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In organic chemistry, the bromine test is a qualitative test for the presence of unsaturation (carbon-to-carbon double or triple bonds), phenols and anilines. An unknown sample is treated with a small amount of elemental bromine in an organic solvent, being as dichloromethane or carbon tetrachloride. Presence of unsaturation and/or phenol or ...
For example, when heated with N-bromosuccinimide (NBS) in the presence of AIBN, toluene converts to benzyl bromide. The same conversion can be effected with elemental bromine in the presence of UV light or even sunlight. Toluene may also be brominated by treating it with HBr and H 2 O 2 in the presence of light. [31] C 6 H 5 CH 3 + Br 2 → C 6 ...
Bromotoluenes are aryl bromides based on toluene in which at least one aromatic hydrogen atom is replaced with a bromine atom. They have the general formula C 7 H 8–n Br n, where n = 1–5 is the number of bromine atoms.
Therefore, they are generated by adding iron filings to bromine or chlorine. Here is the mechanism of this reaction: The mechanism for bromination of benzene. The mechanism for iodination is slightly different: iodine (I 2) is treated with an oxidizing agent such as nitric acid to obtain the electrophilic iodine ("I +", probably IONO 2).
In chemistry, the bromine number is the amount of bromine (Br 2) in grams absorbed by 100 g of a sample.The bromine number was once used as a measure of aliphatic unsaturation in gasoline and related petroleum samples, but this assay has fallen into disuse with the introduction of spectroscopic and chromatographic analyses.
For example, consider radical bromination of toluene: [5] bromination of toluene with hydrobromic acid and hydrogen peroxide in water. This reaction takes place on water instead of an organic solvent and the bromine is obtained from oxidation of hydrobromic acid with hydrogen peroxide. An incandescent light bulb suffices to radicalize.
For example, hexanoyl chloride 1 can be brominated in the alpha-position by NBS using acid catalysis. [ 11 ] The reaction of enolates , enol ethers , or enol acetates with NBS is the preferred method of α-bromination as it is high-yielding with few side-products.
For small-scale laboratory preparations, trifluorotoluene is synthesized by coupling an aromatic halide and trifluoromethyl iodide in the presence of a copper catalyst: [2] PhX + CF 3 I → PhCF 3 (where X = I, Br) Industrial production is done by reacting benzotrichloride with hydrogen fluoride in a pressurized reactor. [3] PhCCl 3 + 3 HF → ...