Question

Complete the curved arrow electron-pushing mechanism of the following E2 elimination of 3-bromopentane and draw the structure of the organic product formed. Use three curved arrows to show the conversion to the product. Draw the organic product of the E2 elimination of the 2-bromopentane.

Answer 1

Concepts and reason

A reaction is given in which a haloalkane is reacting with a hydroxide ion and whose correct elimination product through E2 mechanism needs to be formed and the step of the mechanism needs to be completed using the curved arrow. Generally, reaction elimination of haloalkane results in the formation of alkene.

Fundamentals

1.In E-2 elimination reaction the reaction takes place in one step through the formation of a transition state. In haloalkane, the order of reactivity for the ${\rm{E - 2}}$ elimination is, $3^\circ < 2^\circ < 1^\circ < {\rm{C}}{{\rm{H}}_3}$ .

2.Generally, an arrow starts from a nucleophile and ends to an electrophile showing the attack, that is, from a high electron density region to low electron density region. A leaving group leave by taking the electron density.

The direction of arrow basically shows the movement of electrons as shown below:

Complete the curved arrow representation of the given step of the mechanism as shown below:

Draw the product of the reaction when elimination of water and the bromide ion take place by using the curved arrow mechanism in step 1 as shown below:

Ans:

The correct product of the given reaction is as follows: