BK4 (2b4m) Containing 4-methylpropihenon

[white7proton]

I purchased from a supplier found here, 5kg of BK4 (2b4m) and with help from someone who is experienced we have found out the reason my synthesises are not working because the BK4 contains 4-methylpropihenon. I had to try to wash with boiling water to remove the 4-methylpropihenon layer on top when it forms as an oil. I tried to clean about 150g BK4 and I removed over 15ml of 4-methylpropihenon and then I thought it was clean and my synthesis is still not correct. I'll attach a photo where I am cleaning with hot water and you can see the 4-methylpropihenon on top.

The synthesis when I add acid goes dark, nearly black. See photo attached, the dark liquid is after I add acid to the mix, it goes dark like this because of the 4-methylpropihenon. This is because of it containing the 4-methylpropihenon, mpf causing it.

Not only has it cost me lots of money, I have used so so much BK4 and all has gone to waste. Not only that the time it has taken me to make all of these synthesis. Can we resolve this please, I can't afford to lose this much time and money.

 

[HIGGS BOSSON]

Describe the synthesis technique you used.
Who is the supplier?
In appearance, BK4 powder looks clean. And small amounts of methylpropiophenone should not lead to such results.

 

[w2x3f5]

I check with him. Standard 50 grams bk4+350 dcm+methylamine 40% 100 ml, 2 hours mixed, control temp 30 degrees.
In him 100 gr bk4 have around 15 ml methylpropiophenon, its not good. And washing in hot water not helped, maybe recristallyzation helps

 

[w2x3f5]

The excess of methylamine was washed off with water, ph 8-9. With the addition of half of the HCl from the theoretical one, we get black shit. Explicit reaction of condensation of MPF with BK4 in an acidic catalyst, perhaps some kind of Schiff base is obtained.

 

[G.Patton]

Why do you think it is 4-methylpropiophenone? @white7proton Have you measured melting point of BK4? In general, I agree with @HIGGS BOSSON . I guess you added too much acid. Have you measured pH while HCl 36% addition? Have you used HCl solution in acetone or added it without solvent. pH is very important and you could overoxydize your 4-MMC by fast addition of full volume HCl. Also, have you washed your 4-mmc free base by water from methylamine excess?

 

[G.Patton]

Yes, you are right. My bad. Temperature have to down. Anyway, 4-BK may be recrystallized from benzene with slight warm.

 

[w2x3f5]

no need benzene, for author its hazard, IPA best variant, I think work same great same like with p2np

 

[white7proton]

After attempting on my own i reached out and had @w2x3f5 help me step by step using his method and this is what happens.

 

[w2x3f5]

bk4 melts at temperatures above 60 degrees. To check, we poured bk4 with hot water, about 15 ml of oil floated with a density of less than 1 gram per milliliter (which corresponds to methylpropiophenone), we also know that the density of bk4 in a melted state is more than 1.4 grams per ml (the lowest layer)

 

[white7proton]

Can someone help explain how I can clean the 2B4M so that it doesn't make my mix go black when I add acid.

I'm trying my best to liase with the seller, if you or someone can help with a method to fix / clean the 2B4M I have then I will be happy with that, I just want to fix it so I can finally finish my synthesis.

Or, you can do step by step with me, I will show photos and videos etc and do the whole process and show you that what I am saying is the truth. Please guys.

 

[sierraleone]

I'm sure the reason that you are getting black liquid is that you are adding acid too fast.
It must be added dropwise,very slowly while stirring vigorously.If you think you added it slowly do it even slower.

 

[white7proton]

I did a few drops every 5 seconds until I did 8ml, continuously stirring.

I was doing it slower than the actual videos on shown on this forum.

 

[w2x3f5]

Reason we find and acid he add normal. I count how many acid need add, and he use only 50 percents ml, not just with pH

 

[G.Patton]

How much in ml? Can you describe your calculations? pH must be checked.

 

[w2x3f5]

ph 8 (dark green) if you mean ph free base in dcm after acid. In theory 0.22 mol free base, but I count only 80 percent yield, if HCl 35 percents (around 12 mol/litter) its mean 15 ml maxim HCl

 

[G.Patton]

I bet that an excess of methylamine gives such color in this case. He has to wash it before acid addition. It is quite common problem.

 

[w2x3f5]

He dont have MeNH2 in dcm free base, because ph dcm after washing water not more then 9. MeNH2 give more then 10 ph

 

[w2x3f5]

and methylamine not give color jest give dirty salt with MeNH2 salt. Shiff base from reaction MP+BK4 and acid promotion

 

[G.Patton]

pH Don't prove MeNH2 presence or absence. I recommend to wash it better and evaporate part of DCM with MeNH2 traces after washing by water.

 

[w2x3f5]

How better if he wash him layer 300 ml dcm with total 7 times with 400ml? Its not MeNH2, just understand it pls

 

[w2x3f5]

I think this question we closed, because problem with bk4. About chemistry we can talking in pm )

 

[HIGGS BOSSON]

The first thing I recommend is to reduce the load to 10 g to work out the synthesis technique on the scale volume. I'm not sure if your BK4 contains that much methylpropiophenone because it looks clean and the seller (factory) doesn't benefit from overspending 4-MP. Write me PM, I will help to carry out the synthesis step by step.

 

[w2x3f5]

The author has a problem with the equipment and it will be extremely difficult for him to work with small amounts of substances.
Take a close look at bk4, it is wet and oily.
There are only two ways to purify bk4 by washing and recrystallization, or the second way (it is very wrong), try to halogenate it, but how much MP is there, take the calculation that it is no more than 25 percent, after hallogenation, wash with thiosulfate from excess halogen.
The seller sells the goods not by the actual purity of the goods, but by weight, for him the losses are small on the condition that he gets rid of the low-quality precursor.