Liquid-phase silylation

ODS octadecyl silyl stationary phase used in high performance liquid chromatography... 

Silyl(silyloxy)amino]boranes decompose in the liquid phase to a mixture of products [Eq. (12)] (18,19). Again, the formation of the... 

We here further demonstrate the merits of Fe -exchanged montmorillonite over the conventional homogeneous acid catalysts, applying it to other types of liquid-phase carbon-carbon bond-forming reactions between carbonyl compounds and useful nucleophilic carbanion reagents such as silyl ketene acetal (an ester... 

Figure 7 presents the overall, idealized reaction mechanism. The surface of MCM-48 contains 0.9 OH / nmJ, which react completely with DMDCS in the liquid phase, if NEt3 is used as a catalyst. The majority of the silanols react monofunctionally but a small fraction also reacts further, according to reaction (3) to yield inert, bidentate species. All chlorine functions on the surface are converted towards hydroxyls upon hydrolysis. The VO(acac)2 is reacted in a gas-phase reactor with this silylated, hydrolyzed surface. All recreated silanols react with the VO(acac)2 in a 1 1 stoichiometry, following a ligand-exchange mechanism. Upon calcination at 450°C, the acac ligands are decomposed but the methylsilyl functions remain intact. Most of the V-species are converted into isolated, tetrahedral VvOx species, as indicated in Figure 4. However, a small fraction clusters to form surface oligomers, hereby recreating a fraction of the silanols.

Several enlightening comparisons can be made from the data of Table I. First an estimate of the vapor phase HMDS surface reaction efficiency vs that of the liquid phase can be obtained. The features of the vapor phase and liquid phase treatments are found in Tables II and III. From Table I, the values for Y58 substrates are 0.22 and 0.11, respectively, thus indicating an approximate 100% greater efficiency towards silanol conversion to trimethyl silyl labelled reaction product for the vapor treatment. An approximate 30% gain is obtained for the oxide substrate comparison. 

Reactions of free silyl radicals in the liquid phase (Japan)... 

In epoxidation, the propene-to-CHP molar ratio is 10 1, the reaction temperature is 60 °C and the pressure is sufficient to maintain propene in the liquid phase. The feed to the epoxidation reactor must contain less than 1% water in order to limit the hydrolysis of PO to glycol. The reaction is catalyzed by a proprietary, silylated, titanium-containing silicon oxide catalyst. The conversion of CHP is greater than 95%. Selectivity for PO based on hydroperoxide is 95%, whereas selectivity based on propene is around 99%. By-products of the reaction are aldehydes, such as acetaldehyde and propionaldehyde, alcohols (methanol and propene glycol), ketones and esters (e.g., acetone and methyl formate). The catalyst fixed-bed is structured into multiple catalyst layers, with heat exchangers in between the layers. This prevents excessive increases in temperature due to the exothermal reaction that would cause both thermal decomposition of the hydroperoxide and consecutive reactions of PO. 

Piezoelectric quartz crystal oscillators function on the basis of the well-established relationship (Sauerbery equation) between the oscillation frequency of a quartz crystal and the mass of a thin film deposited on its surface [501]. QCM has been extensively used in measurements in vacuo and in the gas phase, which includes the studies on gas phase silylation for oxygen RIE development [443] (see 6.2) and on resist outgassing [439,502]. The QCM technique has been extended to measurements in the liquid phase including aqueous media and has found powerful utility in studies of dissolution kinetics of phenolic and other acidic resists in aqueous base [503]. 

Typical vapor phase silylating agents used in top surfaee imaging systems include dimethylsilyldimethylamine (DMSDMA), trimethylsilyldimethylamine (TMSDMA), and trimethylsilyldiethylamine (TMSDEA). Typical liquid phase silylating agents used in top surfaee imaging systems inelude 1,1,33,5,5-hexamethylcyclotrisilazane and bis(dimethylamino)dimethylsilane with N-methyl-2- pyrrolidone (NMP) as a diffusion promoter. Typical polymer resins include polyvinyl phenol and novolac/diazoquinone polymer resins. 

M.A. Hartney, R.R. Kunz, L.M. Eriksen, and D.C. LaTulipe, Comparison of liquid and vapor phase silylation processes for 193 nm positive tone hthography, Proc. SPIE 1925, 270 (1993). K. H. Baik, L. Van den Hove, and B. Roland, Comparative study between gas and liquid phase silylation for the diffusion enhanced silylated resist process, J. Vac. Set Technol. B 9, 3399 (1991) K. H. Baik, K. Ronse, L. Van den Hove, and B. Roland, Liquid phase silylation for the DESIRE process, Proc. SPIE 1672, 362 (1992). 

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