DE1207373B - Process for the production of alpha, beta-unsaturated carboxylic acid anhydrides or rides or mixtures thereof - Google Patents

Description

Process for the preparation of α, p-unsaturated carboxylic acid anhydrides or chlorides or mixtures thereof The invention relates to a process for the preparation of anhydrides or chlorides or their mixtures of α, ß-unsaturated carboxylic acids.

It is known. Chlorides and anhydrides of carboxylic acids from chlorinating agents, like phosphorus chlorides. Thionyl chloride. Benzoyl chloride. Chlorosulfonic acid or phosgene. and the free acids or their derivatives. In the same way it was even the production of chlorides and anhydrides of unsaturated carboxylic acids generally described. Difficulties were caused by the production of the chlorides and anhydrides of α, -unsaturated carboxylic acids, which are known to be very reactive are. On the one hand, these compounds tend to under the conditions of implementation rapid polymerization, on the other hand they can be used in the known processes usually formed hydrogen chloride add to the double bond.

These side reactions resulted in the desired compounds were previously only accessible in poor yield. Other disadvantages are with that Associated use of thionyl chloride as a chlorinating agent. The resulting Chlorides and anhydrides are due to the sulfur dioxide produced in the reaction contaminates and cannot be completely freed from it. Because sulfur dioxide is a strong polymerization retarder, prepares the subsequent polymerization the monomer difficulties. It is always a disadvantage when forming the Chlorides and anhydrides of non-volatile by-products arise, of which the desired Reaction product must be distilled off. The distillation of these compounds. especially under normal pressure, there is always considerable losses through polymerization tied together. These difficulties are circumvented by the method of the invention.

The invention now relates to a process for the preparation of a.ß-unsaturated carboxylic acid anhydrides or chlorides or mixtures thereof by reacting the unsaturated carboxylic acids with carbonyl chloride (= phosgene), which consists in using alkali metal or alkaline earth metal salts of a * Xi-unsaturated carboxylic acids general formula in which R is hydrogen or a low molecular weight alkyl group, n is 1 or 2 and Me is an alkali or alkaline earth metal with the valence n, is reacted with carbonyl chloride (= phosgene) at a temperature of 0 to 100 C with exclusion of water in the presence of an inert diluent .

In one embodiment of the process, 2 moles of the salt are used the α, B-unsaturated carboxylic acid with 1 mol of carbonyl chloride to form the carboxylic acid anhydride around.

According to a further embodiment, more than 1 mole is used, however less than 2 moles of the salt of the α-unsaturated carboxylic acid with 1 mole of carbonyl chloride to a mixture of the carboxylic acid anhydride and the carboxylic acid chloride.

Another implementation then consists in adding 1 mole of carbonyl chloride reacted with 1 mol of the salt of the a.ß-unsaturated carboxylic acid.

The anhydrides of the process of the invention are made by reacting of 1 mole of carbonyl chloride with 2 moles of the alkali salt or 1 mole of the alkaline earth salt obtained from the unsaturated carboxylic acid. The acid chlorides are by reacting of 1 mole of carbonyl chloride with 1 equivalent of the salt of the unsaturated carboxylic acid manufactured.

Mixtures of anhydride and acid chloride can be prepared by reacting 1 mole of carbonyl chloride with more than 1 mole but less than 2 equivalents of the salt. The term "equivalent" in this description is intended to refer to the group mean, in which Y is the hydrocarbon radical of the α, ß-unsaturated carboxylic acid. In other words, an "equivalent" is equal to 1 mole of the anion of the monobasic acid.

The salts of the a, fl-unsaturated acids have the general formula in the Me an alkali or alkaline earth metal. n is the valence of Me and R equal to hydrogen or a low molecular weight alkyl group. As salts are sodium. Lithium, potassium, cesium, rubidium, barium, strontium, magnesium, calcium and beryllium acrylate. -methacrylate, -a-ethyl acrylate, -a-propyl acrylate and -a-butyl acrylate can be used.

The reaction between the salts and carbonyl chloride with the formation of the anhydride probably proceeds according to the following formula: 2 CH2 = CH - COONa + COC12 When the acid chloride is formed from the above reactants, the reaction probably proceeds as follows: CH2 = CH - COONa + COM12 CH2 = CH-CO-CI + NaCl + CO2 The a, fl-unsaturated carboxylic acid anhydrides and chlorides are used to produce polymers and copolymers . z. B. the mixed polymer of acrylic anhydride and methacrylic acid methyl ester, can be used. resulting in hard, infusible resins. which can be used to manufacture optical lenses. Acrylic, methacrylic and other low molecular weight α-alkyl acrylic acid chlorides can be used for the production of polymers, and copolymers of acrylic and α-substituted acrylic acid chlorides are known to also form valuable resinous substances.

