Organic solid phase

Miscellaneous organics Solid phase extraction coupled to GLC [472]... 

Application of gel phase NMR to organic solid phase synthesis was first reported by Manatt in 1980 (12). Jones and Leznoff extended this work to show that13 C NMR data could be obtained from polystyrene-supported pheromones and a wide variety of organic substrates (13). The application of 13C gel phase NMR to the study of functional group interconversion of polymer-bound steroids has also been reported (14). High-resolution H gel phase NMR has been reported for an octapeptide (15). The NMR data were obtained by use of a deconvolution method to enhance the spectral resolution. 

Organic Solids. - Phase behaviour and dynamics in ethylammonium halide salts have been studied by Ratcliffe. and NMR spin-lattice... 

The recent interest in organic solid phase synthesis, triggered by the advent of chemical combinatorial methods (1-7), also accelerated methodology development. Simplification of chemical protocols, their robustness, and amenability to handling large arrays of compounds, prepared by combinatorial/ parallel solid phase synthesis, is one area that witnessed numerous novel contributions. This chapter describes an apparatus and method for gaseous cleavage of compounds from solid phase supports. 

Quantitative studies of solid-state organic reactions were performed by Glazman (267. 268). Equal amounts of acetic anhydride and 2-aminothiazole (grain diameter 0.15 mm) were mixed for 20 rain, and the mixture was heated in a glycerol bath at 0.5°C per minute. Heating curves showed that the reaction starts in the solid phase the use of an eutectic composition of organic reactants increases the yields. 

Memfield s concept of a solid phase method for peptide synthesis and his devel opment of methods for carrying it out set the stage for an entirely new way to do chem ical reactions Solid phase synthesis has been extended to include numerous other classes of compounds and has helped spawn a whole new field called combinatorial chemistry Combinatorial synthesis allows a chemist using solid phase techniques to prepare hun dreds of related compounds (called libraries) at a time It is one of the most active areas of organic synthesis especially m the pharmaceutical industry... 

Solid-phase microextractions also have been developed. In one approach, a fused silica fiber is placed inside a syringe needle. The fiber, which is coated with a thin organic film, such as poly(dimethyl siloxane), is lowered into the sample by depressing a plunger and exposed to the sample for a predetermined time. The fiber is then withdrawn into the needle and transferred to a gas chromatograph for analysis. 

In gas-solid extractions the sample is passed through a container packed with a solid adsorbent. One example of the application of gas-solid extraction is in the analysis of organic compounds for carbon and hydrogen. The sample is combusted in a flowing stream of O2, and the gaseous combustion products are passed through a series of solid-phase adsorbents that remove the CO2 and 1T20. 

Volatile analytes can be separated from a nonvolatile matrix using any of the extraction techniques described in Ghapter 7. Fiquid-liquid extractions, in which analytes are extracted from an aqueous matrix into methylene chloride or other organic solvent, are commonly used. Solid-phase extractions also are used to remove unwanted matrix constituents. 

THE SOLID-PHASE REAGENTS FOR THE DETERMINATION OF PHOSPHORUS AND ORGANIC REDUCTANTS... 

Unloaded silica does not recover HPA from aqueous solution. The surface of silica gel modified with quarternary ammonium salts (QAS) gets anion-exchange properties. The aim of the work is the elaboration of solid-phase reagents on the base of ion associate of HPA with QAS immobilized onto silica surface for the determination of phosphoms and organic reductants. Heterocyclic (safranine and lucigenine) and aliphatic (trinonyloctadecyl ammonium iodide and tetradecyl ammonium nitrate) compounds have been examined as QAS. 

In recent years the solid-phase hydrosilylation reaction was successfully employed for synthesis of hydrolytically stable surface chemical compounds with Si-C bonds. Of special interest is application of this method for attachment of functional olefins, in particular of acrolein and some chiral ligands. Such matrices can be used for subsequent immobilization of a wide range of amine-containing organic reagents and in chiral chromatography. 

SOLID-PHASE EXTRACTION IN DETERMINATION OF ORGANIC COMPOUNDS IN WATER BY GC-MS Milyukin M.V. 

Prepai ative isolation of nonvolatile and semivolatile organic compounds fractions (hydrophobic weak acids, hydrophobic weak bases, hydrophobic neutrals, humic and fulvic acids) from natural and drinking waters in optimal conditions was systematically investigated by solid-phase extraction method with porous polymer sorbents followed by isolation from general concentrate of antropogenic and/or toxic semivolatile compounds produced in chlorination and ozonation processes. 

In recent decades the development of preconcentration steps to be implemented prior to analytical determinations of trace level compounds has been explored in considerable depth. With a view to eliminating or at least minimising the use of organic solvents used in conventional liquid-liquid extraction, other methodologies have been developed, such as membrane extraction, solid-phase extraction, solid-phase microextraction, etc. 

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