Aromatic and Heterocyclic Compounds (5D) Practice Test

A synthetic intermediate contains a substituted thiophene intended for selective bromination. The substrate is 2-methylthiophene treated with $\ce{Br2}$ (no radical initiator) at mild conditions favoring EAS. The central concept is regioselectivity via σ-complex resonance stabilization in five-membered heteroaromatics: α-attack (at C2/C5) typically yields more resonance-stabilized intermediates than β-attack (at C3/C4). Which product is most likely?

Numbering: thiophene S is position 1; adjacent carbons are 2 and 5; remaining are 3 and 4. A methyl is at C2.

A researcher compares acidity of N–H protons in aromatic heterocycles as a proxy for conjugate-base stabilization. Two compounds are evaluated: pyrrole (aromatic, N–H; lone pair contributes to aromaticity) and indole (aromatic, N–H in the five-membered ring; lone pair contributes to aromaticity across the fused system). The central concept is resonance stabilization of the conjugate base after deprotonation at nitrogen. Which statement is most consistent with aromaticity and resonance considerations?

Assume: deprotonation occurs at N–H; solvent effects are similar; compare qualitative acidity.