Mixtures of α, α-unsaturated monocarboxylic acid anhydrides and chlorides are useful for making interpolymers that include both anhydride and Contain acid chloride groups, or optionally a third monomer, such as vinyl acetate, added and a tripolymer with anhydride, acid chloride and Ester bonds are made.

The alkali or alkaline earth salt of acrylic acid or one in the a-position Acrylic acid substituted by a low molecular weight alkyl group becomes anhydrous under Conditions with phosgene in opposition was implemented in an inert diluent.

Since the reaction is exothermic, the presence of an inert promotes Diluent distributes the heat generated.

One way to carry out the method is to use one of the above said salts in an inert diluent, such as benzene, and slurry then the carbonyl chloride either in gaseous form or as a solution in an inert Add solvent to the slurry.

By regulating the proportion of salt and carbonyl chloride the type of end product can be determined; so it's possible either only the anhydride or just the acid chloride or a mixture of acid chloride and anhydride to manufacture. The process produces the chloride of the alkali or alkaline earth metal as precipitation.

This can be filtered off and either the remaining mixture Work-up of the compounds to be prepared are used or polymerized.

The reaction can be carried out at atmospheric, reduced or elevated pressure will.

The temperature at which the reaction takes place is also not essential, since the reaction takes place at temperatures down to the liquefaction temperature of the phosgene or up to 100 "C or above takes place. Because of the heat development however, it is advisable to start the reaction at around room temperature leaves and then keeps the temperature below the boiling point of the diluent, so that all carbonyl chloride that evaporates from the reaction space in a reflux condenser is liquefied and returned again. There are also the anhydrides and acid chlorides tend to polymerize at high temperatures, this effect must be avoided as far as possible will. However, it is possible to use in the presence of a polymerization retarder work to prevent polymerization.

Liquid aliphatic diluents can be used as inert diluents Ether, e.g. B. diethyl ether, diisopropyl ether, dibutyl ether and higher alkyl ethers, which are liquid at room temperature; Cycloalkyl ethers such as dioxane; the liquid ketones, such as acetone, methyl ethyl ketone, methyl propyl ketone and dipropyl ketone; saturated liquid aliphatic hydrocarbons such as hexane, heptane, octane and nonane; saturated cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane; aromatic Hydrocarbons such as benzene, toluene, xylene and their halogen derivatives.

In the following examples, all amounts are proportions, if nothing otherwise noted is given in weight units.

Example 1 175 g (1.86 mol) of anhydrous sodium acrylate were in Put a three-necked flask with a mechanical stirrer, a dropping funnel and a water-cooled condenser to protect the contents of the flask wore a calcium chloride tube against humidity. 200 cc of hexane were added to the Flask was added and the mixture was then continuously stirred and onset chilled the flask in an ice bath. Then a solution of 90 g (0.91 mol) of phosgene in 452 g of hexane slowly added from the dropping funnel in about 1 to 11/2 hours. The slurry was then allowed to warm to room temperature. The dropping funnel was replaced with a thermometer.

The mixture was stirred slowly and then heated to 40 ° C. for 2 hours. The warm slurry was then quickly filtered and the filter cake several Washed times with hexane. The combined filtrates were cooled in an ice bath and separating the acrylic anhydride from the hexane.

The acrylic anhydride boils at 53 to 55 "C under 7 mm of mercury. A total of 90 g of anhydride was obtained; it had a purity of 890 / o, which according to the morpholine process (cf.

J. B. Johnson and G. L. Funk, Analytical Chemistry Vol. 27, 1955, pp. 1464) was determined.

Example 2 The apparatus used in Example 1 was also used in applied to this example. An ice cold slurry of 215 g (1.95 moles) dry Potassium acrylate in 250 cc hexane was made.

A solution of 97 g (0.98 mol) of phosgene in 500 cc of hexane was added to the slurry over 1 to 11/2 hours. The stirred Slurry was allowed to warm to room temperature and then an additional 1112 hours warmed to 40 ° C. The potassium chloride was filtered off and the filter cake with fresh Washed hexane. The hexane rapidly became from the filtrate under reduced pressure distilled off and the acrylic anhydride then at 53 to 55 "C and a pressure of 7 mm mercury column distilled in the presence of methylene blue as a retarder.

The anhydride had a purity of 850/0 according to the morpholine process was determined.

