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Chaotropic agent
Introduction
A chaotropic agent is an agent which causes molecular structure to be disrupted; in particular, those formed by noncovalent forces such as hydrogen bonding, Van der Waals interactions, and the hydrophobic effect. Often structural features, as detected by means such as circular dichroism can be titrated in a chaotrope concentration-dependent fashion.
The most commonly used chaotropes are 6~8M urea and 6M guanidinium chloride, with urea being a noncharged molecule and guanidinium chloride being a hydrochloride salt.
High generic salts can have chaotropic properties, by shielding charges and preventing the stabilization of salt bridges. Hydrogen bonding is stronger in nonpolar media, so salts, which increase the dipole moment of the solvent, can also destabilize hydrogen bonding.