The Polarity of 1-Propanol and Its Effect on Organic Systems

1-Propanol is a clear, colorless liquid with an alcoholic odor and a characteristic ripe, fruity flavor. It is soluble in water and miscible with organic solvents (Propanols). It has better dissolution properties than ethanol for fats and oils, and dissolves polar resins in the same way as ethanol. Cellulose nitrate and poly(vinyl acetate) are, however, almost insoluble. For economic reasons propanol is of only limited use as a solvent, and is a starting material for esters.

The oxygen atom has an electronegativity of 3.44 on the Pauling scale whilst the hydrogen that it is covalently bonded to it has an electronegativity of only 2.20 on the Pauling scale. Therefore as the oxygen is so much more electronegative than the hydrogen it will attract the bonding pair of electrons in the O-H bond towards it. This will give the oxygen atom a partial negative charge and the hydrogen atom a partial positive charge. This polarises the 1-propanol molecule. 2-propanol just has it's hydroxyl (OH) group on the middle carbon atom in the chain. This will cause 2-propanol to also be polar.

Vapor-liquid equilibrium data are presented by Khalid Farhod Chasib Al-Jiboury for the binary systems n-hexane - 1-propanol, benzene - 1-propanol and n-hexane – benzene at 760 mm of mercury pressure. In addition ternary data are presented at selected compositions with respect to the 1-propanol in the 1-propanol, benzene, n-hexane system at 760 mmHg. The results indicate the relative volatility of n-hexane relative to benzene increases appreciably with addition of 1-propanol^[1].

Reference

[1] Effect Of Polar Component(1-Propanol) On The Relative Volatility Of The Binary System N-Hexane - Benzene. Al-Khwarizmi Engineering Journal, 4(1), 8–16.