Alkylation immobilized

The stationary phase in RP chromatography— usually an alkyl immobilized on an inorganic support—is less polar than the aqueous-organic mobile phase. Nonpolar samples are more strongly retained than the polar ones, and the retention increases with increasing polarity of the mobile phase, so that very lipophilic samples may require nonaqueous mobile phases. 

A. Surface Density and Wettability on Alkyl-Immobilized Glass Substrates... 

Another positive-working release by cyclization, illustrated by equation 5, starts with an immobile hydroquinone dye releaser (8), where R = alkyl and X is an immobilizing group. Cyclization and dye release take place in alkaU in areas where silver haUde is not undergoing development. In areas where silver haUde is being developed, the oxidized form of the mobile developing agent oxidizes the hydroquinone to its quinone (9), which does not release the... 

The second step introduces the side chain group by nucleophilic displacement of the bromide (as a resin-bound a-bromoacetamide) with an excess of primary amine. Because there is such diversity in reactivity among candidate amine submonomers, high concentrations of the amine are typically used ( l-2 M) in a polar aprotic solvent (e.g. DMSO, NMP or DMF). This 8 2 reaction is really a mono-alkylation of a primary amine, a reaction that is typically complicated by over-alkylation when amines are alkylated with halides in solution. However, since the reactive bromoacetamide is immobilized to the solid support, any over-alkyla-tion side-products would be the result of a cross-reaction with another immobilized oligomer (slow) in preference to reaction with an amine in solution at high concentration (fast). Thus, in the sub-monomer method, the solid phase serves not only to enable a rapid reaction work-up, but also to isolate reactive sites from... 

Another recent patent (22) and related patent application (31) cover incorporation and use of many active metals into Si-TUD-1. Some active materials were incorporated simultaneously (e.g., NiW, NiMo, and Ga/Zn/Sn). The various catalysts have been used for many organic reactions [TUD-1 variants are shown in brackets] Alkylation of naphthalene with 1-hexadecene [Al-Si] Friedel-Crafts benzylation of benzene [Fe-Si, Ga-Si, Sn-Si and Ti-Si, see apphcation 2 above] oligomerization of 1-decene [Al-Si] selective oxidation of ethylbenzene to acetophenone [Cr-Si, Mo-Si] and selective oxidation of cyclohexanol to cyclohexanone [Mo-Si], A dehydrogenation process (32) has been described using an immobilized pincer catalyst on a TUD-1 substrate. Previously these catalysts were homogeneous, which often caused problems in separation and recycle. Several other reactions were described, including acylation, hydrogenation, and ammoxidation. 

Secondary amines, such as pyrrolidine, must be alkylated with care too polar a solvent leads to participation of a second nearby polymer-bound alkylant in the formation of a quaternary ammonium salt, along with the desired immobilized trialkyl amine. The exception, as seen above, is diisopropylamine, which refuses to displace tosylate even in the refluxing pure amine, or in hot dimethyl-formamide or other polar solvent, while metal diisopropylamide is notorious as a powerful non-nucleophilic base. However, carboxamide is not difficult to form from (carboxymethyl)polystyrene, again using toluenesulfonyl chloride as condensing agent this can then be reduced to (diisopropyl-ethylaminoethyl)polystyrene, which is of interest as a polymer-bound non-nucleophilic base. ... 

When the rhodium-catalyzed reaction is performed under a high pressure of CO in the presence of phosphite ligands, aldehyde products (159) are formed by insertion of CO into the rhodium-alkyl bond followed by reductive elimination (Eq. 31) [90]. The bimetallic catalysts were immobilized as nanoparticles, giving the same products and functional group tolerance, with the advantage that the catalyst could be recovered and reused without loss of... 

Cationic palladium(II) complexes are homogeneous catalysts for both intramolecular and inter-molecular hydroamination reactions.267 Palladium species immobilized on silica can be prepared by the simple addition of alkyl- or hydroxopalladium(II) complexes to partially dehydroxylated silica. The silica-bound species are more stable than their molecular precursors and are efficient catalysts for the cyclization of aminoalkynes.268... 

Domino radical transformations on solid support can also be used, as shown by Naito and coworkers [18]. Thus, immobilized oxime ether 10-55 (Wang resin) afforded the tetrahydrofuranones 10-57 after removal of the resin, when it was exposed to BEt3 in the presence of different alkyl iodides 10-56 (Scheme 10.14). 

An example of the appropriate application of organically-modified silica precursors is alkoxides with an alkyl group. When methyltrimethoxy- or methyl-triethoxysilane (Figure 3.2) was added in formulations to increase the hydro-phobicity of ORMOSILs, it resulted in a better enzymatic activity of lipases immobilized in the alkyl-modified silica than in a hydrophilic matrix fabricated by means ofTEOS alone [51,80,129-133]. Similarly, an increased stability of lipase from Candida antarctica B was observed after its immobilization in a silica matrix... 

Totani T, Teramura Y, Iwata H (2008) Immobilization of urokinase on the islet surface by amphiphilic poly(vinyl alcohol) that carries alkyl side chains. Biomaterials 29 2878-2883... 

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