Kinetics of thermal racemization of (2S,3S)-1-13C-1,2,3-d3-cyclopropane followed by vibrational circular dichroism spectroscopy
Article Abstract:
Kinetics and mechanism of the formation and dissociation of a series of (2)pseudorotaxanes which have the alpha-cyclodextrin as the cyclic component have been determined. The length of the polymethylene chain of the thread has a small effect on the rate constant for pseudorotaxane formation. It is important, however, in the kinetics of dissociation reactions. Longer, more hydrophobic chains mean slower pseudorotaxane dissociation. Enthalpies and entropies of activation for formation/dissociation of the (2)pseudorotaxanes go down as size and hydrophobicity of end groups go up. Thus it seems desolvation of the quaternized atoms in the threading/dethreading has a reduced role.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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On the relationship between the rate constants for racemization and isotopic exchange
Article Abstract:
The valid relationship of the rate constants that characterize halide ion catalysis of racemization of optically alkyl halides and the isotopic halide exchange reaction that is related has been demonstrated for two cases. In one case the racemization and exchange mechanisms follow the classical and conventional SN2 path with a symmetrical trigonal transition state. In the other, the trigonal species considered characteristic of the SN2 reaction is seen as intermediate as opposed to a transition state.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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Skeletal vibrational circular dichroism of a series of bicyclic dilactones: the fingerprint region?
Article Abstract:
Skeletal vibrational circular dichroism (VCD) spectra of a series of bicyclic dilactones has been studied to see whether the fingerprint region is involved. VCD spectra analysis is based on operation of a couples oscillator mechanism that involves movement of polar bonds. For the parent dihydro system, bridgehead C-H bond activity seems to dominate the effects on the VCD of vibration transitions they combine with.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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