Aromatic substitution in ball mills: formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
作者:Robert Schmidt、Achim Stolle、Bernd Ondruschka
DOI:10.1039/c2gc16508b
日期:——
Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed.
Inter- and Innermolecular Reactions of Chloro(phenyl)carbene
作者:Murray G. Rosenberg、Udo H. Brinker
DOI:10.1021/jo026521h
日期:2003.6.1
Supramolecular photolyses of 3-chloro-3-phenyl-3H-diazirine (8) were performed within cyclodextrin (CyD) hosts to determine whether these toroidal inclusion compounds could alter the reactivity of the ensuing carbene reaction intermediate, chloro(phenyl)carbene (9). Remarkably, no intramolecular products stemming from carbene 9 could be detected. Instead, modified CyDs were formed via so-called innermolecular
Absolute kinetics of phenylchlorocarbene CH insertion reactions
作者:Robert A. Moss、Shunqi Yan
DOI:10.1016/s0040-4039(98)02196-0
日期:1998.12
Absolute rate constants, activation parameters, a kinetic isotope effect, and hybrid density functional theory computational results are presented for various CH insertion reactions of PhCCl.
Pulverization-activation method was employed to accelerate solid-state organic reactions. Crushing and grinding of solid mixtures of hydrogen halide-treated silica gels, iodosobenzene and organic substrates in the absence of a solvent brought about smooth and rapid reactions to give halogenated and/or oxidized products in good yields. Various sulfides were smoothly converted to sulfonyl chlorides in one step in excellent yields. The surface of silica gel activated by pulverization serves as a reaction field on which reagent molecules can effectively encounter with each other. (C) 1998 Elsevier Science Ltd. All rights reserved.
Spin selectivity in the oxygenation of singlet phenylhalocarbenes with oxygen
Singlet phenylhalocarbenes are shown to react with triplet oxygen and the apparent spin-forbidden oxygenation rates are strongly dependent on substituents, i.e. in the decreasing order of Br>Clmuch greater thanF for halogen and of p-NO2>Hmuch greater thanp-MeO for p-substituents. These results suggest the oxygenation of triplet halocarbene equilibrated with ground-state singlet, resulting in the first estimation of energy difference between the singlet and triplet states. (C) 2003 Elsevier Science Ltd. All rights reserved.