Domain: Organic redox chemistry

A solution of phenothiazine (2.13 g, 11 mmol) in chloroform (75 mL) was stirred at 5 °C and treated dropwise over one hour with a solution of iodine (8.38 g, 33 mmol) in chloroform (175 mL) and water. The mixture was stirred at 5 °C for an additional 30 minutes. The resulting precipitate was filtered, washed with chloroform, and dried to afford compound A. A solution of compound A in methanol was then treated with dimethylamine in methanol at room temperature, leading to formation of compound B.
 Determine the molecular weight of the final product B formed.

Grading rubric:
criterion: Correctly identifies the starting compound as phenothiazine.
weight: 10
criterion: Correctly identifies Step 1 (I_2, CHCl_3, H_2O) as oxidation of phenothiazine.
weight: 10
criterion: Correctly states the Step 1 product A explicitly as phenothiazin-5-ium tetraiodide hydrate.
weight: 20
criterion: Correctly identifies the role of dimethylamine as a nucleophile.
weight: 10
criterion: Correctly states the Step 2 product B explicitly as 3-(dimethylamino)phenothiazin-5-ium triiodide.
weight: 20
criterion: Correctly determines the molecular formula of the final product B.
weight: 10
criterion: Correctly reports the molecular weight of the final product B as 622.05 g·mol⁻¹ (within ±0.05 g·mol⁻¹).
weight: 20

Answer:
622.05 g·mol⁻¹