11-05-03 17:03
No 469002
Ok,
So the major purpose of this is to find out what I exactly need to do a high-pressure thermal re-arrangement. I have search under the premise that Zealot said during his write-up for ketamine... but a pressure bomb just does not seem feasible at a ‘kitchen’ chemistry environment. (PS. The material that I wish re-arranged is 1-hydroxycyclopentyl-(o-chlorophenyl)-ke
The alternatives that I have come up with are as follows:
1) I could obtain a High pressure Sampling Cylinder (maximum PSI is 3500 PSI!!! that is a bunch of pressure)
2) I could obtain a high pressure vessel (maximum 600PSI @ 140 'C)
Then instead of doing a pesky freaking reflux with a condenser (which is why I hate the RP/HI method for Meth), I could place my material in the Sampling cylinder and just heat. Anyone with ideas or thought on this could you help me out and post them? Is 600PSI at 140’c not high enough?
My next idea is similar. I know it would not be considered exactly a typical lab ‘pressure bomb’ but could I just bombard the material in the sampling cylinder with a bunch of pressure? So much so that it would re-arrange the molecule, or would this even be plausible or does it need the heat from the bomb as well?
Thanks all especially those who help me out,
K0dog
"Vanity is defintely my favourite sin"
-Devil's advocate
(Hive Bee)
11-06-03 11:31
No 469186
Why do you want to use a bomb for your ketimine rearrangement? You dont need one if you do it in a high bp solvent such as undecane (bp: 196), o-dichlorobenzene (bp: 180) or without solvent.
It is a thermal rearrangement, I never saw the pressure as an important factor.
Also it is easier to control the temperature with a reflux condenser, as it is the temperature of the refluxing solvent.
(Hive Bee)
11-06-03 15:23
No 469223
Yes you are correct if I had.. well quality lab grade high bp solvants that might be a good well established route... however it seems that the only thing that is readily availble over the counter around swim... is ultrasene (combonations of larger HC's.... but still sketchy for this re-arrangement)...
See theoritically the precursor doesn't 'need' pressure I suppose to to proceed. I mean I 'could do this' in a vacuum... but it seems that would take more heat.. The elevated pressure faciliates this reaction... and is sorta a by product of the heating of this compound...
Contorlling the temperature..... As far As I care.. I don't if I do do this process in a pressurized container... I'll throw the cylinder into a vat of boiling oil... and leave it for maybe like an hour... think about ...over adding energy will do nothing.... but increase yeilds... and if the vessel cannot support the extra pressure maybe explode.... but that is highly unlikely when the maxium PSI is 350... for a 12" cylinder with a diameter of 3.5"... and I would only 1/2 fill it.. anywyas I doubt that the precuror alone (without solvents) when heated to like 190'C or 180' would actually have enough pressure to break this high PSI cylinder... but maybe.. any thoughts?
Peace thanks, once again...
"Vanity is defintely my favourite sin"
-Devil's advocate
(Hive Bee)
11-07-03 09:46
No 469472
anywyas I doubt that the precuror alone (without solvents) when heated to like 190'C or 180' would actually have enough pressure to break this high PSI cylinder... but maybe.. any thoughts?
No, the ketimine alone will not add pressure at that temp, dont worry about that. But the rearrangement is somewhat lower yielding without any solvent.
I was thinking substituting para-dichlorobenzene (avaiable OTC as mothballs) bp 173C for ortho-dichlorobenzene (bp 180C). The only boring thing is that the p-dichlorobenzene melt at 55C, while the o-dichlorobenzene is a liquid at room temperature. What you could do for the rearrangement is to add the ketimine in melted mothball (purified bee4 by distillation), then reflux it an hour or so at 173C, then cool it to ~60-70C and add toluene, then tolu should dissolve both the ketamine and the dichlorobenzene, A/B and extraction will give the ketamine. Or simply you could reflux it, then cool it a bit and setup for vacuum distillation, and evap the dichlorobenzene at the waterpump (bp ~60 @ 10mmHg). Beeware p-dichlorobenzene look like toxic stuff!
No need for a pressure bomb i think.
(Hive Bee)
11-09-03 13:25
No 469835
Do you know for sure that the rxn is lower yeilding if you don't use any solvents or just guessing?
Anyways I did find out that the use of ultrasene will work nicely.. but this mean that afterward you must clean it also very nicely via either re-xtalization with activated carbon. Works nicely... or so I am told...
"Vanity is defintely my favourite sin"
-Devil's advocate