32376-01-5Relevant academic research and scientific papers
Preparation, structure, and unique thermal [2 + 2], [4 + 2], and [3 + 2] cycloaddition reactions of 4-vinylideneoxazolidin-2-one
Horino, Yoshikazu,Kimura, Masanari,Tanaka, Shuji,Okajima, Toshiya,Tamaru, Yoshinao
, p. 2419 - 2438 (2007/10/03)
The terminal allene Cα=Cβ bonds of 4-vinylidene-2-oxazolidinone (2) readily undergo [2 + 2] cycloaddition with a wide variety of terminal alkynes, alkenes, and 1,3-dienes irrespective of their electronic nature under strictly thermal activation conditions (70-100°C) and provide 3-substituted (Z)-methylenecyclobutenes 6, 3-substituted methylenecyclobutanes 7 and 8, and 3-vinylmethylenecyclobutanes 9, respectively, in good to excellent yields. Alkenes react with 2 with complete retention of configuration. The [2 + 2] cycloaddition is concluded to proceed via a concerted [(π2s + π2s)allene + π2s] Hueckel transition state on the basis of experimental evidences and quantum mechanical methods. Some highly polarized enones and nitrile oxide, on the other hand, react with 2 selectively at the internal C4=Cα double bonds and give spiro compounds 10 and 11, respectively. The bent allene bonds (173-176°) and the unique reactivity associated with 2 are attributed to a low-lying LUMO (Cα=Cβ) that is substantiated by a through-space σ*(N-SO2)-π*(Cα= Cβ) orbital interaction.
Thermal Degradation of Polymers. I Integrity of Monomer Derived from Thermal Degradation of Poly(methyl methacrylate) and Poly(methacrylonitrile)
Hodder, Anthony N.,Holland, Kelvyn A.,Rae, Ian D.
, p. 1883 - 1887 (2007/10/02)
A random copolymer of methyl methacrylate and its (D5)analogue has been used to show that thermal degradation of the polymer regenerates the original monomer units.A similar results has been obtained for poly(methacrylonitrile).In each case, thermal degradation at 200 deg produced mainly the (D0)- and (D5)-species, while at higher temperatures some (D2)- and (D3)-ions were observed in the mass spectrum of the recovered monomer.
