Benzoin

#### Benzoin. **Benzoin Tincture **and the various **Benzoin Resinoids**, “**Resin Absolute**”, etc. are described under this heading. The two most important types of raw material, **Benzoin Siam**** **and **Benzoin**** ****Sumatra**, are described in the following monographs. **Benzoin**** ****Tincture**** **is usually prepared only from selected “tears” of **Benzoin**** ****Siam**. Conventional strength is 20 parts by weight of **Siam Benzoin**, macerated with enough alcohol (of 90 or 96% strength by volume) to produce 100 parts by weight of finished tincture. The above quality of **Benzoin **is almost entirely soluble in alcohol, and the tincture will thus represent an approximate 20% solution of the alcohol-soluble resinoid of this benzoin. The tincture is amber colored, and has a sweet, balsamic-vanillin-like odor. The taste is somewhat bitter. **Benzoin**** ****Tincture**** **is used as a fixative in fine perfumery, in colognes, in alcohol for “prefixation” prior to the preparation of colognes and lotions, etc. Benzoin tincture is furthermore used in skin preparations for its skin-healing effect and, occasionally, in certain cosmetic preparations for its antioxidant effect. **Benzoin Resinoid **is produced from all grades of the crude botanical, **Siam **or **Sumatra**, often from a mixture of both. (See following monographs on the two types of **Benzoin**). Evaluation of **Benzoin Resinoid **is thus a difficult task since the customers are confused with respect to the actual standard of true resinoids. Various solvents are used for the extraction of the crude benzoin. **Benzene**** **is the most common, but “cold alcohol” extraction is becoming more popular. It offers several advantages. If ethyl alcohol is used directly, the resulting extract is called a **Resin**** ****Absolute**** **of **Benzoin**. If, in addition, heat is applied, and if the crude benzoin has not been neutralized, the free acids (benzoic acid and cinnamic acid) will esterify part of the ethyl alcohol under formation of ethyl benzoate and ethyl cinnamate. These esters are very useful perfume materials of substantial power and good fixative effect, but they do not represent the natural contents of benzoin, nor is it conceivable that a uniform odor quality of benzoin resinoid can be produced by this method. It is therefore suggested that benzoin should first be extracted with benzene, the extract be filtered and evaporated partially. The concentrated solution is then washed neutral with weak alkali, separated clear, filtered and finally evaporated under gentle vacuum. This yields a neutral resinoid which can be extracted with alcohol to yield an entirely alcohol-soluble **Benzoin Absolute**. This product is very pale in color, and has a most delicate balsamic odor, free from harsh resinous and acid notes. This true absolute is definitely superior to the direct one-step alcohol extract from the crude benzoin. Extraction with ethyl alcohol at a maximum temperature of 40°C., subsequent filtration of the extract and evaporation under vacuum with a “skin temperature” of maximum 50°C. (the temperature of the inner side of the vacuum still,. also called “pot temperature”), and prolonged “airing” under vacuum without heating will produce a very attractive, light-colored and true-tonature “**Resin Absolute of Benzoin**”. This product is not acid-free. The yield of resinoid in the case of **Siam**** ****Benzoin**** **is nearly 95% for the best grades, about 85% for poorer grades. **Sumatra Benzoin **also yields up to 95% in the case of very good grades, while average commercial lots may yield as little as 65% resinoid. Among well-known Sumatra types are the “Penang” and the “Palembang” benzoins which usually give around 65% yield of resinoid. The **Sumatra**** ****Benzoins**** **give darker resinoids, sometimes almost brown, and they can have a styrax-like odor. As stated previously, Benzoin Siam is characterized by its content of Benzoic Acid (10 to 12%), while the major constituent is **Coniferyl Benzoate **(65 to 75%). Other resin acids are present. **Benzoin Sumatra **contains mainly **Benzoresinyl Cinnamate **and **Benzoresinyl Benzoate,**** ****Cinnamic**** ****Acid,**** ****Styrene**** **(characteristic odor, also found in styrax). Both types contain **Vanillin**, but since the consumers apparently expect more of this material in Siam Benzoin than in the Sumatra type, it is not uncommon to add up to 5% vanillin to commercial lots of Benzoin Resinoid. This resinoid may be prepared from a mixture of Sumatra and Siam, mostly the former, and, by the addition of substantial amounts of vanillin, it becomes a “commercial grade” of Siam Benzoin Resinoid, which may even be labelled “absolute”. This high amount of vanillin is not natural to any benzoin, nor is it without significant discoloring effect, e.g. in soap perfumes or in perfumes which contain anthranilates, indol, etc. **Benzoin Resinoid **is used very extensively in perfumery, particularly in soap perfumes (see above on discoloration) where its fixative effect is much appreciated. It is generally applicable, but it has a pronounced odor-depressing effect upon the perfumes in which it is incorporated. This effect is closely connected with the fixative effect, and it is enhanced by the rich sweetness and deep balsamic notes from the resinoid. **Benzoin**** ****Resinoid**** **is occasionally adulterated with Sumatra benzoin extracts, doctored up with vanillin (see above), or it is “stretched” with **Acaroid Resinoid**, abietic alcohols, methyl abietate, benzyl benzoate, copaiba balsam, amyris oil, etc. The addition of smaller amounts of diethyl phthalate as a plasticizer is considered normal “for convenient handling”, and when clearly labelled so.