Trichloroacetonitrile

Tritox

Colorless to yellow, sharp- smelling liquid to corrosive

Liquid

1.44 g · cm -3 ( 25 ° C)

-42 ° C

85.7 ° C

77 hPa ( 20 ° C)

Slightly soluble in water

1.441 (20 ° C)

Risk

• 250 mg · kg -1 ( LD50, rat, oral)
• 1296 mg · kg -1 ( LD50, Rabbit, transdermal)

Template: Infobox chemical / molecular formula search available

Trichloroacetonitrile ( Tritox ) is a chemical compound selected from the group of the nitriles. Bifunctional compounds Trichloroacetonitrile can enter both the trichloromethyl and on the nitrile reactions. The electron-withdrawing effect of the trichloromethyl group activates the nitrile group for nucleophilic addition reactions. The high reactivity makes Trichloroacetonitrile a versatile reagent, caused but also its sensitivity to hydrolysis.

Representation

The representation of Trichloroacetonitrile by elimination of water from trichloroacetamide was first described in 1873 by L. Bisschopinck of the Katholieke Universiteit Leuven.

Trichloroacetonitrile can be obtained by chlorination of acetonitrile in an impregnated with Zn, Cu, and alkaline earth metal halides activated carbon catalyst at 200-400 ° C in 54 % yield.

The high temperatures needed by this process promote the formation of byproducts, such as carbon tetrachloride. However, the chlorination of saturated with hydrogen chloride results in an acetonitrile at 50-80 ° C, in good yields of pure trichloroacetonitrile.

Such as other halogenated acetonitrile trichloroacetonitrile formed from organic substances, such as algae, humic acids and proteinaceous material in the disinfecting water from the chlorination of natural sources.

Properties

Freshly distilled Trichloroacetonitrile is a colorless, fast- yellowish to light brown coloring liquid with a pungent odor, which is incompatible with water, acids and bases.

The bond lengths are 146.0 pm (C -C), 116.5 pm (C -N) and 176.3 pm (C -Cl). The bond angle is 110.0 ° ( ClCCl ).

Use

The substitution of all electronegative substituents in Trichloroacetonitrile by nucleophilic attack of alkoxide anions generated ortho carbonate esters in high yield. Due to the high reactivity of the chlorine atoms can trichloroacetonitrile - particularly in combination with triphenylphosphine - are used for the conversion of allylic alcohols to the corresponding allylic chlorides.

With carboxylic acids, acyl chlorides are obtained.

The Cl3CCN/PPh3 system is because of the mild reaction conditions for the activation of carboxylic acids and linkage with support-bound amino compounds to amides ( peptides ) in solid phase syntheses. From sulfonic the corresponding sulfonyl chlorides are formed analogously. Similarly, the activation of diphenylphosphoric with Cl3CCN/PPh3 and reaction with alcohols or amines to give the corresponding phosphoric esters or amides runs in a friendly and efficient one-pot reaction.

And phenolic hydroxyl groups in the nitrogen-containing aromatic compounds can be converted into the chlorine compounds.

In a Hoesch reaction result from the reaction of substituted phenols with trichloroacetonitrile aromatic hydroxyketones, for example, o-cresol, the o -position Trichloracylderivat in 70 % yield.

The electron-withdrawing effect of the nitrile group of the activated trichloromethyl Trichloracetonitrils to attack nucleophilic O, N and S compounds. Thus, under base catalysis with alcohols in a direct and reversible addition - O Alkyltrichloracetimidate formed, which can be isolated as stable and less susceptible to hydrolysis adducts.

With primary and secondary amines occur in a smooth reaction with good yields N-substituted Trichloracetamidine that can be purified by vacuum distillation and obtained as colorless, foul-smelling liquids. The reaction with ammonia and then with anhydrous hydrogen chloride results in the solid Trichloracetamidin hydrochloride, which is a starting compound for the fungicide etridiazole.

In the Overman rearrangement is the [3,3 ] sigmatropic rearrangement of trichloroacetimidate and diastereoselective formed from an allyl alcohol and Trichloroacetonitrile under base catalysis in an allylamine. The of benzyl alcohol and benzyl trichloroacetimidate Trichloroacetonitrile easily accessible suitable as Benzylierungsreagenz for sensitive alcohols under mild conditions and preservation of chirality.

O -glycosyl trichloroacetimidates for activation of carbohydrates

RR Schmidt and co-workers reported the selective activation of anomeric O-protected hexopyranoses (glucose, galactose, mannose, glucosamine, galactosamine ) and Hexofuranosen and pentopyranoses with Trichloroacetonitrile in the presence of a base, as well as glycosylations under acid catalysis.

β - Trichloacetimidate occur selectively with potassium carbonate as base under kinetic control, while obtained with sodium hydride, cesium carbonate or potassium hydroxide in the presence of phase transfer catalysts exclusively α - trichloroacetimidates ( thermodynamic control ).

Most at -40 ° C to room temperature with boron trifluoride etherate carried out in methylene chloride implementation of trichloroacetimidates with O- protected sugars usually provides better results than the Koenigs- Knorr method using silver salts or the Helferich method with problematic mercury salts. The inversion at the anomeric center leads in the use of α - trichloroacetimidates to β -O- glycosides. The trichloroacetimidate method produced under mild reaction conditions in very good yields often sterically uniform glycosides.

Thioacetic reacts without additional acid catalysis with acetylgeschützter α - Galactosyltrichloracetimidat for thioglycoside from which useful for the separation of racemates of amino acids 1 -thio- β -D-galactose is easily accessible by removal of the protecting groups.

In the first half of the 20th century Trichloroacetonitrile was an important fumigant, but today it is obsolete for this application.