SU180180A1 - METHOD OF OBTAINING ACID - Google Patents

Description

This invention relates to the field of lactic acid production for industry.

It is known to produce lactic acid by oxidation of nitroyl carbon tetroxide with nitrogen, followed by hydrolysis with a 25% solution of nitric acid. The yield of acid is 1.1ll 30% of the theoretical.

For the purpose of noBbinieHHH yield, coi-lacio to the proposed method, after oxidation to masses 1, the rectification of pitaproproponic acid, which is hydrolyzed in the presence of hydrochloric acid or ion-exchange resin KU-2 to polylactic acid, is not carried out with methyl alcohol, is carried out. The resulting methyl lactate is decomposed by boiling with water into free lactic acid and methyl alcohol.

As a raw material for the production of lactic acid, it is possible to use the steam with the propylene propane propylene fraction.

Example 1. Getting an - n and t r and t ohm about l 04 and it acids. 1.61 mol (148 g) liquid nitrogen tetroxide, pomeid, ayut into the reaction flask and cooled to - () С. Gaseous propylene slowly i; within 3 hours, they are introduced into the reactor at a temperature of or -10 to --- ISC. A total of 0.31 mol (13.05 g) of Nro P1leia (8.52 L, concentration penetrated at 81.6%, propane at 18.4%) was passed. Under these conditions, propylene completely reacts without

overshoot. P1-excess nitrogen tetrafox is removed by propium through the reaction mixture; dry air assy npi temperature from -15 to (air flow rate 30 l / h). The mixture of air and oxides of nitrogen is cooled to -15 ° C, while this nitrogen tetroxide is condensed.

The residue after the removal of nitrogen tetrooxide (54.25 g) contains α-n-thratonroponic acid, which the river produces by vacuum extraction.

Obtain 35.6 g (-ntratoiropnonovoy acid (yield 85H) from the theoretical); m.p.

96 C (3 mm Hg.); (J

1.4359.

i, n

T. KIP. 9t) with (3 mm. Literary data: 1.3672; 1.4356. Hg. Art.); d

20

And p and m e r 2. Gd, d about l and. sg - and and t r and t op P ots and about N o in o and to n n slots g, P r and s ys t P P and and K Y - 2. In the reactionary device, spabennyy a shabi for heating , load 18.3 g of a-ntratonopropionic acid. 43 ml of water and 37.8 g of ion-exchange resin KU-2. At a temperature of 90 ° C, the contents of aiparg.ta mix ir1: HOMOHU petr hivak1N of its device for 5 hours. Kgaionite is separated by flitation. After OTIOHKI in vacuo of weak nitric acid, 11.8 g of lactic acid are obtained (B as a 11A10l acid form). Output 96.7% of theoretical.

Example 3. G and d roal iz. A-nitrate supplement and hydrochloric acid and acid in the presence of hydrochloric acid, in a reaction flask equipped with a stirrer, 100 slg 36% hydrochloric acid are loaded. At a temperature of 70 ° C, 90 g of a-nitrate-propionic acid was slowly introduced over 1 hour. After introducing a-nitratopropionic acid into the reaction flask, a weak stream of hydrogen chloride is fed for 3 hours. After the process is complete, the excess hydrochloric acid is distilled off in vacuo. 40 ml of benzene are added to the residue, and water is introduced as an azeotrope.

54.9 g of lactic acid are obtained (in the form of polylactic). Output 90% of theoretical.

Example 4. Preparation of methylate and lactate ata (methyl lactic ester). 42 g of polylactic acid, 96 slugs of metaiol and 0.6 cm of co-centric sulfuric acid are loaded into a special-steel autoclave tube. The mixture is heated at 100 ° C for 4 hours. Obtain 122 g of reaction products containing 39.1% methyl lactate. Exit 83.5o / c from the theoretical.

To isolate the methyl lactate, the reaction mixture is neutralized with 2 g of anhydrous sodium acetate. The sodium sulfate precipitate is filtered off.

Excess methanol is distilled off in a slight vacuum. 30 cm of benzene was added to the residue, the reaction water was introduced as an azeotrope. Methyl lactate is isolated by distillation in vacuo; m.p. 60 ° С (32 mm of mercury); d 1,092;

i20

1.413.

20

Literary data:

1.0895; n 1,413.

- Example 5. Production of lactic acid by methyl lactate hydrolysis. 12.75 g of methyl lactate and 15 cm of water are charged to a reaction flask attached to a distillation column. The mixture is heated to kienn. Methanol is taken as distillate. The level in the reaction flask is maintained by introducing an additional amount of water.

The reaction is completed when the temperature in the cube reaches 100 ° C. 29.1 g of an aqueous solution of lactic acid is obtained (the concentration of lactic acid is 37.8%).

The yield of lactic acid is 99Vo from the theoretical, based on methyl lactate and 70o / o - per propylene.

Subject invention

The method for producing lactic acid by oxidation of propylene with nitrogen tetroxide, characterized in that, after oxidation, after oxidation, α-nitrate-propionic acid is extracted from the reaction mass by distillation, which is treated with hydrochloric acid or KU-2 ion-exchange resin the acid is treated with methyl alcohol with subsequent boiling with water.