How long does it take for 4a molecular sieves to treat acetonitrile
If the activated 4a molecular sieve becomes turbid in the process of acetonitrile dewatering, it can be washed with water first, then put into the muffle furnace for activation, and then used, so that the turbidity will not be dealt with.
Water removal method for acetonitrile treated by 4a type molecular sieve
1. Add phosphorus pentoxide and reflux until phosphorus pentoxide does not turn yellow, and steam it out under nitrogen protection;.
2. Add calcium hydride and reflux for six to eight hours, and steam out under nitrogen protection;
3. Molecular sieve to remove water, dry 4A molecular sieve at about 300° for 6-8 hours, cool it to room temperature under nitrogen protection, add it to acetonitrile under nitrogen protection or let stand for more than 12 hours in a dry environment.
4. Add silica gel or 4A molecular sieve to remove the water in acetonitrile, then add calcium hydride and stir until hydrogen is no longer released, so that acetic acid can be removed, leaving only a small amount of water. Then distill at a high reflux ratio, taking care to prevent moisture from entering. For this reason, reflux on calcium hydride, or add 0.5%-1% phosphorus pentoxide to the distillation flask to remove most of the remaining water. Phosphorus pentoxide should be avoided in excess as it will form an orange polymer.
5. (1) Preliminary water removal Put the acetonitrile into the container, put it into the 4A molecular sieve (dry molecular sieve), and place it in a sealed container for 12 hours.
(2) Rectification. The solution after preliminary water removal is poured into a round-bottomed flask, an appropriate amount of phosphorus pentoxide is added, and a magnetic stirring rotor is used. Distill until the phosphorus pentoxide is no longer darkened in color (usually 5 to 6 hours). The solution in the dispenser was released (used to wash the bottle containing the solution and dried with a hair dryer). After that, the bottle containing the solution was sealed and connected to the lower end of the dispenser, and the heating was continued to distill out the remaining solution, leaving about 100ml. steam out. NOTE: The solution should remain boiling throughout the process.
(3) Preservation: Add the rectified solution to dry molecular sieve, and store it in a sealed place away from light.
6. Acetonitrile is infinitely miscible with water and alcohol, and can form a binary azeotrope with water. Its composition and azeotrope are as follows: azeotrope: 77 degrees Celsius (101.33kpa), acetonitrile content 77% (W) acetonitrile dehydration, due to acetonitrile and Water is infinitely miscible, and acetonitrile is difficult to dehydrate. Acetonitrile and water can form an azeotrope, but the water cannot be separated. For further purification, it can be dried with anhydrous calcium chloride, filtered and added with 0.5-1% five Phosphorus oxide (P2O5) is refluxed, and then distilled under normal pressure. Repeat this operation until the phosphorus pentoxide (P2O5) is no longer colored, and then add newly melted anhydrous potassium carbonate (K2CO3) for distillation to remove a trace amount of phosphorus pentoxide (P2O5).
7. Add phosphorus pentoxide (5-10g/V) to acetonitrile, reflux for 2-3 days, and then steam it out, which can remove most of the water. Note that a calcium chloride drying tube should be added to the condenser tube during reflux. Excessive addition of phosphorus pentoxide should be avoided as orange polymers may be formed. A small amount of potassium carbonate is added to the distilled acetonitrile for re-distillation, which can remove the trace amount of phosphorus pentoxide, and finally use a fractionation column for fractionation. It's very troublesome, but it's purer to get it out.
8. Reflux with KMnO4 and K2CO3 for 8 hours, then steam into a round-bottomed flask with P2O5. Refluxed for an additional 5 hours, then evaporated.
Water removal method for acetonitrile treated by 4a type molecular sieve
1. Add phosphorus pentoxide and reflux until phosphorus pentoxide does not turn yellow, and steam it out under nitrogen protection;.
2. Add calcium hydride and reflux for six to eight hours, and steam out under nitrogen protection;
3. Molecular sieve to remove water, dry 4A molecular sieve at about 300° for 6-8 hours, cool it to room temperature under nitrogen protection, add it to acetonitrile under nitrogen protection or let stand for more than 12 hours in a dry environment.
4. Add silica gel or 4A molecular sieve to remove the water in acetonitrile, then add calcium hydride and stir until hydrogen is no longer released, so that acetic acid can be removed, leaving only a small amount of water. Then distill at a high reflux ratio, taking care to prevent moisture from entering. For this reason, reflux on calcium hydride, or add 0.5%-1% phosphorus pentoxide to the distillation flask to remove most of the remaining water. Phosphorus pentoxide should be avoided in excess as it will form an orange polymer.
5. (1) Preliminary water removal Put the acetonitrile into the container, put it into the 4A molecular sieve (dry molecular sieve), and place it in a sealed container for 12 hours.
(2) Rectification. The solution after preliminary water removal is poured into a round-bottomed flask, an appropriate amount of phosphorus pentoxide is added, and a magnetic stirring rotor is used. Distill until the phosphorus pentoxide is no longer darkened in color (usually 5 to 6 hours). The solution in the dispenser was released (used to wash the bottle containing the solution and dried with a hair dryer). After that, the bottle containing the solution was sealed and connected to the lower end of the dispenser, and the heating was continued to distill out the remaining solution, leaving about 100ml. steam out. NOTE: The solution should remain boiling throughout the process.
(3) Preservation: Add the rectified solution to dry molecular sieve, and store it in a sealed place away from light.
6. Acetonitrile is infinitely miscible with water and alcohol, and can form a binary azeotrope with water. Its composition and azeotrope are as follows: azeotrope: 77 degrees Celsius (101.33kpa), acetonitrile content 77% (W) acetonitrile dehydration, due to acetonitrile and Water is infinitely miscible, and acetonitrile is difficult to dehydrate. Acetonitrile and water can form an azeotrope, but the water cannot be separated. For further purification, it can be dried with anhydrous calcium chloride, filtered and added with 0.5-1% five Phosphorus oxide (P2O5) is refluxed, and then distilled under normal pressure. Repeat this operation until the phosphorus pentoxide (P2O5) is no longer colored, and then add newly melted anhydrous potassium carbonate (K2CO3) for distillation to remove a trace amount of phosphorus pentoxide (P2O5).
7. Add phosphorus pentoxide (5-10g/V) to acetonitrile, reflux for 2-3 days, and then steam it out, which can remove most of the water. Note that a calcium chloride drying tube should be added to the condenser tube during reflux. Excessive addition of phosphorus pentoxide should be avoided as orange polymers may be formed. A small amount of potassium carbonate is added to the distilled acetonitrile for re-distillation, which can remove the trace amount of phosphorus pentoxide, and finally use a fractionation column for fractionation. It's very troublesome, but it's purer to get it out.
8. Reflux with KMnO4 and K2CO3 for 8 hours, then steam into a round-bottomed flask with P2O5. Refluxed for an additional 5 hours, then evaporated.
