Reaction complex-forming

Quack M 1979 Quantitative comparison between detailed (state selected) relative rate data and averaged (thermal) absolute rate data for complex forming reactions J. Phys. Chem. 83 150-8... 

In titrimetric analysis (often termed volumetric analysis in certain books), the substance to be determined is allowed to react with an appropriate reagent added as a standard solution, and the volume of solution needed for complete reaction is determined. The common types of reaction which are used in titrimetry are (a) neutralisation (acid-base) reactions (b) complex-forming reactions (c) precipitation reactions (d) oxidation-reduction reactions. 

The result of the complex forming reaction of the Mathey phosphole (46) is quite different as in this case, the predominant product is the bis(phosphole) complex with cis geometry. (Scheme 18) [62],... 

Complex-forming reactions find a wide utility in chemical analysis and have been used in titrimetric procedures for many years. Recently most attention has been concentrated on the use of ethylenediaminetetraacetic acid (EDTA) and consideration of this reagent in some detail is important. This study will also be useful in that it illustrates nearly all aspects of the use of inorganic and organic complexing agents in titrimetry. 

Generally, there are two approaches to the investigation of mixed adsorbed films at an oil/water interface. One way is to study mixed adsorption of surfactants from the Scime bulk phase and the other is to study adsorption from both of the bulk phases. The former has been done by many workers from the physicochemical viewpoint to clarify the difference in molecular interaction between the adsorbed state and the bulk state. The latter has been made mostly from the practical point of view, e.g., solvent extraction and complex-forming reactions that take place at the interface, though little is known concerning the thermodynamic viewpoint D). The thermodynamic study is actually useful to elucidate the behavior of film molecules in the adsorbed state. 

Complexes of maltose with urea, thiourea, imidazole, methanol, 2-oxazolidinone, N,N-dimethylformamide, and hexamethylphosphoric triamide have been described.131 These complexes were noncrystalline and hygroscopic. Such complex-forming reactions could be valuable in the preservation of food flavors during the dehydration process. Sugars have been shown to complex with ethylenediamine.133,133 The nature of the complex has been suggested to be that of a proton-transfer type, in which the carbohydrate moiety is the proton donor and the amine is the proton acceptor. 

Complexes of alkali metals and alkaline-earth metals with carbohydrates have been reviewed in this Series,134 and the interaction of alkaline-earth metals with maltose has been described.135 Standard procedures for the preparation of adducts of D-glucose and maltose with the hydroxides of barium, calcium, and strontium have been established. The medium most suitable for the preparation of the adduct was found to be 80% methanol. It is of interest that the composition of the adducts, from D-glucose, maltose, sucrose, and a,a-trehalose was the same, namely, 1 1, in all cases. The value of such complex-forming reactions in the recovery of metals from industrial wastes has been recognized. Metal hydroxide-sugar complexes may also play an important biological role in the transport of metal hydroxides across cell membranes. 

Table 1 Complex-forming Reactions Heats of Selected Boranes...

Among the chemical properties of heteroaromatic compounds, complexforming reactions are important. However, they have been described incompletely (96MI1 97AHC). Complex-forming reactions have been presented in thousands of papers. Their account is beyond the limits of this review. Other reviews are devoted both to the general problems of the... 

Calorimetric measurements (42) have shown that the complex-forming reaction, which involves the dissociation of 1—2 protons (37, 43), is in fact associated with an enthalpy increase of about 8 kcal mole-1 at pH 7 (42). The stability is thus linked to an entropy increase of the order 80 cal deg-1 mole-1 at pH 7. 

Rate of complex formation between chiral alcohols and DBTA monohydrate in hexane suspension is quite slow (see Figure 1) and numerous separation steps are necessarry for isolation of the alcohol isomers (filtration of the diastereoisomeric complex then concentration of the solution, decomposition of the complex, separation of the resolving agent and the enantiomer, distillation of the product). To avoid these problems, alternative methods have been developed for complex forming resolution of secondary alcohols. In a very first example of solid phase one pot resolution [40] the number of separation steps was decreased radically. Another novel method [41] let us to increase the rate of complex forming reaction in melt. Finally, first examples of the application of supercritical fluids for enantiomer separation from a mixture of diastereoisomeric complexes and free enantiomers [42, 43] are discussed in this subchapter. 

It is also possible that PolyPs in cells may be combined with other compounds, including polysaccharides, such as polyhexamines and chitin. PolyPs were shown to form complexes with polysaccharides of the cell wall of N. crassa, in vitro (Harold and Miller, 1961). The complex-forming reaction depended on both pH and the PolyP chain length. 

This rather elaborate collection of synthetic routes leading to supra-Cp systems is also intended to provide the reader with some potential solutions for problems he or she might have in designing bulky Cp s. In addition to the substituted cyclopentadiene hydrocarbons whose syntheses are outlined above, the respective bromo-Cp s are also ligand precursors of considerable utility for Cp-metal complex-forming reactions (see Section III and... 

The title reaction is also of considerable interest to combustion [48] and laser chemistries [49]. Theoretically it is one of the best known complex-forming reactions from a fundamental point of view [50]. 

In contrast to Baker s mechanism, Ephraim and co-workers assume the formation of three complexes (1) between two alcohol molecules, (2) between alcohol and the solvent, and (3) between the alcohol and the urethane. Each of these complexes then is thought of being capable of reacting with the isocyanate leading to the formation of the urethane and the complex forming reaction partner according to the following reaction steps ... 

The reaction of trimethyl[(phenylsulfonyl)methyl]silane with 2 mole of n-BuLi, in the presence of Li20 yields the dilithiosulfone derivative, reaction (b). The reaction is conducted at — 90°C, with subsequent warming to 25 C. In the absence of Li20, the tetrameric complex forms [reaction (c)]. Both these derivatives have been structurally characterized. 

Fig. 22.16 Representative complex-forming reactions starting from [OsClg]. Note that reduction to Os(III) occurs in three reactions, and to Os(II) in one. See Table 6.7 and structure 19.23 for ligand abbreviations.

Various other complex-forming reactions have also been investigated using the trajectory method. For instance, the effect of translational energy on the interhalogen reaction F + IC1 has been addressed (92). Complex formation in the Br + I2 reaction has been studied both by simulations and experiment (93). The differential cross section was the chief focus of a study of the reaction Cl + ICH3 - C1I + CH3 (where the CH3... 

When evaluating the effects of complex-forming reactions on the properties of waters it is necessary to take into consideration their rate, for example with respect to the protolytic reactions. 

The problems of complex-forming reactions are solved either numerically or graphically. The distribution diagrams of complex-forming equilibria express the dependence of the distribution coefficient 6 on the ligand concentration. 

Knowing the diflBculties in the synthesis of porphine-like ligands, we expected that the synthesis of bisporphines would be no simple task but that it would also offer some synthetic rewards. The results exceeded our expectations in many respects except for the utility of the products in complex-forming reactions. We could synthesize compounds like 4 and 5... 

On redox- or complex-forming reaction with a solid-phase reactor, some drugs release a constituent metal to an extent proportional to the concentration of the drug in the sample. The released ion can thus be directly monitored, usually through AAS, or by using any other detector, after a chemical reaction. 

Compleximetric titrations are used mainly to determine metal ions by use of complex-forming reactions. Although in theory many complexing agents (cyanide, thiocyanate, fluoride, 1,2-diaminoethane, etc.) could be used for this purpose, in practice the titrants are almost always compounds having the iminodiacetic acid functional group ... 

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