SU549458A1 - The method of obtaining aliphatic carboxylic acids - Google Patents

Description

The invention relates to the production of linear aliphatic carboxylic acids, which are used in the production of sodium and potassium soaps for various purposes (shampoos), plasticizers, lubricants, foundry fixtures, alkyloamides, rubber products and other products. For the preparation of higher carboxylic acids, oxidation of paraffins, alcohols or olefins, as well as carboxylation and carbonylation of olefins, are commonly used. A characteristic feature of these processes is either the use of highly aggressive reagents, which require highly resistant materials, or the impossibility of obtaining straight chain acids of the same structure.

There is also known a method of obtaining carboxylic acids from aluminum trialkyls and carbon dioxide by heating in an autoclave under pressure at 150-250 ° C, followed by liberation of carboxylic acids by decomposing the organoaluminium complex with dilute sulfuric acid.

The main disadvantage of this method of producing aliphatic carboxylic acids is the relatively low yield of carboxylic acids per starting aluminum trialkyl (not more than 50-60%).

In order to increase the yield of the target product, the interaction of carbon dioxide with aluminum trialkyl (carboxylation) is carried out in the presence of an aliphatic trialkylamine, taken mainly in the amount of 90-PO mol. % calculated on the original aluminum trialkyl, when heated from 150 to 250 ° C in an autoclave. The process should be carried out in an inert organic solvent medium, for example, n-naphthaine, cyclic saturated or aromatic hydrocarbon, and sulfuric ether. The amine used can be regenerated and reused.

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Example 1. 25 g of trioctylaluminum in 100 ml of decane and 100. ". Of ether and 6.9 g of triethylamine are loaded into a 0.5 l autoclave cooled to -70 ° C, saturated with carbon dioxide, heated for 4 hours at 220-240 ° C (pressure is increased to 200 bar), cooled, the reaction mass is discharged and triethylamine is distilled off (6.55 g and the solvent. The residue is decomposed with 10% sulfuric acid, extracted with ether, treated with a 10% alkali solution , acidified and treated with ether. After evaporation of the ether, 26.4 g (82%) of pelargonic acid, b.p. 157-159 ° C / 30 mm, is obtained;

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Claims (2)

1.4327 (according to literary data / th 1.4330). The output of pelargonic acid obtained in a known manner, only 60%. Pfimer 2. 29.8 g of triisobutylaluminum in 200 ml of decane and 26 g of tributylamine are loaded into an autoclave cooled to -70 ° C, saturated with carbon dioxide and heated for 4 hours at 225-245 ° C. The maximum pressure is 190 atm. After processing as in Example 1, 37 g of isovaleric acid (80.5%) are obtained, so kin. 93-95 ° C / 33 mm; 1.4028, so pl. anilide 109 ° C (according to literary data, mp. 109-110 ° C). Example 3. A 55 l autoclave was charged with 55.6 g of aluminum triethyl in 100 ml of heptane and saturated with ethylene to a pressure of 45 atm. The mixture is heated to 120-130 ° C until the pressure of ethylene drops almost to the pool. A mixture of higher aluminum trialkyls is obtained, containing (mol%): C2 1.75; C4 7.35; Sat 15.05; Cs 19.95; do 20; Ci2 16.03; C, 9.97; Ci6 6.0; Ci8 3.0; C2o 1.3; C22 0.5; C24 and above 0.3 Rep Xu. The cooled reaction mass is diluted with 200 ml of heptane and 80 / ml ether, 50 g of triethylamine are added to it and transferred to a 1 l autoclave cooled to -70 ° C. The mixture is saturated with carbon dioxide and heated at 200-220 ° C for 3.5 hours After the usual treatment, 226 g of a mixture of carboxylic acids (82%) are obtained. By fractionation in vacuum, 2 g of propionic acid are obtained, that is, bale. 60.5-62 ° C / 30 min; According to 1.3860; 7.9 g of valeric acid, t. Kip. 105-106.5 ° C / 31 mm, "about 1.4084; 21 g of anaic acid, t. Kip. 131 - 133 ° С / 31 mm, / ID ° 1.4220; 36 g pelargonic acid, t. Kip. 157-159 ° C / 30 mm, p 1.4328; 44 g of undecanoic acid, t. Kip. 176.5-178 ° C / 30 mm, n1 ° 1.4295; 42 g tridecanoic acid, t. Kip. 179-181 ° C / 10 mm, so pl. 49-50 ° C, and 72.5 g of higher acids. Claim 1. Method for producing aliphatic carbopic acids by carboxylation of aluminum trialkyls when heated from 150 to 250 ° C in an autoclave, characterized in that, in order to increase the yield of the target product, the process is carried out in the presence of aliphatic trialkylamine. 2. A method according to claim 1, wherein the trialkylamines are used in an amount of 90-PO mol. % relative to the original aluminum trialkyl.