PL163766B1 - Method of obtaining 2,3-dibromide-2-butene-1,4-diole - Google Patents

Abstract

Method for the preparation of 2,3-dibromo-2-butene-1,4-diol by bromination of butin-1,4-diol in an aqueous environment and at a temperature of 10 to 95 ° C, characterized by that 1,4-butin-1,4-diol is used in an excess of 0.01 to 0.1 mol relative to the amount of bromine.

Description

The subject of the invention is a process for the preparation of 2,3-dibromo-2-butene-1,4-diol.

Known methods for the preparation of 2,3-dibromo-2-butene-1,4-diol are based on bromination of 1,4-butine diol in solutions of chlorinated and / or brominated hydrocarbons. For this purpose, bromine solutions in these solvents are used, and the bromination process is carried out in the temperature range from -50 ° C to 0 ° C.

The main disadvantages of this method are the low yield, the need to use crystal-clear 1,4-diol butines and a high proportion of side reactions, which leads to the formation of a contaminated product. Moreover, due to the low concentration of the raw material, it is necessary to use large-volume apparatus. In addition, this process consumes a large amount of toxic solvents, and the exothermic nature of the bromination reaction requires the temperature to be maintained, which leads to a high energy consumption.

U.S. Patent No. 3,746,726 also discloses a method of bromination of butin-2-diol-1,4 with bromine in an aqueous medium at a temperature of -40 ° C to 150 ° C. This reaction uses equimolar amounts of bromine and 1,4-butin-2-diol or an excess of bromine.

In the reaction carried out in this way, a certain amount of unreacted bromine is always produced in the waste water. It is dangerous to the environment due to the toxicity of the wastewater. The presence of bromine in the waste water can be avoided by using an excess of 1,4-butin-2-diol in the reaction. However, it was to be expected that under such conditions a competitive addition of water to the 2-butene-1,4-diol would be formed. Apart from dibromobutendiol, by-products containing hydroxyl groups in the double bond would also be formed. The main product, 2,3-dibromo-2-butene-1,4-diol, would be obtained in much lower yield and contaminated with by-products.

Unexpectedly, it turned out that the bromination reaction of 2-butin-1,4-diol with a deficiency of bromine gave only one product - 2,3-dibromo-2-butene-1,4-diol.

The process according to the invention consists in the bromination of 1,4-butin diol in an aqueous medium and at a temperature of 10 to 95 ° C and is characterized in that 1,4-butin-diol is used in an excess of 0.01 to 0.1 mol. in relation to the amount of bromine.

In the reaction according to the invention, no by-products containing hydroxyl groups on the double bond are formed. 2,3-dibromo-2-butene-1,4-diol is obtained with good yield and high purity. The bromine used for the reaction is completely consumed and is not found in the waste water.

The process according to the invention allows the use of an aqueous solution of 1,4-butin-butin-diol, received directly from an industrial plant for the production of 1,4-butin-1,4-diol in the reaction of acetylene with formaldehyde in an aqueous medium, without isolating the product in a crystalline form as a substrate.

The 2,3-dibromo-2-butene-1,4-diol obtained by the process according to the invention can be used in the textile, plastics and organic industries.

The subject of the invention is explained in more detail in the working examples.

Example 1 400 g (4.65 mol) of crystalline butrn-1,4-diol and 600 g of water were charged to the reactor. The contents of the reactor were thoroughly mixed and then into the obtained solution

720 g (4.50 moles) of liquid bromine was added dropwise deep below the liquid surface. The thickening mixture with the precipitate was cooled down to such an extent that the amount of precipitate formed was small and the resulting pasty reaction mixture was easily mixed. The bromination process was carried out for 1 hour, after which an additional 300 g of water was introduced into the reactor. The total bromine addition time was 100 minutes and the end reaction temperature was 50 ° C. After completion of the reaction, the reaction mixture was cooled to 15-18 ° C with constant stirring, the precipitate formed was filtered off and washed with cold water. After air drying, 985.0 g of 2,3-dibromo-2-butene-1,4-diol were obtained as cream-colored fine crystals, m.p. 111-114 ° C. The process yield was 89%.

Example 5 DLW reactor provided with DCM ^T technical 38% aqueous solution of butyn-diol having a density of 1.05 kg / dm ^3, which is the reaction product of formaldehyde with acetylene in an aqueous medium. This solution contained 1995 g (23.2 mol) of pure butin-1,4-diol. 3552 g (22.2 moles) of liquid bromine were dropped deeply below the liquid surface into the vigorously stirred solution. External cooling kept the reaction temperature below 75 ° C. After the reaction was complete, the resulting dark yellow pasty mixture was cooled to 35-40 ° C and filtered. The filtrate was cooled back to 18-20 ° C, filtered again and air dried. 4000 g of a crude product with an intense yellow-brown color with a yield of 79% were obtained. Then 5 kg of crude dibromobutendiol was boiled with 15 dcm ³ and kept under these conditions for 10 minutes. After the solution had cooled slightly, the clear liquid was poured from the very dark, liquid residue, which was then extracted again with 5 dm3 of toluene and then with 2 dm3 of toluene. Light yellow 2,3-dibromo-2-butien-1,4-diol, m.p. 114-115 ° C, crystallized from the combined toluene extracts. The total crystallization yield was 90% based on the dry weight of the crude dibromobutendiol.

Publishing Department of the UP RP. Circulation of 90 copies Price PLN 10,000

Claims (1)

Patent claim The method of obtaining 2,3-dibromo-2-butene-1,4-diol by bromination of 1,4-butin diol in an aqueous medium and at a temperature from 10 to 9 ° C, characterized in that butin-1,4-diol is used is in excess of 0.01 to 0.1 mol relative to the amount of bromine.