This phenylacetone (P2P) synthesis approach is a simple way how to get phenylacetone from BMK ethyl glycidate and its synthesis from benzaldehyde. PMK ethyl glycidate can be hydrolyzed into P2P. This reaction isn't sensitive to water like BMK methyl glycidate synthesis. There is such advantage like a quite high yield conversion (82% from benzaldehyde to P2P). Moreover, the reaction doesn't take any elaborated equipment and can be easily scailed.
Equipment and glassware:
- Four necked round bottom reaction flask 3 L, equipped with reflux condenser, top stirrer and pressure equalized drip funnel 250 mL;
- Funnel;
- pH indicator paper;
- Water/oil bath;
- Laboratory grade thermometer (up to 10 - 100 °С);
- Glass rod;
- Silicone hoses;
- Measuring cylinders for 100 mL and 1 L;
- Laboratory scale (1-200 g is suitable);
- Glass rod;
- Beakers 3 L; 1 L x2; 500 ml x2;
- Separatory funnel 2 L;
Reagents:
- Dimethylformamide 900 ml;
- Benzaldehyde 300 ml;
- Ethyl 2-chloropropionate 540 g;
- Benzyltriethylammonium chloride (TEBAC) 32 g;
- Potassium carbonate 780 g;
- Sodium hydroxide (NaOH) 135 g;
- Distilled water ~1.9 L;
- Concentrated (37%) aqueous hydrochloric acid (HCl) ~250 mL;
BMK ethyl glycidate synthesis from benzaldehyde
1. Dimethylformamide 900 ml is poured into a 3 L four necked round bottom reaction flask, equipped with reflux condenser, top stirrer and drip funnel.
2. Then, benzaldehyde 300 ml is added. A top stirrer is turned on.3. Ethyl 2-chloropropionate 540 g is poured into the reactor. Benzyltriethylammonium chloride (TEBAC) catalyst 32 g is added. Next, potassium carbonate 780 g is added into the reaction mixture.
4. A heating of the water or oil bath is set at 40°C.
5. Reaction mixture is stirred for 48 h on the warm bath.
6. Sodium hydroxide (NaOH) 30% water solution 450 ml is prepared in advance.
7. After 48h, the stirrer is turned off. Reaction mixture (liquid layer without sediment) is decanted into a large beaker.
8. Pure distilled water 1 L is poured into the beaker and mix thoroughly.
9. A glycidate ester layer is separated down. Layers are separated with help of separatory funnel.
Note: Glycidate ester is used in following reactions without purification. If a chemist wants to use it as a product, he has to distill it from side reaction products due to an excess of ethyl 2-chloropropionate.
BMK glycidic acid (sodium salt) synthesis BMK ethyl glycidate
10. Glycidic ester is loaded back into the clean reaction flask.
11. The previously prepared and cooled NaOH sln. is poured into the drip funnel.12. The stirrer is turned on. NaOH 30% aq. Solution 450 mL is slowly added to the reaction mixture. A reaction mixture temperature has to be maintained below <30°C.
13. Next, the reaction mixture is stirred for 12 h at room temperature.
14. After a while, distilled water 500 ml is added and the mixture is heated a little (no more than 60°C).
15. Benzene, toluene or other similar solvent 500 ml is poured into the heated reaction mixture.
16. The stirrer is turned off. The layers are formed.
17. With help of the separating funnel, the reaction by-products are extracted (not previously distilled ester by-products). The water layer with dissolved BMK glycidic acid (sodium salt) is separated back into the flask.
Phenylacetone (P2P) synthesis from BMK glycidic acid (sodium salt)
18. Using the drip funnel, concentrated (37%) aqueous hydrochloric acid (HCl) is carefully poured into the flask to reach pH1.
19. The mixture is heated to 60°C and decarboxylated with constant stirring for 5 h.20. Then, the stirrer is turned off and the mixture is separated into two layers. BMK layer is a top layer.
Note: If the mixture is cooled down, BMK layer will be at the bottom.
21. BMK layer is separated into a beaker using separatory funnel for further syntheses.
Note: After a while, remaining water in the beaker is completely separated from BMK oil.
BMK yield is ~300 ml (82%).
21. BMK layer is separated into a beaker using separatory funnel for further syntheses.
Note: After a while, remaining water in the beaker is completely separated from BMK oil.
BMK yield is ~300 ml (82%).
