Silica-based diamine

Comparable results were achieved with the silica-based diamine (3.0 equivalents of the amine functionality). At room temperature, the excess anhydride was scavenged within 4 h. On the other hand, microwave heating at 100 °C in a sealed ves-... 

Fig. 7.10 Polymer-supported scavengers polystyrene-bound diamine (top left), silica-based diamine (top right), Stratosphere Plugs (bottom left), and Synphase Lanterns (bottom right).

The carbonylation of 7V1-(2-iodophenyl)-iV1-methylbenzene-1,2-diamine 91, catalyzed by Pd complexed to a silica-based dendrimer ligand (Gi), provided 5-methyl-5//-dibenzo[A ][l,4]diazepin-ll(10//)-one 92 in excellent yield (Scheme 48) <2005JA14776, CHEC-III(13.06.9.1.8)211>. 

Silica-based weak anion exchangers are obtained by direct silanization and are the precursors to strong ion exchangers. Aminopropyl silanes and die-thylaminopropyl silanes are readily available commercially. To increase the exchange capacity, the simple amino group can be replaced with an ethylene diamine or a diethylene triamine function. Silica-based weak cation exchangers with an aliphatic carboxylic acid are available as well. 

In 2003, Sigman et al. reported the use of a chiral carbene ligand in conjunction with the chiral base (-)-sparteine in the palladium(II) catalyzed oxidative kinetic resolution of secondary alcohols [26]. The dimeric palladium complexes 51a-b used in this reaction were obtained in two steps from N,N -diaryl chiral imidazolinium salts derived from (S, S) or (R,R) diphenylethane diamine (Scheme 28). The carbenes were generated by deprotonation of the salts with t-BuOK in THF and reacted in situ with dimeric palladium al-lyl chloride. The intermediate NHC - Pd(allyl)Cl complexes 52 are air-stable and were isolated in 92-95% yield after silica gel chromatography. Two diaster corners in a ratio of approximately 2 1 are present in solution (CDCI3). 

Organic bases attached to mesoporous silica surface Primary, secondary and tertiary amines,1169-1711 diamines,[172] ammonium hydroxide11731 and guanidines have been grafted onto MTS surfaces through direct... 

The brush-type of CSP was introduced by Pirkle who was one of the pioneers of modern enantioselective liquid chromatography [55]. The most frequently used 7i-acceptor phases are derived from the amino acids phenylglycine (DNBPG) (Fig. 6.8) or leucine (DNBLeu) covalently or ionically bonded to 3-aminopropyl silica gel [56, 57]. These CSPs are commercially available for analytical or preparative separation of enantiomers. Further CSPs based on amino acid or amine chiral selectors such as valine, phenylalanine, tyrosine [58] and l,2-tr s-diaminocyclohexane (DACH-DNB phase) [59] and 1,2-traus-diphenylethylene diamine (ULMO phase) [60] were also developed (Fig. 6.8). These CSPs have been applied for the preparative separation of the enantiomers of a few racemic compounds, but the number of reported preparative applications has remained very limited over the last 10 years. 

Silica-gel bound organic bases, such as diamines, ammonium hydroxide, guanidines and 4-methylpyridine, have become of interest in recent years. The best advantage of these silica-gel bound organic bases is that they can be reused for... 

CHEMICAL PROPERTIES Polymerizes to solid in light usually contains a polymerization prohibitor such as hydroquinone or diphenylamine incompatible with acids, bases, silica gel, alumina, oxidizers, peroxides, ozone, 2-amino ethanol, chlorosulfonic acid, ethylene-diamine and heat FP (-8°C) LFL (2.6%) UFL (13.4%) AT (426°C) HC (-9754 Btu/lb). 

Besides styrene, MMA, BA, or their copolymers, and also less commonly used polymers such as poly(styrenesulfonic acid) (PSSA), poly (hydroxyethylmethacrylate) (PHEMA), poly(aminoethylmethacrylate) PAEMA [111], polyethylene (PE) [112], or polyamides [113], were used for the encapsulation of the silica, as reported in the literature. Polyethylene [112] could also be obtained as encapsulating polymer if a nickel-based catalyst which is dispersed in the aqueous continuous phase is used. Here, lentil-shaped hybrid particles with semicrystalline polyethylene or isotropic hybrid particles with amorphous polyethylene are detected. Silica/polyamide hybrid nanoparticles were synthesized by miniemulsifying a dispersion consisting of 3-aminopropyl triethoxysilane (APS) modified silica particles and sebacoylchloride [113] in an aqueous continuous phase where hexamethylene diamine is dropwise added. 

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