Manufacturing Process
2-Ethoxyphenol is first reacted with epichlorohydrin to give 1,2-epoxy-3-(o-
ethoxyphenoxy)-propane.
A mixture of crude (83%) 1,2-epoxy-3-(o-ethoxyphenoxy)propane (19.4
grams), 70.5 grams 2-aminoethyl hydrogen sulfate, 40.0 grams sodium
hydroxide, 400 ml ethanol and 200 ml water is stirred at 60°C for 18 hours
and is then evaporated to dryness. The residue is dissolved in 200 ml water
and the mixture is extracted three times with 150 ml of diethyl ether each
time. The combined extracts are dried over magnesium sulfate and
evaporated to dryness, The crude product (21.5 grams) is dissolved in
isopropanol (20 ml), 10.5 ml concentrated aqueous hydrochloric acid and 75
ml ethyl acetate are added and the mixture is cooled. The mixture is filtered
and there is thus obtained as solid product 2-(o-ethoxyphenoxymethyl)
morpholine hydrochloride, MP 179° to 182°C (8.6 grams; 38% yield based on
total epoxide used), according to US Patent 3,712,890.
Synthesis
Viloxazine was synthesized via a four-step process. In the first step, 2-ethoxyphenol (9.1) was reacted with epichlorohydrin (9.2) in the presence of potassium carbonate and a phase transfer catalyst (n-Bu4NHSO4) to produce the epoxide (9.3) in almost equivalent yield. Next, the epoxide (9.3) was reacted with 2-aminoethylsulfuric acid (9.4) in the presence of a strong base to trigger the opening of the epoxide ring and subsequent cyclization to form 2-morpholine (9.5) in 40% yield. Finally, the free basic amine (9.5) was treated with concentrated hydrochloric acid, and the prepared salt was recrystallized from a water/isopropanol/ethyl acetate mixed solvent to obtain Viloxazine hydrochloride (9) with a purity of 99%.
