Resin loading, preparation

Suzuki, T. M., Bomani, J. O., Matsunaga, H., Yokoyama T., Preparation of porous resin loaded with crystalline hydrous zirconium oxide and its application to the removal of arsenic. React. Fund. Polym. 2000, 43,165-172. 

Prepared Starting Resin Loading (mmol/g) Calculated Loading of AMEBA Resin (mmol/g) Sulfonamide Yield (%) ... 

Experimental Procedure. The resin is washed with MeOH and a small portion (ca. 5 mg) is transferred to a disposable syringe (1 ml) fitted with a polypropylene filter disc. To the resin is added of DMF (1 ml) and the syringe is capped and shaken for 5 min. The DMF is then drained and a freshly prepared solution of Purpald dissolved in 1 M NaOH (250 pi) is added. The syringe is capped and shaken for 5 min. The solution is drained and the resin is washed with DCM (3x1 ml). The resin is then left uncapped for 10 min. The presence of free aldehydes is indicated by brown or purple beads. At lower values of resin loading, a longer air oxidation time may be required for color to develop (up to 20 min). 

The application of resin 13 to the sohd-phase synthesis of other useful target compounds was also explored and an example of this is the multistep synthesis of Meclizine (Fig. 10).26 The starting material, 3-methyl-4-hydro-xybenzaldehyde, is attached to the PFS hnker, and a polymer-bound amine intermediate is prepared by a reductive amination of resin 23 with amine 24. The resulting resin 25 is subjected to a palladium-mediated reductive cleavage to give Meclizine 26 in 80% yield, based on the original resin loading. 

The two epoxide enantiomers (i-) and (-) 7.71 were selected as chemical starting points for library generation Their synthesis from shikimic acid with reasonable overall yields was already known (248, 249), and they had a carboxylic acid handle for SPS. The other key intermediates were the three benzylnitrone carboxylic acids 7.72a-c, which were prepared from the corresponding benzyl alcohols (250,251) (Fig. 7.40). The two epoxycyclohexenols were supported onto a PEG-based resin, loaded with a photolabile linker, to give resin-bound 7.73a,b (from now on only one enantiomer will be shown in the figures, but the synthetic pathway was continued with both... 

Dowex 50 X 4, 100-200 mesh cation exchange resin was prepared by washing successively with concentrated HCl, distilled water, 0.1 m EDTA, distilled water, and 0.1 m NaOH. The Na" " form resin was loaded into a glass column (1.2 cm ID and 5.7 cm length) and equilibrated with acetate buffer of the desired pH prior to the experiment. Glass wool was placed on top of the... 

Ozonides, MO3, containing the paramagnetic, bent [03] ion (see Section 15.4), are known for all the alkali metals. The salts KO3, Rb03 and CSO3 can be prepared from the peroxides or superoxides by reaction with ozone, but this method fails, or gives low yields, for LiOs and NaOs. These ozonides have recently been prepared in liquid ammonia by the interaction of CSO3 with an ion-exchange resin loaded with either Li or Na ions. The ozonides are violently explosive. 

The oxidation of benzyl alcohol to benzaldehyde is reported in Figure 9. Four standard heterogeneous catalysts and two Merrifield bead resins loaded with mthenium are compared with nine FibreCat sanqjles. These were prepared by loading the mthenate (VI) or penuthenate (VII) salts by ion exchange onto the triethylamine based fibres (as illustrated in Figure 8). In each case 10 mol% catalyst with respect to the benzyl alcohol was added to the reaction. Most of the... 

In order to introduce diversity at the PI position, intermediate 73a was constructed from the corresponding polymer-bound pyrrolidine amide 80 (Scheme 18). Anchoring of pyrrolidine amide 78 (MMT = mono-/ -meth-oxytrityl), which was prepared in four steps (76% overall yield) from commercially available (S)-methyl ester isopropylideneglycerate (77a) to (ben-zyloxy)benzyl bromide resin 79 (prepared from Wang resin by treatment with carbon tetrabromide and triphenylphosphine [150]), proceeded in 84% loading yield with minimal racemization (<2%) [151]. 

In order to prepare thin-film samples, the desired elements must usually be chemically or physically separated from the host compound. The elements being determined are collected in a physical form suitable for x-ray analysis using such methods as ion exchange, solvent extraction, or precipitation. Metallic ions, for example, may be collected on resin-loaded paper, which also serves as the mechanical support in the x-ray spectrometer. The absolute sensitivity for elements isolated from the host compound is 0.01 to 1 /ug analysis of elements present in trace concentrations is possible with this preconcentration approach, if the total sample size is sufficiently large. 

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