PL159915B1 - Method for preparation of the 2-ethylhexane aid salts - Google Patents

Abstract

1. A method of producing 2-ethylhexanoic acid salt in a direct reaction of the acid with magnesium and/or calcium and/or zinc oxide, characterised in that the process is carried out in a medium of aliphatic alcohol C1-C5 by successively introducing into the reactor: metal oxides or a mixture thereof, alcohol and 2-ethylhexanoic acid, and further the produced reaction mixture is mixed until the temperature stops increasing spontaneously, and further it is heated up to boiling point for at least 1 hour, the product is possibly filtered under reduced pressure, and the produced filtrate or mixture is distilled first at normal pressure and then under reduced pressure at a temperature of 110-140 degrees C, and further the produced salt is dried to a constant weight under reduced pressure.

Description

The subject of the invention is a process for the preparation of 2-ethylhexanoic acid salts that are used as thermal stabilizers for polyvinyl chloride.

According to known solutions, the calcium, magnesium and zinc salts of organic acids are usually obtained by direct reaction of the oxides or hydroxides of these metals with the corresponding organic acids, the processes being carried out in different phases.

Polish patents Nos. 95 340 and 139 888 disclose a method of fluidized production of calcium, lead, barium, magnesium and zinc salts of fatty acids with a melting point above 40 ° C. The reactants used herein are oxides or hydroxides of these metals, and acids such as steainic, benzoic, lauric and azelaic.

On the other hand, the Polish patent specification No. 94,464 discloses a method of producing salts of organic acids by direct reaction of oxides and / or hydroxides of alkali metals, alkaline earth metals and zinc and cadmium with acids by rubbing in the solid phase, while maintaining such a speed of reaction that the reaction medium it remained in solid and powdered phase.

Both of these methods, fluidized bed and solid-phase grinding, are technologically cumbersome, and the solid-phase process has the additional disadvantage that the need for high purity products requires the use of non-contaminating raw materials.

There are known methods of preparing the salt of 2-ethylhexanoic acid consisting in the reaction of the acid with metal hydroxides or with metallic dust or in ion exchange reactions involving the sodium or potassium salt of 2-ethylhexanoic acid.

There are also known methods involving the reaction of acid with metal oxides. DE 2 554 845 describes the reaction of 2-ethylhexanoic acid with magnesium oxide using kerosene, while Japanese patent publication JP 7 921 419 describes the reaction with zinc oxide and using toluene. Both of these methods are characterized by long reaction times.

The method for producing the 2-ethylhexanoic acid salt according to the invention does not have the disadvantages of the known solutions.

The method according to the invention consists in the direct reaction of magnesium oxide and / or calcium oxide and / or zinc oxide with 2-ethylhexanoic acid in a C1-C5 aliphatic alcohol environment by successively introducing metal oxides or their mixtures, alcohol and acid into the reactor. -ethylhexane. The reaction mixture is stirred until

159,915 until the temperature rise ceases spontaneously, and then it is brought to the boil for a period of at least 1 hour. The resulting product is optionally filtered under reduced pressure and the resulting filtrate or reaction mixture is distilled first under normal pressure and then under reduced pressure at 110-140 ° C. The resulting 2-ethylhexanoic acid salt is dried under reduced pressure to constant weight. It is preferable to use n-butanol as the aliphatic alcohol.

The method according to the invention makes it possible to eliminate the disadvantageous phenomena related to impurities in the raw materials used. This method allows for obtaining single salts or their mixtures with a given composition with high efficiency, showing effective action as stabilizers for polyvinyl chloride. The salts obtained by the process according to the invention are characterized by a satisfactory degree of purity.

