DE1568487B2 - Process for the preparation of acrylic acid and methacrylic acid oxypropyl or oxyethyl esters - Google Patents

Description

290 g of propylene oxide are pumped into the pressure vessel over the course of one hour. It is allowed to cool and distilled after cooling to room temperature, the reaction product in vacuo. One achieves under these Conditions after isolation and purification a conversion of more than 85% based on the used Methacrylic acid. The distilled methacrylic acid hydroxypropyl ester boils at 90 to 93 ° C / 6 mm Hg and is not contaminated by propylene glycol dimethacrylate. Yield 506g.

Example 2

A mixture of 300 g of acrylic acid, 0.3 g of methylene blue and 8 g of triphenylphosphine is placed in a pressure vessel submitted. The reaction vessel is flushed with nitrogen and heated to 85 ° C. Within 300 g of propylene oxide are then added to the batch for 1 hour. The conversion to the hydroxypropyl ester is followed of acrylic acid by determining the acid number and cools at an acid number of 10 Room temperature. The reaction is stopped completely at room temperature. After 24 hours, it is worked up and obtained in a yield of 90% of theory hydroxypropyl acrylate. Kp .: 70 to 7TC / 2 mm Hg. The acrylic acid ester is not through Glycol diacrylate contaminated.

Example 3

A mixture of 300 g of methacrylic acid, 2 g of phenothiazine, 6 g of tributylphosphine and 20 g of benzene is placed in a reaction vessel. 350 g of propylene oxide and 2 g of 2,4-dinitrodiphenylamine are introduced into the reaction space at 90 ^{° C. within 1/2 hour.} In a yield of over 90%, methacrylic acid hydroxypropyl ester, free of by-products with an acid number of 10, is obtained by fractional distillation; Bp. 90 to 93 ° C / 6 mm Hg.

Example 4

In a reaction vessel a mixture of 300 g acrylic acid and 6 g of dibutyl phosphite and a mixture of 450 g of propylene oxide and 2 g of phenothiazine at 100 ⁰ C are reacted. The pressure vessel is freed from traces of oxygen by purging with nitrogen before the reaction; the reaction itself takes place in the presence of nitrogen as an inert gas at a nitrogen partial pressure of 6 atmospheres.

After 2 hours of reaction, a reaction mixture free of polymers is obtained which ^{no longer reacts even on cooling to 50 °} C. and which still contains 30% of the acrylic acid used. After working up by fractional distillation, the hydroxypropyl acrylate is obtained with a boiling point of 70 to 71 ° C./2 mm Hg, free from ethylene glycol diacrylate.

Example 5

Is carried out under conditions as in Example 4 and used in place of Dibutylphosphits triethyl phosphite, then obtained after 2 hours of reaction the same compound, which still contains 20% of acrylic acid employed, and no longer responds by cooling to 5O ⁰ C.

Claims (1)

