1,3-Dibromopropane can be prepared via the between and .

1,3-Dibromopropane is a ated . When at , it is a colorless to light-brown liquid containing sweet odor. Synthetically, it is very useful to form C3-bridged compounds such as through C-N coupling reactions.

Reaction of the anion of 1-butyne with ethyl bromide completes the synthesis.

9.12The proper double-bond stereochemistry may be achieved by using 2-heptyne as a reactant in the final step. Lithium–ammonia reduction of 2-heptyne gives the trans alkene; hydrogenation over Lindlar palladium gives the cis isomer. The first task is therefore the alkylation of propyne to 2-heptyne.


Propyne CH3CC H1,1-Dibromopropane

Propyne CH3CC H 2,2-Dibromopropane

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.