Hydrogen bonding and the phenolic hydroxyl group

The hydrogen bond is an electrostatic interaction between a hydrogen atom bound to an electronegative atom such as oxygen, fluorine or nitrogen, and the free electrons of other atoms. An actual covalent bond is not possible, because that would result in the presence of more than two electrons in the orbital around the hydrogen atom. 

The proton of the hydroxyl group of phenol is an ideal candidate for hydrogen bonding. Shown below (2.7) are three phenol molecules, with the hydrogen bonds indicated by dotted lines. 

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