The kinetics of the reaction of the chloropropanol obtained and of model alcohols with phthalic anhydride was studied at \(100^\circ\) in dry xylene, with an initial phthalic anhydride concentration of 0.0366 mol/L and an equimolar ratio of the reagents.

Freshly distilled phthalic anhydride was used. 9-(2-Hydroxy)ethylcarbazole and 9-(2-hydroxy)propylcarbazole were obtained according to [5] and [6], respectively, and had the melting points indicated by the authors.

References

1. L. A. Kazitsyna, N. B. Kupetskaya. Application of UV, IR, and NMR Spectroscopy in Organic Chemistry. Moscow, “Vysshaya Shkola,” 1971.
2. I. M. Ezrielev, N. A. Larin. Journal of General Chemistry, 26, 791 (1956).
3. A. M. Paken. Epoxy Compounds and Epoxy Resins. Moscow, Goskhimizdat, 1962.
4. A. A. Akhrem, A. I. Kuznetsova. Thin-Layer Chromatography. Moscow, “Nauka,” 1965.
5. V. P. Lopatińskii, E. E. Sirotkina, I. P. Zherebtsov. Izvestiya TPI, 112, 42 (1963).
6. E. E. Sirotkina, V. P. Lopatińskii. Author’s Certificate No. 182161; B.I. No. 11, 1966.

STUDIES IN THE CHEMISTRY OF CARBAZOLE DERIVATIVES.

REACTION OF 9-PROPENYLOXIDE CARBAZOLE WITH HYDROGEN CHLORIDE

I. P. Zherebtsov, V. P. Lopatińskii, N. M. Rovkina

In the reaction of hydrogen halides with unsymmetrical olefin oxides, halohydrins of both “normal” and “abnormal” structure may be formed, which is associated both with the structure of the reacting oxide and with the reaction conditions [1].

We carried out the reaction of 9-propenoxide carbazole with hydrogen chloride (in the form of concentrated hydrochloric acid) in acetone and attempted to determine the nature of the chlorohydrin formed in this process. In accordance with the literature data, we expected the formation of

1-chloro-3-(9-carbazolyl)propan-2-ol or 2-chloro-3-(9-carbazolyl)propan-1-ol, or mixtures thereof.

Under our reaction conditions a product was isolated that was identified as 9-chloropropanol carbazole on the basis of elemental analysis, IR-spectroscopic data, and the hydroxyl number. The presence of bands at 724 and 752 cm\(^{-1}\) indicates the presence of an unsubstituted carbazole nucleus; absorption in the region 3300–3350 cm\(^{-1}\) (in potassium bromide pellets), in the absence of a band near 3450 cm\(^{-1}\), indicates both the absence of a free amino group of carbazole and the presence of a hydroxyl group. Unambiguous identification of the alcohol formed from the IR spectra is difficult because, in the region of the characteristic absorption bands of the hydroxyl group (when recording the spectrum of a solution in carbon tetrachloride), new bands appear, apparently associated with interaction of the hydroxyl group both with the heterocyclic electron-rich carbazole ring and with the chlorine atom [2–4]. In this case the characteristic absorption bands of the hydroxyl group undergo a shift, which makes determination of the nature of the hydroxyl group still more difficult [4].

Absorption in the region 1070 cm\(^{-1}\) in the chlorohydrin we studied indicates, rather, the secondary character of the hydroxyl [2,3]. In this connection we were faced with the task of establishing more definitely whether the chlorohydrin obtained is secondary, primary, or a mixture of isomers.

It is known that primary and secondary alcohols differ sharply in reactivity, for example in esterification reactions. Thus, under certain conditions [5], in reaction with phthalic anhydride from a mixture of primary and secondary alcohols only the primary alcohol reacts, which can serve as an indication both of the nature of the alcohol being tested and of the individuality of the sample. Therefore we subjected to interaction with phthalic anhydride the product of the reaction of 9-propenoxidecarbazole that had not undergone any purification other than drying, since it could contain a mixture of isomers. Carrying out the reaction with phthalic anhydride under the recommended conditions [5] showed the absence of any appreciable interaction of the chlorohydrin under study with phthalic anhydride, which indicates both the individuality of the sample and the fact that the chlorohydrin studied is secondary.

Additional confirmation of the individuality of the hydrochloride obtained was provided by study of its chromatographic behavior by thin-layer chromatography (TLC). The TLC conditions were selected so as to ensure separation of the primary and secondary alcohols [6]; under these conditions, primary 9-(2-hydroxy)ethylcarbazole is clearly separated from secondary 9-(2-hydroxy)propylcarbazole. Attempts to separate the hydrochloride sample under study by varying the TLC conditions were unsuccessful.

Thus, it should be assumed that, under our conditions, the reaction of 9-propenoxidecarbazole with hydrogen chloride gives mainly (at least within the sensitivity limits of the methods used) secondary 1-chloro-3-(9-carbazolyl)propan-2-ol.

Experimental Section

Reagents and materials. 9-Propenoxidecarbazole. Melting point, 108–109°C. Epoxy number, 19.18. According to the literature it melts at 108–109°C [7]. Hydrochloric acid was “chemically pure”; acetone, “chemically pure”; phthalic anhydride, “pure”; xylene, “free of sulfur compounds,” “pure.”

