Aromatic hydrocarbons (Session 33) Ciencias de la tierra II
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 Ciencias de la tierra II
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 1,4 dichloride benzene Ciencias de la tierra II
Ciencias de la tierra II Formulas Common names for some of the aromatic hydrocarbons: CH3 OH Toluene Phenol NH2 COOH Aniline Benzoic Acid Ciencias de la tierra II
Replaced Aromatic Hydrocarbons OH OH CL 2 hydroxy toluene 2 chloro phenol NH2 COOH Br Br NO2 3,5 dibromide aniline 3-nitro benzoic Ciencias de la tierra II
Ciencias de la tierra II 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. Ciencias de la tierra II
Ciencias de la tierra II Chemical Properties Their characteristic reactions are reactions of electrophillic substitution (ionic s): Halogenations Cl + Cl2 Fe Cl3 Ciencias de la tierra II
Ciencias de la tierra II Chemical Properties Nitration NO2 + HNO3 H2SO4 + H2O Nitrobenzene Ciencias de la tierra II
Alkylation reaction of Friedel-Crafts + R - Cl Al Cl3 + HCl Ciencias de la tierra II
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) Ciencias de la tierra II
Ciencias de la tierra II 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 28 2003 on the World Wide Web: http://obr-camd.che.uc.edu/research.html Ciencias de la tierra II