RU2064918C1 - Method of synthesis of 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane - Google Patents

Abstract

FIELD: organic chemistry, chemical technology. SUBSTANCE: 2,2-bis-(4-hydroxyphenyl)propane (diphenylolpropane) is brominated with free bromine in the presence of sodium chlorate at the following sequence of stages. Parental product is suspended in carbon tetrachloride at stirring, water is added (0.2-1 volume of carbon tetrachloride volume), bromine is dosed, then sulfuric acid is added and stirred for 2-10 hr. Mole ratio diphenylolpropane : bromine : acid : sodium chlorate = 1:(2.2-2.3):(0.76-0.8):(0.73-0.77). Product is used for synthesis of complex phenols, in part, bromination of diphenylolpropanol to obtain polymeric material combustion inhibitor. EFFECT: improved method of synthesis. 3 ex

Description

 The invention relates to the improvement of a method for producing 2,2-bis- / 3,5-dibromo-4-hydroxyphenyl / propane, used as a flame retardant of polymeric materials.

A known method of producing 2,2-bis- / 3,5-dibromo-4-hydroxyphenyl / propane by oxidative bromination of 4,4'-isopropylidenebisphenol (diphenylolpropane) with bromine or hydrogen bromide in chlorobenzene in the presence of 50% hydrogen peroxide containing 3% sulfuric acid, at a temperature of 30-40 ^o C, followed by heating to 70-90 ^o C to dissolve the precipitate of the final product [1] At 70-90 ^o C the reaction mass is separated on a separatory funnel into organic and aqueous layers. The organic layer is washed with sodium sulfite and twice with water, then cooled to 20 ^o C, crystallized and filtered. The yield is about 80% based on the loaded diphenylol propane. The final product contains up to 10% chlorobenzene.

 The disadvantages of this method are the use of explosive hydrogen peroxide, low yield of the final product, the use of solvent-chlorobenzene, high boiling and difficult to remove when drying the finished product, as well as the process at elevated temperatures.

There is also a method for producing 2,2-bis / 3,5-dibromo-4-hydroxyphenyl / propane by the oxidative bromination of diphenylolpropane with bromine in acetic acid in the presence of chlorine [2] To increase the yield, a mother liquor from the previous operation is used. Chlorine and bromine are added to diphenylolpropane dispersed in the mother liquor from the previous operation at 20-25 ^° C for 2-3 hours. Then the reaction mixture is purged with air, cooled to 15-16 ^o C and filtered, washing on the filter the precipitate of the target product with acetic acid. Exit
2,2-bis- / 3,5-dibromo-4-hydroxyphenyl / propane is 85% of theory, based on the loaded diphenylol propane. The melting point of the product is 164-165 ^o C.

 The disadvantages of this method are the low quality of the target product, the complex hardware design of the process associated with the use of highly toxic gaseous chlorine, the difficulty of disposing of gaseous waste and mother liquors containing chlorine, bromine, bromide and hydrogen chloride.

The closest to the claimed technical essence and the achieved effect is a method for producing 2,2-bis- / 3,5-dibromo-4-hydroxyphenyl / propane by oxidative bromination of diphenylolpropane with bromine in carbon tetrachloride using chlorine as an oxidizing agent [3] Reaction temperature may be from 0 ^° to 120 ^° C. To diphenylol propane dissolved in carbon tetrachloride, bromine and chlorine are simultaneously added. At the end of the reaction, the precipitate formed is separated, washed twice with carbon tetrachloride and dried. The target product is obtained in the form of colorless crystals with a melting point of 162-178 ^o C and a yield of 87-89%
The disadvantages of this method are the insufficiently high yield of the target product, its low quality, which is characterized by a stretched melting point, complicated hardware design associated with the use of highly toxic gaseous chlorine, the difficulty of disposing of gaseous waste products containing chlorine, bromine, hydrogen chloride and bromide.

 The objective of the invention is to increase the yield and improve the quality of the target product, as well as simplifying the process.

 The problem is solved by the proposed method for producing 2,3-bis / 3,5-dibromo-4-hydroxyphenyl / propane, namely that diphenylolpropane is subjected to oxidative bromination with bromine in carbon tetrachloride and water, taken in the ratio 1: (0.2- 1) by volume using sodium chlorate with mineral acid as an oxidizing agent.

The yield of the finished product is 92.8-96%. Melting point 178-179 ^o C.

 The difference of the proposed method from the known one is the use of sodium chlorate with mineral acid as an oxidizing agent and the process in the presence of water.

