Question

The correct reactivity order of following C = C / $C\equiv$ C bonds towards $B{r}^{\oplus }$ is:

• A. 4 > 3 > 2 > 1
• B. 3 > 2 > 1 > 4
• C. 1 > 3 > 4 > 2
• D. 1 > 3 > 2 > 4

Answer 1

The correct option is D 1 > 3 > 2 > 4

C = C at position 1 is more reactive towards electrophile $B{r}^{\oplus }$ as this is adjacent to O atom to provide +m effect.
C = C at position 3 is more substituted as compared to C = C at position 2.
alkyne is less reactive toward $B{r}^{\oplus }$ as compared to alkene.
Hence correct reactivity order of $B{r}^{\oplus }$ towards C = C / $C\equiv$ C bond is 1 > 3 > 2 > 4