SU859886A1 - Method of aliphatic alcohol quantitative determination - Google Patents

Description

one

The invention relates to analytical chemistry, in particular to methods for the quantitative determination of alcohols.

A known method for the quantitative determination of alcohols involves treating an analyzed sample in pyridine with a solution of 3,5-dinitrobenzoyl chloride in pyridine, hydrochloric acid and hexane, followed by separating and treating the hexane layer with sodium carbonate, adding dimethylformamide and propylene aamine to it and photometricising the resulting solution i.

The disadvantage of the method is the use of hard-to-reach reagents and the difficulty of determination.

The closest to the proposed technical essence and the achieved result is the method of quantitative determination of aliphatic alcohols, which consists in the sequential processing of the analyzed sample with hydrochloric acid, sodium nitrite, sodium carbonate and benzene, separation of the benzene layer and processing it with an analyte in the presence of hydrogen chloride. aniline salts at 20821 ° C, followed by treatment with an aqueous solution of acetone and the color of the resulting dyed bianodia-colored solution 2.

The disadvantage of this method is the low sensitivity of O, O4-O, 08%; the detection time is 3 hours. 4O minutes.

The purpose of the invention is to increase the sensitivity and reduce the duration of the determination;

This goal is achieved by a method for the quantitative determination of aliphatic alcohols, which consists in the sequential processing of an analogous sample of ammonium ammonium sulfate by chloridated calcium, benzene or chlorobewzole, hydrochloric acid, sodium nitrite,. separating the organic complex and treating it with an ethanolic solution of hydrofluoric acid and acetic acid, followed by PM1 by copying the solution thus obtained. 38 On an ego basis, it is highly sensitive to determine in aqueous solutions of a number of alcohols — i-propyl n-amyl, butyl, benaic, with a small amount of analysis. Ethyl alcohol, methyl alcohol, and ethylene glycol are somewhat less sensitive. In the method, other techniques are introduced to increase the stability of alkyl nitrates in the stages of their formation and processing, namely, the use of ammonium sulfate or calcium chloride in a high concentration of solutions, which prevents the hydrolysis of alkyl nitrite V / in an aqueous medium, as an organic solvent in the esterification stage, chlorobenzene is used, along with benzene. These techniques increase the sensitivity of the determinations to 0.003% and reduce the detection time to 2 hours and 20 minutes. PRI me R. In a beaker with 5 g of crystalline ammonium sulphate or calcium chloride, 10 ml of benzene or chlorobenzene, 5 ml of the alcohol solution to be analyzed, cool the contents of the glass until 2 ml of cooled concentrated hydrochloric acid are added and 2 ml of cooled 30% concentrated solution of sodium nitrite. The mass is maintained with cooling and stirring on a magnetic stirrer for 30 min at 5-bS. The contents of the glass are then transferred to a cooled separating funnel, the glass is rinsed with 10 ml of chilled 40% ammonium sulphate or calcium chloride solution, and this solution is added to the bulk in the separating funnel. After separating the layers for 5-10 minutes, the aqueous solution is drained, and the benzene layer in a separating funnel is washed with 20 ml of a cooled solution of ammonium sulphate or calcium chloride for 5 minutes and exfoliated while cooling for 5-1O minutes (after the formation of alkyl nitrite in an amount proportional to the analyzed alcohol, and then the conversion of alkyl nitrite to nitrosodiphenylamine in further operations, the analyzed alcohol is not involved, the active principle is the nitrosogroup). In a 25 ml volumetric flask, add 1 ml of an ethanolic solution of diphenyl.amine 20 mg / ml, 5 ml of glacial acetic acid, and 0.5 ml of benzene solution of alkyl imhydrate. The resulting solution with periodic stirring, incubated at room temperature for 30 minutes After this, the volume in the volumetric flask is made up to the mark with ethanol. 8 ml of a buffer solution with a pH of 1–3 drops of 0.5% gelatin solution in 0.5 and. a solution of hydrochloric acid and 1 ml of a solution of diphenylnitrosamine from a volumetric flask. Carbon dioxide is passed through the solution into the polarographic cell for 10 min and the polarogram is removed in the range of 0.35–0.9 V on a polarograph with a mercury-droplet electrode. The height of the polarographic wave is measured and the alcohol content of the solution to be analyzed is determined from a calibration chart. The programs for building a calibration graph — the dependence of the wave height on the alcohol content in the solution — are removed under the same conditions as for the analyzed solutions. Take the average of 3-4 parallel definitions. The potential of the half-wave in the accepted conditions is equal to -0.62 V. Calibration graphs are plotted separately for the concentration range, mg / ml: 15-5; 5-1; . 1-O, 1; 0.1-0.01; For each graph, the translation is a higher sensitivity. In those cases when the analyzed alcohol solution contains more than 15 mg / ml, the initial alcohol solution is diluted with distilled water, which is taken into account in the analysis results. If the concentration is less than 1 mg / ml, increase the sensitivity of the instrument and determine the approximate alcohol content. Further, if a preliminary determination is obtained in the range of 10, 1 mg / ml, 2O ml of the test solution and 14 g of ammonium sulfate, and 30 ml of the solution and 2 O G ammonium sulfate are taken for esterification if the concentration is less than 0.1 mg / m. In this case, 7 ml of the buffer pacTBofta and 2 ml of the solution from the volumetric flask {half-wave potential –0.67 V) are taken into the polarographic cell. The minimum detectable concentrations are O, 0250, 2 mg / ml for different alcohols, O, 003-O, O2%, and 1-2 mg / ml for ethylene glycol, 0.1-0.2%. The relative error of determination is 14%, for alcohols that are highly soluble in water (miscible with water) are 2-12%. In tab. 1 and 2 are shown for illustration some analytical data on the analysis of aqueous solutions of alcohols in low concentrations according to the proposed method.

5 65SfiSe 6

The proposed method makes it possible to dissolve, as well as in a number of other pactaopB, prohibit different alcohols in small cells, which are indifferent under the conditions of the formation and, in many cases, in the very situation of alkyl nitrites, in the presence of low concentrations with the necessary fine impurities. The method is described for

using a common analysis of many waste and industrial wastes, and

laboratory equipment (polografy) without. also for the determination of alcohols in some of the special complex set of solid substrates, if they are solvents. The definition is possible as in the watermaster c. Wede, benzene or chlorobenzene.

Analysis of isopropyl alcohol solutions. Solution analysis 10.06 1.01 9.77 3.77 0.38 3.68 1, O1 ODO. O, 98 O, O5O O, OO5 O, 048 0, O290 0.0029 0, O285. Analysis of Solutions 2.71 0.271 2.67 0.440 0.0440 0.475 0.311 O, 0311 0.323

Table 1 amyl alcohol 0.98-0.29-2.88 0.37-O, O9-2.39 O, 10.-O, OZ-2.97 0, OO5-O, O02O-4, OC 0 , OO29-0,0005-1,72 ethylene glycol 0,267-O, 04-1,48 0.0475 + 0, O35 + 7.95 0.0323 + 0.012 + 3.86

Claims (1)

Claim A method for the quantitative determination of aliphatic alcohols, including treatment with hydrochloric acid, sodium nitrite, an aromatic hydrocarbon, separation of the organic layer and processing with an aromatic amine, is characterized in that, in order to increase sensitivity and reduce the rate of determination, the analyzed sample is sequentially treated with ammonium sulfate or chloride calcium, benzene or chlorobenzene, hydrochloric acid, sodium nitrite, the organic layer is separated and treated with an ethanol solution of diphenyl ming, acetic acid, followed by polarography the thus obtained solution.