Benzoinum. U. S., Br. Benzoin.
[Gum Benjamin]
"A balsamic resin obtained from Styrax Benzoin Dryander and some other species of Styrax (Fam. Styracaceae) growing in the East Indies and known in commerce as Sumatra Benzoin and Siam Benzoin." U. S. "Benzoin is a resinous solidified balsam obtained from the incised stem of Styrax Benzoin, Dryand. Known in commerce as Sumatra benzoin." Br.
Resina Benzoe, Asa Dulcis; Gum Benjamin; Benjoin, Fr.; Benzoe, P. G.; Benzoeharz, G.; Benzoino, It.; Benjui, Sp.
It is generally believed that Siam Benzoin is obtained from Styrax Benzoin Dryander. It appears to closely resemble the tree growing in Sumatra, which yields a balsamic resin bearing this name. Tschirch considers that the trees yielding Siam and Sumatra Benzoin are physiological varieties of the same species. (Tschirch, "Harze," II. Aufl., p. 195.) Strueff presents a careful morphological paper on the trees of Styrax Benzoin, growing in Siam, Sumatra and Java, in Arch. d. Pharm., 1911, p. 10.
Styrax Benzoin, or Benjamin Tree, is a tall tree of quick growth, sending off many strong round branches, covered with a whitish downy bark. Its leaves are alternate, entire, oblong, pointed, smooth above and downy beneath. The flowers are in compound, axillary clusters, nearly as long as the leaves, and usually hang, all on the same side, upon short slender pedicels. The tree is a native of Sumatra, Java, Borneo, and other islands in the vicinity. By wounding the bark near the origin of the lower branches, a juice exudes, which hardens upon exposure and forms the Sumatra benzoin of commerce. According to the researches of A. Tschirch (Journ. Roy. Microscop. Soc., 1890), the exudation is purely the result of pathological processes, the plant containing no resin receptacles. The trees, which are either wild or cultivated, are deemed of a proper age to be wounded at six years, when the trunks are usually about seven or eight inches in diameter. The operation is performed annually, and the product on each occasion from one tree never exceeds three pounds. The juice which first flows is the purest, and affords the whitest and most fragrant benzoin.
The tree which yields the Siam benzoin is stated to grow in an extremely circumscribed locality, on the bank of the river Mekong, occurring on high ground in clusters of from fifty to sixty trees. According to E. M. Holmes, its leaves are thinner and less distinctly venated than are those of the true Styrax Benzoin. In July and August the Siam trees are notched, and from these notches three months later the hardened benzoin is picked out. According to later studies (Kew Bulletin, 1912, p. 391) the Siam benzoin is derived from a new species, Styrax benzoides Craib. This view is also held by Hartwich. The benzoin of farther India is probably derived from Styrax tonkinensis.
Siam benzoin is usually imported in cubical blocks, which take their form from the wooden boxes in which the soft resin has been packed. It is brittle, with a peculiar, vanilla-like fragrance, but bitter taste. It may be a compact mass, containing more or less numerous opaque white tears embedded in a rich amber-colored translucent resin, mixed to a greater or less extent with bits of bark, wood, etc. In some specimens these tears are exceedingly small, in others almost wanting. The finest variety is composed almost entirely of these tears, loosely agglutinated together. Sumatra benzoin is sent into commerce chiefly from Acheen in Sumatra. It differs from the Siam varieties in having a much grayer color; the resin is grayish-brown, the tears are usually fewer than in the finer variety, and the bits of wood, etc., more abundant. The odor differs from, and is less agreeable than, that of Siam benzoin. Palembang benzoin resembles Sumatra benzoin, but is somewhat more transparent, and is stated to yield a larger percentage of benzoic acid. It is also asserted that it can be distinguished by its tincture, when dropped into water, not producing milkiness, but a flocculent deposit. Penang benzoin also resembles Sumatra benzoin, but has an odor which is more like that of storax, and it is probably yielded by the Styrax Benzoin; possibly it is the product of one of the Sumatran species, S. subdenticulata Miq. For an account of the cultivation and collection of benzoin in Sumatra, by L. M. Vonck, see C. D., 1891, 486-488; also D. C., 1891, 258. Ludy made an investigation of the bark and wood of a benzoin tree which was brought from Java by Tschirch. He reached the conclusion that benzoin balsam was produced from the tannin of the bark. (A. Pharm., 1893, 43, 95.) A variety of benzoin known as Estoraque or Benjui, is produced in Bolivia from the Styrax Pearcei Perk. var. bolivianus. This has been shown by Wichmann (S. W. P., 1912, p. 237) to be of similar composition to the Asiatic resin. According to this author resins are also collected from a number of other species of styrax in South America.
