21328-57-4Relevant articles and documents
[4 + 4]-cycloaddition of isoprene for the production of high-performance bio-based jet fuel
Rosenkoetter, Kyle E.,Kennedy, C. Rose,Chirik, Paul J.,Harvey, Benjamin G.
, p. 5616 - 5623 (2019/10/23)
Isoprene was efficiently converted to 1,6-dimethyl-1,5-cyclooctadiene (DMCOD) by selective [4 + 4]-cycloaddition with a catalyst formed by in situ reduction of [(MePI)FeCl(μ-Cl)]2 (MePI = [2-(2,6-(CH3)2-C6H3-NC(CH3))-C4H5N]). DMCOD was isolated in 92% yield, at the preparative scale, with a catalyst loading of 0.025 mol%, and a TON of 3680. Catalytic hydrogenation of DMCOD yielded 1,4-dimethylcyclooctane (DMCO). The cyclic structure and ring strain of DMCO afforded gravimetric and volumetric net heats of combustion 2.4 and 9.2% higher, respectively, than conventional jet fuel. In addition, the presence of methyl branches at two sites resulted in a-20 °C kinematic viscosity of 4.17 mm2 s-1, 48% lower than the maximum allowed value for conventional jet fuel. The ability to derive isoprene and related alcohols readily from abundant biomass sources, coupled with the highly efficient [Fe]-catalyzed [4 + 4]-cycloaddition described herein, suggests that this process holds great promise for the economical production of high-performance, bio-based jet fuel blendstocks.
Air-Stable α-Diimine Nickel Precatalysts for the Hydrogenation of Hindered, Unactivated Alkenes
Léonard, Nadia G.,Chirik, Paul J.
, p. 342 - 348 (2018/01/17)
Treatment of a mixture of air-stable nickel(II) bis(octanoate), Ni(O2CC7H15)2, and α-diimine ligand, iPrDI or CyADI (iPrDI = [2,6-iPr2-C6H3N=C(CH3)]2, CyADI = [C6H11N=C(CH3)]2) with pinacolborane (HBPin) generated a highly active catalyst for the hydrogenation of hindered, essentially unfunctionalized alkenes. A range of tri- and tetrasubstituted alkenes was hydrogenated and a benchtop procedure for the hydrogenation of 1-phenyl-1-cyclohexene on a multigram scale was demonstrated and represents an advance in catalyst activity and scope for the nickel-catalyzed hydrogenation of this challenging class of alkenes. Deuteration of 1,2-dimethylindene with the in situ-generated nickel catalyst with iPrDI exclusively furnished the 1,2-syn-d2-dimethylindane. With cyclic trisubstituted alkenes, such as 1-methyl-indene and methylcyclohexene, deuteration with the in situ generated nickel catalyst under 4 atm of D2 produced multiple deuterated isotopologues of the alkanes, signaling chain running processes that are competitive with productive hydrogenation. Stoichiometric studies, titration, and deuterium labeling experiments identified that the borane reagent served the dual role of reducing nickel(II) bis(carboxylate) to the previously reported nickel hydride dimer [(iPrDI)NiH]2 and increasing the observed hydrogenation activity. Performing the catalyst activation procedure with D2 gas and HBPin generated both HD and DBPin, establishing that the borane is involved in H2 activation as judged by 1H and 11B nuclear magnetic resonance spectroscopies.
Alkynes and Cumulenes, XIV. - Thermal and Photochemical Dimerization of 1,2,4-Pentatriene (Vinylallene)
Schneider, Ralf,Siegel, Herbert,Hopf, Henning
, p. 1812 - 1825 (2007/10/02)
On heating at 170 degC in the gas phase 1,2,4-pentatriene (1) dimerizes to the six-membered hydrocarbons 2, 5, and 13, to the eight-membered ring hydrocarbons 8 and 18 as well as to the tetrahydronaphthalene 16; in a side reaction 1 cycloisomerizes to 3-methylene-1-cyclobutene (11).The C10H12-hydrocarbons are very likely produced via diradical intermediates, only 2, 5, and 13 being primary products.On the other hand, for the dimers 8, 16, and 18 reasonable electrocyclic reaction paths may be postulated.The sensitized photodimerization of 1 leads to the cyclobutane derivatives 31, 33, 35 and to 28 as a thermally produced secondary product from 33.The exclusive cyclobutane formation suggests that 1 behaves analogously to 1,3-butadiene in sensitized photodimerizations.
