Refractive properties of imidazolium ionic liquids with alanine anion [C n mim][Ala] ( n = 2, 3, 4, 5, 6)

Imidazolium ionic liquids with alanine anion, [C n mim][Ala] ( n = 2, 3, 4, 5, 6), were prepared and characterized. The standard addition method was used to measure refractivity of the synthesized ionic liquids in order to eliminate the effect of water traces in the ionic liquids. The molar refraction and molecular polarizability were also calculated by Lorentz–Lorenz’s method. Using liner extrapolation, the semiempirical estimation method for optical properties of other ionic liquids with amino acid anions was established.