Commonly used reagents —- Triphenylphosphine
【English name】 Triphenylphine
Molecular Formula] C18H15P
Molecular weight] 262.29
【CA Login Number】[603-35-0]
Structural formula] Ph3P
Physical Properties] bp 337 oC/1.0 mmHg, mp 79~81oC, d 1.18 g/cm3. white crystals, soluble in most organic solvents, insoluble in water; soluble in ethanol, benzene, chloroform; very soluble in ether.
Preparation and commercial products]: Crystallized from hexane, methanol or 95% ethanol; dried over CaSO4 or P2O5 at 65 oC/1.0 mmHg to obtain a pure solid. It is sold by large multinational reagent companies.
Precautions] This reagent can irritate the human body under intense sunlight, and is neurotoxic if exposed for a long time, and is a hazardous material, and cannot be coexisted with strong oxidizing reagents. The reactivity of aryl phosphine with oxygen is lower than that of benzyl and alkyl phosphine. However, air oxidizes triphenylphosphine very significantly, generating triphenylphosphine oxides. Triphenylphosphine is less likely to catch fire and explode, but when it is heated to decomposition, toxic phosphine and POx fumes are produced. Handling should be done in a fume hood.
Triphenylphosphine is a fairly common reducing agent, and in most cases the reaction is driven by the formation of triphenylphosphine oxide (a thermodynamically favorable reaction). In addition, triphenylphosphine is widely used as a ligand for metal catalysts.
Deoxygenation reactions
Triphenylphosphine is widely used in the reduction of hydrogen peroxide or endoperoxides.
The reaction is substrate dependent and can produce alcohols, carbonyl compounds or epoxides. The main driving force for these reactions is the ability of triphenylphosphine to form strong P=O bonds with relatively weak O-O bonds (188-209 kJ/mol). For example, triphenylphosphine can be utilized for the reductive decomposition of ozonides and the selective preparation of ketones and aldehydes (Eq. 1) [1].
Reactions with azides [Staudinger reduction].
Triphenylphosphine reacts with organic azides to form iminophosphorane (Eq. 2)[2].
Iminophosphorane is a more active nucleophilic reagent and reacts readily with electrophilic reagents. For example, it reacts with aldehydes and ketones to form imines and triphenylphosphine oxides. This reaction is similar to the Wittig reaction and is called the aza-Wittig reaction, which is also driven by the production of triphenylphosphine oxide (Eq. 3) [3]. The [aza-Wittig reaction (aza-Wittig reaction)]
Reaction with organic sulfides [Eschenmoser desulfurization reaction
Triphenylphosphine at room temperature converts cyclic sulfur compounds to olefins (Eq. 4)[4].
Dehalogenation reaction
α-Bromo ketone reacts with triphenylphosphine to form ketone (Eq. 5)[5].
Reaction with organic epoxides
Refluxing in water and acetone solvents, triphenylphosphine allows the conversion of epoxides to cycloimines with the participation of sodium azide (Eq. 6)[6].
Preparation of substituted pyrroles
The reaction of aniline, furandione with triphenylphosphine produces 1-phenyl-2,5-pyrrolidinedione (Eq. 7) [7].
As a ligand for metal catalysts [Summary of metal-catalyzed reactions].
It is used as a ligand with many transition metals to form a metal catalyst, such as Pd(PPh3)4 is an important catalyst [8],
commonly used to catalyze the coupling reaction, is an important method of constructing carbon-carbon bonds, which is characterized by mild catalytic conditions. For example, the direct reaction of phenylboronic acid with aromatic halogenated hydrocarbons to form biphenyl analogs was carried out in the presence of Pd(PPh3)4 and Ag2O, and the yield of this reaction reached 90% (Eq. 8) [9,10]. In addition to phenylboronic acids and halo-substituents, magnesium reagents [11], zinc reagents [12], tin reagents [13], and silicon compounds [14] can be used as substrates for coupling reactions.
Preparation of halogenated compounds [Appel reaction
The Appel reaction was utilized to convert alcohols to halogenated substances.
Iodination reaction of triphenylphosphine/imidazole/iodine system
Preparation of aliphatic bromo-substituents using triphenylphosphine bromide
Preparation of amides [Preparation of amides by triphenylphosphine-based condensates
Mitsunobu reaction
Reaction in which the SN2 reaction configuration is flipped to obtain a substitution product of opposite configuration using an azodicarboxylic acid ester (usually diethyl azodicarboxylate, DEAD) and a trisubstituted phosphine compound (usually triphenylphosphine), a nucleophilic reagent, and an alcohol.
