DE1226554B - Process for the production of glycid from glycerol monochlorohydrin - Google Patents

Description

Process for the production of glycid from glycene monochlorohydrin Es is known to glycide from glycerol monochlorohydrin by splitting off hydrogen chloride to manufacture.

It can be used to split off the hydrogen chloride alcoholic or Use aqueous alkali lye. In the latter case you have to use the resulting glycid ether and then fractionally distill. It is also known to be glycid by treating glycerol monochlorohydrins dissolved in anhydrous ether with to produce metallic sodium. After one hour of reaction, the The sodium chloride formed is filtered off and the residue is distilled.

There is also the elimination of hydrogen chloride in glycerol monochlorohydrin carried out using soda with the addition of gypsum as a water-binding agent. Included however, no more than about 40% of the theory of glycide was obtained, as presumably a considerable amount of polymeric glycid was produced.

Try the well-known reaction between monochlorohydrin and soda without the addition of gypsum, which is carried out on the water bath at 60 to 80 "C, only glycerine supplies, in acetone at 60 "C, resulted in only a minimal conversion.

Thus, both soda alone and soda in combination were found with plaster of paris as unsuitable, in a rational way from glycerol monochlorohydrin glycid to manufacture.

Finally, it is known to act on glycid in excess from ethylene oxide to glycerol chlorohydrin. This implementation must be due the easy volatility of the ethylene oxide can be carried out in pressure vessels, takes a relatively long time and represents an equilibrium reaction that also declines can run.

There has now been a new process for preparing glycide from glycerol monochlorohydrin found by splitting off hydrogen chloride by means of alkaline compounds, which yields relatively high yields in a short time without the action of excess pressure supplies to Glycid. This process is characterized in that it is considered alkaline acting agent used dry potassium carbonate and in the presence of an indifferent High dielectric constant solvent works.

Preferably, for 1 mol of glycerol monochlorohydrin, at least 1 mol, in particular at least 1.2 mol of potassium carbonate can be used.

Glycerol monochlorohydrin, in particular, is used as the starting material the o; -glycerol chlorohydrin. But it is also possible to use p-glycerol chlorohydrin or mixtures of o; -glycerol and B-glycerol chlorohydrin to be used.

The potassium carbonate should be dry and is expediently as a powder used. The use of much larger amounts than 1.2 moles of potassium carbonate on 1 mol of glycerol monochlorohydrin is not required. An excess, e.g. B. from 2 to 3 moles of K2COS to 1 mole of glycerol chlorohydrin can be used as it is the Reaction does not bother.

The solvent used for the present process is anhydrous organic solvents, which under the reaction conditions compared to glycerol monochlorohydrin, are indifferent to glycide and potassium carbonate. They should have a high dielectric constant and dissolve both glycerol monochlorohydrin and glycid well. The boiling point the solvent should expediently be at least about 20 ° C. below or above from 163 "C, the boiling point of the glycide under normal pressure, to solvents and glycid can easily be separated by distillation. The solvents are used in such amounts that mixtures are still easily stirrable or easily pumpable develop. Suitable solvents are e.g. B. lower ketones, such as acetone or methyl ethyl ketone, or chlorinated hydrocarbons such as methylene chloride, chloroform and dichloroethane, also acetonitrile, further ethers, such as dimethyl ether or diethyl ether des Diethylene glycol. Preference is given to using acetone or methylene chloride. The mentioned Before they are used, solvents are dried in a known manner.

The heterogeneous reaction mixture is expedient during the reaction moves, for example by stirring or pumping to avoid caking of the potassium carbonate or the salt mixture formed during the reaction impede.

The inventive method is carried out at temperatures between about 40 and -1200 ° C., in particular 40 and 80 ° C., and then requires reaction times between about 2 hours and a few minutes or fractions of minutes. At deeper Temperatures, the reaction times become too long for practice, and at higher temperatures Temperatures increase the tendency for the formation of by-products, such as polymeric glycidic compounds.

The reaction can be carried out either batchwise or continuously - - - - The --latter reaction procedure is advantageous, and it is in this one It is often advisable not to let the reaction proceed to completion, but rather to break off at about a 70-0 / 0 degree of conversion. The unused glycerol monochlorohydrin can be used again without further ado. This practically can do that Chlorohydrin can be converted into glycide.

