- Radical condensation between benzylic alcohols and acetamides to form 3-arylpropanamides
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A new radical condensation reaction is developed where benzylic alcohols and acetamides are coupled to generate 3-arylpropanamides with water as the only byproduct. The transformation is performed with potassium tert-butoxide as the only additive and gives rise to a variety of 3-arylpropanamides in good yields. The mechanism has been investigated experimentally with labelled substrates, trapping experiments and spectroscopic measurements. The findings indicate a radical pathway where potassium tert-butoxide is believed to serve a dual role as both base and radical initiator. The radical anion of the benzylic alcohol is proposed as the key intermediate, which undergoes coupling with the enolate of the amide to form the new C-C bond. Subsequent elimination to the corresponding cinnamamide and olefin reduction then affords the 3-arylpropanamides.
- Azizi, Kobra,Madsen, Robert
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p. 7800 - 7806
(2020/08/14)
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- Side-chain alkylation of toluene with propene on caesium/nanoporous carbon catalysts
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Caesium/nanoporous carbon materials are powerful solid-base catalysts, promoting the side-chain alkylation toluene with propene in a continuous flow reactor conditions as mild as 150°C and 50 psig.
- Stevens, Mark G.,Anderson, Melony R.,Foley, Henry C.
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p. 413 - 414
(2007/10/03)
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- DETERMINATION OF COMPOSITION OF REACTION MIXTURES FROM ALKYLATION OF TOLUENE ON PHOSPHORUS-MODIFIED H-ZSM-5 ZEOLITE
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Determination of analytical composition of reaction mixtures formed by alkylation of toluene with ethylene on a phosphorus-modified H-ZSM-5 zeolite was made by capillary high resolution gas chromatography.Identification of individual components on these reaction mixtures was performed by GC-MS method, using the samples obtained at 320 and 400 deg C on H-ZSM-5 catalyst (modul 43.6) modified with 3.4 wt.percent phosphorus at toluene to ethylene molar ratio 4.5:1 and the catalyst loading expressed as weight hour space velocity WHSV (for toluene) = 6.9 h-1.The reaction mixtures contained a total 86 hydrocarbons.It was confirmed that in addition to the main alkylation reaction, there proceeds also ethylene oligomerization with subsequent cyclization and aromatization, disproportionation, alkylation and cyclization reactions of alkylaromatic hydrocarbons to give alkylnaphthalines and alkylindanes.
- Mravec, Dusan,Herain, Jiri,Holotik, Stefan
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p. 1832 - 1839
(2007/10/02)
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- Potassium hydroxide as a promoter for the potassium-metal catalyzed side-chain alkylation of toluene
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Potassium hydroxide acts synergistically with catalyst supports such as alumina, diatomaceous earth, or potassium carbonate to promote the potassium-metal catalyzed side-chain alkylation of toluene with propene.Carrying out the reaction with wet toluene to generate KOH in situ is a particularly effective method for promoting the reaction.The catalyst supports are not inert in the absence of the promoter, because they alter alkylation regiochemistry and increase the formation of methylindan by-products.As a mechanistic probe, the amounts of benzylpotassium that formare compared with propylation reaction rates.This is the first report concerning the amount of benzylpotassium that forms under side-chain alkylation conditions.From this and other data, a previously unrecognized mechanism for the promotion of side-chain alkylation is identified.
- Smith, R. Scott,Ihrman, Kryn G.,LeBlanc, Monica B.
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p. 333 - 343
(2007/10/02)
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- Radical Pathways of Coal Dissolution in Hydrogen Donor Media. 2. β Scission and 1,2 Aryl Migration Reactions of Radicals Derived from Methylindans and Tetralin at 327-627 deg C
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The 1,2-aryl migration and fragmentation reactions of 1-indanylmethyl (1), 2-tetralyl (2), 2-indanylmethyl (3), 1-tetralyl (4), 2-methyl-1-indanyl (5), and 1-methyl-2-indanyl (6) radicals were studied by flash vacuum pyrolysis of the tert-butyl perester precursors at 327-627 deg C and 10-2 torr.Radicals 1 and 2 are interconverted via 1,2 aryl migration which is readily reversible at all temperatures.This equilibrium is depleted by β scission of 1 and recyclization to 4 and by β scission of 2 followed by recyclization to 2 or 3 in modest yields.The reverse neophyle-like rearrangement of 2 to 1 occurs with a lower activation barrier than β-scission of 1 to form a 2-(o-vinylphenyl)ethyl radical.Enthalpies, entropies, and free energies of reactions were calculated for the above reactions from group additivity parameters, and activation energies were estimated from values reported for simple alkyl radicals.It is shown that the β scission of 4 and recyclization to 1 is important only at very high temperatures (>500 deg C) as a mechanism for the isomerization of tetralin and related hydroaromatic structures to alkylindans and that the reverse neophyl-like rearrangement of 2 to 1 is the favored pathway for isomerizations observed during dissolution of coal in hydroaromatic media at elevated temperatures.
- Franz, James A.,Camaioni, Donald M.
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p. 5247 - 5255
(2007/10/02)
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