1,2-Dibromoethane → 9-(2-bromoethyl)-6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-one

Participants

Reaction Steps

199 g. (1 mole) of 6-methyl-1,2,3,4-tetrahydrocarbazol-1-one (m.p.: 199° C., as given in literature: 194°-195° C., 195°-196° C., 195° C., cf. Bloink and Pausacker loc. cit. page 1330), 1520 g. (8.1 moles), 1.2-dibromoethane and 1000 ml. (7.5 moles) of aqueous sodium hydroxide solution (30% strength) are taken initially and admixed, while stirring at room temperature, with 4.25 g. (12.5 m mole) of tetrabutylammoniumhydrogensulfate dissolved in 25 ml of water. With a slight temperature rise, the reaction sets in and while continuously stirring, comes to an end after some seven hours' time. For working up, the aqueous alkaline layer is separated, the organic layer washed with water and the excess dibromoethane distilled off in vacuo. The residue is recrystallized from 200 ml. of ethanol. Obtained are 281 g.=92% of the theoretical of 6-methyl-9-(2-ethylbromide)-1,2,3,4-tetrahydrocarbazol-1-one melting at 103° C. The amount of the tetrabutylammoniumhydrogensulfate used as catalyst can be reduced to 5 m moles per 1 mole of the carbazoline employed. During the procedure the reaction takes twice as long.

Provenance & Evidence