V-molecular sieves

Substituted mesoporous silicas are very promising catalysts for the oxidation of arylamines in the liquid phase. Indeed Gontier and Tuel have reported that the performance of TS-1 was considerably poorer than large pore zeolite Ti- and V-substituted molecular sieves for the oxidation of aniline.36 At low oxidant/ aniline ratios it was found that azoxybenzene was the major product using Ti-substituted molecular sieves. In contrast, V-substituted molecular sieves were very selective towards the conversion of aniline to nitrobenzene. The difference between the Ti and V molecular sieves was attributed to the greater number of active oxidising sites in the V-HMS, leading to further oxidation of azoxybenzene into nitrobenzene. 

By adopting a hydrothermal digestion of vanadium-alumino-sihca glasses in basic solutions at 120 °C, Dubanska claimed the possibiHty to synthesize a number of V-molecular sieves including NU-15, ANA, LTA,KF, SOD [113]. However, no conclusive evidence supporting true incorporation of the heteroatoms was given. 

Flanigen E M, Bennet J M, Grose R W, Cohen J P, Patton R L, Kirchner R M and Smith J V 1978 Silicalite a new hydrophobic crystalline silica molecular sieve Nature 271 512-16... 

McDaniel C V and Maher P K 1968 New ultra-stable form of fau]asite Molecular Sieves (London Society of Chemical Industry) pp 186-95... 

A. V. Kiselev and K. D. Shcherbakova ia "Molecular Sieves," Proceedings 1 st International Zeolite Conference, Eondon, 1967, Society of Chemical Industry, London, 1968. 

Rapid procedure Dry over anhydrous K2CO3 for 24h, followed by further drying for 24h over 3A molecular sieves or boric anhydride, followed by distn. Alternatively, stir over P2O5 (5% w/v) for 24h then distil. However this last method is not suitable for use in reactions with very acid sensitive compounds. 

Rapid purification To dry benzene, alumina, CaH2 or 4A molecular sieves (3% w/v) may be used (dry for 6h). Then benzene is distd, discarding the first 5% of distillate, and stored over molecular sieves (3A, 4A) or Na wire. 

Rapid purification Dry rer/-butanol with CaH2 (5% w/v), distil and store over 3A molecular sieves. 

Rapid purification Pass through a column of basic alumina (Grade 1, lOg/mL of CHCI3), and either dry by standing over 4A molecular sieves, or alternatively, distil from P2O5 (3% w/v). Use immediately. 

Rapid purification Distil, discarding the forerun. Stand distillate over Grade I alumina (5% w/v) or 4A molecular sieves. 

Rapid purification Reflux over CaH (5% w/v) and distil. Store over 4A molecular sieves. 

Rapid purification Stir over CaH2 (5% w/v) overnight, filter, then distil at 20mmHg. Store the distd DMF over 3A or 4A molecular sieves. For solid phase synthesis, the DMF used must be of high quality and free from amines. 

Rapid purification Check for peroxides (see Chapter 1 and Chapter 2 for test under ethers). Pre-dry with CaCl2 or better over Na wire. Then reflux the pre-dried solvent over Na (1 % w/v) and benzophenone (0.2% w/v) under an inert atmosphere until the blue colour of the benzophenone ketyl radical anion persists. Distil, and store over 4A molecular sieves in the dark. 

L. A. Luke and J. V. Brunnock, Separation of naphthenic and paraffinic hydrocarbons up to C from hydrocarbon mixtures by gas cliromatography on faujasite molecular sieves , Ger. Ojfen. 1 908418 (1968). 

J. V. Bmnnock, Separation and distribution of normal paraffins from petroleum heavy distillates by molecular sieve adsorption and gas cliromatogr aphy , Anal. Chem. 38 1648-1652(1966). 

A Welsbach T-816 Ozonator purchased from the Welsbach Corporation, Philadelphia, Pennsylvania, was used. The oxygen stream was dried by passage through dry silica gel and molecular sieves and then introduced into the ozonator with the operating voltage set at 115 V., the gas pressure at 8 p.s.i.g., and the gas flow rate at 1 1. per minute. The resulting ozone flow rate was 0.00245 mole per minute, as determined by titration of a potassium iodide trap. ... 

Henn, SW Ackers, GK, Molecular Sieve Studies of Interacting Protein Systems. V. Association of Subunits of D-Amino Acid Oxidase Apoenzyme, Biochemistry 8, 3829, 1969. 

Dors, M., Mizeraczyk, J. and Nichipor, G.V. (2004) Influence of ammonia on NOx removal in corona discharge-molecular sieve hybrid system,./. Adv. Oxid. Technol. 7, 142-4. 

The NO2 molecule offers an example which illustrates this point. The spectrum of N02 molecules rigidly held on MgO at —196° is characterized by gxx = 2.005, gyv = 1.991, and gzz = 2.002 (29). If this molecule were rapidly tumbling, one would expect a value of Qa.v — 1 999. The spectrum of NO2 absorbed in a 13X molecular sieve indicates an isotropic gzv = 2.003 (.80), which is within experimental error of the predicted value for NO2 on MgO. The hyperfine constants confirm that NO2 is rapidly tumbling or undergoing a significant libration about some equilibrium position in the molecular sieve (81). 

AW, Acid-washed Choi, Cholesterol DMAP, 4-(Dimethylamino)pyridine DMF, N,/V-Dimethylformamide DMTr, Di(p-niethoxyphenyl)phenyl methyl GalNAc, N-Acetylgalactosamine, 2-acetamido-2-deoxy-D-galactose HMF, 5-Hydroxymethylfur-fural, 5-(hydroxymethyl)-2-furaldehyde INOC, Intramolecular nitrile oxide-alkene cycloaddition Lea, Lewisa Lex, Lewisx MOM, Methoxymethyl MP, p-Methoxyphe-nyl MS, Molecular sieves NIS, N-Iodosuccinimide PCC, Pyridinium chlorochromate PDC, Pyridinium dichromate PMA, Phosphomolybdic acid PMB, p-Methoxybenzyl ... 

V-hydroxyglycine ethyl ester affords nitrones in good yields (187). Several a-aryl-iV-methylnitrones have been produced in yields of 80% to 100% without solvents, in the presence of 3A molecular sieves (188). Using 4A molecular sieves, it was possible to carry out the synthesis of novel glycolipidic nitrones — potential antioxidant dmgs for neurodegenerative disorders (Scheme 2.22) (189). 

Milano, G. Venditto, V. Guerra, G. Cavallo, L. Ciambelli, P. Sannino, D., Shape and volume of cavities in thermoplastic molecular sieves based on syndiotactic polystyrene, Chem. Mater. 2001, 13, 506 1511... 

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