Hydrogen titanium-molybdenum system

The Titanium-Molybdenum-Hydrogen System Isotope Effects, Thermodynamics, and Phase Changes... 

Pressure-composition-temperature and thermodynamic relationships of of the titanium-molybdenum-hydrogen (deuterium) system are reported. 0-TiMo exhibits Sieverts Law behavior only in the very dilute region, with deviations toward decreased solubility thereafter. Data indicate that the presence of Mo in the 0-Ti lattice inhibits hydrogen solubility. This trend may stem from two factors for Mo contents >50 atom %, an electronic factor dominates whereas at lower Mo contents, behavior is controlled by the decrease in lattice parameter with increasing Mo content. Evidence suggests that Mo atoms block adjacent interstitial sites for hydrogen occupation. Thermodynamic data for deuterium absorption indicate that for temperatures below 297°C an inverse isotope effect is exhibited, in that the deuteride is more stable than the hydride. There is evidence for similar behavior in the tritide. 

The most important hydrogen bond donating group in directed epoxidations is the hydroxy group. For allylic or homoallylic alcohols, peracids or tert-butyl hydroperoxide/vanadylbis[2,4-pentanedionate] (see Houben-Weyl, Vol. IV/la, p 231) are generally the most efficient reagent systems less common catalysts are tri-te/ f-butoxyaluminum, dibutyltin oxide, and molybdenum- and titanium-based systems (see Houben-Weyl, Vol. IV/la, p 227, Vol. E13/2, p 1176). The two classes of reactions show distinct differences in their stereoselectivity patterns. 

Enantioselective epoxidation of allylic alcohols using hydrogen peroxide and chiral catalysts was first reported for molybdenum 7B) and vanadium 79) complexe. In 1980, Sharpless 80) reported a titanium system. Using a tartaric acid derivative as chiral auxiliary it achieves almost total stereoselection in this reaction. 

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