Question

Predict the major product(s) of each electrophilic aromatic substitution. (a) Cc1cccc(Br)c1 (b) O=[N+]([O-])c1cccc(Br)c1 (c) O=C(O)c1cccc([N+](=O)[O-])c1

Short answer

Question: Predict the major products of electrophilic aromatic substitution reactions for the following compounds and indicate the position of the electrophile in the product: (a) Cc1cccc(Br)c1 (b) O=[N+]([O-])c1cccc(Br)c1 (c) O=C(O)c1cccc([N+](=O)[O-])c1 Answer: (a) The major product will have the electrophile substituted in the ortho-/para-positions with respect to the CH3 group. (b) The major product will have the electrophile substituted in the meta-position with respect to both Nitro and Bromine groups. (c) The major product will have the electrophile substituted in the ortho-/para-positions with respect to the -CO group.

Step-by-step solution

Identify Activating and Deactivating Groups

Analyze the structures given and identify the activating or deactivating groups present on the aromatic ring. (a) Cc1cccc(Br)c1 - The activating group is an alkyl group (attached to carbon :CH3) and the deactivating group is a Bromine atom (-Br). (b) O=[N+]([O-])c1cccc(Br)c1 - The activating group is a Nitro group(NO2) and the deactivating group is a Bromine atom(-Br). (c) O=C(O)c1cccc([N+](=O)[O-])c1 - The activating group is a Carbonyl group(-CO) and the deactivating group is a Nitro group(NO2).

Predict Regioselectivity of the Electrophilic Aromatic Substitution

Using the activating (-R) and deactivating (-M) groups on the ring, predict the regioselectivity (ortho, meta, or para) for the electrophilic aromatic substitution reaction, keeping in mind that activating groups direct ortho/para and deactivating groups direct meta position. (a) Cc1cccc(Br)c1 - The alkyl group will direct the electrophile to the ortho-/para-positions, and the bromine atom will direct it to the meta-position. Since the alkyl group is activating and the bromine is deactivating, the electrophile will favor the ortho-/para-positions. (b) O=[N+]([O-])c1cccc(Br)c1 - Both Nitro group and Bromine atom are deactivating, the electrophilic attack will mostly take place in a position meta to both groups. (c) O=C(O)c1cccc([N+](=O)[O-])c1 - The carbonyl group directs the electrophile to the ortho-/para-positions, while the Nitro group will direct it to the meta-position. The electrophile will favor the ortho-/para-positions since the carbonyl group is activating, and the Nitro group is deactivating.

Identify the Major Product(s) of Each Electrophilic Aromatic Substitution

Using the regioselectivity determined in Step 2, predict the major product(s) for each electrophilic aromatic substitution reaction. (a) Cc1cccc(Br)c1 - The major product will have the electrophile substituted in the ortho-/para-positions with respect to the CH3 group. (b) O=[N+]([O-])c1cccc(Br)c1 - The major product will have the electrophile substituted in the meta-position with respect to both groups. (c) O=C(O)c1cccc([N+](=O)[O-])c1 - The major product will have the electrophile substituted in the ortho-/para-positions with respect to the -CO group.