JPS59128340A - Preparation of 2,3-dichloro-1-propanol - Google Patents

Abstract

PURPOSE:To obtain the titled substance useful as an intermediate for producing epichlorohydrin easily in high yield, by reacting allyl alcohol with chlorine in a highly concentrated aqueous solution of hydrochloric acid optionally at low temperature under pressure. CONSTITUTION:In preparing the titled substance by reacting allyl alcohol with chlorine, 50-75wt% aqueous solution of hydrogen chloride is used as a solvent, and the reaction is carried out at -30-20 deg.C at 0-10atm. (gauge pressure.) After the reaction is over, the concentrated aqueous solution of hydrochloric acid is uniformly dissolved, slight solubility of the reaction product in water is utilized, hydrogen chloride after the reaction is removed, the concentration of hydrochloric acid is lowered, the solution is cooled, and the desired substance can be obtained from an oily layer. EFFECT:By comparison with an existing method to use an organic solvent, problems of separation from organic solvent, admixture of solvent in reaction product, loss of solvent during distillation and reaction product will not take place.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing chloro-1-propanol by converting allyl alcohol into salt X with chlorine in an aqueous hydrochloric acid solution.

2.3-dichloro-1-propatol is a solvent.

It is a compound useful as an intermediate in the production of shrimp chlorohydrin, which is widely used as a raw material for epoxy resin thickening 2 synthetic rubber, a chlorinated rubber stabilizer, etc.

Conventionally, allyl alcohol was chlorinated using chlorine alone.
, 6-dichloro-1-propertool has been proposed in various ways. For example, an early method involves chlorinating anhydrous allyl alcohol with dry chlorine without using a solvent (Tornoe).

Ber, 24.2670 (1891)), a method of chlorination using a carbon disulfide solvent (J, Chem, Soc.
,.

5.1238 (1914)), but the yield of 2,6-dichloro-1-propatol is about 20-40%.

JP-A-46-1661 discloses a method for obtaining dichloropro.ξnol in high yield (97 to 99%) using a saturated solution of hydrogen chloride in a low-boiling ether as a solvent.

In this method, a mixture containing about 10% of 1,3-0-2-propanol in 2,6-dichloro-1-pronominol is produced. There is a loss problem. As a method that does not produce 1,3-dichlorozolonominol as a by-product, a lower aliphatic alcohol saturated with hydrogen chloride is used as a solvent to obtain a high yield (96.9% at -40°C, 93.8% at 0°C). A method for obtaining 2,6-dichloro-1-propanol in (h) is disclosed in Japanese Patent Publication No. 18207/1983. In this case as well, since an organic solvent is used, there are problems such as separation of the product from the solvent and loss of the solvent.

A method of chlorinating in an aqueous solution saturated with hydrogen chloride without using an organic solvent has been proposed (Japanese Patent Publication No. 37-17
No. 206). In this case, it is said that 1.3-fuchloro-2-propatol is not produced as a by-product, but the yield is 50-70%.
%, and as well as glycerin monochloride P being produced as a by-product,
It has the disadvantage of producing oligomers and the like as by-products.

As a result of intensive studies on chlorination in a system using this aqueous hydrochloric acid solution, the present inventors found that the hydrogen chloride concentration was 50 to 75
-% aqueous solution, 1°6-dichloro-2
-Pro-ξnor is 2 with virtually no by-products.
, 3-dichloro-1-pro, o-nol can be obtained with a high yield of 90 coefficients or higher, and the present invention was completed.

That is, the present invention is characterized in that in producing 2,3-dichloro-1-propanol by the reaction of allyl alcohol and chlorine, an aqueous hydrochloric acid solution containing 50 to 75 weight percent of hydrogen chloride is used as a solvent. That is.

As is well known, the maximum concentration of hydrogen chloride in an aqueous solution of hydrochloric acid at normal temperature and pressure is about 36%. Press or do.

However, compared to a system containing only hydrogen chloride and water, in the method of the present invention, it is not so difficult to maintain a high concentration of hydrogen chloride because allyl alcohol coexists as a reaction starting material.

