Synlett 2002(10): 1633-1636
DOI: 10.1055/s-2002-34213
LETTER
© Georg Thieme Verlag Stuttgart · New York

Trichloroisocyanuric Acid as a Novel Oxidizing Agent for the Oxidation of Urazoles Under Both Heterogeneous and Solvent Free Conditions

Mohammad Ali Zolfigol*a, Elaheh Madrakiana, Ezat Ghaemia, Shadpour Mallakpourb
a Chemistry Department, College of Science, Bu-Ali Sina University, Hamadan, 65174, Iran.
e-Mail: Zolfi@basu.ac.ir;
b Organic Polymer Chemistry Research Laboratory, College of Chemistry, Isfahan University of Technology, Isfahan, 84156, Iran
Further Information

Publication History

Received 1 August 2002
Publication Date:
23 September 2002 (online)

Abstract

Trichloroisocyanuric acid was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under both heterogeneous and also solvent free conditions with excellent yields at room temperature.

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Chemicals were purchased from Fluka, Merck, Riedel-deHaën AG and Aldrich chemical companies. Yields refer to isolated pure products. The oxidation products were characterized by comparison of their spectral (IR, UV, 1H NMR, and 13C NMR) and physical data with the authentic samples. All urazoles and bis-urazoles were synthesized according to our previously reported procedures. [1] [4] [5] [10] [11] [21]

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Oxidation of 4-cyclohexyl urazole(1e) to 4-cyclohexyl-1,2,4-triazoline-3,5-dione(2e) with trichloroisocyanuric acid, a typical procedure. A mixture of compound 1e
(0.366 g, 2.0 mmol) and trichloroisocyanuric acid (0.232 g, 1.0 mmol) was shaken at r.t. for 0.25 h and dichloromethane (20 mL) was added to the resulting mixture then filtered. Dichloromethane was removed by water bath (40-50 °C) [25] under simple distillation. The yield was 0.35 g (98%) of crystalline red solid (2e), mp 95-98 °C [Lit [8] mp 95-96 °C]. 1H NMR (FT-90 MHz, CDCl3/TMS): δ = 3.90 (quintet, 1 H, J = 12 Hz), 1.82-1.26 (m, 10 H). 13C NMR (FT-22.5 MHz, CDCl3/TMS): δ = 158.77, 53.93, 28.72, 24.96, 24.28.

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These compounds are sensitive to the light, heat, alcohols, ethers, transition metals and any nucleophiles. Also they are very volatile so that, if temperature rises over than 50 °C in the course of removing of CH2Cl2, some of TADs are removed with solvent simultaneously. Therefore, the temperature must be controlled and dichloromethane is the best solvent for this purpose.

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For running the oxidation reaction under heterogeneous conditions please see ref. 14.