On March 15, 2021, Pinilla Pena, Diana C.; Ruiz Pereyra, Elba N.; Firpo, Guadalupe; Ceballos, Noelia M.; Fueloep, Ferenc; Szakonyi, Zsolt; Iriarte, Ana G.; Pelaez, Walter J. published an article.Electric Literature of 102-07-8 The title of the article was Flash Vacuum Pyrolysis (FVP) of cis-N-phenyl-hexahydro-2H-benzo[d][1,3]oxazin-2-imine and Thiazin-2-imine Derivatives. And the article contained the following:
Cis-N-phenyl-hexahydro-2H-benzo[d][1,3]oxazin-2-imines and cis-N-phenyl-hexahydro-2H-benzo[d][1,3]thiazin-2-imines I (R = H, Me, PhC2; X = O, S) were prepared and subjected to flash vacuum pyrolysis (FVP). N-H- and N-Me tetrahydrobenzoxazines reacted at lower temperatures than N-H and N-Me tetrahydrobenzothiazines, showing lower thermal stabilities, while the N-benzyl tetrahydrobenzothiazine was less stable than the N-benzyl tetrahydrobenzoxazine. Oxazines and thiazines yielded different products through homolytic fragmentations of the heterocycle moiety, the stability of which increased with the N- substitution. Based on the anal. of the reaction temperatures and the unraveling of the obtained products, it is proposed that any heterocyclic ring-opening reactions (initiated by X3-C4, C8a-N1, or C2-X3 bond rupture) require less energy than the retro-Diels-Alder process (RDA) that yields butadiene. This concerted reaction path is only achieved at temperatures higher than 470°C. Kinetic measurements reveal neg. entropies of activation, which suggest a partially concerted way of reaction or slightly asynchronous fragmentation processes, with higher energy of activation (Ea) values for the N-substituted derivatives compared to the unsubstituted ones. Exptl. results agree with calculations at the DFT level (B3LYP/6-311+G(d,p)) and M06-2X (6-311+G(d,p)) from Gaussian09 software. The experimental process involved the reaction of 1,3-Diphenylurea(cas: 102-07-8).Electric Literature of 102-07-8
The Article related to hydrobenzoxazinimine hydrobenzothiazinimine preparation flash vacuum photolysis fragmentation, thermal fragmentation mechanism hydrobenzoxazinimine hydrobenzothiazinimine, calculated transition state structure energy thermal fragmentation hydrobenzoxazinimine hydrobenzothiazinimine, dft method difference calculation transition state structure energy fragmentation and other aspects.Electric Literature of 102-07-8
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