(Stranger)
06-15-04 18:15
No 513580
(Rated as: excellent)
This procedure has been made based on article from an old Russian book. Perhaps, somebody here already used it – I did not check it carefully. It just only one more Experience…
In dry 100 mL round-bottom flask on hot plate magnet stirrer was dissolved 3 g Na-metallic in 40 ml absolute ethanol. It takes about 1 h, after dissolving half portion of Na reflux (cooler+CaCl2-tube!) was needed. During obtaining NaOEt is necessary to prepare dry ethyl acetate. AcOEt was treated 30 min with dry Na2SO4, then 30 min with P2O5. Distillation is desirable, but not necessary.
When Na completely dissolved, hot plate was off, then 15 mL (1.5 equiv) of this dry ethylacetate followed by 11.7 mL (1.0 equiv) of benzyl cyanide were added to reaction flask and its was carefully continue to reflux. After 5 min white precipitate was appear together with foam. Is necessary to control this moment of reaction. When the foam was come down, reflux (with stirring) continued for next 1 h.
After approx one hour reaction mixture was cooled down, dissolved in 70 mL of water, washed twice with CH2Cl2, cooled to 5-10OC and neutralized by addition of 8 mL of acetic acid. Obtained precipitate of Bz(COMe)CN was filtered off, washed with water and used on next stage without additional purification and drying.
To a wet (or dry) Bz(COMe)CN in 250 mL round-bottom flask was added cooled to r.t. mixture of 20 mL of H2SO4 and 8 mL of water and obtained mixture was carefully warmed on hot plate magnet stirrer. At 70-80OC starting material was dissolved, after 5-10 min was exothermic reaction with temperature rise to boiling. The yellow oil with specific smell of P2P was appeared from flask. 50 mL of water was added carefully via cooler and reflux continued for next 1 h. After cooling, P2P was separated, water phase was extracted with 30 mL of ether, combined organic phases dried with Na2SO4 and solvent was removed under reduced pressure. Yield – 10 g of P2P (75%) for two stages. This product can be used on next stage without additional purification with some decrease of yield on next stage.
(Hive Bee)
06-16-04 12:19
No 513764
Hey, this sounds really great! Just a little idea concerning the ethoxide solution: Dissolution of Na-metal in alcohols higher than MeOH can be annoyingly slow, so besides heating you should cut up the metal in very small pieces or if possible get a wire-press (if there's no water around you don't have to be afraid of the Na catching fire, the literature sometimes exaggerates on this).
(Chief Bee)
06-16-04 17:37
No 513791
It's a variation on the synthesis found in ../rhodium /phenyla
The Hive - Clandestine Chemists Without Borders
(Newbee)
06-16-04 18:47
No 513795
Sodium ethoxyde is commercially avilable, but preparing its in citu is cheaper. It depends on current situation.
I have read about this method several years ago, I thought, ist complicate. But practical experience shows that its seems more easy, than it was described in earlier sources.
(Hive Bee)
06-17-04 08:59
No 513913
The methoxide on the other hand, particularly as solution in methanol, is very cheap. I always avoided those commercial alkoxides, because a practical chemistry book stated (was on malonester condensation, I think) that these would sometimes react not as well or not at all. Is this another urban myth? Any comparative experiences?
Sorry, if this was off-topic, but I'd really like to know
...
(Hive Adickt)
06-17-04 09:53
No 513921
Urban myth, the 30% solution from Aldric/Acros ect. is just perfect.
(Newbee)
06-17-04 18:47
No 513981
It is really myth.
I have a big experience of using methoxyde, ethoxyde as solid commercially available powders, also solutions in alcoholes, also I have dissolved Na in alcoholes... No difference for chemistry, It is just depend on situation whats you have in stock or whats you can easy to get...