Homogeneous synthesis

A similar reservation applies to the need to remove ligand precursors or byproducts from the support. This is a particular issue in relation to intrazeolite com-plexation reactions in which the corresponding homogeneous synthesis is less than quantitative. Another difficulty relates to estabUshing the efficacy of ligand synthesis within a zeoUte. Thus, for example, although several reports of the syntheses of metal porphyrin complexes within zeolites have appeared, the ligands are, in fact, domed porphodimethenes (diameter -14 A), or protoporphyrins [138,... 

A series of original synthesis strategies has been also reported recently such as flow-through reactors for the homogeneous synthesis of zeolite membranes [77], centrifugal force field [114] or electrophoresis [115] for the preparation of A-type membranes, and pulse laser deposition (PLD) for the secondary growth of oriented MCM-22 membranes [116]. 

SCHEME 13.9 Homogeneous synthesis of graft copolymers by a-cleavage type photoinitiation. 

In-situ DRS spectroscopy has been used to investigate the crystallization process of MeAPO-5 molecular sieves (with Me = Co, Cr, Ni and V) as a function of the synthesis time and conditions. A specially developed synthesis cell was used, which allows to probe the coordination environment of the transition metal ions in-situ during hydrothermal conditions and to obtain high-quality molecular sieves starting from a homogeneous synthesis gel. 

Cao, Y.L. Zhang, H.Q.J. Homogeneous synthesis and characterization of cellulose acetate butyrate (CAB) in l-aUyl-3- methylimidazolium chloride (AmimCl) ionic liquid. Ind. Eng. Chem. Res. 2004,50 (13), 7808-7814. 

K. Rahn, M. Diarrrantoglou, D. Klemm, H. Berghmans, T. Heinze, Homogeneous synthesis of cellulose p-toluenesulfonates in N,N-dimethylacetamide/IiQ solvent system. Die Angew. Makromolek. Chem. 238 (1) (1996) 143-163. 

DeSimone and coworkers were the first to report the homogeneous synthesis of fluorinated telomers in SC-CO2 (Scheme 9.3) [27, 28]. Most conventional telomerization reactions are carried out in bulk because of the insolubility of fluoro-polymers in all organic solvents other than CFCs. 

The acylation of cellulose with acid chlorides in DMA/LiCl is most suitable for the homogeneous synthesis of readily soluble partially functionalized long-chain aliphatic esters and substituted acetic acid esters (Table 16.3). In contrast to the anhydrides, the fatty acid chlorides are soluble in the reaction mixture and soluble polysaccharide esters may be formed with a very high efficiency. Even in the case of stearoyl chloride, 79 per cent of the reagent is consumed for the esterification of cellulose. 

Rahn K., Diamantoglou M., Klemm D., Beighmans H., Heinze T, Homogeneous synthesis of cellulose p-toluenesulfonates in JVA -dimethylacetamide/LiQ solvent system, Angew. Makromol. Chem., 238, 1996,143-163. 

Camacho Gomez J.A., Erler U.W., Klemm D.O., 4-Methoxy substituted trityl groups in 6-0 protection of cellulose Homogeneous synthesis, characterization, detritylation, Macromol. Chem. Phys., 197, 1996, 953—964. 

Mechanisms. Various mechanisms for homogeneous synthesis of stereoregular polyvinyl alkyl ethers have been proposed by Higashimura et al. (1959), Cram and Kopecky (1959), and Bawn... 

The interfacial synthesis compares favorably with the conventional homogeneous synthesis that makes use of solvents such as pyridine, nitroboizene, chlorobenzene, or mixtures of organic amines with toluene (1-3,9-12). The formation rate, yield, and molecular weight of the polymer product are all comparable to that of the conventional homogeneous synthesis. 

Eaton et al. [31] proposed a mixture of methanesulfonic acid (MSA) and phosphorus pentoxide (P2O5) as the solvent for the homogeneous synthesis instead of PPA. This MS A-P2O5 mixture was afterwards employed to synthesize... 

In contrast to classical homogeneous synthesis, reactions can also be carried out on or in insoluble support materials. These support materials might be inorganic silica particles or organic polymers. The physical properties of the solid support materials and the possible applications vary according to the material from which... 

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