Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA.
Published: November 2004
AI Article Synopsis
Article Abstract
The key elimination step for the formation of 3-chloro- and 3-fluorobenzyne from 2-chloro-6-fluorophenyllithium displays a pronounced solvent-dependent regioselectivity. 6Li and 13C NMR spectroscopic studies on 2-chloro-6-fluorophenyllithium reveal a single monomeric aryllithium, suggested by DFT computational studies to be a trisolvate. Rate studies indicate that the elimination of LiCl and LiF proceeds via trisolvated and disolvated monomers, respectively.
Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology Goshokaido-cho, Matsugasaki, Sakyo-ku Kyoto 606-0962 Japan
Stable planar dithienoarsinines were synthesized and structurally characterized. These compounds exhibit monomeric structures in the solution and solid states, avoiding dimerization, even in the absence of steric protection. They exhibited high global aromaticity with 14 or 22π-electron systems.
Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated naphthalenes (PCNs) are a category of highly toxic and environmentally persistent pollutants released particularly via thermal processes of chlorine-containing materials. However, the detailed reaction mechanism, especially the evolution of related radicals remains elusive for decades. Herein we have for the first time characterized the radicals and intermediates during pyrolysis of 2-chlorophenol resulting in PCDD/Fs and PCNs, using a flow tube reactor coupled with in-situ synchrotron radiation photoionization mass spectrometry (SR-PIMS).
While hypervalent halogens are versatile reagents enabling diverse reactions in organic synthesis, the utility of hypervalent chlorine compounds, particularly cyclic λ-chloranes, remains underdeveloped despite their unique electronic properties and innate enhanced reactivity. Herein, we illustrate the elusive ligand coupling reaction of cyclic λ-chloranes that suppresses the more facile competing reaction modality involving benzyne intermediates. The methodology can be performed in three-component as well as two-component fashions, offering direct access to a wide range of unsymmetrically substituted biaryl molecules in very high yields and excellent -regioselectivity.
The chemistry of -benzyne (-CH) is of fundamental importance due to its role as an essential molecular building block in molecular-weight growth reactions. Here, we report on an experimental investigation of the reaction of -CH with benzyl (CH) radicals in a well-controlled flash pyrolysis experiment using a resistively heated SiC microtubular reactor at temperatures of 800-1600 K and pressures near 30 torr. To this end, the reactants -CH and CH were pyrolytically generated from 1,2-diiodobenzene and benzyl bromide, respectively.
