What Is Benzoin?
Benzoin is an aromatic compound.
Benzoin is a type of perfume used in perfumes and is characterized by a sweet, mellow aroma similar to vanilla. It is extracted as an essential oil from the sap of the anthocarpus tree, which belongs to the euphorbiaceae family.
It is a relatively safe substance, as it does not fall under any of the major national laws and regulations and its toxicity has not been determined.
Uses of Benzoin
Benzoin is used as an analytical reagent. Benzoin causes a silicicidal reaction with zinc. Therefore, it is possible to detect small amounts of zinc ions.
It is also sold as an essential oil under the name benzoin. It is extracted from the resin of a tall tropical tree. It has a sweet, vanilla-like aroma and has a calming effect.
In addition, it serves as an antioxidant and improves the oil’s shelf life.
Properties of Benzoin
At room temperature, benzoin exists as a white solid. It is insoluble in water, but soluble in hot water, hot alcohols, and acetone.
However, benzoin may be altered by light, so it is necessary to take measures such as shielding it from light when storing it.
Structure of Benzoin
Benzoin is designated 2-hydroxy-1,2-diphenylethanone in IUPAC nomenclature. The substructure of Benzoin (-C(=O)CH(OH)-) is called acyloin structure.
Other Information on Benzoin
1. Synthesis of Benzoin
Benzoin is obtained from two molecules of benzaldehyde by a condensation reaction catalyzed by a cyanide ion. This condensation reaction is called benzoin condensation.
Benzoin condensation was reported by Friedrich Wöhler and Justus Freiherr von Liebig, and the reaction mechanism was proposed by Arthur Lapworth.
2. Reaction Mechanism of Benzoin Condensation
First, cyanide ion is added to the aldehyde to form cyanohydrin. Next, a proton on the α-carbon of the cyano group of cyanohydrin is withdrawn to form a carbo anion. In other words, this is a polarity conversion.
The carbo anion is then nucleophilically attached to another molecule of aldehyde to form an adduct. The cyanide ion is desorbed from the cyanohydrin, regenerating the carbonyl group to form benzoin.
3. Reaction of Benzoin
Oxidation of benzoin with nitric acid yields benzyl (benzil), an aromatic diketone. Benzyl is synthesized in the laboratory by condensing benzaldehyde with benzoin to form benzoin, which is then oxidized with nitric acid or copper (II) sulfate.
4. Benzoin as a Flavoring Agent
Since the time of ancient Egypt, benzoin has been used in religious ceremonies as incense. Even today, benzoin is used as a perfume to perfume a room, and is also used in body massage when mixed with carrier oil.
Benzoin volatilizes slowly, so when added to perfumes, its fragrance can be enjoyed for a long time.
5. Scent of Benzoin
Benzoin is divided into two types: Sumatran benzoin and Siamese benzoin. These two types of benzoin differ in origin and aroma.
Sumatra benzoin can be obtained from trees originating in Malaysia and Indonesia. Sumatran benzoin is not only sweet but also spicy, like cinnamon.
Siamese benzoin, on the other hand, comes from Vietnam and Thailand, and is a benzoin from the anthocarpus tree. It is often used in perfumes and has a strong vanilla-like sweet aroma due to its high content of vanillin.