SU65480A1 - Method for separating meconic acid from meconates - Google Patents

Description

The known methods for the isolation of meconic acid (see, for example, Mennel "Journ. F. Pr. Chemie 2, .26, 450, 1883) have significant drawbacks: a high consumption of hydrochloric acid is required, the recrystallization of salts of this acid is associated with significant losses, during crystallization from a hydrochloric acid solution, a product contaminated with comenic acid is obtained.

In order to eliminate these drawbacks, a method for separating meconic acid from meconates is proposed, based on the preliminary formation of a solution of an acidic salt of meconic acid, the separation of impurities and the subsequent preparation of a middle salt, which is converted into free acid by conventional methods.

Details of the proposed method can be removed from the examples below.

Example 1. 1.2 kg of air-dry, coarse meconate powder are poured into a mixture of 4.8 liters of water (preferably distilled) and 1.2 liters of hydrochloric acid (specific weight of 1.19) heated to 85-95 °. After the addition of charcoal, the solution is filtered hot (80-

85 °) through a filter cloth. The crystalline precipitate formed after cooling and standing is sucked off and washed with ice water and alcohol. A wet precipitate (about 1 kg) is introduced into distilled water (4 liters) heated to 70 ° n and a 10% solution of sodium hydroxide is slowly added to a neutral or slightly alkaline reaction (70-80 °). After the addition of charcoal, the hot solution is filtered through a cloth filter without delay. About 500 ml of 13% NaOH was added to the cooled filtrate, with vigorous stirring and little by little. The precipitated yellow precipitate, the middle sodium solp of meconic 1 Slot is sucked off, washed with alcohol and mixed with 3 liters of distilled water heated to 70-75 °. Add hydrochloric acid (specific weight of 1.19) until acidic and the mixture is cooled with meconic acid. It is sucked off and washed with alcohol. Output-400 g, ie, 40% relative to the dry meconate. T. pl. 250-260 ° C with decomposition.

Example 2. 1 kg of finely ground meconate powder with Kamenovo acid salt content

(by taking a sample, the presence of ksmic acid is determined) pour without delay into a mixture of 4 liters of water and 750 ml of hydrochloric acid heated to 85–95 ° (correspondingly less, if there is more comenic acid in the sample). After adding all the powder, the temperature of the solution at 85-90 ° is maintained for about 30 minutes, coal is added, filtered hot, and is fed as in Example 1.

The output of meconic acid reaches 25%, (with a content of comenic acid - 40%).

The admixture of comenic acid in meconic acid can be recognized by a color reaction with ferric chloride in alcohol. Cherry red is characteristic of comenboi acid. Mekonov acid

(without admixture of comenova) paints the alcoholic solution of ferric chloride in yellow.

Pd dm e-t from return

The method of extracting meconic acid from meconates by treating the latter with dilute hydrochloric acid followed by nm dissolving a precipitate in alkali, characterized in that to this precipitate add an amount of alkali solution so that the acid salt of meconic acid forms in the solution, then the solution is filtered from impurities and alkali added to it separate the middle salt of meconic acid, which is then converted into the free acid in the usual way.