Synthetic complex method

For multi-component systems the composition of the equilibrium sohd phase may be determined indirectly by the so-called wet residues method first proposed by Schreinemakers (1893) in which the need for solid-liquid separation by filtration, etc. is avoided. The experimental procedures, together with those of the alternative synthetic complex method, are fully described in section 4.6.5. 

Purdon and Slater (1946) give good accounts of the practical difficulties that may be encountered in applying both the wet-residues and synthetic complex methods of solid phase analysis. 

Only a few isolated allene oxides have been synthesized from allenes and characterized. Most often peracids are used but the oxidative and acidic conditions usually result in a complex mixture of products. To overcome this problem, dimethyldioxirane (DMDO) can be used, which rapidly oxidizes allenes to spirodiepoxides. Several synthetically useful methods have been developed via in situ reaction of the intermediate allene oxide or spirodioxide with different nucleophiles. 

The most usual synthetic routes to the derivatives of platinum group metals are the exchange reactions of the complexes containing halide ligands with alkali metal alkoxides (method 5), alcoholysis of the same kind derivatives (usually by phenols, method 4), alcoholysis of hydroxide complexes (method 3), and redox reactions — reduction of chlorides or 0s04 in alcohol media (method 7) (Table 12.25). 

The reductive fluorophosphination of metal halides in the presence of copper and hydrogen gas at high temperature and pressure offers a useful synthetic route for a number of hydrido trifluorophosphine metal complexes (method A). 

Other synthetic routes reported involve the interactions of trifluoro-phosphine metallates and iodine (method E), displacement of carbon monoxide, alkenes, etc. by PF3 from the corresponding halide complexes (method F), addition of PF3 to dinuclear halogeno-bridged PF3 complexes at low temperatures (method G), and treatment of a metal hydrido- PF3 complex with iodoform (method H). 

Other synthetic routes to alkene-metal complexes reported in the literature involve bridge cleavage reactions of halogeno complexes (method F), facile intermolecular scrambling reactions involving metal-alkene and metal-PF3 complexes (18, 81) (method G) (Scheme 4), and the coupling together of two alkyne units to afford a metallo-cyclopentadiene derivative (method H). 

A useful general synthetic approach involves the insertion of allene or dienes into the metal-hydrogen bond of transition metal hydrido-trifluorophosphine complexes (method C). 

A fairly general synthetic route involves the PF3-induced displacement of ligands such as dienes and phosphines coordinated to metal allyl complexes (method F), and it has also been possible in certain complexes to interconvert /3-allyl-metal-PF3 complexes by an intramolecular thermal rearrangement (method G). 

Direct addition of PF3 to 5-pentadienyl metal complexes offers an alternative synthetic route (method G) and this has been reported in the case of the formation of bis(2,4-dimethylpentadienyl)trifluoro-phosphine complexes of titanium and vanadium [M(C7H11)2PF3] (M = Ti, V) (Scheme 11) 111). 

A useful synthetic route to specific carbonyl-PF3 transition metal complexes (method C) involves displacement of relatively weakly bound ligands such as ammonia, iodide ion, or unsaturated organic ligands (e.g., dienes, arenes) from suitable metal carbonyl complexes. 

Substitution of CO in the perfluoroalkyl metal carbonyl derivative provides a synthetic route to perfluoroalkyl mixed-carbonyl trifluoro-phosphine metal complexes (method D). 

Many of the simple mono- and polyamines are commercially available, but designer specific ligands require the use of conventional organic synthetic techniques. Methods of amine complex synthesis are usually central-metal specific, but summaries of procedures used for Cr n8,9 are... 

In Section 8.2, the aim of analysis is emphasized especially for the API (active pharmaceutical ingredient) and the drug product. The workflows and the rationale at major decision points during synthetic processing steps where HPLC can be applied in process development are elaborated upon. For example, a fast method is needed to monitor reaction conversion of two components. However, a more complex method would be needed for stability-indicating purposes where multiple degradation products, synthetic by-products, and excipient peaks need to be resolved from the active pharmaceutical ingredient. 

The recent and continuing surge of interest in transition-metal complexes of o ,/3-unsaturated /3-keto amines (/3-amino ketones), especially with respect to their stereochemical properties, has resulted in increased efforts to secure general synthetic procedures for these complexes. Methods of preparation of these complexes have been reviewed recently. Although most of... 

Besides rearrangements, ligand exchange, formation of alkanes, alkenes and other products, release of cyclopropanes is one of the most important reactions of metallacyclobutanes. Of course, this latter reaction is only useful in cyclopropane synthesis if the product is not identical with the starting material used to form the metallacyclobutane. Nevertheless, the discovery of a complex formed from hexachloroplatinic acid and cyclopropane and later structural elucidations have initiated intensive investigations on the conversion of cyclopropanes to metallacyclobutanes and release of cyclopropanes from the latter. These results have been thoroughly discussed in several reviews. " Therefore in this section only some general aspects of cyclopropane formation from metallacyclobutanes and selected synthetically useful methods are discussed. 

The designation of a synthetic zeolite as a separate species must be based on characteristic properties (20). The characterization and classification of synthetic zeolites have been hindered by the lack of a systematic chemical method for naming synthetic, complex aluminosilicates. At present, we have followed the historical "Law of Priority and have... 

Post-synthetic modification methods (route A in Figure 36.2) rely on the presence of silanol groups on the inside of the pore walls. The simplest type of post-synthetic modification is the hydrophobization of the calcined mesoporous materials by reaction with alkylchloro- or alkylalkoxy-silanes, - " but functional groups and metal complexes can also be attached. - " ... 

Pd-catalyzed reactions of various allylic compounds via the formation of tt-allylpalladium complexes offer many synthetically useful methods. The following allylic compounds are known to form 7r-allylpalladium complexes by oxidative addition. 

Resolvation may precede the preparation of polymer-immobiUzed nanoparticles. For example, the cryochemical synthesis of colloidal Ag particles is performed in acetone, which is then replaced by formamide. This dispersion is stable for a few days. The system Ag (2-5 nm) formamide is used as a solvent in the preparation of crosslinked polyacrylamide gel. Three dilferent synthetic resolvation methods are documented. In the first version, a Co-nonadecane system obtained by the cryochemical method was mixed with a solution of a polymer in nonadecane with subsequent sonication. In the second version, the nanoparticles of Co or Ni in toluene were added to a solution of low-pressure polyethylene (LPPE) in toluene at 363K. The third variant employs a toluene polymer solution cooled fi om 383K to 185K. The resulting gel-like system was mixed with nanoparticles obtained cryochemically and subjected to sonication. These techniques make it possible to virtually preclude the aggregation of particles at aU intermediate stages. However, along with the peptization and resolvation, more complex interactions of nanoparticles with the solvent may take place. 

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