02-17-02 11:04
No 270818
After about a month of fucking around with KrZ's ethyl nitrite wacker, I finally got it working. And it works damn good. Not only is this method less messy than the benzo wacker but it also has the following advantages:
1)No need for benzo. Ethyl nitrite can be made from sodium nitrite, which is not that hard to get. Plus, the sodium nitrite can be regenerated from the NO gas generated by the reaction.
2)The yield is better.
3)Less PdCl2 is needed.
Now that its perfected, this method is probably the best method around for making ketone. Here's the method that I have developed.
The glassware setup is fairly complicated, but I'll describe it as best I can. There are two parts to it -- A reaction setup and an EtONO (ethyl nitrite) generator. The reaction setup consists of a round bottom flask and a condenser. There should also be some way to input gas between the flask and the condenser. The top of the condenser should have a vacuum outtake attached to it to vent of the toxic NO gas that is produced.
The EtONO generator consists of a flat bottomed flask (round bottom will work too) with a pressure equalized addition funnel on top. A column packed with anhydrous CaSO4 is attached to the top of the addition funnel, and a vacuum outtake adapter should be connected to the top of the column. This vacuum adapter is then connected to the gas inlet on the reaction setup. The vacuum outtake on the reaction setup is connected to a bubbling apparatus or simply out the window. Fuck, that was pretty complicated huh? Too bad I don't have a picture.
Here is a breakdown of the method.
1)Add 140 mL anhydrous EtOH to the round bottom flask of the reaction setup. Now dissolve 775 mg anhydrous CuCl2 and 200 mg PdCl2 in the EtOH. You will have to let it stir for about 30 minutes at 30C to dissolve the PdCl2. When you first put the two solids in the EtOH, it will be a muddy brown color, with particles of PdCl2 floating around. After the PdCl2 is completey dissolved, the solution will turn an orangish color.
2)While you wait for the catalyst to dissolve, prepare a solution of 65 g NaNO2 and 160 mL H20. Pour this in the flat bottomed flask of the EtONO generator.
3)Make a solution of 50 mL H20, 50 g H2SO4, and 46 g EtOH. You must add the H2SO4 to the water first; then let is cool down and add the EtOH. Pour this solution into the addition funnel on the EtONO generator.
4)Once the PdCl2 is dissolved, run ice water through the condenser and begin dripping the contents of the addition funnel into the NaNO2 solution. It will begin producing EtONO gas which will travel up the pressure equilizing arm of the addition funnel, through the drying column, and into the reaction flask where it will condense into the EtOH. Don't worry if you don't see it drip from the condenser. The bp is 18C, so it will condense on the sides of the flask once it mixes with the EtOH vapors. Keep the temp of the rxn flask at 30C.
5)Drip about 1/4 of the solution in the addition funnel. By this time, the solution in the reaction flask will have turned from orangish brown to a very dark brown, almost black color. Keep rxn flask at 30C. Now add 25 g of safrole to the reaction flask. It will immediately begin producing NO gas. This gas will travel up the condenser and into the bubbling apparatus. This apparatus should contain 3% H2O2 and baking soda. The H2O2 oxidizes the NO gas to nitrous acid, which is then neutralized to NaNO2, your hard to obtain starting material. Now ain't that fucking cool.
6)Continue to drip the contents of the addition funnel over the course of an hour (it really doesn't matter how long, just not too fast -- like more than 2 drops per second). The reaction will continue to produce NO gas for about 3 hours. Keep the rxn flask at 30C the entire time and run ice water through the condenser. This keeps EtONO from escaping. This must be done, or too much EtONO will escape and yields will suck. After it stops producing gas, a good deal of solid precipitate can be observed floating around in the solution. The reaction is done.
7)Now add 40 mL H2O and raise the temp to 50C for 45 minutes. This will hydrolyze the ketone as well as drive off any remaining EtONO.
Now for the workup.
1)Let the reaction mixture chill in the freezer. This will precipitate out more solids. Filter the cold mixture over celite (celite isn't necessary, it just makes it easier).
2)Flood the mixture with 10% HCl until it separates into two distinct layers. Keep adding until no more separation occurs.
3)Extract 3x with 30 mL DCM.
4)Wash DCM with 100 mL H2O.
5)Wash DCM 3x with 100 mL 5% NaOH. This will remove most of the black crap from the DCM. The DCM will turn a light brown color after the first wash.
6)Wash the DCM with 100 mL saturated NaCl. It turns dark red. This removes most of the residual water.
7)Dry with MgSO4 and filter.
8)Strip off DCM. You will be left with a very dark red, almost black, oil.
