Triphenylmethyl hexafluorophosphate
Encyclopedia
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.
with triphenylmethyl chloride
:
The second method of generating triphenylmethyl hexafluorophosphate is through the reaction of triphenylmethyl chloride
with an ether complex of hexafluorophosphoric acid
:
Triphenylmethyl chloride is afforded by combining carbon tetrachloride
and benzene
in a Friedel-Crafts reaction
.
.
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.
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.
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
in organic syntheses.
Preparation
Triphenylmethyl hexafluorophosphate is generated by two ways. The first method is by combining silver hexafluorophosphateSilver hexafluorophosphate
Silver hexafluorophosphate, sometimes referred to "silver PF-6," is an inorganic compound with the formula AgPF6.-Uses and reactions:Silver hexafluorophospate is a commonly encountered reagent in inorganic and organometallic chemistry...
with triphenylmethyl chloride
Triphenylmethyl chloride
Triphenylmethyl chloride or trityl chloride is a white solid with the chemical formula C19H15Cl. It is an alkyl halide, sometimes used to introduce the trityl protecting group.-Preparation:Triphenylmethyl chloride is commercially available...
:
- AgPF6+C(C6H5)3Cl→C(C6H5)3PF6+AgCl
The second method of generating triphenylmethyl hexafluorophosphate is through the reaction of triphenylmethyl chloride
Triphenylmethyl chloride
Triphenylmethyl chloride or trityl chloride is a white solid with the chemical formula C19H15Cl. It is an alkyl halide, sometimes used to introduce the trityl protecting group.-Preparation:Triphenylmethyl chloride is commercially available...
with an ether complex of hexafluorophosphoric acid
Hexafluorophosphoric acid
Hexafluorophosphoric acid is the chemical compound with the chemical formula HPF6. This strong Brønsted acid features a non-coordinating anion, hexafluorophosphate . It is formed from the reaction of hydrogen fluoride with phosphorus pentafluoride....
:
- Ph3CCl+HPF6·O(C2H5)2→Ph3C+PF-6+HCl+(C2H5)2O
Triphenylmethyl chloride is afforded by combining carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
and benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
in a Friedel-Crafts reaction
Friedel-Crafts reaction
The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877. There are two main types of Friedel–Crafts reactions: alkylation reactions and acylation reactions. This reaction type is a form of electrophilic aromatic substitution...
.
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 symmetryMolecular symmetry
Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can predict or explain many of a molecule's chemical properties, such as its dipole moment...
.
The hexafluorophosphate of triphenylmethyl hexafluorophosphate readily undergoes hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
.
CPh3PF6+H2O→HOCPh3+HPF6
Triphenylmethyl hexafluorophosphate combined with water in basic conditions undergo hydrolysis to form triphenylmethanol
Triphenylmethanol
Triphenylmethanol is an organic compound. It is a white crystalline solid that is insoluble in water and petroleum ether, but well soluble in ethanol, diethyl ether, and benzene...
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
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...
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.