SU100355A1 - Method for quantitatively determining the halogens in organic substances - Google Patents

Description

To determine the individual halogens when they are present together in organic substances, separate weights are taken, since a method allowing simultaneous and separate determination of halogens from one sample has not been found until now.

The proposed method enables the simultaneous and separate determination of halogens from one sample. The essence of this method is that a portion of the organic matter is decomposed in a stream of oxygen at a temperature of 700-850 ° and gaseous reaction products containing free halogens and hydrohalic acids are passed through three successively connected absorbing tubes. In the first tube heated to 600 ° C and containing a weighed amount of potassium bromide, chlorine is captured, in the second, heated to 450–550 ° C and containing a weighed amount of potassium iodide, the bromine is captured, and in the third tube, not heated and containing a small amount wet potassium iodide, iodine vapors are condensed, the output and ie from the iodide absorber.

The percentage of chlorine and bromine is calculated using the calculation formulas for changing the weight of the first and second absorber tubes, and the percentage of iodine is calculated by the difference between the weight of condensed iodine and the weight contained in the sample of chlorine and bromine (in terms of iodine). This method is not suitable for organic substances containing sulfur.

The analysis proceeds as follows.

Assemble the device (see drawing), consisting of a refractory glass or quartz tube a 700-800 l long and with a diameter of b-20 mm, partially filled with pieces of broken porcelain, and a system of absorption elements. The system of absorption elements contains a tube with bromide, a tube with iodide, attached to the tube with a slit tube d with a small amount of wet potassium iodide and a hook with a 10% potassium iodide solution or sodium thiosulfate titrated solution. Tube d and jib e are designed to trap insignificant amounts of iodine carried away by the gas flow.

The tube and is heated to a temperature of 700-850 °, the tube in with bromide up to 600 ° and the tube with iodide - up to 450-550 °. The tube d, attachediiiyio through a thin section, and the jib e is not heated.

Through the assembled device with heated furnaces 1, 2, 3 v (4, oxygen is passed for 10–15 minutes at a rate of 100–200 ml / min. Then the oxygen is turned off, the tubes are transferred to the weighing room, weighed 30 minutes and again attached to the instrument.

While the newly attached tubes in to c are heated, the analyte (0.1-0.05 g is weighed in a porcelain boat, covered with quartz sand from above and deposited in a tube a; the tubes should be absorbed by the absorbers above the temperature indicated. After that gas flow and decompose the analyzed fuel by gradually sliding the small furnace 1 onto the boat 1. Adjust the speed of the current of oxygen depending on the nature of the analyzed substance. Weighing substances with a high content of halogen or volatile burn more slowly and more expensive.

At the end of the decomposition of Beniec Tv, continued for 20–40 min., The tube is calcined along the entire length for 5–10 min., The complete displacement of iodine from the tube with n is increased in the case of dark spots by 5–10 min. heating of the furnace, Zsilyva with the current of oxygen up to 200-250 ml / min.

After this, decomposition and ingestion are considered complete, the tubes are removed and weighed.

The percentage of halogens is determined by the following standard formulas:

o / „C1-SilA M 79.752 A, a (Br-C1) a

where: C1-gram. equivalent chlorine

35,457,

1 is the decrease in the weight of the tube with bromide, Br-C1 is the difference between the atomic weights of bromine and chlorine, and is the weight of the analyzed substance.

„, P, Vg AZ 100 Vg. ij. 100

/ about S i -

a (J-Er) a (Br-Cl). 170.02 62-179.95 6,

where: Br-gram equivalent of bromine, b.2 - reducing the weight of the tube with iodide. m, J-Br is the difference between the atomic weights of iodine and bromine,

a is the weight of veshchestvo, / 7j is a decrease in the weight of the tube with bromide, Br - C1 is the difference between the atomic weights of the bro. “,, to -J 100”,

 - - aTTooooG 1,2692- -% C1 -% Br, and

where: / g is the number of L1l 0, n solution of NaoSjOj, J is the gram equivalent of iodine, and is the weight of the substance.

Subject invention

Claims (2)

I. A method for the quantitative separation of halogens in organic substances that do not contain sulfur, characterized in that the substance is subjected to decomposition in a stream of oxygen at a temperature of 700-850 ° and the resulting gaseous free halogens and hydrohalic acids are poured in 1 sequence: and heated absorber tubes deposited with potassium bromide and potassium iodide, and the halogen content is calculated from the change in weight of the bromide and iodide absorbers. 2. Acceptance of the method according to claim 1, characterized in that the absorption of chlorine and hydrogen chloride is carried out in an absorber filled with bromide and heated to 600 °, the absorption of bromine and hydrogen broth in an absorber filled with iodide and heated to 450-500 The iodine vapor released from the iodide scavenger is produced in an unheated tube with a small amount of moist potassium iodide in it. g ,