Reaction of 9-propenoxidecarbazole with hydrogen chloride. Into a 250-ml flask were charged 10 g (0.045 mole) of 9-propenoxidecarbazole, 100 ml of acetone, and 5.4 ml of concentrated hydrochloric acid (density 1.19). The reaction mixture was kept at reflux with a condenser for one hour, after which it was poured into 500 ml of water. The precipitate was filtered off, washed with water until the filtrate was neutral, and dried. With the indicated reaction time, as TLC shows, the 9-propenoxidecarbazole reacts completely. The product yield is close to theoretical (98%). Melting point, 61–63°C. If necessary, the product may be purified by recrystallization from a mixture of benzene and heptane in a volume ratio of 1:1.2. After the first recrystallization, \(T_{\mathrm{m}}\) = 62–63°C and does not change further upon subsequent recrystallizations. The yield on recrystallization is 89% of the material taken for recrystallization. The purified product consists of white, fine needles.

Analysis: found, percent: C 69.39; H 5.34; N 5.6; Cl 13.6. For \(C_{15}H_{14}NOCl\), calculated, percent: C 69.37; H 5.43; N 5.43; Cl 13.61. Hydroxyl number (by Verley), 6.48%; calculated value of the hydroxyl number, 6.55.

Interaction of carbazole chloropropanol with phthalic anhydride.
Into a round-bottom flask equipped with a reflux condenser with a trap to prevent atmospheric moisture from entering are placed 1.75 g of carbazole chloropropanol (0.00675 mole), 1.1 g (0.00745 mole) of freshly distilled phthalic anhydride, and 50 ml of xylene dried over sodium. The reaction mixture is kept on a boiling water bath for two hours, after which it is cooled and extracted in a separatory funnel with a saturated aqueous solution of sodium carbonate. The aqueous and xylene layers are collected separately. To the aqueous solution are added 0.5 g of caustic soda, and the resulting mixture is boiled for one hour under a reflux condenser; after cooling it is extracted with benzene.

To determine the nature of the reactions that occurred, the benzene extract and the xylene solution are subjected to TLC. In this case, a sample from the xylene layer gives a spot identical to the spot of the initial 9-chloro-propanol. A sample from the benzene extract gives neither a spot fluorescing in UV light nor a spot colored in nitric-acid vapors, which indicates the absence of carbazole derivatives in the benzene extract. The alkaline aqueous solution is acidified with hydrochloric acid to Congo red; the precipitate that separates is identified as pure phthalic acid (acid number 67.6).

In the work, TLC was used in the ascending variant [6,8]. The sorbent was KSM-grade silica gel, fixed with five percent gypsum. To monitor the completion of the addition of hydrogen chloride to 9-propenoxidecarbazole by the TLC method, a mixture of normal butanol with benzene, 1:250 (by volume), was used as eluent. To determine the nature of the products formed in the reaction of carbazole 9-chloropropanol with phthalic anhydride, and in attempts to separate the chlorohydrin into isomers, various mixtures of solvents were used as eluents; the best of all tested proved to be a chloroform:acetone mixture in a ratio of 100:1 (by volume). In this system, 9-(2-hydroxy)ethylcarbazole and 9-(2-hydroxy)propylcarbazole are well separated. Attempts to use silica-gel layers modified with boric acid did not lead to improved separation of 9-(2-hydroxy)ethylcarbazole and 9-(2-hydroxy)propylcarbazole, nor to separation of the chlorohydrin studied by us.

The chromatograms were developed by viewing them in UV light (in this case the carbazole derivatives fluoresce) and by treatment with nitric-acid vapors. In the latter case, the spots of the substances

derivatives of the carbazole series are colored in various shades of yellow and green (with a limit of identification of about a microgram).

IR spectra were recorded on a UR-14 spectrophotometer in potassium bromide pellets and in solutions in carbon tetrachloride.

References

1. A. A. Petrov. Problems of Chemical Kinetics, Catalysis, and Reactivity. Collection of Articles, 778. Publishing House of the Academy of Sciences of the USSR, Moscow, 1955.
2. L. Bellamy. Infrared Spectra of Complex Molecules. Moscow, IL, 1963.
3. K. Nakanishi. Infrared Spectra and the Structure of Organic Compounds. Moscow, “Mir,” 1965.
4. L. Bellamy. New Data on the Infrared Spectra of Complex Molecules. Moscow, “Mir,” 1971.
5. Methods of Organic Chemistry. Series of monographs edited by A. Weissberger, Vol. II. Determination of the Structure of Organic Compounds by Physical and Chemical Methods, Book 2. Moscow, “Khimiya,” 1967.
6. A. Akhrem, A. I. Kuznetsova. Thin-Layer Chromatography. Moscow, “Khimiya,” 1965.
7. I. M. Ezrieleev, N. A. Larin. ZhOKh, 26, 791, 1956.
8. Chromatography in Thin Layers. Collection edited by E. Stahl. “Mir,” 1965.

STUDY IN THE CHEMISTRY OF CARBAZOLE DERIVATIVES.

98. DETERMINATION OF CARBAZOLE AND ITS DERIVATIVES BY THE METHOD OF THIN-LAYER CHROMATOGRAPHY

I. P. Zherebtsov, V. P. Lopatinskii, S. P. Yudina, N. M. Rovkina,
E. N. Grabanchuk, V. I. Semenova

(Presented by the Scientific-Methodological Seminar of the Chemical-Technological Faculty)

In studying the chemical transformations of carbazole and its derivatives, the need arises for their separate determination when they are present together. The most acceptable method for analyzing such mixtures is chromatography, which makes it possible to separate the mixture into individual components.