d-limonene is a citrus industry by-product from almost fifty years; it is recovered distilling liquids arising from peel pressing, from waste flows, from oil emulsions and fron essential oils concentrations.
It
is the main component in all citrus peel oils; it is belonging to cyclic
monoterpenes family and its brute formula is C10H16. World
d-limonene productions is ranging between 50.000 and 75.000 tons produced
basically in Brazil and Florida. It is used for production of adhesive resins,
for flavors, solvents and degreasing products.
The exact chemical name of d-limonene is (4R)-(+)-4-isoprenil-1-metilcyclohexene and its Chemical Abstract Registry Number is 5989-27-5.
Some of chemical-physical characteristics for raw product recovered from waste heat evaporators are listed below:
|
Value |
|
|
Specific Gravity (20°C) |
0,84 |
|
Refractive Index (20°C) |
1,471 |
|
Optical Rotation (20°C) |
+ 96,7 |
|
Flash Point (°C) |
46 |
|
Boiling Point (°C) |
165 |
|
d-limonene (%, GC) |
94,6 |
|
High boiling Components (%) |
2,3 |
|
Mircene (%) |
1,8 |
|
a -pinene (%) |
0,6 |
|
Sabinene (%) |
0,4 |
|
Aldehydes (%, as C8) |
0,4 |
|
Low boiling Components (%) |
0,1 |
|
Colour |
from colorless to pale yellow |
For resins productions, the terpene is diluted in toluene and polymerized with the aid of a Friedel-Crafts catalyst like aluminum chloride; reaction is exothermic and it is necessary to cool down mixture; at completion of the reaction, product is distempered in water, is washed to remove catalyst and solvent is recovered. Crude polymer is a mixture of polymer units composed from 2 to 12 monomer units.
d-limonene is used in hand-washing pastes, in degreasing liquids like ones used for cleaning printed circuits. It is, also, used as insecticide, as fly-spray component. It is widely used in flavor production as solvent and as starting material for l-carvon synthesis with nitrosyl chloride and for a -terpineol production.
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