The technology for producing 2,2-bis- / 3,5-dibromo-4-hydroxyphenyl / propane according to the proposed method is as follows: diphenylolpropane is loaded into a flask, pour carbon tetrachloride and stir until a homogeneous suspension is added, after which water is added in an amount of 20 100% (preferably 50%) of the carbon tetrachloride taken in volume. Then they begin to drip a solution of bromine in carbon tetrachloride. Due to the exothermic nature of this reaction, the temperature in the mass can spontaneously increase. In order to ensure the safety of the process, it is not recommended to allow a temperature increase above 40 ^o C. Hydrogen bromide released by the reaction is absorbed by water. After adding the entire amount of bromine to the reaction mass, mineral acid is poured, and then the calculated amount of sodium chlorate solution is added.

 At the end of the loading of all components, the reaction mass is stirred for 2-10 hours. In this case, a redox reaction takes place in the aqueous layer: free bromine is regenerated from hydrogen bromide, which reacts with the bromination of diphenylolpropane. Under these conditions, a minimum amount of bromine can be used for bromination and the release of hydrogen bromide into the gas phase can be eliminated.

 After exposure, the suspension of the finished product is filtered off, washed with carbon tetrachloride and water. The mother liquor is placed in a separatory funnel and sucks to separate the layers. The bottom layer of carbon tetrachloride, containing products of incomplete bromination and a certain amount of the final product, is separated and used without regeneration in the next synthesis instead of a pure solvent.

 The invention is illustrated by the following examples.

Example 1. In a reaction flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, 100 cm ^{3 of} carbon tetrachloride, 25 g (0.11 mol) of diphenylol propane are placed and the mass is stirred for 5 minutes. Next, 50 cm ^{3 of} water are charged and 40.3 g (0.252 mol) of bromine are added dropwise to the resulting suspension in 10 cm ^{3 of} carbon tetrachloride. Then 5 cm ^{3 of} concentrated sulfuric acid and 22 cm ^{3 of a} 31.3% sodium chlorate solution are added. The temperature in the mass is maintained no higher than 40 ^o C. Upon completion of the loading of all components, the reaction mass is stirred for 10 hours at 20-25 ^o C, and then the precipitate formed is filtered off. The product on the filter is washed with carbon tetrachloride and water until neutral. After drying, 55.4 g of powder is obtained with a melting point of 178-179 ^° C. The yield of 2,2-bis- / 3,5-dibromo-4-hydroxyphenyl / propane is 92.8% of theory, based on the starting diphenylolpropane.

Example 2. The synthesis is carried out under the conditions of example 1 with the difference that after loading all the components, the reaction mass is stirred for 2 hours at 35-40 ^o C. The yield of the target product is 55.4 g or 92.8% of theoretical, based on the starting diphenylolpropane .

Example 3. The synthesis is carried out under the conditions of example 1 with the difference that the mother liquor from the previous synthesis is used as a solvent. Obtain 57.4 g of the target product with a melting point of 178-179 ^o C. The yield is 96%
The technical result of the proposed method is to obtain 2,2-bis- / 3,5-dibromo-4-hydroxyphenyl / propane with a high yield and quality, simplification of the technical process and improvement of sanitary and environmental characteristics due to the rejection of the use of highly toxic gaseous chlorine and exclusion the formation of hazardous gaseous mixtures containing chlorine, bromine, hydrogen chloride and bromide, reduction of raw materials costs due to the repeated use of organic filtrate without regeneration.

Claims (1)

A method of producing 2,2-bis- (3,5-dibromo-4-hydroxyphenyl) propane by bromination of 2,2-bis- (4-hydroxyphenyl) propane with free bromine in a medium of carbon tetrachloride in the presence of an oxidizing agent of a chlorine-containing compound with stirring at 20 40 ^o With subsequent filtering of the resulting precipitate of the final product, washing and drying, characterized in that water, mineral acid, sodium chlorate as an oxidizing agent are added to the reaction mixture and bromination is carried out in the following sequence of operations: with stirring, suspension 2,2-bis- (4-hydroxyphenyl) propane in carbon tetrachloride is added, bromine is metered, then mineral acid and an aqueous solution of sodium chlorate are added at a molar ratio of 2,2-bis- (4-hydroxyphenyl) propane bromine: mineral acid: chlorate sodium 1: 2.2 2.3: 0.75 0.8: 0.73 0.77, after which the reaction mass is stirred for 2 to 10 hours