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Dolbier HW Solutions 295 - f A nitro substituent is...

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( d ) The methoxy group in anisole is strongly activating and ortho, para-directing. For steric rea- sons and because of inductive electron withdrawal by oxygen, the intermediate leading to para substitution is the most stable. Of the various resonance forms for the most stable intermediate, the most stable one has eight electrons around each oxygen and carbon atom. This intermediate is much more stable than the corresponding intermediate from acylation of benzene. ( e ) An isopropyl group is an activating substituent and is ortho, para-directing. Attack at the ortho position is sterically hindered. The most stable intermediate is or any of its resonance forms. Because of its tertiary carbocation character, this cation is more stable than the corresponding cyclohexadienyl cation intermediate from benzene.
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Unformatted text preview: ( f ) A nitro substituent is deactivating and meta-directing. The most stable cyclohexadienyl cation formed in the bromination of nitrobenzene is This ion is less stable than the cyclohexadienyl cation formed during bromination of benzene. ( g ) Sulfonation of furan takes place at C-2. The cationic intermediate is more stable than the cyclo-hexadienyl cation formed from benzene because it is stabilized by electron release from oxygen. O O SO 3 H O 1 O 1 H 2 SO 4 via Furan Furan-2-sulfonic acid SO 3 H H SO 3 H H N H Br 1 2 1 O O CH(CH 3 ) 2 H NO 2 1 Most stable resonance form H O CCH 3 OCH 3 1 more stable than slightly more stable than OCH 3 H CCH 3 1 O OCH 3 O H CCH 3 1 OCH 3 H CCH 3 1 O REACTIONS OF ARENES: ELECTROPHILIC AROMATIC SUBSTITUTION 289...
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