SU61199A1 - Method for determining the quantitative content of tannins of the pyrocatechol series, for example, willows, in tanning saps and extracts - Google Patents

Description

THE METHOD OF QUANTITATIVE DETERMINATION OF THE CONTENT OF TANVDS OF THE PYROCATEH RANGE, EG WILA, DUBILS was made on December 17, 1939 for 3042/320191 in NKLP Published in Bishletene inventions No. 4 for 1942

A known method for determining the quantitative content of tannids in duoyl juices and extras from tannid precipitation paths in the form of tannates for the subsequent transfer of sediment into solution by the action of a titrated solution of chronum with titration of the excess of the latter, and the precipitation is performed by copper ammonia.

The proposed method differs from the limestone in that the hayimdov osshaid is produced by a solution of copper hydroxide in sulfur-containing ammonium in the presence of a solution of kaline dichroxide or ammonium ammonium, and then the precipitate is washed with copper ammonia containing an excess of ammonia.

The proposed method for determining the quantitative content of tannids provides complete precipitation of the catechidic tacnides, such as willows, and reduces to the following, Usm of the willow tannins solution is placed in a test tube with a capacity of 30-35 cm. The content of tannids in the analytical solution should be g per liter. Then I is added to the taken portion of the solution in the test tube with a "IOJ & ro solution of potassium bichromic acid, and allowed to stand for 2-3 minutes. Instead of two potassium hydrochloric layers, add 1 cm of the solution of the rhodian amoni. Fresh Juice and Extraction

After the addition of dichroic acid (or rodanic acid), the solution is precipitated with a reagent, which is composed as follows: 75 grams of ammonium sulphate is added to 100 s of the 2556 th solution of sulphate of vitriol and the solution is 17 s of an ashshak solution (from an approximate calculation of 2 ammonia molecules per I copper sulfate molecule).

Separate the obtained tannate precipitate by centrifuging the solution for 5 minutes. at a centrifuge speed of 2500-3000 rpm

The separated precipitate of tannates is washed 3 times with ammonia solution of blue vitriol. The latter is obtained by diluting the corresponding more concentrated solution, which is prepared as follows: To 100 cm 25% solution of copper sulphate, add 10 cm of ammonia (based on an approximate calculation of 12 ammonia molecules per molecule of copper sulphate). For washing, a solution diluted with distilled water in a 1: 2 volume ratio is taken. Washing is performed by centrifugation, with 20 cm of solution being taken for each washing.

The washed precipitate is dissolved in a test tube with a measured volume of 0%, C% -all solution of chromic acid (25 cm). Due to the poor solubility, the precipitate is thoroughly rubbed with a glass rod before dissolution, for which purpose it is useful to add some salt to the sediment, such as zinc sulfate. A 0.6 liter solution of chromic acid in the amount of one liter is prepared by dissolving 20 g of potassium dichloride in water, followed by spontaneous addition to the solution of 500 cm of concentrated sulfuric acid (sp. C. 1.84) and bringing the cooled solution to volume with distilled water. Instead of chemically pure sulfuric acid, a B equivalent amount of technical acid can be used with a sufficient degree of frequency.

A solution of tannins in chromic acid is transferred from a tube into a flat-bottomed cone 75-100 cm®; wherein the tube is rinsed 3 times with minimal amounts (I sy) of sulfuric acid diluted in a 1: 1 volume ratio. Thereafter, the solution is heated on a closed hotplate to 130 °. Temperatures are monitored by a suspended thermometer. Immediately after heating, a quantity of cold distilled water is poured into the flask and then finally cooled under running tap water.

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After transferring it to an Erleeierk flask and diluting it, determined the amount of unreacted chroic acid in the resulting solution in order to determine the oxidizer consumption for tannids contained in a portion of the analytical solution. The unspent chromic acid is determined by adding to the solution an excess of the decinnarine salt of Uor, which is titrated back with a solution of peryaganate. It also requires titration of the direct route by the use of ilopa salt in the presence of diphenylamine.

The consumption of the oxidizing agent for I g of willow thaniids is 1850 syngeneic solution. To translate the result of the analysis into weight units, the oxidant consumption is divided by the indicated number.

Method for determining the quantitative content of tannins of the pyrocatechol series, for example, willows, in tanning sap and extracts by precipitating tannids in the form of tannates and then converting the sediment to solution by the action of a titrated solution of chromic acid with sweeping off excess of the latter, which is produced by the solution of hydroxide copper in ammonium sulphate in the presence of a solution of potassium dichloride or ammonium ammonium chloride, and then the precipitate is washed with copper ammoniatoxide containing an excess of ammonia.

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