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The Appel reaction is an organic reaction that converts an alcohol into an alkyl chloride using triphenylphosphine and carbon tetrachloride. [1] The use of carbon tetrabromide or bromine as a halide source will yield alkyl bromides, whereas using carbon tetraiodide , methyl iodide or iodine gives alkyl iodides .
A halogen addition reaction is a simple organic reaction where a halogen molecule is added to the carbon–carbon double bond of an alkene functional group. [1] The general chemical formula of the halogen addition reaction is: C=C + X 2 → X−C−C−X (X represents the halogens bromine or chlorine, and in this case, a solvent could be CH 2 ...
The reaction is named after Cläre Hunsdiecker and her husband Heinz Hunsdiecker, whose work in the 1930s [5] [6] developed it into a general method. [1]The reaction was first demonstrated by Alexander Borodin in 1861 in his reports of the preparation of methyl bromide (CH 3 Br) from silver acetate (CH 3 CO 2 Ag).
The relative rates at which different halogens react vary considerably: [citation needed] fluorine (108) > chlorine (1) > bromine (7 × 10 −11) > iodine (2 × 10 −22).. Radical fluorination with the pure element is difficult to control and highly exothermic; care must be taken to prevent an explosion or a runaway reaction.
This is also called the Wohl–Ziegler reaction. [7] [8] The carbon tetrachloride must be maintained anhydrous throughout the reaction, as the presence of water may likely hydrolyze the desired product. [9] Barium carbonate is often added to maintain anhydrous and acid-free conditions.
CS 2 + 3 Cl 2 → CCl 4 + S 2 Cl 2. But now it is mainly produced from methane: CH 4 + 4 Cl 2 → CCl 4 + 4 HCl. The production often utilizes by-products of other chlorination reactions, such as from the syntheses of dichloromethane and chloroform. Higher chlorocarbons are also subjected to this process named "chlorinolysis": C 2 Cl 6 + Cl 2 ...
The reaction may be carried out under either acidic or basic conditions in an aqueous medium with the corresponding elemental halogen. In this way, chloride , bromide , and iodide (but notably not fluoride ) functionality can be inserted selectively in the alpha position of a ketone .
An example of the Hell–Volhard–Zelinsky reaction can be seen in the preparation of alanine from propionic acid.In the first step, a combination of bromine and phosphorus tribromide is used in the Hell–Volhard–Zelinsky reaction to prepare 2-bromopropionic acid, [3] which in the second step is converted to a racemic mixture of the amino acid product by ammonolysis.