A 17.0 g amount of fraction II from above is subjected to a second very
slow distillation with the same equipment except for a longer Vigreux
column (30 cm).
Estimation of the purity of all fractions by 1H NMR shows that
fraction II was the richest in (4R)-(+)-limonene: >99% [α] 25
D +114.0°
(c 0.264 g/mL, ethanol).
For redistillation