Question

During the steam distillation between citral and lemon grass oil, what effects will make the percentage of recovery higher and lower than expected? Please let me know in detailed!!!

Answer 1

Answer: Using steam distillation technique can be used in the following cases:

a) when two liquids have different boiling point

b) when we need to separate the slightly volatile water insoluble liquid from non volatile liquids

The second case is for citral. Citral is hydrophobic molecule because of presence of the alkyl chain. During steam distillation, when water will start boiling some amount of oil will come with the water vapour and will gather in the condensate. Thus in order to extract more citral time of boiling will matter. After sufficient boiling the condensate should be taken in a separationg funnel. As citral is hydrophobic this will from a separate layer with water. After sepation of citral from condensate, DCM can be added to water layer and then the separating funnel is shaken vigorously. The DCM layer containing citral will separate out. Again collect it. Then in that collected citral some amount of sodium sulfate can be added to remove water.

Thus by boiling the lemongrass oil a little longer time and proper separation of the oil-water of the condensate using separating funnel can increase the yield of citral from lemon grass oil.