Alkenes
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It's about extracting limonene from orange peel. Could you please tell me that after collecting 50 cm3 of distillate in a measuring cylinder, how a sample of pure dry limonene can be obtained. In other words, the purification (and drying) steps after steam distillation.
020608
Corrie writes .....
First the limonene needs to be separated from the water which distilled over with it during steam distiillation. The usual way of doing this would be to shake the distillate with 20 cm3 of a solvent, such as 1,1,1-trichloroethane, in which the limonene dissolves. When the two layers separate, the denser 1,1,1-trichloroethane layer containing the limonene will be on the bottom. This layer can be run off on to some anhydrous sodium sulphate, which will absorb any water present.
Filtering off the solid leaves a dry solution of limonene in 1,1,1-trichloro- ethane. The solvent is then distilled off (B.Pt. 74 oC), leaving the limonene (B.Pt. 176 oC). Further heating to distil the limonene is usually not done as it will start to decompose and oxidise at the temperature required. It could, however, be distilled at reduced pressure ('vacuum distillation'), but this is not usually possible at school level.
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updated: 08 June 2008
