Question

rates of electrophilic aromatic substitution lab using bromine. 1. (3 pts.) Draw the structures of all six reactant arenes that will be used in this lab 2. (6 pts.) Beneath each structure you have a. If the substituent is ring b. If the electrophile will be drawn in question 1, note the following: activating or deactivating directed to an ortho, meta, and/or para position

THESE ARE THE 6 reagents

1) 1-naphthol
2) 4-bromophenol
3)phenol
4) anisol
5) acetanilide
6) diphenyl ether

Answer 1

1. The structure of the given arenes are

CAI 2. OH Br 1-naphthol 4-bromophenol (MI 3. Anisole Phenol CH Acetanilide Diphenyl ether

2.

a) The substituents that donate electron density into the ring are activating and the substituents that withdraw electron density from the ring are deactivating.

  

он Br O atom has two lone pairs that it can donate into the ring Activating OH group is activating Br group is deactivating OCH3 OH group is activating because of O lone pairs Here also OCH3 is activating because of the O lone pairs CH Even though N lone pair is in conjugation with carbonyl, it is activating Again O lone pairs makes it activating

b) As a general rule of thumb, activating groups direct the electrophile to ortho and para positon, while deactivating groups direct the incoming electrophile to meta position. This is because, the carbocation formed after electrophilic addition is more stabilised at ortho and para position of an activated ring because of higher electron density there. In case of deactivated ring, meta positions are relatively more favourable to electrophilic addition.

он Br Ortho and para on the activated ring Marked by asterisk. OH being an activator will direct the electophile. Hence, only ortho as para position is held by Br OCH3 Ortho and para. OCH3 is activating Hence, ortho and para. CH Ortho and para. Ortho and para on both rings

Note, after mono-substitution of electrophile, depending on the nature of the electrophile, where the next electrophile comes will be decided.

Generally activating groups are preferred for electrophilic substitution as they have a better reaction rate as compared to deactivating groups.