Phosphonous and Phosphinous Acids

Compounds containing a free acid function present a nomenclature problem since they can be regarded as derivatives of phosphonous acids (phosphonites), or of phosphinic acid (primary phos-phinates). The free acids have the phosphinic form whereas the amides are phosphonites (6.203). 

The only well-characterised simple phosphinous acid is bis-trifluoromethyl-phosphonous add, (CF3)2P OH, which can be made by reacting the secondary phosphine with mercuric oxide (6.204). The phosphinous acid form RjPOH can be stabilised in certain metal coordination complexes (8.362). 

It is likely that the phosphine oxide is first formed and this then equilibrates to the more stable pyramidal form because of the strong electron-withdrawing CF3 groups. The action of water is to produce trifluoromethyl phosphinic acid (6.205). 

Trifluoromethylphosphonous acid is obtained by hydrolysis of the halophosphine, but its sodium salt is sodium trifluoromethyl phosphinate. 

All other potential phosphinous acids exist as secondary phosphine oxides (6.207). These may be made by oxidation of primary phosphines with hydrogen peroxide at 0°C (6.26), or by the acid-catalysed addition of phosphines to ketones (6.129). 

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Pure tetrahedral coordination probably occurs only ia species where there are four identical groups and no steric distortions. Both PCU and PBr" 4, present ia soHd phosphoms haUdes, appear to have poiat symmetry. Other species, eg, H PO and POCl, have only slightly distorted tetrahedra. Similar geometries occur ia salts, esters, and other derivatives of phosphoric, phosphonic, and phosphinic acids as well as phosphine oxides and phosphonium salts. 

In general, if the desired carbon—phosphoms skeleton is available in an oxidi2ed form, reduction with lithium aluminum hydride is a powerful technique for the production of primary and secondary phosphines. The method is appHcable to halophosphines, phosphonic and phosphinic acids as well as thein esters, and acid chlorides. Tertiary and secondary phosphine oxides can be reduced to the phosphines. 

Monophosphams. The similar tetrahedral geometry and bond lengths of tetracoordinate phosphoms(V) compared to those of sulfur(VI) suggested that phosphonic and phosphinic acid groups might act as biososteres for the sulfonic acid moiety in the parent monobactams. The... 

The chlorination of phosphonic and phosphinic acids and esters are of considerable importance. PCI5 can also act as a Lewis acid to give 6-coordinate P complexes, e.g. pyPClf, and pyz-PCI5, where py = C5H5N (pyridine) and pyz = cyclo-1, 4-C4H4N2 (pyrazine). ... 

There are many parallels between phosphates and sulfates of aliphatic alcohols. Both types of surfactants contain ester bonds undergoing hydrolysis in acid solutions. In that case the starting materials are received once more. By dry heating of the salts above a temperature of 140°C destruction will occur forming the corresponding alkenes and an inorganic acid salt. In the same way as sulfonic and sulfinic acids are formed by C-S bonds, C-P bonds lead to phosphonic and phosphinic acids. 

A differential vapour-pressure technique has been used to determine the molecular weights of phosphonic and phosphinic acids in 95% ethanol. Cryoscopic and n.m.r. studies have been made on solutions of phosphinic acids in sulphuric acid and oleum. Mass spectrometry has indicated the ready formation of phosphinylium ions after electron bombardment of phosphonic and phosphinic acids and their derivatives. However, the cryoscopic results in sulphuric acid indicated that reaction did not proceed beyond protonation, and the n.m.r. study on oleum solutions suggested that sulphonation occurred. 

Wackett LP, SL Shames, CP Venditti, CT Walsh (1987a) Bacterial carbon-phosphorus lyase products, rates and regulation of phosphonic and phosphinic acid metabolism. J Bacterial 169 710-717. 

Preparations of a-diazophosphonoacetic acid derivatives have been described.77 Thus far,(a-diazoalkyl)phosphonic and -phosphinic acids have been known only as their esters. The... 

Reactions and Properties of Phosphonic and Phosphinic Acids and their Derivatives.-A free radical mechanism has been proposed to account for the cleavage of the phosphorus-carbon bond in the alkylphosphonic acids (155) by E coli to give a mixture of alkane (methane only, from methylphosphonic acid) and terminal alkene. 

A series of amides, hydrazides, and azides of phosphoric, phosphonic, and phosphinic acids were synthesized via the corresponding pyrazolides. 

Mixed Anhydrides of Phosphoric, Phosphonic, and Phosphinic Acids with Sulfonic Acids... 

Mixed anhydrides between phosphoric, phosphonic, and phosphinic acids on one side and sulfonic or carboxylic acids on the other are conveniently prepared via phosphor-azolides.[150]... 

Preston, J. S. Solvent extraction of cobalt and nickel by organophosphorus acids. I. Comparison of phosphoric, phosphonic, and phosphinic acid systems. Hydrometallurgy 1982, 9, 115-133. 

Silyl esters of phosphorous, phosphonous, and phosphinous acids... 

At times, confusion arises in noting oxides of primary and secondary phosphines (Figure 1.5). These species participate in equilibria much as the phosphonous and phosphinous acids do and can be named as types of phosphonous and phosphinous acids. 

We should therefore wish an application of the same process to sul-phonic and sulphinic acids to give phosphonic and phosphinic acids respectively ... 

Sulphuric and sulphurous acids are dibasic. Sulphonic and sulphinic acids are monobasic. With them we are at the end of the series of acids generated by replacing OH by H. In the phosphorus series the basicity is always one unit higher, so that having passed from phosphoric and phosphorous adds, which are tribasic, to phosphonic and phosphinic acids, which are dibasic, we can proceed a further step to two monobasic acids, for which the recommended names are very naturally phosphonous and phosphinous acids ... 

In spite of its simplicity, the British system was not found to be universally acceptable. Workers in the field everywhere agreed to the acceptance of phosphonic, phosphinic, phosphonous and phosphinous acids and to derivatives of these provided a P—C link was present, e.g. 

Phosphonic and Phosphinic Acids and their Derivatives.—Further fundamental information on important reactions for preparing phosphonic acid derivatives has... 

Reactions of Phosphonic and Phosphinic Acid Derivatives.—The reactions of phos-phonic and thiophosphonic amides and chlorides with carboxylic acid chlorides and amides have been discussed.101 Dialkyl alkylphosphonates and alkyl dialkylphos-phinates may be used for the iV-alkylation of imidazoles, triazoles, and pyrroles.105... 

FIGURE 1.26 Spectrum of -derivatives of amino acids and corresponding sulfonic, phosphonic, and phosphinic acids for which cinchonan carbamate-based eSPs showed broad enantiomer separation capabilities. 

Selected Examples of Enantiomer Separation Data of N-Derivatized Amino Acids (See Also Table 1.3), Amino Sulfonic, Phosphonic and Phosphinic Acids on tBuCQN-Based CSP ... 

Hydroxy(alkoxy)phosphonium Ions. Olah and McFarland560 studied the protonation in HS03F or HS03F-SbF5 solution of varied phosphorus oxyacids and derivatives. Treatment of tetravalent phosphoms compounds (phosphorus, phosphonic, and phosphinic acid and their trialkyl and triaryl derivatives) results in (9-protonation and the formation of hydroxyphosphonium ions. Trivalent phosphites, in turn, are protonated at the phosphorus atom. The 31P shifts observed for the latter ions are significantly deshielded, which was attributed to significant oxonium ion character. 

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