Chapter 8 Aromaticity Reactions of Benzene and Substituted Benzenes
The first structure for benzene was proposed by August Kekulé in 1872.
Naming Benzene Compounds To name a benzene ring with one substituent, name the substituent and add the word benzene.
phenol aniline toluene anisole styrene benzaldehyde benzoic acid benzonitrile Common Names
ortho-dibromobenzene or o-dibromobenzene or 1,2-dibromobenzene meta-dibromobenzene or m-dibromobenzene or 1,3-dibromobenzene para-dibromobenzene or p-dibromobenzene or 1,4-dibromobenzene
If the two groups on the benzene ring are different, alphabetize the names of the substituents preceding the word benzene. • If one substituent is part of a common root, name the molecule as a derivative of that monosubstituted benzene.
For three or more substituents on a benzene ring: • Number to give the lowest possible numbers around the ring. • Alphabetize the substituent names. • When substituents are part of common roots, name the molecule as a derivative of that monosubstituted benzene. The substituent that comprises the common root is located at C1.
Page 214 Problem 14 More practice….. Page 226 Problem 26
What are the products of oxidation of the following compounds? Another problem…..Page 213 Problem 12
Side Chain Bromination Reaction of an alkylbenzene with N-bromo-succinimide (NBS) and benzoyl peroxide (radical initiator) introduces Br into the side chain.
Reactions of Benzene: Electrophilic Substitution Vs Electrophilic Addition
Di- and Polysubstitution • Existing groups on a benzene ring influence further substitution in both orientation and rate • Orientation • certain substituents direct new substitution preferentially toward ortho-parapositions, others direct preferentially towardmetapositions • Rate • certain substituents are activating toward further substitution, others are deactivatingtoward further substitution
Ortho-para Directors -OCH3 is ortho-para directing