History
Benzoic acid (CAS NO.65-85-0) was discovered in the 16th century. The dry distillation of gum benzoin first described by Nostradamus in 1556, and subsequently by Alexius Pedemontanus (1560) and Blaise de Vigenère (1596). Justus von Liebig and Friedrich Wöhler determined the structure in 1832.They also investigated how hippuric acid is related to it. In 1875, Salkowski discovered the antifungal abilities of Benzoic acid, which was used for a long time in the preservation of benzoate-containing cloudberry fruits.
Specification
1. Introduction of Benzoic acid
Benzoic acid , its cas register number is 65-85-0. It also can be called Benzenecarboxylic acid; Benzeneformic acid; Benzenemethonic acid; Carboxybenzene; Oracylic acid; phenyl carboxylic acid; Phenylformic acid. It is a white crystals or powder and slightly soluble in water. At high temperature it can react with oxidizing reagents.Dust may be irritating to nose and eyes. At elevated temperatures, fumes may cause irritation of eyes, respiratory system, and skin.
2. Properties of Benzoic acid
H-Bond Donor: 1
H-Bond Acceptor: 2
Melting Point: 121-125 °C(lit.)
Water Solubility: Slightly soluble. 0.34 g/100 mL
Refractive index: 1.504
Stability: Stable. Combustible. Incompatible with strong bases, strong oxidizing agents, alkalies.
Surface Tension: 48.7 dyne/cm
Flash Point: 111.4 °C
Enthalpy of Vaporization: 51.4 kJ/mol
Boiling Point: 249.3 °C at 760 mmHg
Vapour Pressure: 0.0122 mmHg at 25°C
3. Toxicity of Benzoic acid
| Organism | Test Type | Route | Reported Dose (Normalized Dose) | Effect | Source |
|---|---|---|---|---|---|
| frog | LDLo | subcutaneous | 100mg/kg (100mg/kg) | "Handbook of Toxicology," 4 vols., Philadelphia, W.B. Saunders Co., 1956-59Vol. 5, Pg. 23, 1959. | |
| guinea pig | LDLo | intraperitoneal | 1400mg/kg (1400mg/kg) | "Handbook of Toxicology," 4 vols., Philadelphia, W.B. Saunders Co., 1956-59Vol. 5, Pg. 23, 1959. | |
| guinea pig | LDLo | oral | 2gm/kg (2000mg/kg) | Muenchener Medicinische Wochenschrift. Vol. 77, Pg. 13, 1930. | |
| human | TDLo | skin | 6mg/kg (6mg/kg) | LUNGS, THORAX, OR RESPIRATION: DYSPNEA SKIN AND APPENDAGES (SKIN): "DERMATITIS, ALLERGIC: AFTER SYSTEMIC EXPOSURE" | Journal of Allergy. Vol. 16, Pg. 195, 1945. |
| man | LDLo | oral | 500mg/kg (500mg/kg) | Food and Cosmetics Toxicology. Vol. 17, Pg. 715, 1979. | |
| mouse | LD50 | intraperitoneal | 1460mg/kg (1460mg/kg) | Comptes Rendus des Seances de la Societe de Biologie et de Ses Filiales. Vol. 160, Pg. 1097, 1966. | |
| mouse | LD50 | oral | 1940mg/kg (1940mg/kg) | BEHAVIORAL: SOMNOLENCE (GENERAL DEPRESSED ACTIVITY) LUNGS, THORAX, OR RESPIRATION: RESPIRATORY DEPRESSION GASTROINTESTINAL: OTHER CHANGES | Iyakuhin Kenkyu. Study of Medical Supplies. Vol. 15, Pg. 359, 1984. |
| rabbit | LD50 | skin | > 10gm/kg (10000mg/kg) | BIOFAX Industrial Bio-Test Laboratories, Inc., Data Sheets. Vol. 28-4/1973, | |
| rabbit | LDLo | oral | 2gm/kg (2000mg/kg) | "Handbook of Toxicology," 4 vols., Philadelphia, W.B. Saunders Co., 1956-59Vol. 5, Pg. 23, 1959. | |
| rabbit | LDLo | subcutaneous | 2gm/kg (2000mg/kg) | "Handbook of Toxicology," 4 vols., Philadelphia, W.B. Saunders Co., 1956-59Vol. 5, Pg. 23, 1959. | |
