SolutionsAlkanes, alkenes, alkynes and arenes
Exercise 1
What products are obtained on ozonolysis with reductive work-up (Me2S) of 1-methylcyclohexene and of (E)-3-methylpent-2-ene?
1-Methylcyclohexene, being cyclic, gives a single molecule with two carbonyl groups: 6-oxoheptanal (CH3CO(CH2)4CHO). 3-Methylpent-2-ene, CH3CH=C(CH3)CH2CH3, gives acetaldehyde and butan-2-one. The alkene geometry is lost, because both carbons of the double bond become carbonyls.
Exercise 2
Propose syntheses of (Z)- and (E)-hex-3-ene from acetylene and ethyl bromide.
Double alkylation of acetylene: NaNH2 in liquid NH3 and EtBr, twice, gives hex-3-yne. Hydrogenation with the Lindlar catalyst gives (Z)-hex-3-ene; reduction with sodium in liquid ammonia gives (E)-hex-3-ene.