Inclusion compounds kinetics

Podates AcycHc analogues of crown ethers /coronands and cryptands (podands, eg, (11) (30) are also capable of forming inclusion compounds (podates) with cations and uncharged organic molecules, the latter being endowed with a hydrogen bond fiinctionahty. Podates normally are less stable than coronates and cryptates but have favorable kinetics. 

Chiral Recognition. The use of chiral hosts to form diastereomeric inclusion compounds was mentioned above. But in some cases it is possible for a host to form an inclusion compound with one enantiomer of a racemic guest, but not the other. This is caUed chiral recognition. One enantiomer fits into the chiral host cavity, the other does not. More often, both diastereomers are formed, but one forms more rapidly than the other, so that if the guest is removed it is already partially resolved (this is a form of kinetic resolution, see category 6). An example is use of the chiral crown ether (53) partially to resolve the racemic amine salt (54). " When an aqueous solution of 54 was... 

Selectivity at formation of a respective inclusion compound and its thermal stability behavior might differ (cf. Tables 1 and 2), since for both representations different processes should be taken into consideration. Formation of a crystal inclusion compound is normally controlled by kinetics, whereas the thermal stability (decomposition property) is a result of thermodynamics. Thus, we speak of formation selectivity , on the one hand, and of binding selectivity , on the other. 

In contrast to the reactions of the cycloamyloses with esters of carboxylic acids and organophosphorus compounds, the rate of an organic reaction may, in some cases, be modified simply by inclusion of the reactant within the cycloamylose cavity. Noncovalent catalysis may be attributed to either (1) a microsolvent effect derived from the relatively apolar properties of the microscopic cycloamylose cavity or (2) a conformational effect derived from the geometrical requirements of the inclusion process. Kinetically, noncovalent catalysis may be characterized in the same way as covalent catalysis that is, /c2 once again represents the rate of all productive processes that occur within the inclusion complex, and Kd represents the equilibrium constant for dissociation of the complex. 

Hersey, A., Robinson, B. H., and Kelly, H. C. 1986. Mechanisms of inclusion-compound formation for binding of organic dyes, ions and surfactantsitoyclodextrin studied by kinetic methods based on competition experimentsJ. Chem. Soc. Faraday Trar 1271-1287. 

Liquid clathrates offer a great advantage over solid-state separations (e.g. by formation of Hoffman-type inclusion compounds, Section 9.4) because of the extremely fast mixing kinetics, the avoidance of the need to wait for crystallisation to occur and the easy separation of the two liquid phases. It should also prove possible to run liquid clathrate separations in a continuous extraction manner. The avalues of a number of liquid clathrate-based separations have been reported and are summarised in Table 13.1. 

Adsorption (Chemical Engineering) Catalyst Characterization Catalysis, Homogeneous Inclusion (Clathrate) Compounds Kinetics (Chemistry) Petroleum Refining Pharmaceuticals... 

F. Cramer, W. Saenger, H. C. Spatz, Inclusion compounds. XIX. The formation of inclusion compounds of a-cyclodextrin in aqueous solutions. Thermodynamics and kinetics, J. Am. Chem. Soc., 1967, 89, 14-20. 

Inclusion Compounds Selectivity, Thermal Stability, o7d Kinetics, p. 696 Macrocye Synthesis, p. 830... 

Inclusion Compounds Selectivity, Thermal Stability, and Kinetics, p. 696 Induced Fit. p. lYl Kinetics of Complexation, p. 774 Macrocycle Synthesis, p. 830 The Template Effect, p. 1493... 

Inclusion Compounds Selectivity, Thermal Stability, and Kinetics... 

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