Problem 1 — Predict the Major Product

Question: Toluene undergoes Friedel-Crafts acylation with acetyl chloride ($CH_{3}COCl$) in the presence of $AlCl_{3}$. Predict the major product and explain the regiochemistry.

Step-by-Step Solution:

Step 1 — Identify the existing substituent on toluene:

• Toluene has a -$CH_{3}$ group. SMILES: Cc1ccccc1
• -$CH_{3}$ is an ortho-para director (weakly activating via +I effect and hyperconjugation)

Step 2 — Identify the electrophile:

• $CH_{3}COCl$ + $AlCl_{3}$ → $CH_{3}CO^{+}$ (acylium ion) + $AlCl_{4}^{-}$
• Acylium SMILES: [CH3][C+]=O

Step 3 — Apply directing effect:

• -$CH_{3}$ directs the incoming acylium to ortho and para positions
• Para position is typically favored due to lower steric hindrance with the o/p mixed product

Step 4 — Major product:

• p-Methylacetophenone (4'-methylacetophenone)
• SMILES: CC(=O)c1ccc(C)cc1

Step 5 — Verify: No rearrangement (acylium is resonance stabilized); no polyacylation (the -CO$CH_{3}$ product deactivates the ring). Only ONE acyl group introduced.

Answer: p-Methylacetophenone, SMILES: CC(=O)c1ccc(C)cc1