Solid supports loading

Two techniques appear to be useful for the bidentate extraction of actinides. The first is liquid-liquid solvent extraction, a method which has several advantages. Currently, however, the type of equipment needed (mixer-settlers, centrifugal contactors, etc.) is not available at RFP. We are better equipped to use a column technique. This can be done by sorbing the bidentate extractant on an inert solid support, loading ion exchange columns with the sorbent, and proceeding with column runs (extraction chromatography). 

This is a very important and well tested method for the quantitative determination of loading of Fmoc protected compounds particularly that of Fmoc (fluorenylmethoxycarbonyl) amino acids on solid support. Fmoc groups can... 

Chemistry on solid support has gained tremendous importance during the last few years, mainly driven by the needs of the pharmaceutical sciences. Due to the robust and tolerable nature of the available catalysts, metathesis was soon recognized as a useful technique in this context. Three conceptually different, RCM-based strategies are outlined in Fig. 11. In the approach delineated in Fig. 1 la, a polymer-bound diene 353 is subjected to RCM. The desired product 354 is formed with concomitant traceless release from the resin. This strategy is very favorable, since only compounds with the correct functionality will be liberated, while unwanted by-products remain attached to the polymer. However, as the catalyst is captured in this process by the matrix (355), a higher catalyst loading will be required, or ancillary alkenes have to be added to liberate the catalyst. 

Cellulose was the first type of solid support introduced for SPPS [91 ] however, the scope of its use is limited by low loading capacity ( 0.1 mmol/g) and chemical stability. In spite of these drawbacks, microwave-assisted synthesis was successfully performed on cellulose membranes [92-94] and beads [95]. 

To perform the cycloaddition on solid-phase, N-l-unprotected pyrazi-nones were coupled with the solid support by treatment of the brominated linker in DMF for 6h at ambient temperature, using CS2CO3 as a base (Scheme 43). The reaction time for complete loading could be dramatically shortened to only 5 min under microwave irradiation at a pre-selected maximum temperature of 70 °C. 

The capacity of the ordered film for supporting loads is between that of the static film and that of the dynamic fluid film. The orientation property of the ordered layer gradually becomes weak with the distance apart from the metal surface. The transition occurs as the ordered film appears more important between the two solid surfaces. The thickness of the ordered film is related to the initial viscosity or molecular size of the lubricant, as shown in Fig. 13, so that we can generally write the critical film thickness as follows ... 

Scanning force microscopy (SFM) is the only tool that allows one to image S-layer protein monolayers on solid supports at molecular resolution (Fig. lb and c) [22-25]. In particular, SFM in contact mode under water with loading forces in the range of <500 pN leads to an image resolution in the subnanometer range (0.5-1.0 nm). 

The high activity of the Rh/y-Al203 system even at such a low Rh loading (0.1% w/w) can be rationalized on the basis that, as indicated by IR studies of adsorbed CO and EXAFS analysis, all the Rh atoms are zerovalent coordination by the NR3 molecules protects them from oxidation by the solid support [24,35]. 

Preliminary studies into a third variable, the partial pressure of water vapor in the system, are discussed in Part 3 of the Results and Calculations section. Each calorimetric sample ( 1 g, 13.47 mass % bitumen) came from a large sample of "reconstructed" oil sand consisting of Athabasca bitumen loaded onto a chemically inert solid support material (60/80 mesh acid washed Chromosorb W) of well-defined particle size. 

Abstract. The direct scale-up of a solid-phase synthesis has been demonstrated with 4-(2-amino-6-phenylpyrimidin-4-yl)benzamide and an arylsulfonamido-substituted hydroxamic acid derivative as examples. These compounds were obtained through combinatorial chemistry and solution-phase synthesis was used in parallel to provide a comparison. By applying highly loaded polystyrene-derived resins as the solid support, a good ratio between the product and the starting resin is achieved. We have demonstrated that the synthesis can be scaled up directly on the solid support, successfully providing the desired compounds easily and quickly in sufficient quantities for early development demands. 

To study the effect of loading, the synthesis depicted in Scheme 1 was repeated using different resin loadings. The conditions during reactions on higher loaded resins (2b and 2c) as compared to the initially used 2a did not need any adjustments. The quality of the product was comparable and the ratio of product to solid support was increased (Table 1). 

Figure 1.25 illustrates the principle underlying LLE in the solid-supported LLE format. In order to facilitate elution with a water-immiscible organic solvent, it is imperative that analytes are in their neutral form during sample load. Thus, for basic analytes, loading should be done in a high pH (9 to 10) buffer and for acidic analytes, a low pH (2 to 3) buffer. 

Several strategies were developed to prevent the formation of unreactive dimers [86], with one of the more successful methods being immobilization of the catalyst on solid support. Whereas normally, most immobilized catalysts lose activity in comparison to their soluble analogues, in this case the rate increased, due to the prevention of deactivation by dimerization. Even more convincing, there was a negative correlation between the loading on the resin and the rate of the reaction (Fig. 44.12). 

Dispersion of POMs onto inert solid supports with high surface areas is very important for catalytic application because the surface areas of unsupported POMs are usually very low (—10 m2g). Another advantage of dispersion of POMs onto inert supports is improvement of the stability. Therefore, immobilization of POMs on a number of supports has been extensively studied. Silica and active carbon are the representative supports [25], Basic supports such as MgO tend to decompose POMs [101-104], Certain kinds of active carbons firmly entrap POMs [105,106], The maximum loading level of POMs on active carbons is 14 wt% [107], Dispersion of POMs onto other supports such as zeolites, mesoporous molecular sieves, and apatites, is of considerable interest because of their high surface areas, unique pore systems, and possibility to modify their compositions, morphologies, and sorption properties. However, a simple impregnation of POM compounds on inert supports often results in leaching of POMs. 

Gas chromatography (GC) employs a gaseous mobile phase, known as the carrier gas. In gas-liquid chromatography (GLC) the stationary phase is a liquid held on the surface and in the pores of a nominally inert solid support. By far the most commonly used support is diatomaceous silica, in the form of pink crushed firebrick, white diatomite filter aids or proprietary variants. Typical surface areas of 0.5-4 m2/g give an equivalent film thickness of 0.05-1 pm for normal liquid/support loadings of 5-50 per cent by mass. 

---