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An effective protocol for the solvent-free fluorination of electron-rich aromatic compounds with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (F-TEDA-BF4) is described. The protocol allows the easy and efficient isolation of fluorinated products in high yields and purities with low E factors (kgwaste kgproduct-1) by vacuum-sublimation without the use of any solvent. The solid-state fluorination of naphthalen-2-ol was studied by differential thermal analysis, and scanning electron microscopy was used to obtain evidence for the solid-state process. The crucial influence of alkali-metal carbonates on the rate of the solvent-free fluorination of hydroxynaphthalenes and estrone was demonstrated. [ABSTRACT FROM AUTHOR]

The olefinic pi-complex of nitrosonium cation has been prepared through reaction of NO+AlCl4- with 1,2,3,3,4,5,6,6-octamethyl-1,4-cyclohexadiene in SO2/CD2CL2 or SO2/SO2ClF/CD2CL2 at -90 degrees celsius. The complex was observed to undergo a degenerate pi,pi-rearrangement, as confirmed by nuclear magnetic resonance data. Data show that diolefins can form fluxional pi-complexes with NO+.

The noncatalytic bromination of benzene is shown experimentally to require high 5-14 M concentrations of bromine to proceed at ambient temperatures to form predominantly bromobenzene, along with detectable (<2%) amounts of addition products such as tetra and hexabromocyclohexanes. The kinetic order in bromine at these high concentrations is 4.8 ± 0.06 at 298 K and 5.6 ± 0.11 at 273 K with a small measured inverse deuterium isotope effect using D6-benzene of 0.97 ± 0.03 at 298 K. These results are rationalized using computed transition states models at the B3LYP+D3/6-311++G(2d,2p) level with an essential continuum solvent field for benzene applied. The model with the lowest predicted activation free energies agrees with the high experimental kinetic order in bromine and involves formation of an ionic, concerted, and asynchronous transition state with a Br8 cluster resembling the structure of the known Br9−. This cluster plays three roles; as a Br+ donor, as a proton base, and as a stabilizing arm forming weak interactions with two adjacent benzene CH hydrogens, these aspects together combining to overcome the lack of reactivity of benzene induced by its aromaticity. The computed inverse kinetic isotope effect of 0.95 agrees with experiment, and arises because CBr bond formation is essentially complete, whereas CH cleavage has not yet commenced. The computed free energy barriers for the reaction with 4Br2 and 5Br2 for a standard state of 14.3 M in bromine are reasonable for an ambient temperature reaction, unlike previously reported theoretical models involving only one or two bromines. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

1H and 13C NMR studies and quantum chemical calculations show the interaction between 2,11-dithia-5,6,8,9-tetramethyl[32](1,4)cyclophane and nitrosonium cation to result in the formation of π- and n-complexes. According to DFT/B3LYP/6-31G(2d,p) calculations, formation of nitrosonium complexes is a strongly exothermic process both in gas phase and in SO2. Affinity of single-charged complexes to NO+ is usually larger than that of double-charged and triple-charged complexes, affinity of all the charged complexes to nitrosonium cation in SO2 being larger than that in gas phase. The π-complex with nitrosonium cation coordinated to the methylated aromatic ring is the most stable with structural characteristics being close to those obtained by X-ray diffraction for nitrosonium π-complexes of hexamethylbenzene and other arenes. The N-O bond lengths in all the complexes are quite close to each other and larger than that in NO+ cation. The S-N bond length increases upon transition from single-charged to double-charged and polycharged complexes. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]