| rat | LC50 | inhalation | > 26mg/m3/1H (26mg/m3) | SENSE ORGANS AND SPECIAL SENSES: LACRIMATION: EYE BEHAVIORAL: SOMNOLENCE (GENERAL DEPRESSED ACTIVITY) | BIOFAX Industrial Bio-Test Laboratories, Inc., Data Sheets. Vol. 28-4/1973, |
| rat | LD50 | intraperitoneal | 1600mg/kg (1600mg/kg) | Bollettino Chimico Farmaceutico. Vol. 112, Pg. 53, 1973. | |
| rat | LD50 | intravenous | 1700mg/kg (1700mg/kg) | Acta Physiologica Polonica. Vol. 12, Pg. 173, 1961. | |
| rat | LD50 | oral | 1700mg/kg (1700mg/kg) | International Polymer Science and Technology. Vol. 3, Pg. 93, 1976. |
4. Safety Information of Benzoic acid
Hazard Codes:
.gif){kind=small}
Xn,.gif){kind=small}
T Risk Statements: 22-36-42/43-36/37/38-40-63-43-23/24/25-45
22: Harmful if swallowed
36: Irritating to the eyes
42/43: May cause sensitization by inhalation and skin contact
36/37/38: Irritating to eyes, respiratory system and skin
40: Limited evidence of a carcinogenic effect
63: In case of accident by inhalation, remove casualty to fresh air and keep at rest
43: In case of fire, use ... (indicate in the space the precise type of fire-fighting equipment. If water increases the risk add - Never use water)
23/24/25: Toxic by inhalation, in contact with skin and if swallowed
45: May cause cancer
41: Risk of serious damage to eyes
37/38: Irritating to respiratory system and skin
20/21/22: Harmful by inhalation, in contact with skin and if swallowed
Safety Statements: 26-45-37/39-24-22-36/37-24/25-23-53
26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice
45: In case of accident or if you feel unwell, seek medical advice immediately (show label where possible)
37/39: Wear suitable gloves and eye/face protection
24: Avoid contact with skin
22: Do not breathe dust
36/37: Wear suitable protective clothing and gloves
24/25: Avoid contact with skin and eyes
23: Do not breathe gas/fumes/vapor/spray (appropriate wording to be specified by the manufacturer)
53: Avoid exposure - obtain special instruction before use
36: Wear suitable protective clothing
RIDADR: UN 3077 9/PG 3
WGK Germany: 1
RTECS: DG0875000
F: 21
Hazard Note: Harmful
5. Use of Benzoic acid
The usage of the Benzoic acid as following:
1.Feedstock: It is an important precursor for the synthesis of many other organic substances.
2.Food preservative: It and its salts are used as a food preservative.
3.Medicinal
4.Biology and health effects
6. Preparation of Benzoic acid
Benzoic acid is cheap and readily available, so the laboratory synthesis of benzoic acid is mainly practiced for its pedagogical value.
For all syntheses, it can be purified by recrystallization from water because of its high solubility in hot water and poor solubility in cold water. The avoidance of organic solvents for the recrystallization makes this experiment particularly safe. Other possible recrystallization solvents include acetic acid (anhydrous or aqueous), benzene, petroleum ether, and a mixture of ethanol and water.
It can be manufactured by the liquid-phase oxidation of toluene by air in a continuous oxidation reactor operated at moderate pressure and temperature:
2C6H5CH3 + 3O2 → 2C6H5COOH + 4H2O
It also can be obtained as a by-product of the manufacture of benzaldehyde from benzal chloride or benzyl chloride.