Benzylic Phosphates in Friedel-Crafts Reactions with Activated and Unactivated Arenes: Access to Polyarylated Alkanes
Easily reachable electron-poor/rich primary and secondary benzylic phosphates are suitably used as substrates for Friedel-Crafts benzylation reactions with only 1.2 equiv activated/deactivated arenes (no additional solvent) to access structurally and electronically diverse polyarylated alkanes with excellent yields and selectivities at room temperature. Specifically, diversely substituted di/triarylmethanes are generated within 2-30 min using this approach. A wide number of electron-poor polyarylated alkanes are easily accomplished through this route by just tuning the phosphates.
Pallikonda, Gangaram,Chakravarty, Manab
p. 2135 - 2142
(2016/03/15)
Manganese catalysts for methane transformations in the absence of oxygen. Part II. Catalysts characterization by toluene, methylcyclohexane and cyclohexane transformations
Catalytic properties of supported manganese oxide catalysts were studied using cyclohexane, methylcyclohexane and toluene test reactions. It was found that silicaalumina/MnOx systems possess both acid and redox centres of moderate strength. These sites are able to activate σ C-H bonds of cyclohexane and methylcyclohexane as well as σ CAryl-CAlk bonds in toluene and they undergo a slow deactivation. Alumina supported manganese oxide is able to activate σ C-H and σ C-C bonds, but it undergoes fast deactivation. The GC-MS analyses of minor reaction products allow to propose detailed reaction schemes and to correlate fast deactivation of alumina based catalysts with the action ofredox sites, which catalyze radical transformations of test molecules.
Marczewski,Marczewska,Mufid,Golcbiewska
p. 1562 - 1572
(2007/10/03)
PREPARATION OF SOME TRIMETHYL- AND METHYLETHYLBIPHENYLS AND REACTIVITY OF AROMATIC HYDROCARBONS IN THE GOMBERG REACTION
Trimethyl- and methylethylbiphenyls with the alkyl groups in the both phenyl rings have been prepared by the Gomberg reaction and identified by the capillary gas-liquid chromatography.Depending on choice of the aromatic hydrocarbon either individual isomers or their mixtures (three at the most) have been obtained which were contaminated with compounds of diarylmethane type in many cases.The methylethylbiphenyls have only been prepared as mixtures contaminated with diarylmethanes.These side products have been prepared by independent syntheses.A method has been developed for isolation and separation of mixtures of trimethyl- and methylethylbiphenyls from the reaction products containing tarry products.The method is suitable for preparation of small amounts of some analytical standards.The HMO method has been used for calculation of values of the radical superdelocalizabilities at individual centres in the molecules of o-, m- and p-xylene, toluene and ethylbenzene, and these values have been compared with composition of the Gomberg reaction products from these hydrocarbons.The competitive technique has been used for comparison of the reactivities of the mentioned aromatic substrates in the Gomberg reactions.
Novrocik, Jan,Novrocikova, Marta,Titz, Milos
p. 3140 - 3149
(2007/10/02)
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