Benzoin, chemically PhCH(OH)C(O)Ph, is an aromatic compound with a hydroxyl group and a carbonyl group. It exhibits a pleasant almond-like scent and finds applications in perfumery and as a precursor in organic synthesis.
| IUPAC Name | 2-Hydroxy-2-phenylacetophenone |
| Molecular Formula | C14H12O2 |
| CAS Number | 119-53-9 |
| Synonyms | Benzoine; Benzoic acid phenyl ester, 2-Hydroxy-1,2-diphenylethanone, Benzoylphenylcarbinol |
| InChI | InChI=1S/C14H12O2/c15-14(12-8-4-2-5-9-12)13-10-6-1-3-7-11-13/h1-11,15H |
Benzoin Properties
Benzoin Formula
The formula of benzoine is PhCH(OH)C(O)Ph, where Ph represents the phenyl group. It consists of two benzene rings connected by a carbon atom with a hydroxyl group (OH) and a carbonyl group (C=O) attached to it. This formula reflects the molecular structure of benzoine.
Benzoin Molar Mass
The molar mass of benzoine can be calculated by adding up the atomic masses of its constituent atoms. In the case of benzoine, which has the molecular formula C14H12O2, the molar mass is approximately 212.25 grams per mole (g/mol).
Benzoin Boiling Point
Benzoine exhibits a relatively high boiling point compared to many other organic compounds. It typically boils at around 343 degrees Celsius (650 degrees Fahrenheit). This high boiling point indicates that benzoine requires significant energy to convert from its liquid to gaseous state.
Benzoin Melting Point
The melting point of benzoine, which signifies the temperature at which it changes from a solid to a liquid state, is approximately 132 to 137 degrees Celsius (270 to 279 degrees Fahrenheit). This characteristic melting range enables benzoine to be easily manipulated in various applications.
Benzoin Density g/mL
The density of benzoine, expressed in grams per milliliter (g/mL), varies depending on the specific form and temperature. Generally, benzoine exhibits a density in the range of 1.30 to 1.33 g/mL. This density value provides information about the mass per unit volume of benzoine.
Benzoin Molecular Weight
The molecular weight of benzoine is determined by summing up the atomic weights of its constituent elements. With a molecular formula of C14H12O2, benzoine has a molecular weight of approximately 212.25 grams per mole (g/mol). This value is essential for various calculations and conversions in chemical reactions.
Benzoin Structure
Benzoine has a distinct molecular structure consisting of two benzene rings connected by a carbon atom bearing a hydroxyl group and a carbonyl group. This structure imparts unique chemical and physical properties to benzoine, making it valuable in various applications such as perfumery and organic synthesis.
Benzoin Solubility
Benzoine exhibits limited solubility in water. It is sparingly soluble in cold water but slightly more soluble in hot water due to increased molecular motion. However, benzoine demonstrates better solubility in organic solvents such as ethanol, methanol, and ether. This solubility behavior is influenced by the intermolecular forces between benzoine molecules and the solvent molecules.
| Appearance | White crystals or powder |
| Specific Gravity | 1.30 – 1.33 g/mL |
| Color | Colorless to off-white |
| Odor | Pleasant almond-like scent |
| Molar Mass | 212.25 g/mol |
| Density | 1.30 – 1.33 g/mL |
| Melting Point | 132 – 137 °C (270 – 279 °F) |
| Boiling Point | 343 °C (650 °F) |
| Flash Point | 152 °C (306 °F) |
| Water Solubility | Sparingly soluble |
| Solubility | Soluble in organic solvents such as ethanol, methanol, and ether |
| Vapour Pressure | Not available |
| Vapour Density | Not available |
| pKa | 9.46 |
| pH | Approximately neutral (7) |
Benzoin Safety and Hazards
Benzoine should be handled with caution due to potential safety hazards. It is important to avoid direct contact with the skin, eyes, and inhalation of its dust or vapors. Skin contact may cause irritation or allergic reactions in some individuals. In case of contact, it is recommended to wash the affected area thoroughly with water. Proper ventilation should be ensured when working with benzoine to prevent inhalation of airborne particles. Additionally, the use of appropriate personal protective equipment, such as gloves and safety goggles, is advisable. Benzoine should be stored in a cool, dry place away from incompatible substances to minimize potential risks.
| Hazard Symbols | Xi (Irritant) |
| Safety Description | – Avoid direct contact with skin and eyes<br>- Ensure proper ventilation<br>- Wear appropriate protective equipment<br>- Store away from incompatible substances |
| UN IDs | Not available |
| HS Code | 2914.50.00 |
| Hazard Class | Not classified |
| Packing Group | Not applicable |
| Toxicity | Low to moderate toxicity |
Benzoin Synthesis Methods
There are several methods for synthesizing benzoine, each involving different reaction pathways.
