1. Aromatic hydrocarbons
(Session 33)
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2. Aromatic Hydrocarbons
Compounds that have, at least one ring of six atoms of carbon in a continual system if double bond
Benzene and its derivatives constitute the class of compounds called aromatic hydrocarbons.
The molecular formula of benzene is C6H6
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3. Nomenclature
Many of the aromatic hydrocarbons have common names. These common names are used in the IUPAC nomenclature.
When the aromatic hydrocarbon is substituted, it is necessary to name the substitute and its position ( with numbers or letters) according to the basic rules of the IUPAC nomenclature.
For the base name the common name of the aromatic hydrocarbons are used. For example:
Br Cl Br Cl
1,2 dibromine benzene ,4 dichloride benzene
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Formulas
Common names for some of the aromatic hydrocarbons:
CH OH
Toluene Phenol
NH COOH
Aniline
Benzoic Acid
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5. Replaced Aromatic HydrocarbonsOH OH CL
2 hydroxy toluene
2 chloro phenol
NH2
COOH Br Br
NO2
3,5 dibromide aniline
3-nitro benzoic
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Physical Properties
All the aromatic hydrocarbons are liquids or solids at room temperature.
Their boiling points are higher then the non aromatic hydrocarbons with the same or similar molecular weight.
Are low polar or non polar.
Are less dense then water.
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Chemical Properties
Their characteristic reactions are reactions of electrophillic substitution (ionic s):
Halogenations Cl
+ Cl2
Fe Cl3
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Chemical Properties
Nitration
NO2
+ HNO3
H2SO4
+ H2O
Nitrobenzene
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9. Alkylation reaction of Friedel-Crafts
+ R - Cl
Al Cl3
+ HCl
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10. Application and importance of the aromatics
Excellent dissolvent in the industry and in Labs.
Polystyrene is obtained from the polymerization of styrene Trinitrotoluene is an excellent explosive.
Colorants (anthracene)
Naphthalene (naftalenic)
Insecticides (chlorinated aromatic hydrocarbons like DDT)
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Bibliography
Bloomfield, M. (1997) Chemistry in living organisms. 1st ed. Mexico: LIMUSA
Rakoff, H. et al. (1992) Fundamental Organic Chemistry. 1st ed. Mexico: LIMUSA
Solomons, G. (1996) Fundaments of Organic Chemistry. 2nd. ed. Mexico: LIMUSA
Computer Aided Molecular Design (2003). Benzene on Graphite [Image]. Computer Aided Molecular Design. Extracted on May on the World Wide Web:
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