Dolbier HW Solutions 276

Dolbier HW Solutions 276 - CH 2 CH 3 Ethylbenzene (most...

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to alkynes consists of bromine addition followed by a double dehydrohalogenation in strong base. ( d ) The conversion of phenylacetylene to butylbenzene requires both a carbon carbon bond for- mation step and a hydrogenation step. The acetylene function is essential for carbon carbon bond formation by alkylation. The correct sequence is therefore: ( e ) The transformation corresponds to alkylation of acetylene, and so the alcohol must f rst be converted to a species with a good leaving group such as its halide derivative. ( f ) The target compound is a bromohydrin. Bromohydrins are formed by addition of bromine and water to alkenes. 11.38 The stability of free radicals is re F ected in their ease of formation. Toluene, which forms a benzyl rad- ical, reacts with bromine 64,000 times faster than does ethane, which forms a primary alkyl radical. Ethylbenzene, which forms a secondary benzylic radical, reacts 1 million times faster than ethane.
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Unformatted text preview: CH 2 CH 3 Ethylbenzene (most reactive) CHCH 3 Secondary benzylic radical 1 Br 1 HBr CH 3 Toluene 1 Br CH 2 Primary benzylic radical 1 HBr Ethane (least reactive) 1 Br CH 3 CH 3 Primary radical 1 HBr CH 3 CH 2 CH 2 KOC(CH 3 ) 3 (CH 3 ) 3 COH C 6 H 5 CH 2 CH 2 Br C 6 H 5 CH Br 2 H 2 O 2-Phenylethyl bromide 2-Bromo-1-phenylethanol Styrene C 6 H 5 CHCH 2 Br OH C 6 H 5 CH 2 CH 2 Br C 6 H 5 CH 2 CH 2 Br 2-Phenylethyl bromide 2-Phenylethanol C 6 H 5 CH 2 CH 2 OH PBr 3 1 NaC CH 2-Phenylethyl bromide CH C 6 H 5 CH 2 CH 2 C 4-Phenyl-1-butyne Sodium acetylide CCH 2 CH 3 C 6 H 5 C H 2 Pt C 6 H 5 CH 2 CH 2 CH 2 CH 3 Butylbenzene 1 CH 3 CH 2 Br CCH 2 CH 3 C 6 H 5 C 2 Na 1 C C 6 H 5 C NaNH 2 NH 3 Phenylacetylene CH C 6 H 5 C 2 Na 1 C C 6 H 5 C Phenylacetylene CH 2 C 6 H 5 CH Styrene 1,2-Dibromo-1-phenylethane Br 2 C 6 H 5 CHCH 2 Br Br NaNH 2 NH 3 C 6 H 5 C CH 270 ARENES AND AROMATICITY...
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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.

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