Reorganization of hydrogen bonds

Lefevre N, Fustin C-A, Gohy J-F. Reorganization of hydrogen-bonded block copolymer complexes. Langmuir 2007 23(8) ... 

In an ene reaction, there is a transfer of the allylic hydrogen and subsequent reorganization of the bonding. An example of an ene reaction is the addition of ethene (the enophile) to propene (the ene), thereby producing 1-pentene ... 

Generally, the formation of hydrogen-bonded complexes is regarded as a very fast, diffusion-controlled process with no energy barrier. On the other hand, even ultrafast molecular reorientations in solution require energy for reorganization of... 

The most inclnsive definition of hydration shell describes it as consisting of all thermodynamically altered water molecnles in the vicinity of a solnte. From a thermodynamic standpoint, hydration can be viewed as binding of water molecnles to the hydration sites of a solnte. The energetics of this association is modulated by the type of solute-solvent interactions (electrostatic, hydrogen bonding, van der Waals) and by solnte-indnced solvent reorganization. The latter occnrs even in the absence of appreciable solute-solvent interactions becanse the eqnUib-rium distribution of hydrogen-bonded water networks of the bulk becomes disrupted at the solute surface. 

Ene reaction is a classic example of group transfer reactions. It involves the addition of a compound with a double bond having an allylic hydrogen (the ene ) to a compound with a multiple bond (the enophile ) with transfer of the allylic hydrogen and a concomitant reorganization of the bonding, as illustrated in Scheme 6.10. 

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