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• 75-89-8 2,2,2-trifluoroethanol 
• 64-19-7 acetic acid 

Relevant academic research and scientific papers

Stereoselective halogenations of alkenes and alkynes in ionic liquids

(matrix presented) Room-temperature ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium chloride, are used as "green" recyclabl

Radical bromination of 1,1- and 1,2-diphenylethylenes in 1,2-dichloroethane

The radical bromination of 1,1- and 1,2-diphenylethylenes in 1,2-dichloroethane was investigated on the basis of kinetic and product distribution data. Whereas the ionic process followed a third-order rate law (second order in Br2), the radical

Preassociation, free-ion, and ion-pair pathways in the electrophilic bromination of substituted cis- and trans-stilbenes in protic solvents

Rates and products of electrophilic bromination of ring-substituted cis- and trans-stilbenes have been investigated in acetic acid, trifluoroethanol, ethanol, methanol, and water-methanol mixtures. The mY(Br) relationships (linear for nucleophilic solvent

Formation of Bromocarbenium Bromide Ion Pairs in the Electrophilic Bromination of Highly Reactive Olefins in Chlorinated Aprotic Solvents

The kinetics and the products of bromination of several substituted stilbenes with tetrabutylammonium tribromide (TBAT) have been investigated in aprotic solvents at different temperatures. Stilbenes bearing electron-withdrawing or moderately electron-donating substituents gave stereospecifically the anti addition products. The reactions followed a second-order rate law, and an inverse kinetic isotope effect (KIE), kH/kD = 0.85(0.05), was found for the bromination of cis-stilbene. The reactions of cis- and trans-4,4-dimethoxystilbenes yielded mixtures of meso and d,l dibromides both in chloroform and 1,2-dichloroethane. The rate constants (kBr3-) measured for the latter olefins deviated considerably from the Hammett correlations, and added bromide had a significant effect on the rates. The reactions of these activated stilbenes with molecular Br2, carried out at low Br2 concentration, followed a mixed second/third-order rate law. The kinetic and product distribution data for the reaction, with TBAT, of stilbenes bearing electron-withdrawing or moderately electron-donating substituents are interpreted on the basis of the known mechanism involving a product-and rate-determining nucleophilic attack by bromide on the olefin-Br2 π-complex. The data related to the bromination of the more activated methoxystilbenes are rationalized considering that, for these olefins, even in aprotic solvents, the ionization of the initially formed 1:1 π-complex to a bromocarbenium bromide ion pair can compete both with the formation of a bromonium-tribromide ion pair and with the nucleophilic attack by Br-. For this second-order process (first order in Br2), the kinetic constants and the activation parameters have been measured in chloroform and 1,2-dichloroethane and the activation parameters have been compared with those related to the third-order Br2 addition and to the reaction with TBAT.

Different Reversibility of Bromonium vs β-Bromocarbonium Ions Formed during the Electrophilic Bromination of Substituted Stilbenes. Evidence for Rate Determination during the Product-Forming Step

In order to check the relative reversibility of brominium and β-bromocarbonium ion formation, the product distributions of the reactions of Br2 with cis- and trans-stilbene (1b and 2b) and with their p-methyl (1a and 2a), p-(trifluoromethyl) (1c and 2c). and p,p′-bis(trifluoromethyl) derivatives (1d and 2d) in 1,2-dichloroethane have been determined in the 10-1-10-4 M concentration range. The rate constants (k3) for the bromination of these stilbenes at 25 °C spanned 7 orders of magnitude. The observed dibromide ratios showed that an open β-bromocarbonium ion was the intermediate of the bromination of 1a and 2a, whereas bridged or partially bridged ions were involved with all other olefins. In these cases, the extent of bridging increased, and equilibration to the more stable trans bromonium ion occurred at the lowest reagent concentrations to give the erythro (or meso) dibromide 3 as the main product. The increase in 3 was always accompanied by an increase in cis-trans olefin isomerization during the bromination of the cis olefin. This is attributed to a return of the trans bromonium ion to the corresponding olefin. This process was maximum with 1d, and minimum with 1a. It is concluded that, whereas the formation of the β-bromocarbonium ion intermediate is completely rate-determining in the case of 2a, both the formation of the trans bromonium ion and the following dibromide formation are partially rate-determining in the case of 2d.