In order to maintain the hydrogen chloride concentration in the aqueous solution at 50% by weight or more, chlorination is carried out as necessary at a temperature of -30 to 20°C and a pressure of D to 10 atmospheres (gauge pressure). When allyl alcohol is chlorinated in an aqueous solution with a high concentration of hydrogen chloride in this way, the amount of by-products such as glycerin monochloride and oligomers can be drastically reduced, but the pressure is too high. If the hydrogen chloride concentration is increased too much, other by-products, especially 1, 2, 3-) lychlorpronogne, allyl chloride, etc., will increase, and this tendency becomes more pronounced as the temperature increases. As a result of this discovery and intensive study, the temperature was below 20℃ and the pressure was 10 atm (gauge pressure).
It has been found that the amount of by-products can be substantially eliminated by reacting under the following conditions.

The lower the reaction temperature, the better the yield, but if the reaction is carried out at too low a temperature, the energy for cooling increases and, depending on the composition, the reaction solution may solidify. Therefore, it is preferable to carry out the reaction at a temperature of -20°C or higher.

In the method of the present invention, the amount of chlorine consumed in the reaction is about 1.05 mol or less based on allyl alcohol, and 2,3-dichloro-1-zolonognol can be obtained almost quantitatively from alcohol. The yield is improved by more than 20 cm compared to the conventional method.

After the reaction, the raw acidified 2,6-dichloro-1-propanol is uniformly dissolved in the concentrated hydrochloric acid solution, but since the rice product is poorly soluble in water, hydrogen chloride is removed after the reaction is completed. After lowering the concentration of hydrochloric acid, the oil layer (lower layer) and water layer (
The upper layer) is separated, neutralized if necessary, the oil layer is extracted with a solvent, the extract is distilled, and 2,3-dichloro-1
-Prozonol may be obtained, but when carrying out the next reaction in an aqueous solution, for example, when using it as a raw material for the production of epichlorohydrin, it is convenient to use it as it is in the aqueous solution state without solvent extraction. .

According to the present invention, separation of the organic solvent into the product, which is a drawback of conventional methods utilizing organic solvents, can be avoided.

Problems such as solvent contamination, loss of solvent and product during distillation, etc. do not occur.

The manufacturing method of the present invention will be explained below with reference to Examples.

Example 1 11.21 g of hydrogen chloride gas (concentration as an aqueous solution of hydrochloric acid: 52.8% by weight) was blown into a mixed solution of 10 y of water and 0.1 mol (5.8 P) of allyl alcohol at 0° C. and under normal pressure.

The reaction solution was externally cooled to maintain a temperature of 0° C., and 0.1 mol (0,354 P) of chlorine was blown into the reactor over 40 minutes while stirring.

After the reaction was completed, analysis by liquid chromatography revealed that 2゜3-dichloro-
1-,/'lonognol was produced in a yield of 95.0%.

Example 2 Water 101.71 at -10°C, 4 to 9/d<gauge pressure)
Hydrogen chloride gas was blown into a mixture of 1 mol (5,8y-) of J-rualcohol until it was saturated. Dissolved hydrogen chloride company is 22
．． ! M- (concentration as an aqueous hydrochloric acid solution=692% by weight). While maintaining this temperature and pressure, 0.1 mole of chlorine was blown in over 40 minutes. After the reaction was completed, analysis by liquid chromatography revealed that 2,6-dichloro-
1-Pronozonol was produced in a yield of 97.0%.

Claims (1)

[Claims] 1) By the reaction of allyl alcohol and chlorine, 2.3-
1. A method for producing 2,3-dichloro-1-pronognol, which comprises using an aqueous solution containing 50 to 75% by weight of hydrogen chloride as a solvent in producing dichloro-1-propanol. 2) The manufacturing method according to claim 1, wherein the reaction is carried out at a temperature of -60 to 20°C and a pressure of 0 to 10 atmospheres (gauge pressure).