Oleum Copaibae, B.P. Oil of Copaiba.
Related entries: Copaiba
Oil of copaiba is obtained by distillation from copaiba, the resin of Copaifera Lansdorfii, Desf. (N.O. Leguminosae), and other species of Copaifera indigenous to Brazil, Venezuela, New Granada, and other parts of Central and South America. It is also official the U.S.P. It occurs as a colourless or pale yellow liquid having the characteristic pepper-like odour of the balsam, a bitter, pungent, persistent taste, and a neutral reaction. Specific gravity, 0.896 (B.P., 0.900) to 0.910 (0.890 to 0.905 at 25°), varying considerably with age and exposure to air. Boiling-point, between 250° and 275°; rotation -7° to -35°. The chief adulterant of oil of copaiba is gurjun or wood oil, but this may readily be recognised by its high specific gravity, its difficult solubility, high boiling-point, and strong rotatory power. The following colour test has been recommended for its detection :-In a test-tube place 1 mil of glacial acetic acid, add 2 decimils (0.2 milliliters) of pure, concentrated nitric acid, and mix, then add 2 decimils (0.2 milliliters) of oil to this, mixture, allowing the oil to float on top; if gurjun or wood oil be present, in a few minutes a reddish or purple zone will be developed between the layer of oil and the acid mixture. No reaction occurs if the oil is pure. Oil of African copaiba, another adulterant, is not soluble in an equal volume of absolute alcohol, and is dextrorotatory. Copaiba oil is frequently used in adulterating other volatile oils. Para copaiba yields 60 to 90 per cent. oil; Maracaibo copaiba about 40 per cent.
Soluble in alcohol (1 in 20); in all proportions of absolute alcohol; nearly insoluble in 60 per cent. alcohol.
Constituents.—The chief and only well-defined constituent of oil of copaiba is the sesquiterpene, caryophyllene, C15H24, identical with that from oil of cloves. This, on treatment with glacial acetic acid and sulphuric acid, yields a hydroxide, C15H25OH, in crystals melting at 96°. A crystalline acid (melting-point, 140°) which has been identified as a symmetric dimethyl succinic acid, C6H10O4, has also been obtained (about 1 ½ per cent.), but whether it originates in caryophyllene or some minor constituent is not known. A small amount of terephthalic acid has been obtained on oxidising the oil.
Action and Uses.—Oil of copaiba resembles the oleoresin in its action. It may be administered as an emulsion or enclosed in a gelatin capsule.
Dose.—3 to 12 decimils (0.3 to 1.2 milliliters) (5 to 20 minims).