recommendations on apparatus and uses thereof
In order to make a 48-72 hour synthesis involving reductive aminations that call for inert gas at least during the application of STAB. I plan to
pump the air out of the glassware to 1 torr, twice before flushing with Ar. I tried this before and one of two or maybe both things happened. The
inert atmosphere was more critical than I realized and I lost it when I added the STAB. Or the gas had impurities, being a welding gas, that I failed
to remove. The plan is to attempt this again using a powder addition funnel to maintain the inert environment and to put an inline system to remove
the CO2, O2, and/or water from the gas. Also previously I only pumped the air out once and only to about 10 torr. I will use the balloon method to
keep Ar pressure on and I will check against CO2 with Ba(OH)2. I can get two funnels for about the same (choke) price. One is 250ml; the other 500.
I'd wait a month for the larger one but wouldn't have to refill it during the addition. This is the possible weakness of the plan or one of them
anyway. Refilling the 250. I ordered it but backorded the other and told Sigma I might return the 250 and get the 500 instead. I'm seeking specific
advice on that issue; scale down to avoid re-filling, wait a month or refill with the gas running fast enough to hold the air back if feasible. Also
any other comments, advice reflections ..? Thanks, CRX
as an example of the conditions (but not the reactions) has anyone done this?
Typical Procedure. To a mixture of benzoic acid (244 mg, 2.0 mmol) and triethylamine (0.28 mL, 2.0 mmol) in dry CH2Cl2 (2 mL)
under argon were added successively trichloroacetonitrile (288 mg, 2.0 mmol) and triphenylphosphine (524 mg, 2.0 mmol) dropwise at room temperature.
The reaction mixture was allowed to react for 1 h. The mixture was then diluted with CH2Cl2 (4 mL) and washed with water (3 mL). The organic layer was
dried over anhydrous MgSO4. After filtration and removal of the solvent, the residue was separated with column chromatography on silica gel
(hexanes/EtOAc 4:1) to give benzoic anhydride
[Edited on 22-12-2007 by chemrox]
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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