17171-71-0Relevant academic research and scientific papers
Synthesis and optical reactivity of 6,13-α-diketoprecursors of 2,3,9,10-tetraalkylpentacenes in solution, films and crystals
Katsuta, Shuhei,Saeki, Hiroyuki,Tanaka, Katsuki,Murai, Yuki,Kuzuhara, Daiki,Misaki, Masahiro,Aratani, Naoki,Masuo, Sadahiro,Ueda, Yasukiyo,Yamada, Hiroko
, p. 986 - 993 (2014/02/14)
Tetraalkylpentacenes having alkyl chains at 2,3,9,10-positions (Et-PEN, Pr-PEN and Hex-PEN) were prepared from their precursors Et-PDK, Pr-PDK and Hex-PDK, respectively. Photoreactions proceeded both in solutions, thin-films, and crystals, thus the properties of Et-PDK in films can be studied despite the instability of the pentacenes in solution. Et-PEN showed significantly different aggregation-nature compared with the parent pentacene. The hole mobilities of Et-PEN and Pr-PEN in films were 3.4 × 10-6 and 8.1 × 10-7 cm2 V-1 s-1, respectively, determined by space-charge-limited current measurement, comparable with the order 10-6 cm2 V-1 s-1 of the electron mobility of Alq3.
Catalytic dehydroaromatization of n-alkanes by pincer-ligated iridium complexes
Ahuja, Ritu,Punji, Benudhar,Findlater, Michael,Supplee, Carolyn,Schinski, William,Brookhart, Maurice,Goldman, Alan S.
experimental part, p. 167 - 171 (2012/03/27)
Aromatic hydrocarbons are among the most important building blocks in the chemical industry. Benzene, toluene and xylenes are obtained from the high temperature thermolysis of alkanes. Higher alkylaromatics are generally derived from arene-olefin coupling, which gives branched products-that is, secondary alkyl arenes-with olefins higher than ethylene. The dehydrogenation of acyclic alkanes to give alkylaromatics can be achieved using heterogeneous catalysts at high temperatures, but with low yields and low selectivity. We present here the first catalytic conversion of n-alkanes to alkylaromatics using homogeneous or molecular catalysts-specifically 'pincerg'-ligated iridium complexes-and olefinic hydrogen acceptors. For example, the reaction of n-octane affords up to 86% yield of aromatic product, primarily o-xylene and secondarily ethylbenzene. In the case of n-decane and n-dodecane, the resulting alkylarenes are exclusively unbranched (that is, n-alkyl-substituted), with selectivity for the corresponding o-(n-alkyl)toluene.
BENZOTHIAZOLE DERIVATIVES HAVING BETA-2-ADRENORECEPTOR AGONIST ACTIVITY
-
Page 30, (2008/06/13)
Compounds of Formula (I) in free or salt or solvate form, wherein X has the meaning indicated in the specification, are useful for treating conditions that are prevented or alleviated by activation of the ?2-adrenoreceptor. Pharmaceutical compositions that contain the compounds and processes for preparing the compounds are also described.
Regioselective bromomethylation of 1,2-dialkylbenzenes
Garg, Nupur,Lee, T. Randall
, p. 310 - 312 (2007/10/03)
This paper describes a systematic exploration of the regioselective bromomethylation of 1,2-dialkylbenzenes as a function of the reaction temperature and the chain length of the alkyl groups. At both 80 and 110 °C, bromomethyl groups can be introduced into the 4 and 5 positions of 1,2-dialkylbenzenes with high selectivity when the alkyl chains consist of two or more carbon atoms.
Selective Mono-Alkylation and Arylation of Dichlorobenzenes by Palladium-Catalyzed Grignard Cross-Coupling
Katayama, Tatsuo,Umeno, Masayuki
, p. 2073 - 2076 (2007/10/02)
Palladium(II)-phosphine complexes, especially PdCl2(dppf) where dppf stands for 1,1'-Bis(diphenylphosphino)ferrocene, are effective catalysts for the cross-coupling of Grignard reagents with dichlorobenzenes to produce selectively mono-alkylated and arylated benzenes.The addition of ligands is also effective for the cross-coupling of Grignard reagents containing a β-hydrogen(s).
Kinetic Evidence for the Formation of Discrete 1,4-Dehydrobenzene Intermediates. Trapping by Inter- and Intramolecular Hydrogen Atom Transfer and Observation of High-Temperature CIDNP
Lockhart, Thomas P.,Comita, Paul B.,Bergman, Robert G.
, p. 4082 - 4090 (2007/10/02)
Upon being heated, alkyl-substituted cis-1,2-diethynyl olefins undergo cyclization to yield reactive 1,4-dehydrobenzenes; the products isolated may be derived from either unimolecular or bimolecular reactions of the intermediate. (Z)-4,5-Diethynyl-4-octene (4) undergoes rearrangement to yield 2,3-di-n-propyl-1,4-dehydrobenzene (17).Solution pyrolysis of 4 in inert aromatic solvent produces three unimolecular products, (Z)-dodeca-4,8-diyn-6-ene (7), benzocyclooctene (9), and o-allyl-n-propylbenzene (10), in high yield.When 1,4-cyclohexadiene is added to the pyrolysis solution as a trapping agent, high yields of the reduced product o-di-n-propylbenzene (12) are obtained.The kinetics of solution pyrolysis of 4 in the presence and absence of trapping agent establish that 2,3-di-n-propyl-1,4-dehydrobenzene is a discrete intermediate on the pathway leading to products.When the reaction was run in the heated probe of an NMR spectrometer, CIDNP was observed in 10.This observation, along with kinetic and chemical trapping evidence, indicates the presence of two additional intermediates, formed from 17 by squential intramolecular hydrogen transfer, on the pathway to products.The observation of CIDNP, coupled with the reactivity exhibited by 17 and the other two intermediates, implicates a biradical description of these molecules.Biradical 17 has been estimated to have a lifetime of about 10-9 s at 200 deg C and to lie in a well of about 5 kcal per mole with respect to the lowest energy unimolecular pathway ( hydrogen transfer).Ring opening (expected to be the lowest energy process for 1,4-dehydrobenzenes in which intramolecular hydrogen transfer is unlikely) to the isomeric diethynyl olefin 7 appears to have an activation enthalpy of about 10 kcal/mol.Upon thermal reaction in the gas phase (400 deg C) or in solution in inert solvents (Z)-2,3-diethylhexa-1,5-diyn-3-ene (5) rearranges in good yield to the isomeric diethynyl olefin (Z)-deca-3,7-diyn-5-ene (8) again presumably via 2,3-diethyl-1,4-dihydrobenzene 20 (addition of 1,4-cyclohexadiene to the reaction solution leads to a good yield of o-diethylbenzene, the expected trapping product of biradical 20).The absence of products due to intramolecular hydrogen transfer indicates that this process is at least 1 or 2 orders of magnitude slower than hydrogen transfer in 17.At 500 deg C in the gas phase products due to hydrogen transfer begin to appear.
