Aluminium methylphosphonate

Sawers LJ, Carter VJ, Armstrong AR, Brace PG, Wright PA, Gore BE (1996) Ab initio stracture solution of a novel aluminium methylphosphonate from laboratoiy X-ray powder diffraction data. J Chem Soc-Dalton Trans 3159-3161... 

As a specific example. Fig. 9.36 shows 5Q MAS spectra corresponding to the tetrahedral aluminium sites in the microporous aluminium methylphosphonates (a) AlMePO-a and (b) AlMePO-p [175]. In Fig. 9.36b, three distinct sites can be distinguished in the isotropic (F,) dimension. In a MAS experiment (this corresponds to the projection onto the F2 dimension), only a single peak is observed in the tetrahedral region. AlMePO-p can be converted by a thermal transformation into AlMePO-a. As discussed in [175], insight into this process is provided by the subtle but significant differences between the 5Q MAS spectra for a physical mixture of the two forms (Fig. 9.36c) and for a sample in which the thermal transformation was interrupted (Fig. 9.36d). 

Figure 2.27 The aluminium methylphosphonate polymorphs a and p (above, left and right) and the scandium methylphosphonate (below) possess inorganie frameworks lined with rapidly rotating methyl groups.

Phosphonic acid analogues of aspartic acid, glutamicacid C-benzy1g1ycine,191 and the phosphor inane (70)1 92 have been studied, also the oxime (71)193 a phosphonopiperidinol - with a very distorted chair structure,194 the phosphonate (72),195 a pyrazole,196 a thiocarbamoy1phosphonate, 97 and two iminobis-(methylphosphonic acids).198 Additionally there have been studies of the new bicyclic sulphur heterocycle (73),199 the oxazaphospho1idine (74)200 and a triaminophosphetanium aluminium betaine.201... 

Sarin can be made by more than one method, but in the usual large scale route chloromethane, phosphorus trichloride and aluminium chloride, and then water react to give methylphosphonic dichloride this, on treatment with hydrogen fluoride (or sodium fluoride), gives a mixed chlorofluoride, which, by reaction with isopropyl alcohol, pelds Sarin (Figure 3). 

A high yield of methylphosphonous dichloride can be obtained by heating phosphorus trichloride with methyl iodide and aluminium trichloride. A complex is first formed (Kinnear-Perrin reaction), and this can then be reduced with aluminium (6.151). In an extension of this reaction, dimethyl-phosphinous chloride can be obtained from the monomethyl compound by treatment with methyl and aluminium chlorides in a similar way (6.152). 

With aluminium hydride, reduction to a phosphine can be effected (6.58). Hydrolysis yields methylphosphonous acid which exists in the tautomeric methylphosphinic add form (6.164). Although this seems fairly general for RPX2 compounds, it appears that steric hindrance can prevent hydrolysis of the second P-Cl bond and the product is RPH (0)C1, when R is 2,4,6 tri-tertiary butyl benzene. 

Aluminium tris(methyl methylphosphonate) has been patented as a low-volatility fire retardant (12.225) [62]. 

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