Ambucaine

Originator

Ambucaine,ZYF Pharm Chemical

Manufacturing Process

A stired mixture of 4-nitro-2-hydroxybenzoic acid, anhydrous potassium carbonate and n-butyl benzenesulfonate in xylene was refluxed under a continuous water separator for about 19 h. The insoluble potassium salts were filtered off and washed with hot dry toluene. The combined filtrate and washings were distilled under reduced pressure to remove the solvents, thereby leaving a residual oil which solidified on cooling. The solid yields of greater than 95% of n-butyl 4-nitro-2-n-butoxybenzoate (recrystallized from methanol).
The n-butyl 4-nitro-2-n-butoxybenzoate obtained was dissolved in 50% aqueous ethanol. To this solution was added 2 - 3 molecular equivalents of sodium carbonate, and the resulting mixture, was stirred under reflux for about 16 h. After the ethanol has been distilled off under reduced pressure, the remaining aqueous solution was diluted with water and made acidic with concentrated hydrochloric acid. The precipitated yellow solid was filtered, washed with water, dried in a vacuum oven at 90°C and recrystallized from ethyl acetate. There was thus obtained a 4-nitro-2-n-butoxy-benzoic acid (95.5% yield), melting point 120.9°-122.8°C (corr.).
A mixture of 4-nitro-2-n-butoxybenzoic acid, anhydrous potassium carbonate and 400 ml of dry toluene was refluxed and stirred under a continuous water separator. When the evolution of water had ceased (3 h), the water separator was removed and there was added diethylaminoethyl chloride. The mixture was then refluxed with stirring for about 20 h, filtered while hot, and the solvent was removed from the filtrate by distilling in vacuo. The residual oil was dissolved in dilute hydrochloric acid, the solution was decolorized with activated carbon and the base was liberated by the addition of excess ammonia. The base was extracted with ethyl acetate, the solution was dried, and the ethyl acetate was removed by distilling in vacuo, yielding 2- diethylaminoethyl 4-nitro-2-n-butoxybenzoate as a pale yellow oil.
The 2-diethylaminoethyl 4-nitro-2-n-butoxybenzoate in ethanol is hydrogenated using 50 lbs. pressure of hydrogen at 25°C in the presence of Raney nickel (alternatively platinum oxide monohydrate). After the rapid exothermic reaction, the catalyst is filtered off and the filtrate evaporated to dryness to give the 2-diethylaminoethyl 4-amino-2-n-butoxybenzoate.

Therapeutic Function

Local anesthetic