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Triphenylmethyl Hexafluorophosphate

Names
Other names Trityl hexafluorophosphate Triphenylcarbenium hexafluorophosphate
Identifiers
CAS Number	437-17-2
ECHA InfoCard	100.006.467
CompTox Dashboard (EPA)	DTXSID40883238
Properties
Chemical formula	C19H15F6P
Molar mass	388.31 g/mol
Appearance	brown powder
Melting point	145 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Y verify (what is  ?) Infobox references

Triphenylmethyl hexafluorophosphate is an organic salt with the formula C(C₆H₅)₃PF₆. This compound is a brown powder that is air sensitive and changes colors when exposed to light. Triphenylmethyl hexafluorophosphate is used as a catalyst and reagent in organic syntheses.

Preparation

Triphenylmethyl hexafluorophosphate is generated by two ways. The first method is by combining silver hexafluorophosphate with triphenylmethyl chloride:

AgPF₆+C(C₆H₅)₃Cl→C(C₆H₅)₃PF₆+AgCl

The second method of generating triphenylmethyl hexafluorophosphate is through the reaction of triphenylmethyl chloride with an ether complex of hexafluorophosphoric acid:

Ph₃CCl+HPF₆·O(C₂H₅)₂→Ph₃CPF₆+HCl+(C₂H₅)₂O

Triphenylmethyl chloride is afforded by combining carbon tetrachloride and benzene in a Friedel-Crafts reaction.

Structure and Properties

The trityl group can exist in three oxidation states: trityl cation, trityl, and trityl anion. The trityl cation is the form present in triphenylmethyl hexafluorophosphate. The triphenylmethyl cation effectively has D3h molecular symmetry.

The hexafluorophosphate of triphenylmethyl hexafluorophosphate readily undergoes hydrolysis.

CPh₃PF₆+H₂O→HOCPh₃+HPF₆

Triphenylmethyl hexafluorophosphate combined with water in basic conditions undergo hydrolysis to form triphenylmethanol and the conjugate acid hexafluorophosphoric acid. When acidic conditions are present, the reaction will proceed in the opposite direction and triphenyl methanol will form triphenylmethyl hexafluorophosphate and water.

Main Reactions

Triphenylmethyl hexafluorophosphate is used in hydride and alkoxy abstractions. For example, it has been used for abstracting hydride from transition metal alkene and diene complexes. For example, triphenylmethyl hexafluorophosphate can also ionize an alkoxy substituted and cyclopentadienyliron dicarbonyl complexes. Some examples are:

Hydride Abstraction:

Alkoxy Abstraction:

Triphenylmethyl perchlorate is a common substitute for triphenylmethyl hexafluorophosphate. However, perchlorate is not used as widely because it is an oxidizer with Cl having and oxidation state of +7. Perchlorate readily combusts releasing Cl₂ and O₂ gas which is potentially explosive. Both triphenylmethyl hexafluorophosphate and triphenylmethyl perchlorate have shown similar results and yields in most reactions.

Footnotes

1. ^ Urch, C. (2001). "Triphenylmethyl Hexafluorophosphate". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt363f.
2. Sharp, D., Shepard, N. (1956). "Complex Fluorides. Part VIII". University Chemical Laboratory, Cambridge: 674–682.{{cite journal}}: CS1 maint: multiple names: authors list (link)
3. ^ Olah, G., Svoboda, J., Olah, J. (1972). "Preparative Carbocation Chemistry; IV. Improved Preparation of Triphenylcarbenium (Trityl) Salts". Synthesis: 544.{{cite journal}}: CS1 maint: multiple names: authors list (link)
4. Fernandez-Galan, R.; Manzano, B; Otero, A; Lanfranchi, M; Pellinghelli, M. (1994). "F and P NMR Evidence for Silver Hexafluorophosphate Hydrolysis in Solution". Inorg. Chem. 33: 2309–2312. doi:. {{cite journal}}: Check |doi= value (help); replacement character in |doi= at position 25 (help)CS1 maint: multiple names: authors list (link)

• Aromatic compounds
• Hexafluorophosphates