 to 60 ° C. After completion of the reaction, the catalyst is filtered off, and the filtrate is distilled under reduced pressure to remove unreacted crotonaldehyde to obtain polyester (87.8 g, yield 98%).

Example 4

After adding crotonaldehyde (112.15 g) to the flask, a catalyst (10 g) coated with 5% by weight of copper sulfate was added to zeolite X, followed by vigorous stirring. The gaseous ketene (33.6 g) is injected into the reaction while the temperature of the reaction solution is maintained at 40 to 60 ° C. After completion of the reaction, the catalyst was filtered off, and the filtrate was distilled under reduced pressure to remove unreacted crotonaldehyde to obtain polyester (87.81 g, yield 98%).

Example 5

After adding crotonaldehyde (112.15 g) to the flask, a catalyst (10 g) coated with 5% by weight of copper sulfate was added to zeolite Y, followed by vigorous stirring. The gaseous ketene (33.6 g) is injected into the reaction while the temperature of the reaction solution is maintained at 40 to 60 ° C. After completion of the reaction, the catalyst is filtered off, and the filtrate is distilled under reduced pressure to remove unreacted crotonaldehyde to obtain polyester (88.7 g, 99% yield).

Example 6

The experiment was carried out in accordance with Example 1 using a catalyst (10 g) coated with 5% by weight of copper sulfate on zeolite L to obtain polyester (87.81 g, yield 98%).

Example 7

The experiment was carried out in accordance with Example 1 using a catalyst (10 g) coated with 5% by weight of copper sulfate on zeolite omega to obtain polyester (89.6 g, yield 100%).

Example 8

The experiment was carried out according to Example 1 using a catalyst (10 g) coated with 5% by weight of copper sulfate on chabazite to obtain polyester (86.0 g, yield 96%).

Example 9

The experiment was carried out in accordance with Example 1 using a catalyst (10 g) coated with 5% by weight of copper sulfate on mordenite to obtain polyester (86.9 g, yield 97%).

Example 10

The experiment was carried out in accordance with Example 1 using a catalyst (10 g) coated with 5% by weight of copper sulfate on erionite to obtain polyester (86.91 g, yield 97%).

Example 11

The experiment was carried out according to Example 1 using a catalyst (10 g) coated with 5% by weight of copper sulfate on faujasite to obtain polyester (87.8 g, yield 98%).

Example 12

The experiment was carried out in accordance with Example 1 using a catalyst (10 g) coated with 5% by weight of copper sulfate on clinoptilolite to obtain polyester (87.8 g, yield 98%).

Example 13

Experiment was carried out in accordance with Example 1 using a catalyst (10 g) coated with 2.5% by weight of copper sulfate on ZSM-5 (manufactured by DuPont) to obtain polyester (89.6 g, yield 100%).

Example 14

The experiment was carried out in accordance with Example 1 using a catalyst (10 g) coated with 1% by weight of copper sulfate on ZSM-5 (manufactured by DuPont) to obtain polyester (88.7 g, yield 99%).

Comparative Example 1

Crotonaldehyde (112.15 g) is added to the flask followed by ZSM-5 and vigorous stirring. The gaseous ketene (33.6 g) is injected into the reaction while the temperature of the reaction solution is maintained at 40 to 60 ° C. After completion of the reaction, the ZSM-5 used in the reaction was filtered off and the filtrate was distilled under reduced pressure to remove unreacted crotonaldehyde, leaving only a trace of polyester.

Comparative Example 2

The catalyst used in the reaction is made as follows. Zeolite is added to a solution of copper salts dissolved in water. The mixture is stirred at 50 ° C. for 1 hour, after which the heterogeneous product is concentrated under reduced pressure. After concentrating sufficiently, it is further dried under vacuum oven at 50 ° C. The zeolite substituted with a copper salt is reduced by flowing hydrogen while heating and used for the reaction.

Comparative Example 3

According to Example 1 using Zn (acac) 2, XH ₂ O (0.9 g) (GB 1193137), catalysts dissolved in crotonaldehyde, polyester (84.2 g) had a good yield (94%). Was obtained.

As described above, the solvinic acid production method according to the present invention has the effect of producing a high yield of the target even under more economical and good operating conditions due to the use of a new catalyst different from the conventional.

Claims (6)

A method for producing sorbinic acid, characterized in that a catalyst is prepared by reacting crotonaldehyde and ketene in the presence of a catalyst and preparing sorbic acid therefrom using a catalyst coated with an inorganic copper salt on a zeolite support. The method of claim 1, wherein the amount of inorganic copper salt applied to the zeolite is applied in the range of 0.5 to 20% by weight relative to the zeolite as the support. The method for producing sorbinic acid according to claim 1 or 2, wherein the inorganic copper salt is a monovalent or divalent copper salt. The method of claim 3, wherein the inorganic copper salt is selected from monovalent or divalent copper halide salts, copper hydroxide, copper nitrate salts or hydrates thereof, and copper sulfate or hydrates thereof. The method of claim 1, wherein the zeolite used as the support is a method for producing sorbic acid, characterized in that represented by the formula (1). Formula 1 here, N is the balance value of cation M, W is the number of water molecules per lattice of zeolite units, X and Y represent the total number of tetrahedera per unit lattice. The zeolite of claim 5, wherein the zeolite is chabazite, mordenite, erionite, faujasite, clinoptilolite, zeolite A, zeolite. X, zeolite Y and zeolite yomega is selected from the method for producing a solvate.