Properties.—Benzoin has a fragrant odor, with very little taste, but when chewed for some time leaves a sense of irritation in the mouth and fauces. It breaks with a resinous fracture, and presents a mottled surface of white and brown or reddish-brown; the white spots being smooth and shining, while the remainder, though sometimes shining and even translucent, is usually more or less rough and porous, and often exhibits impurities. In the inferior kinds the white spots are very few, or entirely wanting. Benzoin is easily pulverized, and, in the process of being powdered, is apt to excite sneezing. Its sp. gr. is from 1.063 to 1.092. The U. S. Pharmacopoeia recognizes both Sumatra and Siam benzoins. The official descriptions of these follow:
"Sumatra Benzoin.—In blocks or lumps of varying size, made up of tears, compacted together with a reddish-brown, reddish-gray, or grayish-brown resinous mass; tears externally yellowish or rusty-brown, milky-white on fresh fracture; hard and brittle at ordinary temperatures, but softened by heat and becoming gritty on chewing; odor aromatic and upon digesting with boiling water suggesting the odor of cinnamic acid or storax; taste aromatic and slightly acrid. Heat a few fragments of Sumatra Benzoin in a test tube; a sublimate is formed consisting of plates and small, rod-like crystals that strongly polarize light. Add carefully an ethereal solution of Sumatra Benzoin to a small Quantity of sulphuric acid contained in a porcelain dish; the solution is colored a brownish-red. Not less than 75 per cent. of Sumatra Benzoin dissolves in alcohol; the alcoholic solution, upon the addition of water, becomes milky and is acid to litmus. Sumatra Benzoin does not yield more than 2.5 per cent. of ash.
"Siam Benzoin.—In pebble-like tears of variable size, compressed, yellowish-brown to rusty-brown externally, milky-white on fracture, separate or very slightly agglutinated; hard and brittle at ordinary temperatures, but softened by heat and becoming plastic on chewing; odor agreeable, balsamic, vanilla-like; taste slightly acrid. Heat a few fragments of Siam Benzoin in a test tube; a sublimate is formed directly above the melted mass consisting of numerous long, rod-shaped crystals, which do not strongly polarize light. Add carefully an ethereal solution of Siam Benzoin to a small quantity of sulphuric acid contained in a porcelain dish; the solution is colored purplish-red. Not less than 90 per cent. of Siam Benzoin dissolves in alcohol; the alcoholic solution upon the addition of water becomes milky and is acid to litmus. Siam Benzoin does not yield more than 2 per cent. of ash. The tests which follow apply to Sumatra and Siam Benzoin: Heat gently 1 to 2 Gm. of Benzoin with 15 mils of purified petroleum benzin, and, after cooling, transfer the supernatant liquid to a separatory funnel, wash once with 10 mils of saturated sodium bicarbonate solution and then with water until free from bicarbonate; on the addition of 20 mils of a copper acetate solution (1 in 200) and vigorously shaking the mixture, no green color is noticeable in the petroleum benzin layer (rosin and foreign resins). Treat about 1 Gm. of powdered Benzoin with 15 mils of warm carbon disulphide, filter the solution, wash the filter with an additional 5 mils of carbon disulphide and allow the mixed liquids to evaporate spontaneously; not less than 12.5 per cent. of residue remains, which corresponds to the tests for identity under Acidum Benzoicum." U. S.
"Hard brittle masses consisting of numerous whitish tears embedded in a greyish-brown translucent matrix. Odor agreeable, similar to that of storax; taste slightly acrid. When cautiously heated in a dry test-tube it melts and evolves whitish fumes with an irritating odor. When 0.5 gramme is slowly heated to about 40° C. (104° F.) with 10 millilitres of solution of potassium permanganate an odor of benzaldehyde is evolved (distinction from Siam benzoin). Not more than 15 per cent. insoluble in alcohol (90 per cent.). Ash not more than 5 per cent.
When heated it melts, and emits thick, white, pungent fumes, which excite coughing when inhaled, and consist chiefly of benzoic acid. It is wholly soluble, with the exception of impurities, in alcohol, and is precipitated by water from the solution, rendering the liquid milky. It yields to boiling water a. notable proportion of benzole acid. Lime water and the alkaline solutions partially dissolve it, forming benzoates, from which the acid may be precipitated by the addition of other acids. Its chief constituents are resin and benzoic acid, and it therefore belongs to the balsams. The white tears and the brownish connecting medium are said by Stoize to contain nearly the same proportion of acid, which, according to Bucholz, is 12.5 per cent., to Stoize, 19.8 per cent. In a more recent examination by Kopp, the white tears were found to contain from 8 to 10 per cent. of acid, and the brown 15 per cent. (J. P. C., 3e ser., iv, 46.) The resin is of three kinds, one extracted with the benzoic acid by a boiling solution of potassium carbonate in excess, another dissolved by ether from the residue, and the third affected by neither of these solvents. Besides benzoic acid and resin, the balsam contains a little extractive and traces of volatile oil. Benzoin retards the oxidation of fatty matters, and thus tends to prevent rancidity.
