Hydrochloric Acid → 4-n-Propylamino-cyclohexanone-ethyleneketal

Participants

Reaction Conditions

Reaction Steps

A mixture of n-propyl amine (162 ml, 1.474 mol) in methanol (500 ml) was chilled to 0-5° C. To this solution was added methanolic hydrochloric acid (155 ml, 44.47%) dropwise over a period of 30 minutes to achieve a pH of 6-7. Cyclohexandione monoethyleneketal 1 (100 g, 0.641 mol) was charged at 5° C. and the reaction was stirred for 15 minutes. Sodium cyanoborohydride (60 g, 0.952 mol) was added in 15 minutes at 5° C. The pH increased to about 8 and methanolic hydrochloric acid (15 ml, 44.47%) was added to bring the pH to 6-7. The reaction was allowed to come to 24-26° C. Stirring was continued for 2 hours. Methanol was distilled off (450 ml). Sodium carbonate (95 g, 0.896 mol) was dissolved in water (850 ml) and charged to the reaction mass at ambient temperature in one shot. The reaction mass was extracted with dichloromethane (2500 ml). The dichloromethane layers were combined and dried over sodium sulfate (8.5 g). The dichloromethane layer was concentrated to dryness at 40° C. and 15 mbar pressure. The product 2 was light yellow viscous oil. The weight of the product 2 obtained was 135 g (105.8%); GC purity 97.74%.

Provenance & Evidence