Example 3 Using the same apparatus as in the example 1 was a slurry of 215 g (2.28 moles) of anhydrous sodium acrylate in 250 cc benzene and cooled in an ice bath, then 112.5 g (1.14 mol) Phosgene in 600 cc of benzene was slowly added through a dropping funnel.

The mixture was allowed to warm to room temperature and then 11/2 Heated to 40 "C for hours.

The sodium chloride was filtered off and the filter cake with benzene washed. The filtrate, containing the acrylic anhydride, was removed without further purification used for polymerization. 134 g of polymer were obtained, corresponding to 920% the theoretical yield based on sodium acrylate.

Example 4 A cold slurry of 114 g (1.46 moles) dry Lithium acrylate in 250 cc hexane was made. A solution of 86 g (0.86 mol) Phosgene in 500 cc of hexane was slowly added to this slurry. The mixture was then allowed to warm to room temperature and then to 40 "C for 11/2 hours warmed up. The lithium chloride was filtered off and the filter cake with something fresh Washed hexane. The filtrate containing acrylic anhydride was polymerized and resulted in a polymer with a cation capacity of 15.22 mVal per gram (mVal = Milliequivalent).

In a further experiment, 128 g (1.2 mol) Sodium methacrylate reacted with 58 g (0.6 mol) of phosgene and then the resulting Methacrylic anhydride polymerizes. It 75 g of polymer were obtained, accordingly 84% of the theoretical yield based on the sodium methacrylate.

Example 5 A slurry of 250 g (0.905 moles) anhydrous Barium acrylate in 250 cc hexane was cooled in an ice bath. About this slurry was a solution of 91.5 g (0.925 mol) of phosgene in 600 ccm of hexane within 11/2 hours given. The slurry was allowed to warm to room temperature and then heated to 40 ° C. for 11/2 hours. The barium chloride was filtered off and the filter cake washed with hexane. The filtrate containing acrylic anhydride, was polymerized to give a polymer with a cation capacity of 15.58 mVal per gram.

Example 6 A slurry of 1.95 moles of anhydrous sodium methacrylate in 500 cc benzene was produced. This slurry was added to within A solution of 97 g of phosgene (0.98 mol) in 800 cc of benzene was added for 11/2 hours. During the addition of phosgene, the temperature of the mixture rose to 40 ° C. The slurry was held at this temperature for 3 hours, and then the sodium chloride filtered off. The filter cake was washed with fresh benzene and the filtrates were combined and the benzene was distilled off by vacuum distillation. Thereafter the methacrylic anhydride was at 70 to 75 "C under a pressure of 3 mm of mercury distilled. The yield of methacrylic anhydride was 850 / o of theory.

Example 7 A slurry of 230 grams (2.1 moles) of anhydrous sodium methacrylate in 230 cc of hexane was made up and cooled in an ice bath. A solution from 103.8 g (1.05 mol) of phosgene in 500 cc of hexane was slowly drawn from a dropping funnel added to the slurry. The mixture was then allowed to warm to room temperature and then heated to 40 ° C. for 2 hours. The sodium chloride was filtered off and the filter cake washed with fresh hexane. The filtrates were combined and the hexane removed by vacuum distillation.

Methylene blue was added to the alembic as a retarder. The crude methacrylic anhydride was obtained by fractional distillation using further purified from methylene blue as a retarder. The main faction was at 75 up to 76 "C under a pressure of 7 mm of mercury. The purity of the Methacrylic anhydride was 99.14% and the yield was 670/0.

Example 8 A slurry of 1.5 moles of anhydrous sodium acrylate in 250 cc of benzene was made up and cooled in an ice bath. Then 1 mole Phosgene dissolved in benzene was added to the cooled slurry. The mixture was allowed to warm to room temperature and then warmed to 40 "C for about 2 hours. The Sodium chloride was filtered off and the filter cake washed with fresh benzene. The benzene filtrate contained a mixture of acrylic anhydride and acrylic acid chloride. the Half of the filtrate was placed in a distillation flask, a trace of methylene blue added and distilled under normal pressure. There was thus obtained 20 g of acrylic acid chloride obtained that boiled at 75 to 76 C. By determining the hydrolyzable chloride the acrylic acid chloride content of the distillate was calculated to be 67 percent by weight.

The benzene was then reduced from the distillation residue Pressure distilled off and the acrylic anhydride finally at 63 to 65 "C below distilled under a pressure of 10 mm of mercury. This distillate contained X5,501o Acrylic anhydride. determined by the morpholine method. The yield was 23 G. corresponding to 37io the theoretical.

