Hydrogen Sulfide → 1,9-dimethyl-10H-phenothiazine

Participants

Reaction Conditions

Reaction Steps

Put di(2-tolyl)amine (11.7 g, 59.3 mmol) in a 3-neck 100 mL round-bottom flask and added elemental sulfur (3.9 g, 121.65 mmoles, 2 eq.), crushed iodine (0.44 g, 1.73 mmoles, 3 mole %), then o-dichlorobenzene (22 mL). Added an outlet to a dilute bleach solution (for hydrogen sulfide evolution) then put under argon. Refluxed at 180° C. for 4 h. Removed solvent under reduced pressure. Purified with column chromatography using 2% ethyl acetate/98% hexane to obtain product as white crystals (2 g, 8.8 mmoles, 15% yield). (Alternatively, put di(2-tolyl)amine (either purified or impure from the aforementioned reaction; 8.9525 g, 45.3 mmoles) in a round bottom flask. Added elemental sulfur (2.98 g, 92.9 mmoles, 2 eq.) then crushed iodine (3.28 g, 12.9 mmoles, 28% mole). Added an outlet to a dilute bleach solution (for hydrogen sulfide) then put under argon. Stirred at 210° C. for 30 min or until no starting material was present by LC/MS. Let the reaction cool to about 60° C. then added hexane for extraction. Repeated hot hexane extractions (at least one overnight; minimum time of half an hour for each extraction) of reaction until product was no longer seen in residue (about 4 times). Combined hexane extractions and concentrate in vacuo. Purified resulting residue either through repeated hot acetone/isopropanol crystallizations (or triturations) or Isco column chromatography using 2% ethyl acetate/98% hexane to obtain product as white crystals (2.92 g, 12.8 mmoles, 28% yield).)

Provenance & Evidence