Dolbier HW Solutions 217

Dolbier HW Solutions 217 - The designated starting material,

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
9.6 Both 1-pentyne and 2-pentyne can be prepared by alkylating acetylene. All the alkylation steps involve nucleophilic substitution of a methyl or primary alkyl halide. A third isomer, 3-methyl-1-butyne, cannot be prepared by alkylation of acetylene, because it re- quires a secondary alkyl halide as the alkylating agent. The reaction that takes place is elimination, not substitution. 9.7 Each of the dibromides shown yields 3,3-dimethyl-1-butyne when subjected to double dehydro- halogenation with strong base. 9.8 ( b ) The f rst task is to convert 1-propanol to propene: After propene is available, it is converted to 1,2-dibromopropane and then to propyne as described in the sample solution for part ( a ). ( c ) Treat isopropyl bromide with a base to effect dehydrohalogenation. Next, convert propene to propyne as in parts ( a ) and ( b ). ( d ) The starting material contains only two carbon atoms, and so an alkylation step is needed at some point. Propyne arises by alkylation of acetylene, and so the last step in the synthesis is
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: The designated starting material, 1,1-dichloroethane, is a geminal dihalide and can be used to prepare acetylene by a double dehydrohalogenation. 1. NaNH 2 , NH 3 2. H 2 O CH 3 CHCl 2 1,1-Dichloroethane HC CH Acetylene 1. NaNH 2 , NH 3 2. CH 3 Br HC CH Acetylene CH 3 C CH Propyne (CH 3 ) 2 CHBr NaOCH 2 CH 3 Propene Isopropyl bromide CH 3 CH CH 2 CH 3 CH 2 CH 2 OH H 2 SO 4 heat Propene 1-Propanol CH 3 CH CH 2 1. 3NaNH 2 2. H 2 O or or (CH 3 ) 3 CCCH 3 Br Br 2,2-Dibromo-3,3-dimethylbutane (CH 3 ) 3 CCH 2 CHBr 2 1,1-Dibromo-3,3-dimethylbutane Br (CH 3 ) 3 CCHCH 2 Br 1,2-Dibromo-3,3-dimethylbutane (CH 3 ) 3 CC CH 3,3-Dimethyl-1-butyne 1 1 E2 CH 3 CHCH 3 Br Isopropyl bromide HC CH Acetylene CH 2 CHCH 3 Propene HC Acetylide ion C 2 1. NaNH 2 , NH 3 2. CH 3 CH 2 Br Acetylene 1-Butyne 2-Pentyne CH HC 1. NaNH 2 , NH 3 2. CH 3 Br CH 3 CH 2 C CH CH 3 CH 2 C CCH 3 Acetylene 1-Pentyne CH HC CH CH 3 CH 2 CH 2 C 1. NaNH 2 , NH 3 2. CH 3 CH 2 CH 2 Br ALKYNES 211...
View Full Document

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.

Ask a homework question - tutors are online