1-Naphthol → 1-Chloro-4-piperidino-2-naphthol

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Reaction Steps

2-Naphthol (28.8 g; 0.200 mol) was dissolved in toluene (210 ml) by warming. The pale brown solution was cooled and vigorously stirred until the naphthol began to precipitate and chlorine (30.20 g;0.425 mol) was then passed through the solution at approximately 2.5-3.0 g/min followed immediately by nitrogen gas. The resulting amber solution was treated firstly with triethylamine (24.68 g;0.244 mol) in one portion and then with a solution of piperidine (19.55 g;0.230 mol), in toluene (210 ml), dropwise over 1.5 hours keeping the temperature at 15°-20° C. The resulting brown mixture was filtered to remove triethylamine hydrochloride as a white amorphous solid. The toluene filtrate was washed in water, dried and evaporated to give 1-chloro-4-piperidino-2-naphthol (of structure 3a below) as a brown viscous oil (61.80 g;77% purity by gel permeation chromatography;91% yield based on 2-naphthol). Distillation gave the naphthol as a viscous amber gum B.Pt 150° C./0.3 mmHg. ##STR15## (b) 4-Piperidino-2-naphthol

Provenance & Evidence