Triphenylmethane

Structural formula
General
Surname	Triphenylmethane
other names	Tritan Triaryl methane
Molecular formula	C 19 H 16
Brief description	crystalline, colorless to yellowish solid
External identifiers / databases
CAS number 519-73-3 EC number 208-275-0 ECHA InfoCard 100.007.524 PubChem 10614 Wikidata Q424277
properties
Molar mass	244.34 g mol −1
Physical state	firmly
density	1.01 g cm −3
Melting point	93 ° C
boiling point	359 ° C
solubility	almost insoluble in water soluble in hot ethanol , diethyl ether and chloroform
Refractive index	1.5839 (99 ° C)
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Triphenylmethane , also known as tritane (derived from the trityl group for the triphenylmethyl group ), is an organic compound in which three phenyl rings are grouped around a central carbon atom . Triphenylmethane is the parent substance of triphenylmethane dyes .

synthesis

Triphenylmethane can be synthesized by Friedel-Crafts alkylation from benzene and trichloromethane ( chloroform ) or in significantly better yield from benzene and benzal chloride . It is an electrophilic aromatic substitution . The Lewis acid aluminum trichloride (AlCl ₃ ) is required as a catalyst for both reactions . Hydrogen chloride is produced as a by-product .

properties

Triphenylmethane is colorless, but the dyes have a delocalized electron system of the corresponding cation or anion, which is stabilized by the mesomeric effect of the substituents . One then speaks of a conjugated π-electron system . The flash point is> 100 ° C.

Since the hydrogen atoms of the phenyl radicals interfere with each other spatially, a planar arrangement of the rings is not possible; they are therefore twisted to one another like a propeller.

Triphenylmethane can easily be oxidized to triphenylmethanol . In addition, triphenylmethane acts as a very weak acid , e.g. B. it can react with strong bases (or with alkali metals with elimination of hydrogen ) to the triphenyl methanide anion , which is also mesomeric stabilized.

use

Triphenylmethane forms the base for the group of triphenylmethane dyes (e.g. indicators, textile and food dyes). These include a. Fuchsine , crystal violet , phenolphthalein , fluorescein , eosin , bromophenol blue , etc.

See also

• Triphenylmethyl group

Individual evidence

1. ↑ ^{a b c} Entry on triphenylmethane. In: Römpp Online . Georg Thieme Verlag, accessed on May 28, 2014.
2. ↑ ^{a b c d e f} Entry on triphenylmethane in the GESTIS substance database of the IFA , accessed on December 20, 2019(JavaScript required) .
3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-512.