Tetraphenylphosphonium chloride
Encyclopedia
Tetraphenylphosphonium chloride is the chemical compound with the formula (C6H5)4PCl, abbreviated Ph4PCl or PPh4Cl. Tetraphenylphosphonium and especially tetraphenylarsonium salts were formerly of interest in gravimetric analysis
of perchlorate
and related oxyanions. This colourless salt
is used to generate lipophilic salts from inorganic and organometallic anions. Thus, Ph4P+ is useful as a phase-transfer catalyst, again because it allows inorganic anions to dissolve in organic solvents.
In X-ray crystallography
, PPh4+ salts are of interest as they often crystallise easily. The rigidity of the phenyl groups facilitates packing and elevates the melting point
relative to alkyl-based quaternary ammonium salts. Also, since these salts are soluble in organic media, a wide range of solvents can be employed for their crystallisation.
with triphenylphosphine
catalysed by nickel salts:
The compound was originally prepared as the corresponding bromide salt (CAS# 2751-90-8), which in turn was synthesized by passing dry oxygen through the reaction of phenylmagnesium bromide
and triphenylphosphine
The synthesis probably proceeds via the reaction of the Grignard reagent with triphenylphosphine oxide
.
Gravimetric analysis
Gravimetric analysis describes a set of methods in analytical chemistry for the quantitative determination of an analyte based on the mass of a solid...
of perchlorate
Perchlorate
Perchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a...
and related oxyanions. This colourless salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
is used to generate lipophilic salts from inorganic and organometallic anions. Thus, Ph4P+ is useful as a phase-transfer catalyst, again because it allows inorganic anions to dissolve in organic solvents.
Structure and basic properties
The cation is tetrahedral. PPh4Cl crystallises as the anhydrous salt, which is normal item of commerce, as well as a monohydrate and a dihydrate.In X-ray crystallography
X-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
, PPh4+ salts are of interest as they often crystallise easily. The rigidity of the phenyl groups facilitates packing and elevates the melting point
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
relative to alkyl-based quaternary ammonium salts. Also, since these salts are soluble in organic media, a wide range of solvents can be employed for their crystallisation.
Space-filling model In chemistry a space-filling model, also known as calotte model, is a type of three-dimensional molecular model where the atoms are represented by spheres whose radii are proportional to the radii of the atoms and whose center-to-center distances are proportional to the distances between the atomic... of part of the crystal structure Crystal structure In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry... |
Ball-and-stick model In chemistry, the ball-and-stick model is a molecular model of a chemical substance which is to display both the three-dimensional position of the atoms and the bonds between them... of part of the crystal structure |
Preparation
PPh4Cl and many analogous compounds can be prepared by thereaction of chlorobenzeneChlorobenzene
Chlorobenzene is an aromatic organic compound with the chemical formula C6H5Cl. This colorless, flammable liquid is a common solvent and a widely used intermediate in the manufacture of other chemicals.-Uses:...
with triphenylphosphine
Triphenylphosphine
Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...
catalysed by nickel salts:
- PhCl + PPh3 → Ph4PCl
The compound was originally prepared as the corresponding bromide salt (CAS# 2751-90-8), which in turn was synthesized by passing dry oxygen through the reaction of phenylmagnesium bromide
Phenylmagnesium bromide
Phenylmagnesium bromide, with the simplified formula , is a magnesium-containing organometallic compound. It is so commonly used that it is commercially available as a solution in diethyl ether or tetrahydrofuran . Phenylmagnesium bromide is a Grignard reagent...
and triphenylphosphine
Triphenylphosphine
Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...
The synthesis probably proceeds via the reaction of the Grignard reagent with triphenylphosphine oxide
Triphenylphosphine oxide
Triphenylphosphine oxide is the chemical compound with the formula OP3. Often chemists abbreviate the formula by writing Ph3PO or PPh3O . This white crystalline compound is a common side product in reactions involving triphenylphosphine...
.
- PhMgBr + Ph3PO → Ph4POMgBr
- Ph4POMgBr + HBr → Ph4PBr + “Mg(OH)Br”