Do Aromatics Form Hydrogen Bonds

Whether aromatics can act as H bonding bases has great practical as well as theoretical interest. There have been many experimental studies of H bonding substances dissolved in benzene with the apparent implication that the solvent is considered inert. The theoretical interest stems from the proposal that the H bonding base need not be a highly electronegative atom. 

Of course, H bonding affects band intensities and band widths as well as frequencies. The measurements of the IR spectral properties of a variety of H bonding systems by Huggins and Pimentel are informative (979). Their work shows that benzene, though quite a weak base, has behavior which correlates very well with the criteria for well recognized H bonding systems. Additional data which show that the characteristic intensification of results from interaction with the aromatics is provided by the CDCU-aromatic systems (980). 

There are numerous types of data indicating association of some type which could be H bonding. Solubility data for HCl in aromatics (298) and H2O in benzene (1935) reveal association, as do freezing point dia- 

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