Oleum Amygdalae Amarae. U. S. Oil of Bitter Almond.

Botanical name: 

Ol. Amygd. Amar. [Bitter Almond Oil]

Related entry: Amygdala Amara

"A volatile oil obtained by maceration and distillation from the ripe kernels of Prunus Amygdalus amara DeCandolle (Fam. Rosaceae), and from other kernels containing amygdalin. It yields not less than 85 per cent. of benzaldehyde [C7H6O] and not less than 2 per cent. nor more than 4 per cent. of hydrocyanic acid [HCN]. The botanical source from which it is derived must be stated on the label. Preserve it in small, well-stoppered, completely filled, amber-colored bottles protected from light and air. Oil showing crystals of benzoic acid must not be dispensed.

"NOTE: This Oil is intended for medicinal use; it must not be used for flavoring foods." U. S.

Oleum Amygdalarum (Amararum) Aethereum; Oleum Amygdalae Volatile; Volatile Oil of Almond, Huile volatile d'Amande amere, Fr. Cod.; Essence d'Amandea ameres, Fr.; Bittermandelol, G.; Esencia de almendras amargas, Sp.

When bitter almonds are expressed, they yield a bland fixed oil, and the residuary cake, reduced to powder by grinding, and submitted to distillation with water, yields oil of bitter almond. This does not pre-exist in the almond, but is produced by the action of water upon the amygdalin contained in it, through the intervention of an enzyme called emulsin (see Amygdala Amara), according to the reaction:

C20H27NO11 + 2H2O = C7H6O + 2C6H12O6 + HCN

It is obtained also by the distillation of the leaves of the cherry-laurel, by the bark of the wild cherry, and of various products of the genera Amygdalus, Cerasus, Prunus, etc. Whipple obtained, upon an average, from the ground bitter almond cake, 1.35 per cent. of the oil. (P. J., x, 297.) Pettenkofer has ascertained that the yield is greater if the cake be macerated in water for forty-eight hours before being submitted to distillation. (J. P. C., May, 1862, p. 432.) It is sometimes produced from peach kernels. Schimmel's Report for April, 1914, refers to the fact that the sole source of the oil at that time was apricot kernels.

Oil of bitter almond has a yellowish color, a bitter, acrid, burning taste, and the odor of the kernels in a high degree. It is heavier than water, soluble in alcohol and ether, according to Fluckiger soluble in 300 parts of hot or cold water, and deposits, upon standing, a white crystalline substance consisting chiefly of benzoic acid. It is officially described as "a clear, colorless or yellow, strongly refractive liquid, having the characteristic odor and taste of benzaldehyde. It is slightly soluble in water and soluble in all proportions in alcohol or ether. It dissolves, forming a clear solution, in 2 volumes of 70 per cent. alcohol. Specific gravity: 1.038 to 1.060 at 25° C. (77° F.). Refractive index: 1.5428 to 1.5439 at 20° C. (68° F.) (see Part III, Test No. 22). It is optically inactive or dextrorotatory, not exceeding +0° 10' in a 100 mm. tube at 25° C. (77° F.). When first prepared, the Oil is neutral to litmus paper, but afterwards develops an acid reaction due to the formation of benzoic acid. It does not respond to the Test for heavy metals in volatile oils. Hold the looped end of a piece of clean copper wire in a non-luminous flame until it glows without coloring the flame green, cool the wire, dip the loop into Oil of Bitter Almond, ignite the latter and hold it so that the liquid burns outside of the non-luminous flame. On slowly bringing the flame from the burning Oil of Bitter Almond on the loop in contact with the lower outer edge of the non-luminous flame, no green tinge is discernible (chlorinated products). Add 10 drops of the Oil to a little alcohol, then add a small amount of zinc dust and 2 mils of acetic acid and boil the mixture for a short time; no odor of phenylisocyanide develops after rendering it strongly alkaline with potassium hydroxide T.S., adding a few drops of chloroform and heating (nitrobenzene)." U. S.

Besides the peculiar volatile oil, it contains also hydrocyanic acid, with usually a small proportion of benzoic acid produced by oxidation of the aldehyde. It may be obtained pure by agitating it strongly with calcium hydroxide and a solution of ferrous chloride, submitting the mixture to distillation, and drying the oil which comes over by digestion with calcium chloride. George Whipple states that if crude oil be redistilled into a solution of silver nitrate, and again distilled from a fresh solution of the same salt, it is obtained entirely free from hydrocyanic acid, which reacts with the silver and remains behind as silver cyanide. (See A. J. P., xxvi, 348.) Thus purified, it is colorless, but still retains its peculiar odor, with a burning, aromatic taste, and is destitute of those poisonous properties of the crude oil which are dependent on hydrocyanic acid. The odor of the oil of bitter almond has been erroneously ascribed to that acid, which, on examination, will be found to have a different and more feeble odor. Like most other volatile oils, this may produce deleterious effects if taken very largely. Hippuric acid is found in the urine of animals to which the oil has been given freely. The sp. gr. of the crude oil varies from 1.052 to 1.082, and is said to be greater when the oil is distilled from salt water than when distilled by the ordinary mode. That of the purified oil is 1.060, and its boiling point 180° C. (356° V.). It is benzoic aldehyde, C6H5.COH, which may also be produced by the action of oxidizing agents upon benzyl alcohol, C6H5.CH2OH, and yields itself, when oxidized, benzoic acid, C6H5.COOH. The benzoic acid which the oil of bitter almond deposits on standing does not pre-exist in it, but results from the absorption of oxygen, as just stated.

If sulphuric acid produce with the oil a bright-red instead of a brownish-red color, the oil has probably been distilled with salt water, in which case it is prone, according to Ferris, to deposit a blood-red substance, occasionally complained of by druggists.

Uses.—The unpurified volatile oil of bitter almond, which is the product directed by the Pharmacopoeia, acts physiologically like hydrocyanic acid. Death is said to have occurred in a man ten minutes after taking two fluidrachms (7.5 mils) of the oil. It might be substituted with advantage for medicinal hydrocyanic acid, if it always contained a uniform percentage of the acid, as the acid contained in the oil is much less liable to decomposition, remaining for several years unaltered, provided the oil be preserved in well-stoppered bottles. According to Schrader, 100 parts of the oil contain sufficient acid for the production of 22.5 parts of Prussian blue, but the proportion is not constant, varying, according to Groves, from 8 to 12.5 per cent.. the U. S. official standard is, however, not less than 2 per cent. and not more than 4 per cent. It has been employed externally, dissolved in water in the proportion of one minim (0.06 mil) to a fluidounce (30 mils), in prurigo senilis and other cases of troublesome itching. To facilitate the solution in water, the oil may be previously dissolved in spirit. Oil of bitter almond is sometimes used to conceal the taste of cod liver oil and of castor oil.

Dose, one-fourth to one minim (0.015-0.06 mil.).

Off. Prep.—Aqua Amygdalae Amarae, U. S.; Spiritus Amygdalae Amarae, U. S.; Elixir Amygdalae Compositum, N. F.; Elixir Anisi (from Spirit), N.F.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.