Hallo guys,
I also prefer method in DCM.
I mixed 100g of Bromketon in 300ml DCM and slowly added 200ml of Methylamin 40%a.q. solution.
Now my question, what temperature and what time would be the best.
Last time I kept temperature at 36 - 37 degrees and reaction-time was 3hours.
But the product was extremly blue after acification.
How can I repair the relation between temperature and cooking time best.
Smaller temperature = longer reaction time?
Which temperature are not working.
Can anybody help and explain the reasons of temperature and cooking time?
Thank you a lot.
I also prefer method in DCM.
I mixed 100g of Bromketon in 300ml DCM and slowly added 200ml of Methylamin 40%a.q. solution.
Now my question, what temperature and what time would be the best.
Last time I kept temperature at 36 - 37 degrees and reaction-time was 3hours.
But the product was extremly blue after acification.
How can I repair the relation between temperature and cooking time best.
Smaller temperature = longer reaction time?
Which temperature are not working.
Can anybody help and explain the reasons of temperature and cooking time?
Thank you a lot.
- By TheVacuumGuy
experimentsciMy experience is that you can easily do it at 40 (rm temp! Use glass thermometer which goes into your mixture). DCM seems very reluctant to start actually boiling (like it has some buffer zone of sorts). If I increase temp it stubbornly keeps sitting at 40.
Either way. That relation time/temp thing is only important for those in a constant hurry. The fact that a reaction takes a certain time doesn't mean you need to stopwatch tightly. Product doesn't walk away. On 35 overnight, 25 overnight, 40 in 2 hours, 40 in 8 hours . you'll get the same output (where, imho, longer = better).
Either way. That relation time/temp thing is only important for those in a constant hurry. The fact that a reaction takes a certain time doesn't mean you need to stopwatch tightly. Product doesn't walk away. On 35 overnight, 25 overnight, 40 in 2 hours, 40 in 8 hours . you'll get the same output (where, imho, longer = better).
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TheVacuumGuyThank you very much for your answer. I am just afraid, that, when I let everything react longer, that more side-products will increse and impury my product.
My last batch, I washed out the blue colour with acetone during filtering. I will send product to a labor to check, if it is good.
I also checked, that I used a little to much Methylamine. For 100g Bromketone I added 200ml Methylamine 40%a.q. solution.
I think 160ml should be enough (after calculation 1mol Bromketone vs. 2 moles Methylamine and a little buffer for Methylamine)
My last batch, I washed out the blue colour with acetone during filtering. I will send product to a labor to check, if it is good.
I also checked, that I used a little to much Methylamine. For 100g Bromketone I added 200ml Methylamine 40%a.q. solution.
I think 160ml should be enough (after calculation 1mol Bromketone vs. 2 moles Methylamine and a little buffer for Methylamine)
- By TheVacuumGuy
experimentsciAfaik methylamine is added in quadruple excess (foolproof). It depends on the conditions. High temps, rapid stirring, open vessel, ensures a lot of it evaporates (which is not what we want).
I roughly use x 1.5
It's actually a matter of just trying and find the optimal variables as you go . There are too much for a "one size fits all".
Last Saturday did 200g batch using 400ml ethyl acetate and 400ml methylamine. That failed heavily (twice).
as I'm typing, doing another 200g batch (image). 350ml methylamine, 500ml ethyl acetate. Never fails (for me, at least).
If I would use DCM i take 600ml DCM.
I roughly use x 1.5
It's actually a matter of just trying and find the optimal variables as you go . There are too much for a "one size fits all".
Last Saturday did 200g batch using 400ml ethyl acetate and 400ml methylamine. That failed heavily (twice).
as I'm typing, doing another 200g batch (image). 350ml methylamine, 500ml ethyl acetate. Never fails (for me, at least).
If I would use DCM i take 600ml DCM.
Attachments
- By TheVacuumGuy
TheVacuumGuy400g bromoketone
1000ml DCM
800ml Methylamine
39 Celsius
6 hours (unintentionally, fell asleep)
In the morning added 1000ml water.
1000ml DCM
800ml Methylamine
39 Celsius
6 hours (unintentionally, fell asleep)
In the morning added 1000ml water.
- By TheVacuumGuy
$!$It finished drying to complete dryness just now. i got 265,5 gram. Could have been higher if i actually didn't forget to wash it 3 times.
Will also get losses when crystallization to account for, so finally it will end up bit lower.
Will also get losses when crystallization to account for, so finally it will end up bit lower.
Last edited:
- By TheVacuumGuy
$!$265,5.
The reaction I did shortly thereafter was one from 200g but used 800 dcm. This one yielded 165g. So that's around 75 percent (when accounted for some losses during crystallize). Much better than the one where used too little DCM.
So the 6 hour reaction I have to admit it didnt work as good (for future readers)
The reaction I did shortly thereafter was one from 200g but used 800 dcm. This one yielded 165g. So that's around 75 percent (when accounted for some losses during crystallize). Much better than the one where used too little DCM.
So the 6 hour reaction I have to admit it didnt work as good (for future readers)
- By $!$
TheVacuumGuy2h 40° to najlepszy sposób na dcm true.
A lot u lost when u wash it acetone much product is still on dcm when u wash it
A lot u lost when u wash it acetone much product is still on dcm when u wash it
- By w2x3f5
experimentsciYou have a problem with bromoketone, most likely it is dirty. you need to watch its melting point and try to recrystallize the bromoketone, or you will have aniline homologues mixed with mmc
