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sodium methylate; In ethylene glycol; at 65℃; for 8h;Conversion of starting material;
Palmitamide Starting Materials Methyl palmitate 0.5 mol (135 g) Ammonia Excess, bubbled through the system. Sodium methoxide (catalyst) 5 g. Ethylene Glycol 50 g. Operating Conditions Pressure Atmospheric Temperature/time regime 65 C./8 h. Reaction Progress Monitored by means of the qualitative ferric hydroxamate test for esters. Work-up The reaction mass was cooled, transfered to a beaker, diluted with 500 mL methanol and 200 mL water, stirred for 30 minutes and filtered. The filter cake was then washed with water, drained and dried at 70-80 C. overnight. 116 g. of white powdery crystals (m.p. 102-103 C.) were obtained (literature m.p. 106-107 C.); the IR spectrum (KBr pellet) shows the ?amide I Band? at 1647.42CM-1 and the ?C-N Stretch? at 1421.72 CM-1. Yield 91%
With sodium hydroxide; In methanol; at 55℃; under 11.2511 - 16.5017 Torr; for 3.0h;Large scale;
To 3000 kg of the compound of formula (la) which is known as Vitamin A acetate, in its crystalline form, 2750 kg of compound of formula (I la) which is known as methyl palmitate have been added. Afterwards 10 kg of NaOH have been dissolved in about 60 I of methanol, which was then added to the mixture of Vitamin A acetate and methyl palmitate. This reaction mixture was heated up to 55C and the pressure was reduced to about 1500 - 2200 Pa. The reaction time was about 3 hours. During this process the main side product (methyl acetate) was removed continuously by distillation. The reaction was stopped by the addition of water and CO2. Afterwards the compound of formula (Ilia) which is known as Vitamin A palmitate was isolated from the reaction solution by extraction. The yield of compound of formula (Ilia) was 96%.
at 60℃; under 0.750075 Torr; for 3.0h;Large scale;
3.28 kg of vitamin A acetate and 16.5 g of potassium methoxide were added to 33 L of methanol under nitrogen protection, and the reaction was carried out at 30 C for about 3hour;After completion of the reaction, it was concentrated to dryness under reduced pressure at 40 C to give a yellow oil as a vitamin A alcohol.The obtained vitamin A alcohol was mixed with 2.80 kg of methyl palmitate.The mixture was heated to 60 C and then the pressure was reduced to about 100 Pa for about 3 hours.The reaction was terminated by nitrogen gas, and 20 L of n-hexane and 165 g of activated carbon were added.After decolorizing for 30 minutes, the silica gel was filtered, and the filtrate was concentrated to dryness under reduced pressure.A pale yellow oil of 4.93 kg was obtained with a yield of 94%.The obtained oil was analyzed according to the method of the United States Pharmacopoeia USP28, and the result showed that the purity of vitamin A palmitate was 1.77 million IU/g.
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