Benzoin Picture, flower and seedsBenzoinum
Monograph of the U.S.D. 1926.

Edited by
Ivor Hughes.

BENZOIN Benzoin.
Benzoin is a balsamic resin obtained from Styrax Benzoin Dryander and other species of Styrax (Faro. Styracece), and known in commerce as Sumatra Benzoin and Siam Benzoin. Sumatra Benzoin yields not less  than 75 per cent. of alcohol-soluble extractive and not more than 1 per cent. of acid-soluble ash.
Siam Benzoin yields not less than 90 per cent. of alcohol-soluble extractive, contains not more than 1 per cent. of foreign organic matter, and yields not more than 0.5 per cent. of acid-soluble ash. 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. Benfoin, 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 81 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.) Rordorf (Schweiz. Apot..  Ztg.,1917) concludes that the tree producing Siam Benzoin, while very similar to the S. Benzoin, offers distinct differences and proposes a new species, S.  siamensis (Rordorf.) Strueff presents a careful morphological paper on the trees of Styrax Benzoin, growing in Siam, Sumatra and Java, in A.  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 bowers 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 not certainly determined. According  to E. M. Holmes its leaves are thinner and less distinctly venated than those of  the Styrax Benzoin. Hartwich believes it to be a new species, Styrax benzoides Carib (see Kew Bulletin, 1912, p. 391). Holmes (P. J., 1916) attributes it,  however, to the S. tonkinense. Rordorf (P. J.1917, xcix, p.111) received some fruits which were sent him from Bangkok as specimens supposedly derived from the Benzoin  tree; these do not agree with any species previously described and he proposed a  new species, S. Siamensis Rordorf.

The territory from which the balsam is derived is a quite limited district in  the Province of Laung Probang along the River Mekong.

The Siam Benzoin
appears in commerce either in the form of separate tears  or in masses composed of tears cemented together by a rich amber-colored  translucent resin, these masses usually being in cubical blocks which take their  form from the wooden boxes in which the soft resin has been packed. The tears  are small, mostly less than 2 or 3 cm, in length, opaque, brittle and milky  white on the interior, but on keeping gradually oxidize into the brownish  translucent resin. 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.

Palenbang Benzoin resembles Sumatra Benzoin, but is some what more  transparent, and is stated to yield a larger percentage of benzoic acid. It is also asserted that is 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 Mig. 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. After long storage it  becomes covered with a thin yellow transparent film which Reinitzer finds is due  to oxidation of the proper resin (Schim. Rep., April,1915) .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. Pharmacopeia  recognizes both Sumatra and Siam Benzoins. The official descriptions of these  follow:

Unground Sumatra Benzoin. 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. When digested with boiling  water the odor suggests cinnamic acid or storax; taste aromatic and slightly acrid.

Unground Siam Benzoin. 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 aromatic and slightly acrid.

The solution of Benzoin in alcohol becomes milky upon the addition of  water and is acid to litmus paper, Heat a few fragments of Benzoin in a test tube: Sumatra Benzoin evolves a sublimate consisting of plates and small,  rod-like crystals that strongly polarize light. Siam Benzoin evolves a  sublimate directly above the melted mass consisting of numerous long, rod-shaped  crystals, which do not strongly polarize light. Treat about 0.25 Gm. of Benzoin  with 5 cc. of ether, decant about 1 cc. of the ethereal solution into a porcelain dish, and add to it 2 or 3 drops of sulphuric acid:  the solution of Sumatra Benzoin produces a deep red-brown coloration of the  sulphuric acid and the solution of Siam Benzin produces a deep purplish-red  coloration.

Heat about 0.5 Gm. of Benzoinin a test tube with 10 cc. of potassium  permanganate T .S.: only the Sumatra variety develops in odor of benzaldehyde.  Treat about 1 Gm. of powdered Benzoin with 15 cc. of warm carbon disulphide,  filter, wash the filter with an additional 5 cc. of carbon disulphide, and allow  the filtrate to evaporate spontaneously: the residue does not exceed 12.5 per  cent. This residue responds to the tests for identity under Acidum  Benzoicum. Benzoin does not show the presence of rosin.

Assay. Proceed as directed under alcohol-soluble extractive. 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. 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."  Br.

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 benzoic 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.

The percentage of alcohol-soluble matter require to be present by the U.S.P.  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.) Benzoin retards  the oxidation of fatty matters, and thus tends to prevent rancidity.

Constituents. The chief constituents of benzoin are resin, benzoic and cinnamic acids and their esters. The resinous portion, which constitutes about three-fourths of  the drug, is made up of esters of benzoresinol (siaresinol), constituting  from 7 to 8 per cent. of the resin, and of an undetermined alcohol.

This latter has been stated to be sumaresinotannol. Zinke and Dzrimal (J. P.  0., 1921, xxiv, 350) report the presence of a distinctive compound lubanyl benzoate, C6H3OH.OCH3.CH=CH.CH2O.CO C6H5. This occurs in crystalline masses melting at 72  C.

The total amount of free acids is from 15 to 17 per cent. In the Sumatra  Benzoin cinnamic acid predominates, and in the Siam Benzoin benzoic  acid is more abundant; indeed Beckurts and Brueche state that Siam Benzoin  contains no cinnamic acid ( see also Tschirch and Ludy, A. Pharm., 1893,500). 

There is present also some 9 or 10 percent. of esters of these acids, cinnamyl, cinnamate,
phenylpropyl cinnamate, and traces of vanillin, benzaldehyde, styrol and  styracin.

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  Luddy. 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 Borthelot 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. (B. Chem. G.,  1874.) 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 acts as a stimulating 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  (see .Acidum Benzoicum) ; 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 lndies,  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.