SU1399670A1 - Method of analysis of salts of organic hydroxy-acids - Google Patents

Abstract

This invention relates to analytical chemistry, in particular to the determination of salts of organic hydroxy acids. The purpose of the invention is to simplify the method and reduce the time of determination. The latter lead by potentiometric titration of the analyzed sample 0.1 n. HC1 solution in a mixture of acetone and ethyl nglycol in a volume ratio of 7: 3. Titration is carried out in an organic solvent medium containing a mixture of acetone and ethylene glycol, taken in volume ratios of 98-5: 2-95, respectively. The titration method allows one to determine the proportion of the hydroxy acid salt in the mixture. 1 tab. i (L with so

Description

It is related to anashitic chemistry, specifically to methods for the quantitative determination of hydroxy-carboxylic acid salts in the presence of alkali and soda, and 8 sulphate cellulose production of black liquor can be used.

The aim of the invention is to increase the selectivity of the determination, reduce the process and reduce the time required.

The method is carried out as follows.

An 8 titration beaker is placed on the sample to be analyzed (hydroxy acid salt: mixtures with alkali and soda), diluted with acetone to a certain volume, and ethylene glycol is added to a certain ratio. The resulting mixture is potentiometrically titrated to 0.1 n. ilTBopoM HCl, prepared in a mixture of basement and egylene glycol in a 7: 3 volume ratio, using glass and calomel electrodes. The titration is carried out to the third jump of Jia with constant stirring of the boron on a magnetic stirrer. The first jump corresponds to the neutralization of free alkali and 1/2 of potassium carbonate or sodium, the second jump to the complete neutralization of their mixture and the third jump corresponds to neutral ia (HH hydroxy acid salt. I The mass fraction of hydroxy acid salt (X f% is calculated by the formula

(V, - Vi) - N-3-100g,

Fde Vj is the volume of hydrochloric acid, followed by titration of the amount of caustic potash (or sodium), potassium carbonate (or sodium) and hydroxy acid salt (the volume of hydrochloric acid consumed to achieve the third potential jump) ml

V is the volume of hydrochloric acid, followed by titration of the amount of caustic potash (or sodium) and potassium carbonate (or sodium), ml j

N is the normality of hydrochloric acid

E is the mg equivalent of the hydroxy acid salt;

g - sample weight, g. Example 1. The initial mixture contains caustic potassium, potassium carbonate.

X

Q

5 Q 5 Q

About 5

-e

with

five

and 27.0 mg, salts of lactic acid (solution in ethylene glycol).

The test mixture is placed in a titration dish, diluted with ethylene glycol to 20 mp, 40 mp of acetone is added and titrated with hydrochloric acid to the third potential jump. To achieve the first equivalence point spent 1.9 ml 0.1 n. HC1 solution, 2.6 ml was spent on reaching the second equivalence point and 4.7 titrants were spent on reaching the third equivalence point. 4.7–2.6 2.1 ml of HC1 was spent on titration of potassium lactate.

Found potassium lactate 26.88 mg. Relative error of determination .- 0.4%. The volume percentage of acetone: ethylene glycol, taking into account the volume of the titrant 67:33.

PRI mme R 2. The initial mixture contains 54.0 mg of y-lactone D-arabonic acid, alkali and potassium carbonate.

54.0 mg of β-lactone of D-arabonic acid are placed in a titration dish, 5 ml of 0.1 N are poured. a solution of potassium hydroxide in ethylene glycol, 15 ml of ethylene glycol, is added 60 mp of acetone and allowed to saponify the lactone for 30 minutes. After the specified time, the resulting solution is titrated with 0.1 n. HC1 solution to the third potential jump. To achieve the first equivalence point spent 1.3 ml 0.1 n. HC1 solution, 2.2 ml of HC1 was spent on reaching the second equivalence point and 6.4 ml of titrant was spent on achieving the third equivalence point. The titration of lactone spent 6.4 - 2.2 4,2 mp HC1.

Found lactone 54.6 mg. The relative error of determination is + 1.1%. The volume percentage of acetone: ethylene glycol is based on the volume of the titrant 75:25.

The table shows the results of the analysis of various hydroxy acids at different volume ratios of acetone and ethylene glycol. Examples 16-17 correspond to the definition under the conditions of a known method.

Thus, on the basis of the above data, it can be seen that the proposed method is more selective than the known one.

Claims (1)

Due to the use of a mixture consisting of acetone and ethylene glycol as a solvent, the proposed method provides differentiated titration of the hydroxy acid salt mixed with alkali and soda, which allows determining the proportion of the hydroxy acid salt in the analyzed mixture in one titration. As a result, the analysis is simplified and accelerated. Invention Formula The method for determining the salts of organic hydroxy acids, by potentiometric titration of the analyzed a solution of hydrochloric acid in an organic solvent medium containing acetone or alcohol, characterized in that, in order to increase the selectivity of the determination, simplify the process and shorten the determination time, ethylene glycol is used as the alcohol and the titration is carried out in a mixture of acetone and ethylene glycol, taken in volume ratios of 98-5: 2-95, respectively, and O as a solution of hydrochloric acid are used; 1 n it is used in a mixture of acetone and ethnlenglycol in a volume ratio of 7: 3. 50:50 80:20 95: 5 1.5: 98.5 11.70 mg-lactone 10.97 -0.73 D-arabonic acid 24.53 mg salt milk - 25.2 - "0.67 acid acid 16.65 mg glyx salt 16.38 -0.27 left acid Example for 19.36 ng salt of milk — Certain acid cannot be 1.0: 99.0 95.5: 4.5 31.80 mg J Glacton Oprvde-D-aravoNovoic acid pouring fuels 14.85 mg of glyco-ooredelic acid salt cannot be -6,2 2,7 -t, 6 On the titer-and-no curve there is a jump corresponding to the neutralization of potassium carbonate at stage II of dissociation. The hydroxy acid salt is determined together with soda. Analysis is not possible Also The jump in the potential, corresponding to neutralization of potassium carbonate at stage II of the association, becomes fuzzy. 98i2 I have a way 25,70 itrj-lacto a g-ap boioscate acid Itrv elit nelz 9.04 mg of soya yoloch- 9.95 0.91 my acid 17 18.07 mg of j-lactone 21.25 g-arabonic acid which makes it impossible to set the end point of the titration. Analysis is not possible Also 0.91 10.0 3.18 17.6 To determine the mass of the hydroxy acid salt, additional operations are required associated with passing the test solution through a column of cationite and then removing carbonic acid by heating the sample. The analysis is much more complicated. Also