Oxidized to a cooh group h3 c ch 3 k2 cr 2 o 7 14

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Unformatted text preview: e benzene ring, each is oxidized to a -COOH group H3 C CH 3 K2 Cr 2 O 7 1,4-Dimethylbenzene ( -xylene) p Not responsible for mechanism H2 SO4 O HOC O COH 1,4-Benzenedicarboxylic acid (terephthalic acid) 12 Organic Organic Lecture Series Benzylic Chlorination • Chlorination (and bromination) occurs by a radical mechanism 13 Organic Lecture Series Benzylic Bromination • Bromination can be conducted with NBS: 14 Organic Organic Lecture Series Benzoyl Peroxide as a Radical initiator 15 Organic Lecture Series Benzylic Reactions • Benzylic radicals (and cations also) are easily formed because of the resonance stabilization of these intermediates – the benzyl radical is a hybrid of five contributing structures 16 Benzylic Halogenation Organic Organic Lecture Series – benzylic bromination is highly regioselective – benzylic chlorination is less regioselective 17 Organic Lecture Series Reactions of Benzene & Its Derivatives Chapter 22 18 Organic Organic Lecture Series Reactions of Benzene The most characteristic reaction of aromatic compounds is substitution at a ring carbon: 19 Organic Lecture Series Reactions of Benzene Sulfonation: H + SO3 H2 SO4 SO3 H Benzenesulfonic acid Alkylation: H + RX A lX 3 R + HX An alkylbenzene Acylation: O H + RC X O A lX 3 CR + H X An acylbenzene 20 Organic Organic Lecture Series Carbon-Carbon Bond Formations: 21 Organic Lecture Series Electrophilic Aromatic Substitution • Electrophilic aromatic substitution: a reaction in which a hydrogen atom of an aromatic ring is replaced by an electrophile • In this section: – several common types of electrophiles – how each is generated – the mechanism by which each replaces hydrogen 22...
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This note was uploaded on 11/21/2011 for the course CH 51455 taught by Professor Colapret during the Spring '11 term at University of Texas.

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