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In chemistry, the haloform reaction (also referred to as the Lieben haloform reaction) is a chemical reaction in which a haloform (CHX 3, where X is a halogen) is produced by the exhaustive halogenation of an acetyl group (R−C(=O)CH 3, where R can be either a hydrogen atom, an alkyl or an aryl group), in the presence of a base.
Tetraethyllead was produced from ethyl chloride and a sodium–lead alloy: [11] [12] 4 NaPb + 4 CH 3 CH 2 Cl → Pb(CH 3 CH 2 ) 4 + 4 NaCl + 3 Pb Reductive dechlorination is rarely useful in chemical synthesis, but is a key step in the biodegradation of several organochlorine persistent pollutants .
The chloroform molecule can be viewed as a methane molecule with three hydrogen atoms replaced with three chlorine atoms, leaving a single hydrogen atom. The name "chloroform" is a portmanteau of terchloride (tertiary chloride, a trichloride) and formyle, an obsolete name for the methylylidene radical (CH) derived from formic acid. [citation ...
Chloroethane is produced by hydrochlorination of ethylene: [11]. C 2 H 4 + HCl → C 2 H 5 Cl. At various times in the past, chloroethane has also been produced from ethanol and hydrochloric acid, from ethane and chlorine, or from ethanol and phosphorus trichloride, but these routes are no longer economical.
The original reaction was a mixture of the reagents phenol, chloroform, and acetone in the presence of a sodium hydroxide solution. [2] Prior to Bargellini's research, the product attributed to this multi-component reaction (MCR) had been described as a phenol derivative in chemistry texts at the time.
Liebig treated anhydrous ethanol with dry chlorine gas. [3] Chloral is produced commercially by the chlorination of acetaldehyde in the presence of hydrochloric acid, producing chloral hydrate. Ethanol can also be used as a feedstock. This reaction is catalyzed by antimony trichloride: H 3 CCHO + 3 Cl 2 + H 2 O → Cl 3 CCH(OH) 2 + 3 HCl
In the laboratory, sodium formate can be prepared by neutralizing formic acid with sodium carbonate. It can also be obtained by reacting chloroform with an alcoholic solution of sodium hydroxide. CHCl 3 + 4 NaOH → HCOONa + 3 NaCl + 2 H 2 O. or by reacting sodium hydroxide with chloral hydrate. C 2 HCl 3 (OH) 2 + NaOH → CHCl 3 + HCOONa + H 2 O
Bromoform was discovered in 1832 by Löwig who distilled a mixture of bromal and potassium hydroxide, as analogous to preparation of chloroform from chloral. [5]Bromoform can be prepared by the haloform reaction using acetone and sodium hypobromite, by the electrolysis of potassium bromide in ethanol, or by treating chloroform with aluminium bromide.