Steam P2P Distillation as a Purification Method

Introduction

Phenylacetone is key-reagent for methamphetamine synthesis and can be used for amphetamine manufacturing as well. Our experiments have clearly showed that P2P purity have direct impact on methamphetamine yield and its purity via sodium borohydride (NaBH4) methylamination reduction method. The purer P2P is used, the higher yield is obtained. To top it off, BB Forum research team decided that it is strategy important to represent such substantial purification way as steam distillation of P2P.

Equipment and glassware:

• Distillation flask 500ml with funnel;
• Straight condenser;
• Heating plate;
• Flsk for steam generation 500 ml;
• Reciver flask 250 ml;
• Retort stand and clamp for securing apparatus;
• pH indicator paper;
• Beakers 1 L x2; 500 ml; 250 ml
• Separating funnel 2 L;

Reagents:

• Impure P2P (phenylacetone) 145 ml;
• Potassium carbonate 50 g;
• Distilled water 500 ml;
• Silica gel;
• Sodium chloride 100g (NaCl);

Steam Distillation Procedure

1. Potassium carbonate solution is prepared. Water is poured into a beaker with potassium carbonate, then the mixture is stirred.

Note: Indicator paper shows alkaline pH.

2. Boiling chips (or glass rods) are placed into the distillation flask. Impure P2P is placed into the flask. Potassium carbonate solution is also poured there up to half volume of the flask.

3. Setup for the P2P steam distillation is assembled.

Important: the steam volume from the steam generator must be greater than vapor volume, which is obtained from the normal boiling of P2P in the flask. Therefore, the flask with P2P should have smaller volume than the steam generator flask.

4. P2P solution is boiled (heated to a boiling temperature) and P2P is condensed as oily droplets in the condenser. The receiving flask is collected distillate of the purest P2P with water.

5. As the receiving flask is filled, the distillates are combined and settled until layer separation.

6. Distillation is considered completed when only water vapor (without oily fraction) is condensed in the condenser. After a while, the P2P solution in the distillation flask becomes cloudy. A tarry sediment on the flask bottom can be formed. These are heavy insoluble impurities. The resulting P2P distillate have to be separated from the water layer.

7. An aqueous solution of sodium chloride (NaCl) is prepared (100g NaCl per 500 ml water). The mixture is vigorously stirred until the NaCl is completely dissolved.

Note: Solution of NaCl is needed to change the water density in the mixture with P2P. This helps P2P to float as a transparent top layer and not to lie in the form of bubbles throughout the volume of the flask.

8. P2P distillate solution is poured into a 2 L separating funnel. Then NaCl solution is added. It takes several hours until the complete layers separation. P2P will be at the top level.

9. The lower aqueous layer is removed. It can be reused to distill new portions of impure P2P. Only the P2P layer should remain in the funnel with no visible water residue. However, water particles are still in P2P. The resulting oil should be dehydrated.

10. For drying ~100 ml P2P oil, you need ~10 g of silica gel. The P2P layer is dried over silica gel ~2 h, then decanted. The purest Р2Р yield 100.02 g (68.98%) is obtained.

Note: P2P can be stored with silica gel in the same flask to avoid a moisture absorption.

Bibliography

• Ferreira, Fernanda Nunes, et al. "Determination of low‐molecular‐weight amines and ammonium in saline waters by ion chromatography after their extraction by steam distillation." Journal of Separation Science 39.8 (2016): 1454-1460. https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/abs/10.1002/jssc.201501387
• Malle, P., and S. H. Tao. "Rapid quantitative determination of trimethylamine using steam distillation." Journal of Food Protection 50.9 (1987): 756-760. https://www.sciencedirect.com/science/article/pii/S0362028X23002946