1 2 esters compared to a thermally initiated polymer Claim: sation and against the formation of glycol diesters very too if esters with an acid number of less Process for the production of oxypropyl or as 2 are formed. When using FeCl ₃ oxyethyl esters of acrylic acid or methacrylic acid as a catalyst, the reaction of acrylic acid or acid takes place by reacting propylene oxide or methacrylic acid with ethylene oxide or propylene oxide, ethylene oxide with acrylic acid or methacrylic acid, even after the reaction mixture has cooled in the presence of a catalyst, and where appropriate, and the production of products with a lower, if a solvent, expediently 80 to a defined acid number is practically impossible. The 130 ⁰ C, characterized in that io catalysts according to the invention now allow the halogen-free triphenylphos reaction of the alkylene oxides with z. B. methacrylic acid phin, tributylphosphine, triethyl phosphite or at any time by cooling the reaction mixture to dibutyl phosphite. Temperatures of 10 to 25 ° C must be completely prevented. Although it is known from Journal of the American Chemical 15 Society 87, p. 2683, tert. Phosphines and React alkylene oxides, but these react Components with the formation of olefins. The catalytic effectiveness of trivalent phosphorus compounds in the reaction of alkylene oxides with It is known that unsaturated polymerizable carboxylic ² ° unsaturated carboxylic acids was therefore not vorausbonsäuren such as acrylic acid and methacrylic acid with watch. Alkylene oxides, such as ethylene oxide or The compounds, such as. B. triphenylphosphine Propylene oxide to the corresponding oxyalkyl esters is also particularly suitable as catalysts of acrylic acid or methacrylic acid in the presence of, because these catalysts convert any catalysts. The use of cleanly ² 5 stabilizers, which performs a polymerization of the ren catalysts formed thereby more or less based inhibit the monomers during processing or during formation of diesters of the alkylene oxides storage, are not deactivated, glycols located (see FIG. USA. Patents 1,710,424, while, for example, catalysts such as anhydrous FeCl ₃ and 1,810,318), while basic catalysts, as with some inhibitors, fail. Especially in the case of, for example, tertiary amines, long reaction times 3 ° lead to large-scale implementation of reactions that require and do not lead to industrially interesting methacrylic acid or acrylic acid with alkylene oxides (cf. US Pat Poly and 2 929 835). merisaten during manufacture and during the It has also been proposed to purify acrylic acid from (meth) acrylic acid oxyalkyl esters or methacrylic acid with ethylene oxide or propylene 35 avoid. oxide in the presence of iron (III) chloride or of The composition of the reaction mixture Implement iron (III) alcoholates as catalysts. is advantageously chosen so that one in the reaction Only temperatures can be selected here, carboxylic acid / alkylene oxide the alkylene oxide up to which are below 90 ° C. in order to use about 3-fold molar excess despite the addition of Inhibi-. At a prevent polymerisation. Acquaintance- 4 <> Purification of the unsaturated, polymerizable Reakweise but the conversion at temperatures below tion products by distillation are possibly in 90 ° C low, so that the excess alkylene oxides used in the known process is easier to reduce amount / time yield do not go over 1.5 mol / h separate. (See German Auslegeschriften 1 144 262 and The amount of catalyst to be used changes 1 147 938). 45 deal with the reaction conditions and the desired There has now been a method for producing th conversion levels. In general, 0.5 to Oxypropyl or ethyl esters of acrylic acid or 4 percent by weight of catalyst, based on the men-methacrylic acid by converting propylene oxide to acrylic or methacrylic acid used, or ethylene oxide with acrylic acid or methacrylic acid. in the presence of a catalyst, and optionally 5 °, it is particularly advantageous, consists unsaturated polymerieines appropriate solvent at 80 to 13O ⁰ C, matable carboxylic acids and alkylene oxides in kontiwelches that implement the catalyst used halo- nuierlicher procedure. Self-verging triphenylphosphine, tributylphosphine, tri-course can be used inert organic solvents ethyl phosphite or dibutyl phosphite. add the reaction mixture such. B. benzene, Compared to the known catalysts, the 55 have chlorberizole, dimethylformamide or anisole. The pre-phosphorus-containing catalysts have the advantage that the most favorable reaction temperature is generally the reaction of the alkylene oxide with the methacrylic between 80 and 130 ⁰ C, but preferably between acid or with the acrylic acid and the subsequent 90 and 110 ⁰ C and is in the individual cases by distillation of the esters without the separation of poly preliminary tests to the extent that it runs in the merization products and a formation of ^6o reaction mixtures, the unreacted carbon diesters of ethylene glycol or propylene glycol acid by titration with z. B. caustic soda determined practically does not take place. Another benefit this can be.
Phosphorus catalysts are that the reaction of the un- _. . . . saturated carboxylic acids with ethylene or propylene egg oxide only at temperatures above about 5O ⁰ C ⁶ H 5 In a pressure vessel, a mixture of 350 g at all runs. As is known from the USA patent methacrylic acid, 1 g of phenothiazine and 10 g of triphenyl script 2,929,835, the sensitive phosphine is submitted, the reaction vessel is then flushed with unsaturated polymerizable oxyalkyl nitrogen and brought to 80.degree. Afterward