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

P ^{r yk} I. In order ^k olbia ^AGL round of ^{d p} ennej of ojemno ^COG of ¹ m ^{3 d p} atrzonej assumed for the ^DL mixture ^and a reflux condenser and a thermometer the following order 21.9 grams of magnesium oxide with a purity of 89% / comprising 19.5 g of pure MgO and 1.4 g of impurities in the form of a mixture of Mg / OH / 2, MgCO3 and other impurities /, 246 g of technical butanol of 99.2% purity / containing 0.23% water and 0.57% volatile of impurities /, 147 g of technical 2-ethylhexanoic acid of 98% purity / containing 1.4 g of water and 0.7 g of volatile impurities / and 82 g of technical butanol. Temperature rise was observed during the addition of the acid and the stirrer was started. After all the starting materials had been introduced, the contents of the flask were agitated until the temperature spontaneously ceased. After stabilizing the temperature, the reaction mixture was heated to reflux for 5 hours. The temperature of the mixture was 110 ° C. After this time, the conversion of 2-ethylhexanoic acid was determined to be 100% by means of NMR spectrum and thin layer chromatography. The reaction mixture was then filtered on a Buchner funnel using filter cloth using a pressure of 25 mmHg. The filtrate was subjected to a distillation which was carried out initially under normal and then under reduced pressure with an oil bath temperature of 110140 ° C. After the butanol had been separated off, the precipitate formed was dried in a vacuum oven for 24 hours at a temperature of 110 ° C and a pressure of 10 hPa. 155.3 g of the magnesium salt of 2-ethylhexanoic acid were obtained with a yield of 98.8%. The obtained salt has a slightly yellow color, it is a solid and it is well soluble in organic solvents, but it is insoluble in water. The conducted elemental analysis showed the content of C 61.87%, H - 7.12% and Mg - 7.70% with the theoretical content of C - 61.93%, H - 6.97% and Mg - 7.8%. NMR spectrum analysis and thin layer chromatography showed no indication of 2-ethylhexanoic acid in the resulting product.

Example Π. In the apparatus and under the conditions as in example 1, with the difference that instead of MgO, 31.7 g of technical calcium oxide was introduced / with the content of pure CaO - 25.05 g, Ca / OH / 2 - 4.0 g and 2.65 g CaCO3 and other impurities) and heating the reaction mixture under reflux for 1 hour, yielded 172.3 g of calcium 2-ethylhexanoic acid. The process yield was 99.0%. The resulting salt is a white crystalline substance containing 1 mole of crystallization water per mole of salt. It is well soluble in butanol and chloroform, insoluble in water and slightly soluble in methanol, acetone and toluene. Elemental analysis showed the content of C - 55.52%, H - 9.50% and Ca - 1,151% with theoretical content of C - 55.81%, H - 9.30% and Ca - 11.63%. NMR spectrum and thin layer chromatography showed no indication of 2-ethylhexanoic acid in the resulting product.

Example 111 Under the same conditions as in Example 1, except that instead of MgO, 40.76 g of zinc oxide containing 0.08 g of impurities were introduced, and after 5 hours of heating at 110 ° C, the reaction mixture was distilled directly, skipping the filtration step. 174.6 g of zinc salt of 2-ethylhexanoic acid were obtained with a yield of 98.3%. The salt obtained is a thick, slightly yellow liquid, soluble in organic solvents and insoluble in water. Elemental analysis of this salt showed the content of C - 54.48%, H - 8.35% and Zn - 18.92% with the theoretical content of C - 54.70%, H 4

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8.55% and Zn - 18.6%. NMR spectrum analysis and thin layer chromatography showed no presence of 2-ethylhexanoic acid in the tested product.

Example IV. Under the conditions as in example 1, with the difference that instead of a single oxide, 31.42 g of a mixture of Mg, Ca and Zn oxides were introduced into the system (including 3.05 g of pure MgO, 17.66 g of pure CaO and 5.62 g of pure ZnO) ), 170.5 g of a mixture of these metal salts were obtained with a yield of 98.5%. In the obtained salt, the weight ratio of magnesium salt to calcium salt to zinc salt of 2-ethylhexanoic acid was 1: 5: 1.

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

Claims (2)

Patent claims Method for the production of 2-ethylhexanoic acid salts by direct reaction of the acid with magnesium and / or calcium and / or zinc oxide, characterized in that the process is carried out in a Ci-C5 aliphatic alcohol environment by successively introducing metal oxides or their mixture, alcohol into the reactor and 2-ethylhexanoic acid, the resulting reaction mixture is stirred until the temperature rises spontaneously, then it is heated to reflux for a period of at least 1 hour, then the resulting product is optionally filtered under reduced pressure, and the filtrate or reaction mixture obtained is subjected to distillation is carried out first under normal and then under reduced pressure at a temperature of 110-140 ^° C, and the salt obtained is then dried under reduced pressure to constant weight. 2. The method according to p. The process of claim 1, wherein the aliphatic alcohol is n-butanol.