ACIDE BENZOIQUE - (65-85-0)

introduction

prénom: benzoic acid
* IUPAC
Numero CAS: 65-85-0
Formule chimique: C7H6O2 or C6H5COOH
Masse molaire: 122.12134 g
Pourcentage de masse: C 68.845 %; H 4.9521 %; O 26.202 % 

Classification

Usages / Fonction

• "It and its sodium salt inhibit decay and fermentation." 1

• "More than half of all the benzoic acid produced in the United States is used in the manufacture of various polymeric producs, primarily the family of plastics known as the polyvinyl acetates (PVAs). The PVAs, in turn, are used as adhesives, caulks, sealants, and coatings for paper, film, and plastic foil. About a quarter of all benzoic acid is converted to its sodium and potassium salts, sodium benzoate (C6H5COONa) and potassium benzoate (C6H5COOK), for use as food preservatives. Sodium benzoate and potassium benzoate are now the most widely used food preservatives in the world. They are added to a host of products, such as soft drinks and fruit juices, jams, and jellies, baked goods, and salad dressings. They are also added to a number of non-food products such as mouthwashes, toothpastes, cosmetic creams, and deodorants.

Other uses of benzoic acid include:
• As an additive to antifreezes, where it acts to prevent the corrosion of engine parts;
• As a seasoning agent in the processing of tobacco products;
• As a stabilizing agent in the processing of photographs; and
• For the treatment of fungal infections.

Benzoic acid and its sodium and potassium salts pose moderate health hazards to people who work directly with them. They may cause skin, nose, and eye problems if inhaled or deposited on the body. In the form of finely divided dust, they may also pose a fire or explsoive risk. Most people do not encounter any of these compounds in a form in which they pose a health risk. All three compounds are considered safe by the U.S. Food and Drug Administration as food additives provided their concentration in foods does not exceed 0.1 percent. Other nations have set a safe level for the three compounds as food additives as high as 1.25 percent." 2

• "A white crystalline material having a slight odor; used in keratolytic ointments and as a food preservative. Saccharin is a derivative of this acid." 3

Propriétés physiques

Point de fusion:*
122.4°C 4 = 395.55 K = 252.32°F
Point d'ébullition:*
249.2°C 4 = 522.35 K = 480.56°F
Densité (g/cm3):
1.2659 at 15°C 4
* - 1 atm pressure

Solubilité

Qualitatif:
miscible:  • • • 4

Bonding

Obligations doubles: 4
Obligations Triple: 0
Obligations Sigma: 15
Obligations Pi: 4
Total: 19
carboxyl Groupes: 1
Les groupes hydroxylés: 0
Hybridation: all carbons and double bonded oxygen are sp2; single bonded oxygen is double bonded oxygen is sp3

Thermochimie

ΔHf° (s): -92.03 kcal/mol 5 = -385.05 kJ/mol
S° (s): 40.05 cal/(mol•K) 6 = 167.57 J/(mol•K)
ΔGf° (s): -58.62 kcal/mol 7 = -245.27 kJ/mol
The heat of combustion is the amount of heat released when one mole of a substance undergoes combustion according to the general reaction equation:
CxHyOz + 0.25(4x+y-2z) O2 (g) → x CO2 (g) + 0.5y H2O (ℓ)

ΔHcomb° (s): -771.265 kcal = -3227.00648 kJ

Pour plus d'informations

Sources

(1) - Brownlee, Raymond B., Fuller, Robert W., and Whitsit, Jesse E. Elements of Chemistry; Allyn and Bacon: Boston, Massachusetts, 1959; p 321.
(2) - Schlager, Neil, Weisblatt, Jayne, Newton, David E., and Montney, Charles B. Chemical Compounds Vol. 1; Thomson-Gale: Detroit, MI, 2006; p 107.
(3) - Taber's Cyclopedic Medical Dictionary, 18th ed.; F. A. David Company: Philadelphia, PA, 1997; p 20.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 3-69.
(5) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:67.
(6) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:67.
(7) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:67.