The other half of the filtrate was used to make up the total consumption of NaOH and the total content of hydrolyzable chlorine. That calculated Cation neutralizing power of a mixture of 50% acrylic anhydride and 500/10 acrylic acid chloride was 1.66 meq per gram a neutralization capacity of 1.80 mVal per gram.

The filtrate contained 1.280 m in hydrolyzable chlorine versus one calculated value of 1.49% for a mixture of equal parts of acrylic acid chloride and acrylic acid anhydride.

Example 9 A slurry of 174 grams (0.95 moles) of anhydrous calcium acrylate in 500 cc of hexane was made up and cooled in an ice bath. After that were slow 94.5 g (0.95 mol) of phosgene in 500 cc of hexane were added to the slurry.

After the addition of phosgene was complete, the mixture rose to room temperature Allowed to warm up and then heated to 400 ° C. for 2 hours. The calcium chloride formed was filtered off from the hexane solution. In this way it became a solution of acrylic anhydride obtained in hexane.

Example 10 To a slurry of 160 g (0.95 moles) of magnesium acrylate 94 g (0.95 mol) of phosgene dissolved in 500 cc of hexane were added to 250 cc of hexane. As in the previous examples, the solution was in an ice bath before the phosgene was added chilled. After the end of the phosgene addition, the mixture lasted for 11k hours 40 "C and then filtered off the magnesium chloride from the liquid. The Hexane contained monomeric acrylic anhydride.

Example 11 Methacrylic acid chloride is prepared by reacting a slurry of 231 g (2.13 mol) of sodium methacrylate in 1000ccm of hexane with a solution of 213.5 g (2.16 mol) of phosgene in 1500 cc of hexane. After adding the phosgene solution the mixture was heated to 40 ° C. for 2 hours. The mixture was then spun off, the supernatant liquid is poured off and the hexane is distilled off. After that it was the methacrylic acid chloride, which boiled at 98 to 99 C under atmospheric pressure, recovered. The sodium chloride was obtained in the amount calculated for this reaction. Thereafter a complete implementation is to be assumed.

Mixture of alkali and alkaline earth salts of in a-position with a lower alkyl substituted acrylic acids can be used to produce mixed Acid anhydrides or acid chloride mixtures can be used; z. B. can a Mixture of sodium acrylate and sodium methacrylate with phosgene to form a mixture Acrylic anhydride, methacrylic anhydride and a mixed anhydride of acrylic and methacrylic acid are reacted. Mixtures of the salts can also be used; z. B. mixtures of sodium and potassium salts or salts of an alkali and an alkaline earth metal of acrylic acid or one in a-position by a low molecular weight Acrylic acid substituted by alkyl groups or mixtures of these salts with carbonyl chloride to acid chlorides, anhydrides and mixed anhydrides of α, -unsaturated acids implemented.

Claims (4)

Claims: 1. A process for the preparation of aB-unsaturated carboxylic acid anhydrides or chlorides or mixtures thereof by reacting the unsaturated carboxylic acids with carbonyl chloride (phosgene), characterized in that alkali or alkaline earth salts of a, -unsaturated carboxylic acids of the general formula in which R is hydrogen or a low molecular weight alkyl group, n is 1 or 2 and Me is an alkali or alkaline earth metal with the valency n, reacted with carbonyl chloride at a temperature of 0 to 100 "C with exclusion of water in the presence of an inert diluent. 2. The method according to claim 1, characterized in that 2 mol of the salt of the α, -unsaturated carboxylic acid with 1 mol of carbonyl chloride to form the carboxylic acid anhydride implements. 3. The method according to claim 1, characterized. that one more than 1 mole but less than 2 moles of the salt of the α, fl-unsaturated carboxylic acid with 1 mole of carbonyl chloride to form a mixture of the carboxylic acid anhydride and the carboxylic acid chloride implements. 4. The method according to claim 1, characterized in that 1 mol Carbonyl chloride is reacted with 1 mol of the salt of the α, -unsaturated carboxylic acid. Documents considered: German Patent No. 840 687; British Patent No. 401,643; French Patent No. 839,231; Bulletin de la Societe Chimique de France, 1954, 56; Richter-Anschütz, chemistry of carbon compounds, 12th edition. 1928, vol. 1, p. 346; H o u b e n - W e yl, Methods of Organic Chemistry, Vol. 8, Oxygen Compounds, III, 1952, p.471 to 473; R. B. Wagner - H. D. Zook, Synthetic Organic Chemistry, 1953, p. 549, section 339; R. F u s o n, Advanced Organic Chemistry, 1950, p. 103.