Ch_322a_7.013

Ch_322a_7.013 - reagents and alkyl halides. solution CH 3...

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Replacement of the Alkynyl Hydrogen: Alkylation The acidity of the alkynyl hydrogen is the basis of an alkylation reaction wherein an alkyl group is introduced. A Two-Step Synthesis RC C- H terminal alkyne pK a ~ 25 + NaNH 2 sodium amide RC C: - Na + + NH 3 pK a = 38 sodium alkynide Alkylation S N 2 RC C- R' + NaX RC C: - Na + a good nucleophile + R' X alkyl halide
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CH 3 CH 2 C C: - Na + + CH 3 CH 2 Br liquid NH 3 -33 o C CH 3 CH 2 C CCH 2 CH 3 3-hexyne HC CCH 2 C 6 H 5 3-phenyl-1-propyne HC C: - Na + + C 6 H 5 CH 2 Br benzyl bromide liquid NH 3 -33 o C Examples of Alkylation Reactions A Limitation: With 2 o and 3 o alkyl halides, the E2 dominates. RC C: - Na + + C C R H Br H H R' RC CH + R'CH=CHR
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Quiz 7.013 Provide a synthesis of pentane from propene using any needed
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Unformatted text preview: reagents and alkyl halides. solution CH 3 CH=CH 2 CH 3 CH 2 CH 2 CH 2 CH 3 Retrosynthetic analysis suggests the following steps to couple the two hydrocarbon units: CH 3 CH 2 CH 2 CH 2 CH 3 CH 3 C C-CH 2 CH 3 CH 3 C C:- + XCH 2 CH 3 CH 3 CH=CH 2 proposed synthesis CH 3 CH=CH 2 Br 2 CH 3 CHBrCH 2 Br (i) 3 eq NaNH 2 (ii) workup NH 4 Cl CH 3 C CH (i) NaNH 2 (ii) CH 3 CH 2 Br CH 3 C CCH 2 CH 3 excess H 2 Pt CH 3 CH 2 CH 2 CH 2 CH 3...
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This note was uploaded on 07/22/2009 for the course CHEM 322AL taught by Professor Jung during the Summer '07 term at USC.

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Ch_322a_7.013 - reagents and alkyl halides. solution CH 3...

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