Strong or Weak Hydrogen Bonds

The effect of a solvent in a particular reaction cannot, however, be related simply to the dipole moment or the dielectric constant (Section II,A,3). Special properties, such as the ability to form strong or weak hydrogen bonds and steric considerations in the formation of solvates, also play a part. Displacement of the bond polarity is closely linked with solvation and this, coupled with the blocking of the potential sites for reaction by solvate molecules, is the basic cause of the effect on the reaction. In this connection, spectroscopic properties of the solvent are more revealing than the value of the dipole moment or dielectric constant. Thus the charge... 

Molecular alignment in the monomer crystals is controlled by several intermolecular interactions, such as strong and weak hydrogen bonds, leading to the formation of various types of stereoregular polymers via a topochemical polymerization process. This approach to the stereocontrol of polymers differs from other conventional ways in the control of the propagating chain end using catalysts or additives in solution polymerization. 

Strong and weak hydrogen bonds have very different properties. A case can be made for the view that strong hydrogen bonds are quantitatively different in most of their properties from moderate or weak bonds [49]. 

Thble 2.2. Properties of very strong and "normal or weak hydrogen bonds... 

Strong and normal (or weak) hydrogen bonds have very different properties (Table 2). With very strong hydrogen bonds A-H B, such as F — H F , the structural distinction... 

Table 2 Properties of Veary Strong and Normal or Weak Hydrogen Bonds...

Once m the organic phase cyanide ion is only weakly solvated and is far more reactive than It IS m water or ethanol where it is strongly solvated by hydrogen bonding Nude ophilic substitution takes place rapidly... 

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