Sulfuric Acid → 5-ethyl-2,3-dihydro-1H-indole-2,3-dione

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Reaction Steps

The title compound is prepared starting from 30 g (0.248 mol) of p-ethylaniline (Fluka, Buchs, Switzerland), 54 g (0.326 mol) chloral hydrate, and 750 g sodium sulfate in 800 ml water followed by the addition of 60 g (0.863 mol) NH2OH—HCl in water. By treating the intermediate with conc. H2SO4, the final product is obtained. (For the procedure, see Ng. Ph. Buu-Hoi et. al. in J. Chem. Soc., 4867 (1952)). The crude compound is used in the next step without further purification. Only a small sample is crystallized from methanol for analytical purposes. mp: 135-137° C. (Lit.: 135° C.); MS: 174 (M+−+1); HPLC: tret=8.74 min (Grad 1).

Provenance & Evidence