Naslov
New Insights Into the Solid-State Rearrangement of P-Bromobenzeneazotribenzoylmethane

Autori
Halasz, Ivan ; Cindro, Nikola ; Dinnebier, Robert ; Vančik, Hrvoj

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, pp prezentacija, znanstveni

Skup
44th Annual Midwest Regional Meeting of the Amarican Chemical Society

Mjesto i datum
Iowa City (IA), Sjedinjene Američke Države, 21.10.2009. - 24.10.2009

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
solid-state reaction ; time-resolved powder diffraction ; variable temperature

Sažetak
The thermal solid-state rearrangement of p bromobenzeneazotribenzoylmethane (1), which has been thoroughly investigated in the past [e.g. Dimroth, O. ; Hattmann, M. Ber. 1907, 40, 2404. ; Puckett, R. T. ; Pfluger, C. E. ; Curtin, D. Y. J. Am. Chem. Soc. 1966, 88, 4637–4642. ; Curtin, D. Y. ; Byrn, S. R. ; Pendergrass, Jr., D. B. J. Org. Chem. 1969, 34, 3345–3349.] yields two products. In the first product, the benzoyl group of 1 migrates to the oxygen atom of another benzoyl group forming an enol benzoate (2), whereas in the second product, the benzoyl group migrates to the azo-nitrogen atom forming a benzoylphenylhydrazone (3). The mechanism of the rearrangement reaction, however, remained unknown owing to the difficulty to characterize the intermediates and the product within the reacted solid. In this work we have applied in situ time- and temperature-resolved X-ray powder diffraction (XRPD) to structurally characterise crystalline intermediate phases as well as the crystal structure of the final rearrangement product. The studies presented herein reveal conclusively that the intermediate crystalline phase of 2 also undergoes a thermal rearrangement reaction. Therefore, in a rough description, the mechanism of this reaction includes direct rearrangements 1 → 2 and 1 → 3 and parallel to them, the rearrangement 2 → 3. XRPD techniques have proved essential to determine the crystal structure of the final product as a different polymorph is obtained by solvent crystallisation. This work underpins the utility of modern time- and temperature-resolved XRPD in the elucidation of reaction mechanisms in the solid state.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA