Unformatted text preview: 1 6-28 (a) 1 ,2-dichlorobenzene (ortho) (b) 4-nitroanisole (para) (c) 2,3-dibromobenzoic aci d (d) 2,7 -dimethoxynaphthalene 16-29 (5 (e) 3-chlorobenzoic aci d (meta) (0 2 ,4,6-trichlorophenol (g) 2-sec-butylbenzaldehyde (ortho) (h ) cycIopropenium tetrafluoroborate t oluene CH3 � o-xylene 1 ,2,3-tri methylbenzene llA CH l CH3 q CHl C H3 CH3 1 ,2,4-tri methylbenzene 1 ,3,5-trimethylbenzene (common name: mesitylene) 1 6-30 Aromaticity is one of the strongest stabilizing forces in organic molecules. The c ycIopentadienyl system is stabilized in the anion form where it has 6 'It e lectrons, a Huckel number. The question then becomes: which of the four structures can lose a proton to become aromatic? 3 Whi le the first, third, and fourth structures can lose protons from sp carbons to give resonance stabilized anions, onl y the second structure can make a cycIopentadienide anion. It w i l l lose a proton most easily of these four structures which, by definition, means it is the strongest acid. £
C H3 CHJ p-xylene 1 6-31 (a) H yly H H VH
H H H H �
H H AROMATIC H H H H �� H H H H H H H 351 H ...
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