Tetraalkoxy(hydroxy)phosphoranes were postulated as intermediates in the hydrolysis of alkyl(ary1)phosphates some time ago ['], but until now could only be synthesized in a few cases by oxidation of the corresponding hydrogen phosphoraned*]. Hydrolysis of the halospirophosphoranes 2a and 2b, obtainable by treating the trihalophosphor a n e~[~" ' l a and l b with dilithium perfluoropinacolate in neutral or alkaline aqueous ether solution, led to the hydroxyphosphorane 3 (m. p. = 72 "C, 78% yield) and potassium phosphorane oxide 5 (m. p. = 118 "C, 100% yield), respectively, without cleavage of the P-0 ring bonds to form a P=O bond. A tautomeric monocyclic form[21 of 3 is not observed. The methoxy derivative 4 (m. p. = 68 "C, 92% yield) is obtained in the same way using methanol. X 3 R = H 1, R = M e 2 5 Scheme I. @ I : I ; -196 to + 160°C (10 h) and + 2 0 " C (24 h), respectively, petroleum ether extraction, Et:O, sublimation: 2a (62%, m. p.=62"C) and 2b(43%, m.p.= 82"C), respectively. @ I mL of water or methanol is added to a stirred solution of 0.003 mol 2a or 2b in 20 mL of EbO; after 30 min the organic phase is separated off and the aqueous phase extracted three times with ether. The mixture was then dried over Na2S04, concentrated and the product recrystallized from Et,O. 0 1.0 g of KOH in 5 mL of water is added to a stirred solution of 0.01 mol 2a or 2b in 30 mL of EtrO; after 1 h the mixture is extracted three times with 20 mL of ether, dried over NarS04 and the solvent removed; yield 7.5 g 5.

"Hydrothermal synthesis" usually refers to heterogeneous reactions in aqueous media above 100°C and 1 bar. The previously common distinction between hydrothermal conditions below and pneumatolytic conditions above the critical point is no longer made, since no discontinuities are observed upon exceeding the critical conditions. Under hydrothermal conditions, reactants otherwise difficult to dissolve go into solution as complexes, in whose formation water itself or very soluble "mineralizers" can participate. Thus, one can obtain the conditions of chemical transport reactions,"' of which hydrothermal syntheses can be considered a special case. During recent decades in the geological sciences-in which the method is also historically rooted-it has received a strong impulse, whose effect on preparative solid state chemistry is discussed here.

Lithium ionic conductivity of Czochralski-grown Li3N single crystals using electrochemical transport measurements is reported. The highest Li ionic conductivity was found perpendicular to the hexagonal c axis, the anisotropy decreasing from two to one decade between 20 and 200 °C. Ambient Li ionic conductivity parallel to the Li2N planes of the layer structure was found to be σ=10−3 Ω−1 cm−1 with an activation energy of 0.25 eV. These values are comparable with the best data reported for Li β-alumina single crystals.

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