Isolation of Limonene - The TA\'s name was Chathuri Kombala. PDF

Preview

Summary

The TA's name was Chathuri Kombala. ...

Description

Dana Woods Chathuri Kombala Chem 243A 2 November 2015 Isolation of Limonene Discussion The objective of this lab was to isolate limonene from a citrus fruit (my specific fruit was an orange). A distillation procedure was completed in order to isolate and purify the limonene. Finally, an IR spectra and gas chromatography was performed on the product to verify its identification (in this case, limonene).

S-(-)-Limonene R-(+)-Limonene When a molecule is chiral, it means it has a carbon with four different groups attached to it. Therefore, this molecule will have a related molecule with identical composition and connectivity, but with a different arrangement in space (known as enantiomers). They are non-superimposable, meaning the mirror image cannot be placed on top of the original image and be exactly the same. Enantiomers are classified by either R or S, which tells if their configuration is right- or left-handed. Enantiomers occur naturally, and there are ways to distinguish whether it is the R or S enantiomer. For example, receptors in our nose can tell if we are smelling the R-(-)-carvone enantiomer (spearmint scent) or the S-(+)-carvone enantiomer (caraway seed scent).

For this experiment, we looked at limonene. The two different limonene enantiomers are optically active, which means they can rotate plane-polarized light. The direction in which they rotate light depends on if it is dextrorotatory (the R-(+)-limonene enantiomer) or levorotatory (the S-(-)-limonene enantiomer). We were able to calculate the specific rotation for both enantiomers. For the R-(+)-limonene, the specific rotation was 146.24, and the specific rotation for the S-(-)-limonene was 120.08. The limonene was obtained by using steam distillation. This specific distillation...