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The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
Likewise, tripolyphosphoric acid H 5 P 3 O 10 yields at least five anions [H 5−k P 3 O 10] k−, where k ranges from 1 to 5, including tripolyphosphate [P 3 O 10] 5−. Tetrapolyphosphoric acid H 6 P 4 O 13 yields at least six anions, including tetrapolyphosphate [P 4 O 13] 6−, and so on. Note that each extra phosphoric unit adds one extra ...
Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula H 3 P O 4. It is commonly encountered as an 85% aqueous solution, which is a colourless, odourless, and non-volatile syrupy liquid. It is a major industrial ...
Phosphonites are generally more reactive than phosphite esters. They react to produce phosphinates. Heating is also required for the reaction, but pyrolysis of the ester to an acid is a common side reaction. The poor availability of substituted phosphonites limits the usage of this class of reagent in the Arbuzov reaction.
The phosphorus reagent can be used in catalytic quantities. [5] [6] The corresponding alkyl bromide can also be synthesised by addition of lithium bromide as a source of bromide ions. A more sustainable version of the Appel reaction has been reported, which uses a catalytic amount of phosphine that is regenerated with oxalyl chloride. [7]
Phosphotungstic acid (PTA) or tungstophosphoric acid (TPA), is a heteropoly acid with the chemical formula H 3 P W 12 O 40]. It forms hydrates H 3 [PW 12 O 40]·nH 2 O. It is normally isolated as the n = 24 hydrate but can be desiccated to the hexahydrate (n = 6). [2] EPTA is the name of ethanolic phosphotungstic
Hypophosphorous acid was first prepared in 1816 by the French chemist Pierre Louis Dulong (1785–1838). [4] The acid is prepared industrially via a two step process: Firstly, elemental white phosphorus reacts with alkali and alkaline earth hydroxides to give an aqueous solution of hypophosphites: P 4 + 4 OH − + 4 H 2 O → 4 H 2 PO − 2 + 2 H 2
Pyrophosphoric acid, also known as diphosphoric acid, is the inorganic compound with the formula H 4 P 2 O 7 or, more descriptively, [(HO) 2 P(O)] 2 O. Colorless and odorless, it is soluble in water, diethyl ether, and ethyl alcohol.