While not as sophisticated as spectroscopic measurements, refractometry can provide a degree of insight into the molecular organization of a liquid. This information is beneficial for solutions that deviate from ideal behavior due to intermolecular forces such as hydrogen bonding. Refractive index measurements offer an expedient means to probe the temperature and concentration dependence of solutions where at least one of the components can self-associate. To explore the effects of temperature, composition, and hydroxyl position on the extent of hydrogen bonding, we performed measurements on binary solutions of 1-heptanol, 2-heptanol, 1-octanol, and 3-octanol in cyclohexane at four temperatures. Experimental results are compared with non-hydrogen-bonding ethers (homomorph) as well as the theoretical predictions of the Lorentz-Lorenz expression. Our findings suggest that larger refractive index values correlate with a higher degree of association within a particular chain length.

Review of molecular association using refractometry

ACS Spring 2022

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