SU1762230A1 - Method for quantitative determination of dialkyl(aryl)-bis (p-arylaminophenoxy)-sylanes - Google Patents

Abstract

SUMMARY OF THE INVENTION: Acetic acid solution of dialkyl (aryl) bis (p-arylaminophenoxy) silanes is oxidized with a sulfate solution of potassium permanganate, followed by determination of oxidant consumption by iodometric method. 1 tab.

Description

The invention relates to analytical chemistry, in particular to methods for the quantitative determination of dialkyl (aryl) bis (p-arylaminophenoxy) silanes, which are effective antioxidants of monomeric and polymeric materials, and can be used to determine the mass fraction of the basic substance in disubstituted di (arylaminophenoxy) silanes.

A known method for determining the mass fraction of the basic substance in dimethyl bis (p-phenylaminophenoxy) silane (C-1) by acid-base titration with potentiometric indication of the equivalence point. The titrant is a 0.5N solution of perchloric acid in glacial acetic acid, and the titration medium is a mixture of chloroform and acetic acid in a ratio of 1: 4.

A disadvantage of the known method is the use of a high concentration for analysis of a titrant and a small potential jump at the equivalence point, which causes a significant variation in the results and a large total error of the analysis result (± 2%).

Closest to the claimed method is the determination of C-1 by bromination with molecular bromine in a glacial acetic acid medium, followed by the determination of the consumption of bromine by the iodometric method. For the analysis, about 0.0500-0.0600 g of the product is dissolved in 30 cm3 of glacial acetic acid, 25 cm 0.1 n is added. a solution of bromine in glacial acetic acid, 2 drops of pyridine, thoroughly mixed and kept in a dark place for 30 minutes. Then 10 cm of a solution of potassium iodide is added and the liberated iodine is titrated with 0.1 N. sodium thiosulfate solution in the presence of starch.

The disadvantage of this method is the use of highly hazardous and toxic molecular bromine and pyridine, the duration of exposure during bromination, the difficulty of accurately fixing the equivalence point due to the unclear transition of the solution color in the analysis of industrial

cl

with

VI

ON Yu ihO GJ O

dark colored samples and therefore low accuracy and convergence of the basic substance for the base material. The lack of accuracy of the known method is also due to the possibility of loss of molecular bromine during long exposure.

The aim of the invention is to improve the accuracy of determination and reduce its duration.

This goal is achieved by the proposed method of determining dialkyl (aryl) bis (p-arylaminophenoxy) -silane, which consists in the oxidation of their acetic acid solutions with a potassium permanganate sulphate solution, followed by the determination of oxidant consumption by the iodometric method.

The analyzed sample is dissolved in acetic acid and treated with an aqueous sulphate solution of potassium permanganate, kept in a dark place for 1.5-10 minutes (depending on the analyzed product) at room temperature. Then, the iodometric determination of the oxidant consumption is carried out.

The mass fraction of the main substance in dialkyl (aryl) bis (p-arylaminophenoxy) silane in percent is calculated by the formula:

Uh (vi .100

m

 E is the mass of dialkyl (aryl) -bis- (p-arylaminophenoxy) -silane, corresponding to 1 cm of exactly 0.1 N sodium thiosulfate solution, g;

Vi, 2 is the volume of exactly 0.1N sodium thiosulfate solution consumed for titration in single and working experiments, cm3;

p - dilution;

m is the mass of the sample of the analyzed product,

The discrepancy in the results of parallel determinations is 0.0-0.7%.

For example, 0.10090 g of dimethyl bis (p-naphthylaminophenoxy) silane (C-41) is dissolved in acetic acid in a 100 cm3 volumetric flask and the volume in the flask is made up to the mark with acetic acid. 10 cm of the solution obtained are transferred to a conical flask with a ground stopper with a capacity of 250 cm, 25 cm 3 of 0.1 N potassium permanganate solution in 1 N, sulfuric acid solution is added and kept in a dark place for 1.5 minutes at room temperature. . Then, 10 cm of a 20% solution of potassium iodide is poured in, the eluted sodium iodide (0.1N) is titrated for 5 minutes in the presence of a 1% starch solution. In these

same conditions, but without a product, a blank experiment is carried out.

000878g

, 90 cm3, 40 cm3

, 10090 g

0,000878 (22.90-11.40) .10-100 0.10090

 100%

Example 2. Under the conditions of example 1

determination of the mass fraction of the main substance in dimethyl-bis- (p-phenylaminophenoxy) -silane (C-1) is carried out. Exposure 10

min

, 000711 g

, 20 cm3, 15 cm3

, 10075 g

X

 0.000711 (24.20 - 10.15) .10.100 25 l0,10075

 99.15%

X

The standard deviation of the average result at, 12, the confidence interval of 99.28 ± 0.28 at, 95.

Example 3. Under the conditions of example 1, determination of the mass fraction of the main substance vdiphenyl-bis- (p-phenyl-aminophenoxy) -silane (C-3) is carried out. Exposure time 10 minutes.

, 000918 g, 30 cm3, 50cM3, 10855 g

0.000918 (23.30 - 11.50) .10.100

0.10855 99.80%

The standard deviation of the average result at, 07, the confidence interval is 99.9 ± 0.19.

EXAMPLE 4 Under the conditions of Example 1, the content of the main substance in diethyl bis (p-naphthylaminophenoxy) silane (C-127) is determined. Exposure 2 min. , 000925 g, 50 cm3, 60cM3, 10100 g

v 0.000925- (22.50 - 11.60) .1Q.10Q

l - i ----

99.8%

0,10100

Example 5. Under the conditions of Example 1, determination of the mass fraction of the main substance in diphenyl-bis- (p-naphthylaminophenoxy) -silane (C-131) is carried out. Exposure 2.5 min.

001085 g

, 45 cm3

, 70cM3

, 10615r

Y 0.001085. (22.45-12.70) .10.100

0.10615 99.6%

The table shows the comparative metrological characteristics of the proposed and known methods by the example of the analysis of the industrial sample C-1 and the laboratory sample C-3.

As can be seen from the table, the standard deviation of the average result of the proposed method is 3.4-5.3 times less than the known. The confidence interval of the analysis result according to the proposed method is within ± 0.28% (for

C-1) and ± 0.19% (for C-3), and by what is known - only within ± 2.66% (for C-1) and ± 1.03% (for C-3).

This method, in contrast to the known one, allows one to quantitatively determine the content of the mass fraction of the basic substance in all the tested products.

The method makes it possible to significantly improve the accuracy and convergence of the determinations, reduce the analysis time by 2–4.6 times (depending on the product being analyzed) and eliminate the use of highly toxic bromine and pyridine.

Claims (1)

Invention Formula Method for quantitative determination of dialkyl (aryl) bis (p-arylaminophenoxy) silanes by treating acetic acid sample solution with an oxidizing agent followed by iodometric titration, characterized in that, in order to increase the determination accuracy and shorten its duration, as the oxidizing agent is using potassium permanganate sulfate. Comparative analysis