To work up the mixtures obtained in the process according to the invention, the salt formed is filtered off and the glycide is separated from the solvent and unreacted glycerol monochlorohydrin by distillation. The degree of conversion can easily be calculated from the chlorine content of the resulting salt mixture, since the reaction proceeds according to the following equation: The glycide falls in high purity during the first distillation. and has almost the theoretical epoxy oxygen content.

Example 1 In a glass vessel equipped with a stirrer, 165.8 g of glycerol-cc-monochlorohydrin (1.5 mol) dissolved in 500 ml of anhydrous acetone and heated to 60PC. 228 g of dry material were added to this solution with vigorous stirring Finely powdered potassium carbonate (1.65 mol) added all at once. The mix was Stirred for a further 10 minutes at 60 ° C. and then up within 2 minutes 209C cooled. It was filtered off and washed with acetone for:. The solid residue which consists of a mixture of potassium chloride, potassium carbonate and excess Potassium carbonate existed, was dried and the content of potassium chloride was determined.

This resulted in a conversion of 75.3%.

After stripping off the acetone used as the solvent, the Fractional distilled residue 81 g of glycide (boiling point at 12 torr 60 to 66 ° C.). This corresponds, based on the conversion, to 980% of theory. The unreacted glycerol monochlorohydrin was recovered in the distillation and can be used again in the reaction.

Example-2 In one equipped with a stirrer and reflux condenser Glass reaction flasks became a solution of 332 g of glycerol-α-monochlorohydrin in 1 l of dry methylene chloride at once 456 g of dry, finely powdered potassium carbonate given. The mixture was refluxed for 2 hours with constant stirring. Then it became as described in Example 1, the salt separated, washed, dried and the Degree of conversion - determined to be 91.5%. - - --- --- -The filtrate was distilled. at a pressure of 12 Torr and 60 to 66 "C, 243 g of glycide were obtained. This corresponds to 91% of theory, based on sales. Unconverted glycerine monochlor hydrin was recovered.

Comparative experiment Ä In a 1/4 l three-necked flask, which With a stirrer, thermometer and reflux condenser, a mixture was made 110 g each of glycerol monochlorohydrin, anhydrous soda and gypsum in a water bath Maintained with stirring at 80 ° C. for 1/2 hour. This was followed by 4 hours 38.5 g of glycide were distilled off from the mixture at a vacuum of 16 torr. The salary of epoxy oxygen in the product obtained was 17 ° lo.

The yield of pure glycide (epoxy oxygen 21.6%) - to 390% of theory, corresponding to 29 g.

The chloride content in a sample of the salt mixture was 13.5%. determined From this, a complete conversion of the organically bound chlorine can be determined getting closed.

The salt mixture obtained in the reaction was further 12 hours extracted in Soxhlet with methylene chloride. After distilling off the methylene chloride 15.5 g of a viscous liquid with an epoxy number of 1.02% were obtained. It is a low molecular weight, polymeric glycid.

Comparative experiment B In a 21 capacity three-necked flask, which was provided with a stirrer, thermometer. and reflux condenser, a mixture of 331 g glycerol monochlorohydrin (3 mol), 350 g anhydrous sodium carbonate (3.3 mol) and 1 l of acetone heated to 600 ° C. for 1 hour with vigorous stirring.

It was then filtered off and the salt residue was washed with acetone. The chloride content was determined in a sample of the salt mixture 5% conversion calculated.

Claims (4)

Claims: 1. Process for the production of glycid - from glycerol monochlorohydrin - by splitting off hydrogen chloride by means of alkaline agents, characterized in that, that one uses dry potassium carbonate as an alkaline agent: zund in the presence of an inert solvent with a high dielectric constant -is working. 2. The method according to claim 1, characterized in that the Reaction at temperatures of about 40 to 120 "C, in particular about 40 and 80 ° C, performs. 3. The method according to claim 1 and 2, characterized in that one as an indifferent solution medium acetone and / or methylene chloride used. 4. The method according to Claiml to 3, characterized in that on 1 mol of glycerol monochlorohydrin at least 1 mol, in particular at least 1.2 mol, Potassium carbonate is used.