4-Phenyl-1,2,4-triazole-3,5-dione
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Names | |
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Preferred IUPAC name 4-Phenyl-3H-1,2,4-triazole-3,5(4H)-dione | |
Other names PTAD | |
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ECHA InfoCard | 100.021.993 ![]() |
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InChI
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Properties | |
Chemical formula | C8H5N3O2 |
Molar mass | 175.15 |
Appearance | red solid |
Melting point | 165 °C (329 °F; 438 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). ![]() ![]() ![]() Infobox references |
4-Phenyl-1,2,4-triazoline-3,5-dione (PTAD) is an azodicarbonyl compound. PTAD is one of the strongest dienophiles and reacts rapidly with dienes in Diels-Alder reactions.[1] The most prominent use of PTAD was the first synthesis of prismane in 1973.[2]
Synthesis
The compound was first synthesized in 1894 by Johannes Thiele and O. Stange. The oxidation of 4-Phenylurazol with lead tetroxide in sulfuric acid yielded small quantities of the substance.[3] It took until 1971 when a practical synthesis was published. The synthesis starts from hydrazine and diethyl carbonate. The product of this step is reacted with phenyl isocyanate and subsequently transformed to the 4-Phenylurazol. Cyclization and subsequent oxidation yields PTAD (6).[4]
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Synthesis_PTAD.svg/440px-Synthesis_PTAD.svg.png)
References
- ^ Korobitsyna, I. K.; Khalikova, A. V.; Rodina, L. L.; Shusherina, N. P. (1983). "4-Phenyl-1,2,4-triazoline-3,5-dione in organic synthesis (review)". Chemistry of Heterocyclic Compounds. 19 (2): 117–136. doi:10.1007/BF00506417. S2CID 98081187.
- ^ Katz T. J., Acton N. (1973). "Synthesis of Prismane". Journal of the American Chemical Society. 95 (8): 2738–2739. doi:10.1021/ja00789a084.
- ^ Thiele, J.; Stange, O. (1894). "Ueber Semicarbazid". Justus Liebigs Annalen der Chemie. 283 (1–2): 1–43. doi:10.1002/jlac.18942830102.
- ^ Cookson, R. C. (1971). "4-Phenyl-1,2,4-triazole-3,5-dione" (PDF). Organic Syntheses: 121. doi:10.1002/0471264180.os051.30. ISBN 0471264229. Also Organic Syntheses, Coll. Vol. 6, p.936 (1988)