Limonene

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Limonene is a colourless liquid hydrocarbon, classified as a cyclic terpene. The D-isomer is the most common form encountered. The name comes from the lemon, as many citrus fruits and some evergreen plants contain high amounts of the D-isomer. It may be recognized as the smell of oranges, lemons, or other citrus fruits.

Properties

Chemical

Limonene is a relatively stable terpene and can be distilled without decomposition, although at elevated temperatures it cracks to form isoprene.

Physical

Limonene is a colorless liquid hydrocarbon. It has a strong smell of orange or lemon peels.

Availability

Limonene can be extracted from citrus fruit peels via steam distillation.

Pure limonene can also be bought online.

Preparation

The synthesis of limonene from basic hydrocarbons is complex, instead it's more efficient to extract it from citrus fruit juice.[1] It is often prepared in introductory organic chemistry classes by steam distilling an orange peel.

Projects

  • Extract various alkaloids from plants

Handling

Safety

Limonene and its oxidation products are skin and respiratory irritants, and limonene-1,2-oxide (formed by aerial oxidation) is a known skin sensitizer.

Storage

Should be stored under an inert gas, as it will slowly oxidize in contact with air.

Disposal

Limonene can be safely burned, however this produces lots of soot. Due to it's relative high flash point (50 °C) and to reduce soot, mix limonene with a more flammable solvent and then burn it. Best to do it outside.

References

  1. http://www.sciencemadness.org/scipics/Nicodem/Limonene.pdf

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