Patent ID: 8293950
Filing Date: 2012-10-23
Classification: C07C

Abstract:
1. A method for preparing pentaerythritol, the method comprising: (a) a condensation reaction comprising: adding 15-50% (w/v) of alkaline solution and 60-99% (w/v) of acetaldehyde solution to 10-25% (w/v) of formaldehyde aqueous solution under an initial temperature of 25-45° C. with stirring to obtain a solution of formaldehyde, acetaldehyde and alkaline at a molar ratio of 4.2-10.2 to 1 to 1.05-1.25, and reacting the solution for 30-100 minutes at a final reaction temperature of 45-70° C. and a reaction pressure of 0-0.2 Mpa; and after the reaction, neutralizing the solution to a pH of 5.5-6.5 with formic acid to obtain a neutralized solution; and (b) a monopentaerythritol separation comprising: removing aldehyde and alcohol present in the neutralized solution of step (a) to form a pentaerythritol solution; concentrating the pentaerythritol solution to a specific gravity of 1.25-1.28; crystallizing and centrifuging the concentrated pentaerythritol solution to obtain 90-95% of pentaerythritol crude product and a mother liquor; isolating the mother liquor for use in a further separation process; adding water to dissolve the pentaerythritol crude product with heating; and then recrystallizing, centrifuging, drying and obtaining monopentaerythritol from the pentaerythritol crude product.