Triphenylphosphine dichloride
Encyclopedia
Triphenylphosphine dichloride, Ph3PCl2, is a chlorinating agent
widely used in organic chemistry. Applications include the conversion of alcohol
s and ether
s to alkyl chlorides, the cleavage of epoxide
s to vicinal dichlorides and the chlorination of carboxylic acid
s to acyl chloride
s.
solvents such as acetonitrile
or dichloromethane
solutions, Ph3PCl2 adopts an ionic phosphonium salt
structure, [Ph3PCl+]Cl−, whereas in non-polar solvents like diethyl ether
it exists as a non-solvated trigonal bipyramidal molecule. Two [Ph3PCl+] species can also adopt an unusual dinuclear ionic structure—both interacting with a Cl− via long Cl–Cl contacts.
.
Both reagents are typically used in solution to ensure the correct stoichiometry
.
Alternatively, Ph3PCl2 can be obtained by chlorination of triphenylphosphine oxide
with, for example, phosphorus trichloride
, as in Grignard's original 1931 synthesis.
Halogenation
Halogenation is a chemical reaction that incorporates a halogen atom into a molecule in substitution of hydrogen atom. Halogenation takes place in the gas phase. There are four types of halogenation: fluorination, chlorination, bromination, and iodination...
widely used in organic chemistry. Applications include the conversion of alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s and ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
s to alkyl chlorides, the cleavage of epoxide
Epoxide
An epoxide is a cyclic ether with three ring atoms. This ring approximately defines an equilateral triangle, which makes it highly strained. The strained ring makes epoxides more reactive than other ethers. Simple epoxides are named from the parent compound ethylene oxide or oxirane, such as in...
s to vicinal dichlorides and the chlorination of carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
s to acyl chloride
Acyl chloride
In organic chemistry, an acyl chloride is an organic compound with the functional group -CO-Cl. Their formula is usually written RCOCl, where R is a side chain. They are usually considered to be reactive derivatives of carboxylic acids. A specific example of an acyl chloride is acetyl chloride,...
s.
Structure
In polarChemical polarity
In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...
solvents such as acetonitrile
Acetonitrile
Acetonitrile is the chemical compound with formula . This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture...
or dichloromethane
Dichloromethane
Dichloromethane is an organic compound with the formula CH2Cl2. This colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. Although it is not miscible with water, it is miscible with many organic solvents...
solutions, Ph3PCl2 adopts an ionic phosphonium salt
Phosphonium salt
A phosphonium salt is a salt containing the phosphonium ion such as phosphonium iodide . More commonly, phosphonium refers to a quaternary organic derivative such as tetraphenylphosphonium chloride, 4P+ Cl- and tetramethylphosphonium iodide, [P4]+I−.Alkyltriphenylphosphonium salts are widely...
structure, [Ph3PCl+]Cl−, whereas in non-polar solvents like diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
it exists as a non-solvated trigonal bipyramidal molecule. Two [Ph3PCl+] species can also adopt an unusual dinuclear ionic structure—both interacting with a Cl− via long Cl–Cl contacts.
Synthesis
Triphenylphosphine dichloride is usually prepared fresh by the addition of chlorine to triphenylphosphineTriphenylphosphine
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...
.
- Ph3P + Cl2 → Ph3PCl2
Both reagents are typically used in solution to ensure the correct stoichiometry
Stoichiometry
Stoichiometry is a branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of whole numbers...
.
Alternatively, Ph3PCl2 can be obtained by chlorination of 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...
with, for example, phosphorus trichloride
Phosphorus trichloride
Phosphorus trichloride is a chemical compound of phosphorus and chlorine, having chemical formula PCl3. Its shape is trigonal pyramidal. It is the most important of the three phosphorus chlorides. It is an important industrial chemical, being used for the manufacture of organophosphorus compounds...
, as in Grignard's original 1931 synthesis.