Properties of D-Limonene
- Density: 0.84 g/cm3
- Boiling point: 176 degrees Celsius
- Unsaturated hydrocarbon with chemical formula C10H16
D-Limonene
Method
> Scrape the white pith from the skins of 4 medium oranges
> Blend with distilled water until a fine puree is formed
> Transfer to 250 ml round-bottomed flask
> Attach flask to distillation apparatus. Turn on hotplate to highest setting
> When the thermometer shows 100 degrees Celsius, turn on the tap to run water through the condenser
> The distillate contains D-Limonene and water. D-Limonene should form a layer on top of the water and can be removed using a dropper
> If there is no distinct separation extract using NaCl and dichloromethane
> Confirm presence of D-Limonene by adding extract to aqueous bromine. Bromine should decolourise.
Distillation apparatus
D-Limonene forms a layer above water
Calculating yield
|
Mass of orange peel/g
|
50.50
|
|
Mass of d-limonene/g
|
1.20
|
% yield = mass of limonene/mass of orange peel x 100
= 1.20/50.50 x 100 = 2.4%
D-Limonene yield is considerably higher than yield lavender essential oil, which is about 0.3% mass-for-mass.
An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. The essential oil of orange is made of more than 90% D-Limonene. D-Limonene is secreted from little pockets on the surface of orange peel and gives orange its distinctive smell.
SEM image of citrus peel
When the water and peel puree is heated, water and volatile compounds (including D-Limonene) vapourise and enter the condensor. They are then condensed to form the hydrosol, a mixture of water and orange essence. The D-Limonene, being hydrophobic and less dense than water, forms a layer on top of the water.
D-Limonene is used in perfumes and household cleaners for its fragrance. It is also a safe, effective and environmentally-friendly solvent used in adhesive and stain removers, cleaners and paint strippers.
Orange essential oil is a byproduct of orange juice manufacturing that can be obtained by centrifugation. D-Limonene can then be extracted from the orange oil by steam distillation. Because orange oil, unlike other essential oils, is a byproduct, it is one of the cheapest, making D-Limonene cost-effective.
References
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