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Triphenylmethane



Triphenylmethane
Chemical name Triphenylmethane
Chemical formula C19H16
Molecular mass 244.33 g/mol
CAS number [519-73-3]
Density 1.014 g/cm3
Melting point 92-94 °C
Boiling point 359 °C
SMILES c1ccccc1C(c2ccccc2)c3ccccc3
Disclaimer and references

Triphenylmethane, or triphenyl methane, is a hydrocarbon. It is a colorless to light brown powder. It is the basic skeleton of many synthetic dyes called triarylmethane dyes, many of them are pH indicators, and some display fluorescence. It is insoluble in water and soluble in chloroform.

Additional recommended knowledge

The pKa of the hydrogen on the central carbon is around 31. Triphenylmethane is significantly more acidic than most other hydrocarbons because the planar trityl anion is stabilized by extensive delocalization over three phenyl rings. The trityl anion absorbs strongly in the visible region, making it red. This colour can be used as an indicator when maintaining anhydrous conditions with calcium hydride; the hydride reagent reacts with water to form solid calcium hydroxide, while it is also a strong enough base to generate the trityl anion. If the hydride is used up then the solution will turn colourless.

Triphenylmethane can be synthesized by Friedel-Crafts reaction from benzene and chloroform with aluminium chloride catalyst. Synthesis from benzylidene chloride, prepared from benzaldehyde and phosphorus pentachloride, is used as well.

Triarylmethane dyes

Examples of triarylmethane dyes are bromocresol green:

or malachite green:

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Triphenylmethane". A list of authors is available in Wikipedia.
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