( f ) Friedel – Crafts alkylation occurs when biphenyl is treated with tert-butyl chloride and iron (III) chloride (a Lewis acid catalyst); the product of monosubstitution is p-tert-butylbiphenyl. All the positions of the ring that bears the tert-butyl group are sterically hindered, so the sec-ond alkylation step introduces a tert-butyl group at the para position of the second ring. ( g ) Disulfonation of phenol occurs at positions ortho and para to the hydroxyl group. The ortho, para product predominates over the ortho, ortho one. 12.27 When carrying out each of the following syntheses, evaluate how the structure of the product differs from that of benzene or toluene; that is, determine which groups have been substituted on the ben-zene ring or altered in some way. The sequence of reaction steps when multiple substitution is de-sired is important; recall that some groups direct ortho, para and others meta. ( a
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This note was uploaded on 09/26/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.