SU444764A1 - The method of obtaining-aldehyde limit - Google Patents

Description

The invention relates to a process for the preparation of GL, j - unsaturated aldehydes used in the manufacture of plasticizers.

There is a known method for obtaining the terminal aldehydes by condensation of n-butyraldehyde with isobutyraldehyde in the presence of aqueous alkali at a temperature higher than the starting material, butyraldehyde and isobutyraldehyde are used in a ratio of 1: 1.5-4, the yield of unsaturated aldehyde is not greater than -88 calculated on converted aldehydes.

The disadvantages of this method are the relatively low selectivity of formation of o (, narrow aldehydes, and the need to use a large excess of isobutyraldehyde, which complicates the process. In addition, excess isobutyraldehyde is involved in a number of side reactions, drive px, for example, to form 1, 5 and salts

organic kitty; The originating by-products impede the further conversion of the octenals into the OB alcohols and affect the quality of plasticizers obtained from the alcohols. The purpose of this invention is to increase the selectivity of o (, J3-unsaturated aldehydes) by condensation of n-butyraldehyde with isobutyraldehyde in the presence of an aqueous solution of alkali, at a temperature above 65 ° C, and also to simplify the technology of this process.

5 The goal is achieved by the fact that the mixture of n-butyraldehyde and isobutyraldehyde is dispersed by known methods in an aqueous solution of alkali to an average diameter of droplets of the organic phase not more than I mm, mostly 0.07-0.3 mm,

According to the invention, it is advisable that the aldol mixture, together with the alkali metal solution, be directed to the reactor through a nozzle, where due to the rotation of the mixture, the two streams are effectively mixed.

cove However, the transformation of a mixture of aldehydes in a reactor with rotating plates is also possible, the mixture of aldehyde and an alkali metal aqueous solution being introduced into the rector by countercurrent, and a significant part of the alkali water solution used is recycled, in order to maintain a constant alkaline hydroxide concentration in the reaction zone. the alkaline solution is replaced with fresh alkali. It is advisable to conduct the process when the ratio of the volumes of the alkali solution and the mixture of aldehydes, 0.5-1: 1.

In accordance with the method proposed, it is advantageous to use a slice of aldehydes in which the ratio of isobutyraldehyde and n butyraldehyde is 0.5-2: 1, preferably 1-1.25: 1,. “. - Under these conditions, always in definite kolzhesZD image is 2ethel ii hexal: I. The n butyraldehyde used is converted almost completely to octenal.

The process is preferably carried out at 80-120 ° C. When operating in the specified temperature range, a pressure of 3 to 6 atm is required, which is maintained with a buffer gas, for example, nitrogen or arthotes. Exothermicity of the process does not require heat supply to the reactor if the reactants are

four

The reactor is heated to the reaction temperature. by rotating the mixture. there is a mixture of two threads. The linear feed rate of the mixture into the reactor, filled with 4-5 Å-alkaline solution, is 25 m / s, the droplet size of the organic phase in the reactor is 0.07– 0.3 mm. The reaction is carried out under a pressure of 4 at temperature. Nitrogen is used as a buffer gas. After the separation of the organic phase from the aqueous solution in the separation tank, the alkali solution is returned to the counter current, and 50 soda liquors are replaced with fresh alkali containing 5% sodium hydroxide. From the organic phase, distilled octenals and unconverted isobutyraldehyde are recovered, which is recycled to the process. Upon distillation, 29.9 kg of 2-ethyl-4-methyl-2-pentanal -1, 16.2 kE8-ethyl-2-hexaeal -1, and 15.9 kg of unconverted isobutyraldehyde are obtained. The output of the octenal is 93.8, based on the converted aldehydes and based on the converted isoo-thyraldehyde. Examples 2-4. The process is carried out as described in example I, using starting aldehydes in

different ratios. The results are shown in the table. INVENTIONS I, method of obtaining og, 4 / s - nlpreddelt1X aldehydes copiacensia n butyraldehyde izobuhiraddegidoi in the presence of an aqueous solution of the scam at a temperature not lower than 63 ° C after the last time and after extraction of the target matter at a matter of application. simplification of the gr technology, Sme. 444 5 10 64 n of butyraldehyde and isobutyraldehyde disperses the lams by means of an aqueous alkaline solution to an average drop of organic phase droplets of no more than I mm, preferably: 0.07-0.3 mm. 2, the method according to p. 1, characterized in that the mixture of aldehydes together with an aqueous solution of alkali in the reactor through the nozzle.