One commonly used method is the benzoine condensation reaction. In this process, benzaldehyde, an aromatic aldehyde, undergoes a reaction with a nucleophilic compound, usually sodium cyanide or potassium cyanide, which serves as a cyanide source. The reaction takes place in the presence of a catalyst, often an ammonium salt like ammonium acetate or ammonium chloride. The resulting intermediate undergoes further reaction and eventually forms benzoine as the desired product.
Another method requires the coupling of two aromatic aldehydes, such as benzaldehyde, by utilizing an oxidizing agent such as air or oxygen gas. Typically, one carries out this reaction by adding a base, such as sodium hydroxide or potassium hydroxide. The reaction proceeds through a radical mechanism, forming a dimeric intermediate which then undergoes further transformations to yield benzoine.
Moreover, one can synthesize benzoine through the crossed aldol condensation reaction. This method involves the reaction between an aromatic aldehyde, like benzaldehyde, and a ketone, such as acetone. A strong base, such as sodium hydroxide or potassium hydroxide, facilitates the reaction, leading to the production of benzoine.
These synthesis methods demand cautious management of reagents and strict adherence to safety protocols, as they involve the utilization of toxic or hazardous materials. Furthermore, the choice of specific reaction conditions and catalysts can influence the yield and selectivity of benzoine synthesis.
Benzoin Uses
Benzoine finds various applications in different industries and fields due to its unique properties. Here are some notable uses of benzoine:
- Perfumery: Perfume makers, cologne producers, and other fragrance product manufacturers value benzoine for its pleasant, warm, and sweet vanilla-like scent, and they frequently incorporate it into their products.
- Flavoring Agent: Food and beverage manufacturers use benzoine as a flavoring agent to add a rich and aromatic note to baked goods, confectionery items, and liqueurs.
- Pharmaceutical Industry: The pharmaceutical industry relies on benzoine as a precursor in the synthesis of various pharmaceutical compounds, utilizing it in the production of antibiotics, antiseptics, and cough syrups.
- Cosmetic Formulations: Cosmetic and skincare product manufacturers incorporate benzoine into creams, lotions, and ointments to take advantage of its soothing properties, which provide relief for dry or irritated skin.
- Incense and Aromatherapy: Producers of incense sticks and cones use benzoine for its pleasing fragrance, while aromatherapists utilize it to create a calming and relaxing atmosphere.
- Organic Synthesis: Benzoine plays a crucial role as a versatile building block in organic synthesis, participating in reactions to form compounds such as esters, acids, and alcohols. This contributes to the synthesis of pharmaceuticals, dyes, and other organic chemicals.
- Adhesive Applications: Manufacturers of adhesives incorporate benzoine resin into their formulations to enhance adhesive properties, resulting in better bonding for products like woodworking glues and adhesive tapes.
- Traditional Medicine: Benzoine has a longstanding history in traditional medicine due to its expectorant and antiseptic properties. People use it as a remedy for coughs, sore throats, and skin irritations.
The diverse range of applications demonstrates the significance of benzoine in industries related to fragrance, flavoring, pharmaceuticals, cosmetics, and more.
Questions:
Q: How to burn benzoin resin?
A: To burn benzoine resin, place a charcoal disc in a heat-safe container, ignite it, and then sprinkle the benzoin resin on the hot charcoal, allowing it to release its aromatic smoke.
Q: How to work with benzoin gum?
A: Working with benzoine gum involves crushing or grinding the resin into a powder or smaller granules for easier handling and incorporation into various applications like perfumes or incense.
Q: Is tincture of benzoin toxic?
A: Tincture of benzoine is generally considered safe for topical use, but ingestion or inhalation in large quantities may be harmful. It is important to follow recommended usage guidelines and seek medical advice if needed.
Q: What is benzoin oil made of?
A: Benzoine oil is derived from the resin of the Styrax benzoine tree. It is typically obtained through solvent extraction or steam distillation, resulting in an aromatic oil with a rich vanilla-like scent.
Q: Is benzil more acidic than benzoin?
A: Yes, benzil is more acidic than benzoine. Benzil possesses two carbonyl groups, allowing for greater acidic character due to the presence of two potential hydrogen bond donors.
Q: How to apply steri strips with benzoin?
A: Before applying steri strips, clean and dry the area. Then, apply benzoin tincture to the skin surrounding the wound to enhance adhesion, wait for it to dry, and carefully place the steri strips over the wound.
Q: What does benzoin smell like?
A: Benzoine has a pleasant, warm, and sweet scent reminiscent of vanilla or almond, with hints of balsamic and floral notes.
Q: Is benzoin polar?
A: Yes, benzoine is polar due to the presence of polar functional groups such as the hydroxyl (OH) and carbonyl (C=O) groups.
Q: What is the difference between benzoin oil & tincture of benzoin?
A: Benzoine oil refers to the essential oil extracted from the resin, while tincture of benzoine is a solution made by dissolving benzoin resin in alcohol, often used as a topical adhesive or skin protectant.
Q: What is benzoin tincture?
A: Benzoine tincture is a solution made by dissolving benzoine resin in alcohol. It is commonly used as a topical antiseptic, adhesive, or protective agent for the skin.