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Intramolecular hydrogen bonding, effect

Kim YH, Cho DW, Yoon M, Kim D (1996) Observation of hydrogen-bonding effects on twisted intramolecular charge transfer of p-(N, N-diethylamino) benzoic acid in aqueous cyclodextrin solutions. J Phys Chem 100(39) 15670-15676... [Pg.307]

There are numerous other transmission mechanisms for substituent effects. Those connected with unsaturated frameworks, such as mesomeric effects and correlations with it charge densities and Hammett-type reactivity constants, and intramolecular hydrogen-bonding effects are beyond the scope of this article and are discussed elsewhere (1,8,25,57). [Pg.230]

Rates of reaction between acids and hydroxyl ions are found to follow a similar pattern to rates of reaction between bases and hydrogen ions, in that they are diffusion-controlled on condition that the bond being formed is stronger than the bond being broken, and there are no complicating factors. Variations in the rate coefficients can be explained in terms of steric effects, ionic charge effects, solvent structure effects and intramolecular hydrogen-bond effects. A short list of rate coefficients for... [Pg.211]

For phenolic oxygens the picture is as seen for 15 (see above) and 16. This shows a low frequency shift caused by hydrogen bonding. A similar picture is seen for intramolecularly hydrogen bonded nitro compounds. However, these data consist of both intra- and intermolecular hydrogen bonding effects as well as proximity effects. [Pg.340]

Hydrogen bonds and intramolecular interactions (electrostatic, van der Waals) stabilize the native structure of the protein in a co-operative manner. Upon denaturation, the co-operative effect is lost, resulting in tmfolding of the molecule and exposure of the inner hydrophobic core to the hydrophilic aqueous environment. For small globular proteins, denaturation is an almost all-or-none... [Pg.369]

Due to the involvement of nonbonded and lone electron pairs in n —> n intramolecular charge-transfer transitions, hydrogen-bonding effects play a major role in the appearances of these spectra. Dipolar effects are most pronounced in intramolecular charge-transfer spectra because of the large dipole-moment changes accompanying the associated transitions. [Pg.222]

Hydrogen-Bonding Effects. When intramolecular (internal) hydrogen bonding is present, the C=0 is shifted to a lower frequency, as predicted in Section 2.14A (p. 54) and shown in the spectrum of methyl salicylate (Fig. 2.51). [Pg.66]

Gattin, Z., Kovacevic, B. and Maksic, Z.B. (2005) Cooperative intramolecular hydrogen bonding effect and basicity - an ab initio and DFT study of the superbasic properties of N-[(dimethylamino)alkyl]-2,3-diaminocycloprop-2-ene-l-imines. European Journal of Organic Chemistry, 3206-3213. [Pg.319]

Similarly, enone 38 has been shown to undergo ketone-directed epoxidation when treated with MCPBA to give exclusively the syn epoxyketone 40. As for the mechanism, hydrogen bonding effects were discounted on the basis of solvent insensitivity. Intramolecular attack by some oxidized form of the ketone moiety could be operative, although labelling studies have ruled out a dioxitane intermediate as... [Pg.49]

Panda SS, Oliferenko AA, Marwani HM, Katritzky AR (2014) Effects of preorganization and hydrogen bonding on intramolecular chemical ligation of (A)- and (O)-acyl isopeptides. Mendeleev Commun 24 75-77... [Pg.266]

Intermolecular and/or intramolecular hydrogen bonding effects are shown by most amines under suitable conditions. As with the hydroxyl group, no attempt will be made to review all the work — especially in the overtone region — which has been carried out in this connection, as a number of excellent reviews already exist [25, 26, 62], but a general indication of the conditions under which frequency shifts may be expected, and of the extent to which they are likely to occur, is given below. [Pg.283]


See other pages where Intramolecular hydrogen bonding, effect is mentioned: [Pg.160]    [Pg.103]    [Pg.144]    [Pg.132]    [Pg.413]    [Pg.157]    [Pg.68]    [Pg.69]    [Pg.151]    [Pg.24]    [Pg.211]    [Pg.89]    [Pg.15]    [Pg.351]    [Pg.444]    [Pg.369]    [Pg.384]    [Pg.177]    [Pg.117]    [Pg.272]    [Pg.322]    [Pg.54]    [Pg.276]    [Pg.120]    [Pg.3]    [Pg.234]    [Pg.230]    [Pg.214]    [Pg.316]    [Pg.4865]    [Pg.279]    [Pg.56]   
See also in sourсe #XX -- [ Pg.230 ]




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