Research in the Chemistry of Carbazole Derivatives
Abstract Generated abstract
A quantitative analytical procedure is described for determining 9-acylcarbazoles, motivated by studies of reactions involving carbazole derivatives and complex vinyl ethers. The method adapts alkaline saponification to these compounds by refluxing a sample with 0.1 N potassium hydroxide in 50% methanol, followed by back-titration with 0.1 N hydrochloric acid using phenolphthalein. Tests on several derivatives, including 9-acetylcarbazole, 3-chloro-9-acetylcarbazole, 9-caproylcarbazole, and 9-formylcarbazole, gave generally satisfactory recoveries with absolute errors rarely exceeding 2%. The procedure is also reported to be applicable to mixtures of carbazole with 9-acylcarbazoles when the carbazole content does not exceed 90%.
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RESEARCH IN THE CHEMISTRY OF CARBAZOLE DERIVATIVES
41. Quantitative Determination of 9-Acylcarbazoles
V. P. Lopatinskii, Yu. P. Shekhirev
(Recommended by the scientific-methodological seminar of the Faculty of Chemical Technology)
In studying the reaction of carbazole and its derivatives with complex vinyl ethers, the need arose to develop a method for the quantitative determination of 9-acyl derivatives of carbazole. According to the literature, for the quantitative determination of \(N\)-acyl groups, saponification with a \(0.5\,N\) alcoholic solution of alkali is usually used [1, 2]; however, it is noted that the strength of the bond of the acyl group depends on the chemical nature of the compound, and therefore the procedure in each case must be adapted to the substance being analyzed.
The results of the investigations we carried out showed that the most convenient method for the quantitative determination of 9-acyl derivatives of carbazole is their saponification with a \(0.1\,N\) solution of caustic potash in 50% methanol.
Analytical procedure
To a \(0.2\) g sample of 9-acylcarbazole, 25 ml of a \(0.1\,N\) solution of KOH in 50% methanol is added, and the mixture is boiled under a reflux condenser for 15 min. A blank experiment is carried out simultaneously. After cooling to room temperature, the contents of both flasks are titrated with \(0.1\,N\) HCl in the presence of phenolphthalein until decolorization. The content of the 9-acyl derivative of carbazole is determined by the formula:
\[ x = 0.001\,M \cdot N_{\mathrm{HCl}}(V_x - V), \]
where \(x\) is the amount of 9-acylcarbazole, g;
\(M\) is the molecular weight of 9-acylcarbazole;
\(N_{\mathrm{HCl}}\) is the normality of the HCl solution;
\(V_x\) is the volume of HCl solution used for titration of the blank experiment, ml;
\(V\) is the same for the sample, ml.
The results of analyses of some 9-acyl derivatives of carbazole by this procedure are given in the table.
The results obtained show that this method gives quite satisfactory results; the absolute error of determination rarely exceeds 2%. Using 9-acetylcarbazole as an example, we have also shown that mixtures of carbazole with 9-acylcarbazoles can be analyzed in this way; in this case the method gives reliable results if the content of carbazole in the mixture does not exceed 90%.
Table
Results of analyses of several 9-acylcarbazoles
| Substance | Sample weight, g | Found 9-acylcarbazole, g | Found 9-acylcarbazole, % |
|---|---|---|---|
| 9-Acetylcarbazole | 0,1808 | 0,1799 | 99,5 |
| 9-Acetylcarbazole | 0,2016 | 0,2008 | 99,6 |
| 9-Acetylcarbazole | 0,1027 | 0,1025 | 99,8 |
| 9-Acetylcarbazole | 0,2114 | 0,2092 | 99,0 |
| 3-Chloro-9-acetylcarbazole | 0,2240 | 0,2217 | 99,8 |
| 3-Chloro-9-acetylcarbazole | 0,1493 | 0,1486 | 99,4 |
| 3-Chloro-9-acetylcarbazole | 0,1896 | 0,1877 | 98,7 |
| 9-Caproylcarbazole | 0,0538 | 0,0530 | 99,5 |
| 9-Caproylcarbazole | 0,0558 | 0,0557 | 99,9 |
| 9-Formylcarbazole | 0,0998 | 0,0976 | 97,8 |
| 9-Formylcarbazole | 0,1097 | 0,1083 | 98,1 |
Conclusions
A method has been developed for the quantitative determination of 9-acylcarbazoles and their mixtures with carbazole, which gives satisfactory results.
LITERATURE
- B. Borbanskii. Quantitative Analysis of Organic Compounds. GKhI, Moscow, 1961.
- K. Bauer. Analysis of Organic Compounds. IL, Moscow, 1953.