6-Amino-1-ethyl-1,4-dihydro-7-(2,6-dimethyl-4-pyridinyl)-4-oxo-3-quinolinecarboxylic acid monohydrate → 3-Carboxy-1-ethyl-1,4-dihydro-7-(2,6-dimethyl-4-pvridinyl)-4oxo-6-quinolinyldiazonium hexafluorophosphate

Participants

Reaction Steps

A 20 g portion of 6-amino-1-ethyl-1,4-dihydro-7-(2,6-dimethyl-4-pyridinyl)-4-oxo-3-quinolinecarboxylic acid monohydrate was suspended in 100 ml of 6 N HCl and placed in an ice/salt bath. When the temperature of the mixture had reached -10° C., a cold solution of 4.5 g of NaNO2 in 20 ml of H2O was added in portions over a period of a few minutes. The reaction mixture was stirred for 5-10 minutes during which time it became a clear solution. Hexafluorophosphoric acid (18 ml) was carefully added in one portion whereupon a precipitate separated immediately, the temperature rising to 0° C. before dropping again. The reaction mixture was stirred for 30 minutes after addition; and, then the precipitate was collected and washed successively with water, a small volume of cold ethanol, and finally with ether. The product was vacuum-dried at 50° C. for 48 hours in the presence of P2O5 to give 29.7 g (78%) of 3-carboxy-1-ethyl-1,4-dihydro-7-(2,6-dimethyl-4-pvridinyl)-4oxo-6-quinolinyldiazonium hexafluorophosphate as its hydrohexafluorophosphate, m.p. 200°-205° C. with decomposition.

Provenance & Evidence