Silanisation reaction

The modification of glass surfaces can be readily achieved through silanisation chemistry (Figure 3.2). In contrast to gold-based SAMs, the silanisation reactions typically require slightly harsher conditions. They are therefore generally not carried out in the presence of the peptides but are used to modify the glass surface with other functionalities before attachment of the peptide material. 

Effect of Rubber Type on the Silica Silanisation Reaction... 

Ability to tune the surface chemistry by chemical reaction, e.g. silanisation or coating processes, respectively,... 

Silanisation is a heterogeneous reaction. Silanes can be in the gas or liquid phase or in solution. The reaction is carried out at elevated temperatures, depending on the volatility of the silane and solvent, in a vessel under gentle stirring or in a fluidized bed reactor. To enhance the kinetics, catalysts are added. With chlorosilanes, organic bases are added as acid scavengers acids are employed in case of alkoxysilanes as reagents. By-products must be carefully removed by extraction with solvents. 

HMDS is useful for on-column silanisation since the by-product of the reaction is nitrogen, which will not harm the metallic surfaces of the... 

Hydroxylation of phenol and anisole was investigated using TS-1, a silanised TS-1 and Al-free Ti-Beta. Pore geometry, solvent, external surface and substrate govern the selectivity of the hydroxylation reaction. In medium pore TS-1 the formation of hydroquinone in phenol hydroxylation is favoured due to the geometric constraint on the formation of catechol in the pores. A similar effect is observed for formation of ortho- and para hydroxy-anisoles in Al-free Ti-Beta. Solvents affect activity and selectivity of the hydroxylation reactions through adsorption and co-ordination to the titanium active site. The external surface of TS-1 plays a substantial role in hydroxylation reactions. 

Levarato has developed a series of quantitative methods for the determination of prednisolone along other corticoids after extraction from preparations and separation by TLC on silica gel plates and determination by spectrophotometric (absorption at 240 nm) or colorimetric methods (INH-hydrazone formation, tetrazolium reaction) (81). A simple, fast and quantitative TLC-method for the determination of prednisolone in tablets is described. The method is stability-indicating with respect to accuracy, specificity, sensitivity and precision. The coefficient of variation was between 1.26 and 1.96 % and the sensitivity was about 25 ng. The chromatographic separation was performed on a silicagel plate using two step development of the plate (82). A simple TLC method of separation of prednisolone from other corticosteroids is reported (83). Prednisolone and the dephosphorylated D-homosteroid can be separated on silanised silica gel TLC plates (36). 

The experimental procedure involved immersing a plasma cleaned SAW device into liquid DPTMDS, pulling vacuum on the reaction chamber and heating to 170%. The reaction was allowed to continue for 12 hours, and the silanised sensor was solvent cleaned with, toluene, methanol, and chloroform. 

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