635-81-4Relevant academic research and scientific papers
Unraveling the Homologation Reaction Sequence of the Zeolite-Catalyzed Ethanol-to-Hydrocarbons Process
Chowdhury, Abhishek Dutta,Lucini Paioni, Alessandra,Whiting, Gareth T.,Fu, Donglong,Baldus, Marc,Weckhuysen, Bert M.
supporting information, p. 3908 - 3912 (2019/02/20)
Although industrialized, the mechanism for catalytic upgrading of bioethanol over solid-acid catalysts (that is, the ethanol-to-hydrocarbons (ETH) reaction) has not yet been fully resolved. Moreover, mechanistic understanding of the ETH reaction relies heavily on its well-known “sister-reaction” the methanol-to-hydrocarbons (MTH) process. However, the MTH process possesses a C1-entity reactant and cannot, therefore, shed any light on the homologation reaction sequence. The reaction and deactivation mechanism of the zeolite H-ZSM-5-catalyzed ETH process was elucidated using a combination of complementary solid-state NMR and operando UV/Vis diffuse reflectance spectroscopy, coupled with on-line mass spectrometry. This approach establishes the existence of a homologation reaction sequence through analysis of the pattern of the identified reactive and deactivated species. Furthermore, and in contrast to the MTH process, the deficiency of any olefinic-hydrocarbon pool species (that is, the olefin cycle) during the ETH process is also noted.
Preparation and conformation of octaethylbiphenylene
Taha,Marks,Gottlieb,Biali
, p. 8621 - 8628 (2007/10/03)
Dimerization of tetraethylbenzyne (generated by reaction of 1,2-dibromo-3,4,5,6-tetraethylbenzene (8) with 1 equiv of BuLi) afforded in low yield octaethylbiphenylene (3), together with a major product which was characterized as 2,3,4,5,3',4',5'-heptaethyl-2'-vinylbiphenyl (9). X-ray diffraction indicates that biphenylene 3 adopts in the crystal a conformation of approximate C(2h) symmetry with the ethyl groups within each phenylene ring arranged in an alternated up-down fashion. Notably, pairs of vicinal ethyl groups located at peri positions are oriented in a syn arrangement in the crystal. Low temperature NMR spectroscopy is consistent with the presence in solution of either the crystal conformation or a fully alternated conformation lacking any syn interaction. Molecular mechanics (MM3), semiempirical (AM1, PM3), and ab initio calculations indicate that the crystal conformation is a high energy form, and that the lowest energy conformation is the fully alternated form. The topomerization barrier of the methylene protons of the ethyl groups of 3 is 9.4 ± 0.1 kcal mol-1, which is between the rotational barriers of 8 and 1,2,3,4-tetraethylbenzene 7 (9.9 ± 0.1 and 8.2 ± 0.1 kcal mol-1, respectively). The similarity in rotational barriers suggests that a given tetraethylphenylene subunit does not markedly affect the rotational barrier of the ethyl groups of the other subunit.
Effect of transition-metal complexation on the stereodynamics of persubstituted arenes. Evidence for steric complementarity between arene and metal tripod
Kilway, Kathleen V.,Siegel, Jay S.
, p. 255 - 261 (2007/10/02)
The stereodynamics in l,4-dimethoxy-2,3,5,6-tetraethylbenzene (5), 1,4-bis(metboxymethyl)-2,3,5,6-tetracthylbenzene (6), and l,4-dineohexyl-2,3,5,6-tetraethylbenzene (7) and their respective tricarbonylchromium complexes, 5(Cr), 6(Cr), and 7(Cr), have bee
