694-87-1Relevant articles and documents
Fabricating nickel phyllosilicate-like nanosheets to prepare a defect-rich catalyst for the one-pot conversion of lignin into hydrocarbons under mild conditions
Cao, Meifang,Chen, Bo,He, Chengzhi,Ouyang, Xinping,Qian, Yong,Qiu, Xueqing
supporting information, p. 846 - 857 (2022/02/09)
The one-pot conversion of lignin biomass into high-grade hydrocarbon biofuels via catalytic hydrodeoxygenation (HDO) holds significant promise for renewable energy. A great challenge for this route involves developing efficient non-noble metal catalysts to obtain a high yield of hydrocarbons under relatively mild conditions. Herein, a high-performance catalyst has been prepared via the in situ reduction of Ni phyllosilicate-like nanosheets (Ni-PS) synthesized by a reduction-oxidation strategy at room temperature. The Ni-PS precursors are partly converted into Ni0 nanoparticles by in situ reduction and the rest remain as supports. The Si-containing supports are found to have strong interactions with the nickel species, hindering the aggregation of Ni0 particles and minimizing the Ni0 particle size. The catalyst contains abundant surface defects, weak Lewis acid sites and highly dispersed Ni0 particles. The catalyst exhibits excellent catalytic activity towards the depolymerization and HDO of the lignin model compound, 2-phenylethyl phenyl ether (PPE), and the enzymatic hydrolysis of lignin under mild conditions, with 98.3% cycloalkane yield for the HDO of PPE under 3 MPa H2 pressure at 160 °C and 40.4% hydrocarbon yield for that of lignin under 3 MPa H2 pressure at 240 °C, and its catalytic activity can compete with reported noble metal catalysts.
Rodlike Tetracene Derivatives
Roth, Michael,Ahles, Marcus,Gawrisch, Christian,Schwalm, Thorsten,Schmechel, Roland,Melzer, Christian,von Seggern, Heinz,Rehahn, Matthias
, p. 13445 - 1345 (2017/09/14)
Efficient and versatile synthetic access to rodlike tetracene derivatives was developed by means of Diels–Alder cycloaddition, halogenation, halogen–metal exchange, and transition metal mediated coupling reactions. Herein, the synthesis and structural, electrical, and charge-transport properties of three of the resulting materials, namely, 2-(tetracen-2-yl)tetracene, 1,4-bis(2-tetracenyl)benzene, and 2,5-bis(2-tetracenyl)thiophene, are presented. Good crystallization behavior on SiO2 substrates, narrowing of the bandgap by 0.2 eV, and a decrease of the ionization potential of more than 0.5 eV compared to tetracene were observed. Charge-carrier field-effect mobilities on the order of 10?1 cm2 V?1 s?1, on/off ratios of 105, and threshold voltages Vth15 V were found in thin-film organic field-effect transistors prepared by standard high-vacuum deposition techniques.
Thermochemistry and photochemistry of spiroketals derived from indan-2-one: Stepwise processes versus coarctate fragmentations
Bucher, Goetz,Heitmann, Gernot,Herges, Rainer
, p. 1668 - 1676 (2013/10/22)
Coarctate reactions are defined as reactions that include atoms at which two bonds are made and two bonds are broken simultaneously. In the pursuit of the discovery of new coarctate reactions we investigate the fragmentation reactions of cyclic ketals. Three ketals with different ring sizes derived from indan-2-one were decomposed by photolysis and pyrolysis. Particularly clean is the photolysis of the indan-2-one ketal 1, which gives o-quinodimethane, carbon dioxide and ethylene. The mechanism formally corresponds to a photochemically allowed coarctate fragmentation. Pyrolysis of the five-ring ketal yields a number of products. This is in agreement with the fact that coarctate fragmentation observed upon irradiation would be thermochemically forbidden, although this exclusion principle does not hold for chelotropic reactions. In contrast, fragmentation of the seven-ring ketal 3 is thermochemically allowed and photochemically forbidden. Upon pyrolysis of 3 several products were isolated that could be explained by a coarctate fragmentation. However, the reaction is less clean and stepwise mechanisms may compete.