The percentage of soluble matter required to be present by the U. S. Pharm. in benzoin is very high, and if rigidly enforced by the customs would exclude Sumatra benzoin in all but its very finest varieties. Robt. C. Pursel and Willard Graham obtained from five commercial varieties of Sumatra benzoin, in the American market, an average of 86 per cent. of soluble matter. (Proc. Pennsylvania Pharm. Assoc., 1902.) John Barclay, in England, found the average of ten samples to be 69.9 per cent. (P. J., Jan., 1903.)
It appears from various researches that benzoin, besides its own characteristic acid, often contains also cinnamic acid, which is found more especially in the white tears. Indeed, Hermann Aschoff obtained from some benzoin of Sumatra a pure cinnamic acid, without any benzoic; and Kolbe and Lautermann, upon examining a specimen of the tears, discovered what they at first supposed to be a peculiar acid, but which on further investigation proved to be a mixture of cinnamic and benzole acids. H. Beckurts and W. Brueche confirm the statement that Siam benzoin contains no cinnamic acid, which is usually present in Sumatra benzoin. They found the specific gravity from 1.120 to 1.171; ash from 0.05 to 2.38 per cent.; portion insoluble in alcohol from 2.1 to 9 per cent. On the other hand, Tschirch and Ludy (A. Pharm., 1893, 500) extracted benzoic acid from Siam benzoin by the wet process. They found Sumatra benzoin to contain esters which yielded by saponification 32.9 per cent. of cinnamic acid, the proportion of esters being benzoresinol cinnamate, 7.4 per cent., and resinotannol cinnamate, 92.6 per cent., at least 75 per cent. of Sumatra benzoin consisting of cinnamates yielding from 20 to 24 per cent. of cinnamic acid. (See also A. Pharm., 1893, 461; A. J. P., 1893, 223; and J. P. C., 1894, 172.) In a later research they found that Siam benzoin did not contain cinnamic acid, either free or in combination as ester. Besides some free benzoic acid and vanillin it contains only esters of benzoic acid. These, on saponification, yielded 38.2 per cent. of benzole acid, 56.7 per cent. of isoresinotannol, and 5.1 per cent. of benzoresinol. (Tschirch, Harze und Harzbehälter, 1900, p. 155.) Benzoin may be rapidly tested for cinnamic acid by heating a small quantity with a little soda and water and warming the filtrate with potassium permanganate, when the odor of bitter almond will be developed. (A. Pharm., 1892,ccxxx.)
Aschoff recommends the following method of detecting cinnamic acid. Boil the benzoin with milk of lime, filter, decompose with hydrochloric acid, and add either potassium dichromate with sulphuric acid, or potassium permanganate, when, if cinnamic acid be present, the odor of oil of bitter almond will be perceived.
According to T. T. Cocking and J. D. Kettle (Tr. Br. Ph. Conf., 1914, 357), the important analytical data to be considered in valuing benzoin are (1) the percentage soluble in 90 per cent. alcohol, and (2) the quantity of aromatic acids present, both free and combined. Methods of obtaining these factors are given in detail and also tables giving the results of such examinations of a number of commercial samples. Reinitzer (A. Pharm., cclii) has made an exhaustive study of Siam benzoin, in which he contradicts some of the previously published statements of Tschirch and Ludy. He claims that the resinotannol of these authors does not exist in the drug, but is an oxidation product created during the analysis.
Rump (1878) treated Siam benzoin with caustic lime, precipitated the benzoic acid with hydrochloric acid, and agitated the liquid with ether. The latter on evaporating afforded a mixture of benzoic acid and vanillin, C8H8O3. Subjected to dry distillation, benzoin affords as the chief product benzoic acid, together with empyreumatic products, among which Berthelot has proved the presence (in Siam benzoin) of styrol, C8H8. The latter was also obtained in 1874 by Theegarten from Sumatra benzoin by distilling it with water. (Ber. d. Chem. Ges., 1874, p. 727.)
Sumatra benzoin is sometimes heavily adulterated with stony debris, sand and bark. Schneider reports finding as much as 75 per cent. of bark in a commercial article.
Uses.—Benzoin is stimulant and expectorant, and was formerly employed in pectoral affections, but, except as an ingredient of the compound tincture of benzoin, it has fallen into disuse. Trousseau and Pidoux recommend strongly its inhalation in chronic laryngitis. Either the air of the chamber may be impregnated with its vapor by placing a small portion upon some live coals, or the patient may inhale the vapor of boiling water to which the balsam has been added. It is occasionally employed in pharmacy for the preparation of benzoic acid; the milky liquor resulting from the addition of water to its alcoholic solution is sometimes used as a cosmetic, under the impression that it renders the skin soft. A tincture has been strongly recommended in anal fissure. In the East Indies, the balsam is burnt by the Hindus as a perfume in their temples of worship.
Dose, fifteen to thirty grains (1-2 Gm.).
Off. Prep.—Adeps Benzoinatus, U. S. (Br.); Tinctura Benzoini, U. S.; Tinctura Benzoini Composita, U. S., Br.; Sevum Benzoatum, Br. (N. F.); Unguentum Picis Compositum (from Tincture), N. F.
