BENZENE* - (71-43-2)

Introducción

Nombre: benzene*; phenyl hydride; benzol
* IUPAC
Número CAS: 71-43-2
Fórmula química: C6H6
Masa molar: 78.11184 g
Porcentaje de masas: C 92.257 %; H 7.7422 % 

Clasificación

• orgánico • aromático

Usos / Función

• "Manuf[acture] of industrial chemicals such as polymers, detergents, pesticides, pharmaceuticals, dyes, plastics, resins. Solvent for waxes, resins, oils, natural rubber, etc. Gasoline additive." 1

• "Benzene is an important industrial chemical, usually about 15th on the list of the top 50 chemicals produced annually in the United States. It is used as a solvent and is also the starting point for making thousands of different compound by replacing the H atoms of the ring." 2

• "By far the most important use of benzene is as a raw material in the synthesis of other organic compounds. More than 90 percent of the benzene produced in the United States is used to make ethylbenzene (55 percent), cumene (24 percent), and cyclohexane (12 percent). The first two compounds rank fifteenth and twentieth, respectively, among all chemicals produced in the United States each year. Another five percent of benzene production goes to the synthesis of a large variety of other organic compounds, including nitrobenzene, chlorobenzene, and maleic anhydride, a raw material for the manufacture of plastics. Smaller amounts of benzene are used as a solvent for cleaning purposes, in chemical reactions, and as a gasoline additive.

As with most chemicals, benzene can enter the body in one of three ways: through the skin, the nose, or the throat. People who handle or work with benzene in their workplaces are at greatest risk of exposure to benzene and should take precautions in working with the material. Because of its serious health hazards, benzene is no longer included in most materials with which the average person comes in contact. On those occasions when a person does come into contact with benzene, first aid and medical attention should be sought for the treatment of the exposure.

The health effects of exposure to liquid benzene or benzene fumes depends on the amount of benzene taken into the body. The most common symptoms of benzene exposure include irritation of the mucous membranes, convulsions, depression, and restlessness. At greater doses, a person may experience respiratory failure, followed by death. Even at low concentrations, benzene can cause long term effects for people who are regularly in contact with the compound. The most important of these effects is carcinogenic. Benzene is known to cause damage to bone marrow, resulting in a form of cancer of the blood known as leukemia." 3

Propiedades físicas

Punto de fusion:*
5.5°C 4 = 278.65 K = 41.9°F
5.5°C 5 = 278.65 K = 41.9°F
Punto de ebullición:*
80.1°C 5 = 353.25 K = 176.18°F
80.0°C 4 = 353.15 K = 176°F
Densidad (g/cm3):
0.8765 at 20°C 4
* - 1 atm pressure

Solubilidad

Cualitativo:
ligeramente soluble:  5
soluble:  • • 5

Vinculación

Los enlaces dobles: 3
triples enlaces: 0
enlaces sigma: 12
enlaces pi: 3
Total: 15
Grupos carboxilo: 0
Grupos hidroxilo: 0
Hibridación: sp2
Vinculación: polar covalent
Ionic Character: 10.61 %

termoquímica

ΔHf° (ℓ): 11.71 kcal/mol 6 = 48.99 kJ/mol
ΔHf° (g): 19.82 kcal/mol 6 = 82.93 kJ/mol
S° (ℓ): 41.41 cal/(mol•K) 7 = 173.26 J/(mol•K)
S° (g): 64.34 cal/(mol•K) 7 = 269.20 J/(mol•K)
ΔGf° (ℓ): 29.72 kcal/mol 8 = 124.35 kJ/mol
ΔGf° (g): 30.99 kcal/mol 8 = 129.66 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° (ℓ): -780.955 kcal = -3267.54464 kJ
ΔHcomb° (g): -789.065 kcal = -3301.47688 kJ

reacciones

Para más información

Wikipedia
revistas:
French, Ind. Chemist 39, 9-12 (1963)
Thorne et al., Ind. Eng. Chem. Anal. Ed. 17, 481 (1945)
F. P. Schwartz, Anal. Chem. 52, 10 (1980)
Kimura et al., Toxicol. Appl. Pharmacol. 19, 699 (1971)
R. Snyder et al., Rev. Biochem. Toxicol. 3, 123-154 (1981)
David B. Richardson, Environ. Health Perspect. 116, 370-374 (2008)
Nadar G. Abraham, Environ. Health Perspect. 104, 1277-1282 (1996)
Lester B. Lave, Amer. Statistician 36, 260-261 (1982)

Fuentes

(1) - The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 13th ed.; Budavari, S.; O'Neil, M.J.; Smith, A.; Heckelman, P. E.; Kinneary, J. F., Eds.; Merck & Co.: Whitehouse Station, NJ, 2001; entry 1066.
(2) - Kotz, John C. and Treichel, Paul. Chemistry & Chemical Reactivity 4th ed.; Thomson Brooks/Cole: Belmont, CA, 1999; p 498.
(3) - Schlager, Neil, Weisblatt, Jayne, Newton, David E., and Montney, Charles B. Chemical Compounds Vol. 1; Thomson-Gale: Detroit, MI, 2006; pp 101-102.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 3-26.
(5) - Estok, George K. Organic Chemistry: A Short Text; W.B. Saunders: Philadelphia, 1959; p 58.
(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.
(8) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:67.
(9) - Jolly, William L. The Chemistry of the Non-Metals; Prentice-Hall: Englewood Cliffs, New Jersey, 1966; p 4.
(10) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 223.