Intramolecular effects hydrogen bonding cooperativity

It has been pointed out321-324 that the two groups of solvents differ by some definite structural features. In particular, ED, 1,2-BD, and 1,3-BD possess vicinal OH groups that can form intramolecular hydrogen bonds. For these solvents, the ability of the organic molecule to interact with neighboring molecules is reduced. This results in the possibility of a different orientation at the interface because of different interactions of the OH groups with the Hg surface.323 The different molecular structure leads to different dipolar cooperative effects. As a result, the dependence of C on the bulk permittivity follows two different linear dependencies. 

In 1959, Eberson (1959, 1992) found that a family of derivatives of succinic acid shows a remarkably large negative cooperativity, i.e., gjj < < 1, which is difficult to explain on the basis of electrostatic theories only. We shall discuss these compounds in Subsection 4.8.6. At present, there is no satisfactory molecular interpretation of these findings. One of the more popular ideas, originally suggested by Jones and Soper (1936) and further elaborated upon by McDaniel and Brown (1953), is that an intramolecular hydrogen bond would facilitate the first dissociation of the proton, i.e., Kj becomes smaller (or Kj becomes larger). Also, the second proton will dissociate with more difficulty. The net effect would be a... 

Berthelot and colleagues have estimated the pATes values of the phenohc OH group in the intramolecular hydrogen-bonded systems 1, 2 and 3. The higher basicity pATes of 1 and 2 compared to phenol (—0.07) can be explained by cooperative effects involved in hydrogen-bond formation the oxygen electron pairs are more basic in OH- B than in the free OH group . The push-puU effect shown by the curved arrows in 3 opposes the cooperativity effect and pATes falls. 

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. 

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