9)Add 10 mL stripped safflower oil and vacuum distill the ketone. Collect all volatile oils. Then fractionally distill the distillate to collect pure ketone. Yield is greater the 20g. Probably 22-23 g. Yield might improve, as this was my first time to get it working.
Well, that wasn't hard, now was it. Beats the hell out of benzo. To recover NaNO2, just crystallize it from the bubbler liquid.
(Pioneer Researcher)
02-18-02 02:54
No 271046
I like your procedure, I'm interested in nitrites wacker form the beginning of the times. Let me say two things, first one is that catalyst could/should be reduced to at least a 0.7 % nolar ratio (0.5 acording with the patent) and that the solvent of rxn could be replaced with anhydrous emthanol, with has the advantage of being more handy, and theoretically it should work the same or even better than methanol. Patent says that is preferabe to use an alcohol with the same chain that the nitrite just for practical question (recovering etc...) and not for other reasons. Using methanol the procedure will be more practical, denatured alcohol could be used for nitrite generation and anhydrous methanol as rxn solvent, what makes the procedure more accesible. I guess that the only side rxn using this system solvent is that a part o the ethyl nitrite can be converted in methyl nitrite, what theoretically will even increase yields. I also supposes that the receiving flask should be at 0 C or so while receiving the nitrite and then heat it to 30 C. If you could perform this easier variation an post results, may be we'll find a improved procedure or may be not, but anyway a research will be made, what has his own value.
Congratulations friend.
(Newbee)
02-18-02 18:55
No 271323
I might give the MeOH solvent a shot. As for adding the EtONO to a cold flask, I have already tried this. The problem is that once the reaction is started (i.e. the flask is heated to 30C), EtONO escapes without the use of an ice cold condenser. I have even tried it with twice the molar quantity of EtONO, but the reaction still did not go to completion. Most likely, the EtONO is driven off with the NO gas that is produced. One thing that may have caused this to fail, though, is that when I was running the reaction this way, I was distilling EtONO into EtOH and then adding the catalyst. I believe that the catalyst must first be completely dissolved in the EtOH before EtONO is added. Mabey all the EtONO can be added at once to cold EtOH with dissolved catalyst. Personally, though, I prefer to drip it in as the reaction is going on.
As far as reducing the catalyst goes, I will try using less. Currently, I am using KrZ's amounts. Besides, 0.7% is 192 mg, and I am using 200 mg. 0.5% would be 137 mg.
(Pioneer Researcher)
02-18-02 20:39
No 271365
Sorry, I was worng with the catalyst, you are right, and it is a very desirable ratio, that could be even refined, although it is already in an appropiate range.
I'm convinced that MeOH will work as well, and if it really works, your procedure would be a gem, at least for me.
It's evident that you are enough creative to ressolve by yourself the problems you find, but anyway let me say that I'll keep the refrigerant and the receiving flask at 0 C till total addition of the acid, then I would start heating slowly rxn to 30 C. If EtONO escapes, you can use more solvent, or just change your ice cold refrigerant to the rxn flask.
The rxn needs a minimum of 2 mols of EtONO for mol of oleoffin (stechemoetric amount), so at least 2.5 mols are desirable, and better 3 or even more if you feel you are lossing nitrite, I told you there's a typo in KrZ write up.
When I made the methyl nitrite with full catalyst, it was not any semll of safrol after rxn, conversion was quantitative (although no selective), it is a primitive analytical method, but it will help you.
You should estimate the purity of your ketone with an amination for example.
Are you sure that H2O2 oxidizes NO to HNO2?
(Hive Addict)
02-18-02 23:51
No 271442
Instead of ethyl nitrite, you could also try isopropyl nitrite, or even the nitrite from isobutanol, which have much higher boiling points.
(Newbee)
02-22-02 22:28
No 272179
I'm begining to think that the H2O2 does not react with the NO. When I bubble the NO into a solution of 3% H2O2 and NaHCO3, a very flammable gas that burns with a white/blue flame is produced. I think this is H2. My theory is that the NO reacts with water in the following equation:
NO + H2O --> HNO2 + 1/2H2
If you have any idea what happens to NO when bubbled into this solution, please tell me what it is.
Also, butyl nitrite would work, but with lower yields. Isopropyl nitrite probably doesn't work, though, due to steric hindrance.
(Pioneer Researcher)
02-23-02 00:10
No 272223
I don't know, but it seems elementary inorganic chemistry, and probably there is a lot of people here that can answer the question. I'm almost sure that NO in water does not produce H2.
(Hive Bee)
02-24-02 02:32
No 272711
Cheese wants to make butyl nitrite....you know "RUSH".... no, cheese ain't a fag .LOL
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