Oligo-Tetracenes, Production and Use Thereof
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Page/Page column 2-3, (2008/12/08)
Described are oligotetracenes of formula I which may either be unsubstituted or carry one or more substituents R and R′ which are selected from the group comprising halogen,CN,alkyl or alkoxy radicals containing 1 to 18 carbon atoms,aryl radicals containing up to 10 carbon atoms which may also contain one or moreheteroatoms, and/orfluorinated or perfluorinated alkyl or alkoxy radicals containing 1 to 18 carbon atoms, where n is an integer from 1 to 20, preferably 1 to 6, very particularly preferably 1 or 2, and X stands for a single bond, an alklyene group containing 1 to 6 carbon atoms, a hydrocarbon chain having one or more conjugated double bonds, an aryl group, or a system composed of one or more condensed aromatic rings. In the oligotetracenes according to the invention, one or more of the condensed aromatic six-atom rings may be substituted by a five-atom ring which may also contain a heteroatom. Also described is a method for preparing the referenced oligotetracenes, and use thereof as semiconductors in organic field-effect transistors (OFET's), organic light-emitting diodes (OLED's), sensors, and organic solar cells.
Synthesis of optically active benzocyclobutene and biphenylene based unusual α-amino acid derivatives
Kotha, Sambasivarao,Halder, Somnath
, p. 863 - 872 (2007/10/03)
Optically active benzocyclobutene and biphenylene based unusual α-amino acid derivatives have been prepared via a six step sequence using Schoellkopf chiral auxiliary in a very high diastereoselective manner.
Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
, p. 402 - 415 (2007/10/03)
Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
Determination of the photochemical efficiency of o-quinodimethane ring closure in room-temperature solutions by using time-delayed, two-color photolysis technique
Ouchi, Akihiko,Sakuragi, Masako,Kitahara, Haruo,Zandomeneghi, Maurizio
, p. 2350 - 2357 (2007/10/03)
Photochemical efficiency of o-quinodimethane (3) ring closure at room temperature was determined by using a time-delayed, two-color photolysis technique. o-Quinodimethane (3) was generated by the photolysis of 1,2- bis[(phenylseleno)methyl]benzene (1) by a KrF (248 nm) laser pulse and thus- generated 3 was photolyzed by a subsequent XeCl (308 nm)/XeF (351 nm) laser pulse with varying delay time of 0 to 3 s. The time profile of 3 was monitored by the chemical analyses of benzocyclobutene (5) (a photochemical product of 3), which was formed by a one-photon process, and the spiro dimer of 3 (4) (a thermal product of 3) in the two-color photolysis experiments. The time profile of 3 followed a second-order decay kinetics. The photochemical efficiency was obtained by the analysis of the delay-time dependence of the product yields; those of the consumption of 3 and the conversion 3 → 5 by a single pulse of the excimer laser were 81% and 5.7% for the XeCl laser, and 73% and 2.3% for the XeF laser. This difference was attributed to the different excited states involved in the photolysis. In contrast to the photolysis of 3 in argon or rigid organic matrixes, it was revealed that photochemical conversion 3 → 5 was not the main path in the solutions, and intermolecular reactions predominated.
First synthesis of optically active benzocyclobutene and biphenylene-based unusual α-amino acid derivatives
Kotha, Sambasivarao,Sreenivasachary, Nampally,Halder, Somnath
, p. 2565 - 2568 (2007/10/03)
Various optically pure benzocyclobutene and biphenylene-based α-amino acid derivatives are prepared in a very high diastereoselective manner via a six step sequence using Schollkopf chiral auxiliary.
Cyclization of benzyne-tethered alkyllithiums: Preparation of 3-substituted benzocyclobutenes and 5-substituted tetralins
Bailey, William F.,Longstaff, Sarah C.
, p. 6899 - 6901 (2007/10/03)
A five-step, one-pot preparation of isomerically pure 3-substituted benzocyclobutenes or 5-substituted tetralins in 20-40% yield from the appropriate α-(2-fluorophenyl)-ω-iodoalkane, involving generation and subsequent 4-or 6-exo cyclization of a benzyne-tethered alkyllithium, is described.
