Brazilian sweet orange oil (36 g) containing 90% of (R)-(+)-limonene
is subjected to fractional distillation in vacuo at 1000 Pa in the stream
of an electronically regulated heat gun with an outlet temperature of
120 °C. A 10 cm Vigreux column is used and the distillation is run ratherslowly.
The refractive index of the orange coloured starting material is
nD 1.4714 at 24 °C. Two cuts are made the mass of which is 27 g in total
(see table below). The distillation is then interrupted for safety reasons
although no increase in the boiling point is observable. The remaining
material has nD 1.4745 at 24 °C and a mass of 9 g. The two fractions
obtained are clear and colourless with an odour not as heavy in its citrus
fruit note as that of the starting oil.