Problems with vacuum distillation

1. Are you sure the ester is colorless?； 2. Your distillation temperature is too high ； 3. A separation column may be needed for separation, or the length is insufficient ；

1. First, determine whether the dicarboxylic acid ester is colored. 2. It is recommended to use a conical distillation column for distillation. rather than simple distillation. 3. It is recommended to introduce nitrogen for displacement at the start of distillation. Or add antioxidants to the material to prevent it from changing color at high temperatures.

I have an industrial distillation unit; it’s difficult to modify it for use in distillation. The color of the ester is quite dark, with an APHA value of around 150. The vacuum level in the system is at this level only, and the liquid temperature cannot be reduced. Under such conditions, adding activated carbon during the distillation process didn’t have any effect. Do anyone have any other good suggestions? Urgent

Possible reasons are as follows: 1. The packing height of the existing distillation tower or the reflux ratio is insufficient, resulting in heating and flushing that carries colored substances to the top of the tower； 2. High temperature tower height; the material undergoes reaction ；

“I have a binary alcohol carboxylate with a dark color and a high boiling point; its boiling point is around 360 degrees or slightly higher. I want to use vacuum distillation to reduce its color. The vacuum level in the distillation system is about 100 Pa, which is equivalent to around 1 millimeter of mercury. The temperature of the ester during distillation is around 200 degrees. However, the color of the ester after vaporization and condensation becomes even darker. I hope experienced users can help diagnose what the problem is ” It is likely that the \"diol carboxylate\" is oxidized at high temperatures or undergoes other chemical reactions that result in the formation of colored groups. It is recommended that LZ consider other methods, such as using activated carbon for adsorption or introducing nitrogen gas during the reaction process for producing the diol carboxylate.

The results are not satisfactory. This ester is synthesized in an open system, with a large amount of gaseous substances being produced during the reaction. Using nitrogen for protection seems to be difficult to implement in this case. If the reaction takes place in a closed system, it may take longer; moreover, high temperatures also have a negative effect on the appearance of the ester. Ugh, what should be done? What about choosing a catalyst that exhibits good catalytic performance in low-temperature regions? Please, fellow sailors, recommend some. . . . .