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Triphenylphosphine oxide can be difficult to remove from reaction mixtures by means of chromatography. It is poorly soluble in hexane and cold diethyl ether . Trituration or chromatography of crude products with these solvents often leads to a good separation of triphenylphosphine oxide.
The hydrolysis of phosphorus(V) dihalides also affords the oxide: [9] R 3 PCl 2 + H 2 O → R 3 PO + 2 HCl. A special nonoxidative route is applicable secondary phosphine oxides, which arise by the hydrolysis of the chlorophosphine. An example is the hydrolysis of chlorodiphenylphosphine to give diphenylphosphine oxide: Ph 2 PCl + H 2 O → Ph ...
Phosphine oxide is the inorganic compound with the formula H 3 PO. Although stable as a dilute gas, liquid or solid samples are unstable. Unlike many other compounds of the type PO x H y, H 3 PO is rarely discussed and is not even mentioned in major sources on main group chemistry.
In some cases, the phosphine oxide is unintentionally generated by air-oxidation of the parent phosphine ligand. Since phosphine oxides are weak Lewis bases, they are readily displaced from their metal complexes. This behavior has led to investigation of mixed phosphine-phosphine oxide ligands, which exhibit hemilability.
Triphenylphosphine undergoes slow oxidation by air to give triphenylphosphine oxide, Ph 3 PO: 2 PPh 3 + O 2 → 2 OPPh 3. This impurity can be removed by recrystallisation of PPh 3 from either hot ethanol or isopropanol. [8] This method capitalizes on the fact that OPPh 3 is more polar and hence more soluble in polar solvents than PPh 3.
Calcium bromide forms complexes with triphenylphosphine oxide, allowing for removal of triphenylphosphine oxide from reaction mixtures without the use of chromatography. [ 3 ] References
Tributylphosphine reacts with oxygen to give the corresponding phosphine oxide (here tributylphosphine oxide): 2 P(CH 2 CH 2 CH 2 CH 3) 3 + O 2 → 2 O=P(CH 2 CH 2 CH 2 CH 3) 3. Because this reaction is so fast, the compound is usually handled under an inert atmosphere. The phosphine is also easily alkylated.
Triphenylphosphine or tributylphosphine are most commonly used, yielding tributylphosphine oxide or triphenylphosphine oxide as a side product in addition to the desired amine. An example of a Staudinger reduction is the organic synthesis of the pinwheel compound 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene.