Question

How many of the following addition reactions are $syn$ addition reaction?

Answer 1

(a) Addition of $B{r}_2$ in $CC{l}_4$ goes through anti fashion. On cis alkene, it gives a racemate.

(b) Hydrogenation in presence of $Ni$ catalyst takes place in syn fashion.

(c) Cold basic $KMn{O}_4$ does syn dihydroxylation of alkene.

(d) Alkynes on reduction with sodium in liquid ammonia form trans alkenes.

(e)Alkynes on reduction with Lindlar’s catalyst give cis alkene.