Propylene Glycol Diacetate (PGDA) is an organic compound widely used in the fields of chemicals, pharmaceuticals and food. As an important raw material for the production of chemicals, the manufacturing method of Propylene Glycol Diacetate has attracted much attention. In this paper, the manufacturing method of propylene glycol diacetate will be introduced in detail, including raw material preparation, reaction process, post-treatment and other aspects.
I. Raw material preparation
The main raw materials for manufacturing propylene glycol diacetate are propylene glycol and acetic anhydride. Propylene glycol is a colorless, odorless, transparent, viscous liquid with strong hygroscopicity and humectancy. Acetic anhydride, on the other hand, is a colorless and transparent liquid that is irritating and corrosive. In the preparation of propylene glycol diacetate, propylene glycol and acetic anhydride need to be mixed according to a certain molar ratio.
II.Reaction process
The reaction process of propylene glycol and acetic anhydride needs to be carried out under certain temperature and catalyst. First, propylene glycol and acetic anhydride are added to the reactor in a certain ratio, and then heated up to a certain temperature. At this temperature, acetic anhydride will esterify with propylene glycol to form propylene glycol diacetate and water.
In order to promote the reaction, certain catalysts need to be added. Commonly used catalysts include sulfuric acid, p-toluenesulfonic acid and other acidic catalysts. In the presence of the catalyst, the reaction is accelerated and the conversion of propylene glycol and acetic anhydride is increased.
During the reaction process, the acidity and temperature of the reaction solution need to be constantly monitored to keep the reaction proceeding stably. At the same time, it is also necessary to discharge the water generated by the reaction in time to promote the reaction in the direction of generating propylene glycol diacetate.
Three, post-treatment
After the reaction, the reaction solution needs to be post-treated to obtain pure propylene glycol diacetate. First, the reaction solution needs to be cooled to room temperature, and then an alkaline absorbent is added to neutralize the remaining acid catalyst. Commonly used alkaline absorbents include sodium hydroxide and potassium hydroxide.
Next, the reaction solution needs to be distilled to separate out the propylene glycol diacetate and other impurities. During the distillation process, it is necessary to select appropriate distillation temperature and pressure conditions according to the difference between the boiling point of propylene glycol diacetate and the boiling point of other impurities, so as to ensure the purity and yield of propylene glycol diacetate.
Finally, the quality inspection of the propylene glycol diacetate obtained by distillation is required to ensure that it meets the relevant standards and requirements. The inspection items include purity, acidity, moisture, color and other indexes.
In conclusion, the manufacturing method of propylene glycol diacetate includes raw material preparation, reaction process and post-treatment. In the preparation process, the reaction conditions and post-treatment process need to be controlled to ensure the purity and yield of the product.
