Why do I always fail acidification?

[dnBQByvHb8Zkawbjpx]

There is something in your free base layer that should not be there. I've had this problem several times, per my understanding it was unreacted bk4 in my case. Focus on your initial reaction where stirring and temperature control are key. What solvent did you use, the amount, stirring method and how did you heat the RM? What amount of MMA, is it good or possibly stale with decreased potency?

The following photo and video are from my last cook where I used ethyl acetate, strong magnetic stirring and I heated the RM to 50-55 °C peak with the total reaction time of 30 minutes. The acidification was the cleanest job that I ever did.

 

[Aliexpress]

I did not measure the yield of this batch.

 

[dnBQByvHb8Zkawbjpx]

I did not measure the yield of this batch.

 

[dnBQByvHb8Zkawbjpx]

As for the acid, show us the exact HCl product that you are using. Find it being sold online or go to the manufacturer's website and download the safety sheet. In it you'll find detailed composition and whether it contains any coloring, adulterants, inhibitors or anything else. It should contain only HCl and water.

Oh and as I may have told you previously, I am not convinced about the pH levels that you are reporting. It cannot jump to 1-2 without you adding a large amount of acid at once, which you say you don't do. How exactly do you measure pH - with an electronic device or test strips? Give as much detail as possible. The amount of HCl is not enough to bring this amount of mixture down to pH 1-2 so there must be something wrong with the measurement.

Finally, per my experience 4MMC precipitates at around pH 5.5, so as soon as the pH of your mixture passes through this value and continues to go down you'll see any 4MMC in the mixture precipitate. Do you see any precipitate, half way or after using all acid you planned to use? How about any changes of color of the mix?

 

[abis777]

ph strips. I dip the strip then i take it out after 2 sec and read it

 

[dnBQByvHb8Zkawbjpx]

That looks alright, I use basically the same. It should be pure HCl, just not at maximum concentration but that's acceptable.

 

[abis777]

so it might by the acetone then? The amination reaction looks good to to me, what do you think?

 

[dnBQByvHb8Zkawbjpx]

I doubt that. The absence of any precipitate and the rapid decrease of pH makes me convinced the problem lies in the initial reaction that fails to produce 4mmc free base.

 

[abis777]

aha

 

[Dr. MMX]

what is the problem i dont understand? Please be more precise.

on acidification, its best to use water/ice bath outside, but in small scale its enough if mixture is cold, so temp doesnt rise 20celcius +
acid is added 1 drip per 1s so you dont fail

for 1 mole of mmc you use 1 mole of hcl.

 

[abis777]

I will do again and come back with more precise information

 

[abis777]

same thing after another synthesis, everthyng good until acidification. I have 120 ml freebase than I add a bit over 120 ml acetone and start acidification like in the video and iget ph 2 only after 20 ml acid hcl (I did 50g bk4 batch). I got clean white mix

 

[abis777]

The colors of the rm were very clean and nice through the entire process (I checked with others that do like this) so I don't think my mistakes are in the previous steps

 

[abis777]

after 20 ml acid hcl I stopped seeing that ph and now I will filter and see what I got

 

[animeboro]

If u dont get white liquid then throw to freezer on night next day need get out

 

[abis777]

I got white liquid

 

[animeboro]

Put to freezer then u get more mmc because HCl have 70% water all water take your mmc and if u filtr liquid a lot mmc u throw to toilet if u use freezer then all water be like ice and all mmc get out this all

 

[dnBQByvHb8Zkawbjpx]

That looks nice and clean, you're getting precipitate and there's no change of color of the RM.

Based on my calculations, for 100 g of BK4 you need 16.05 g of pure HCl (no water), which is contained in 51.78 g of HCl 31 %. Divide by 2 to get the weight for 50g BK4 -> 26 grams, which is 22.5 ml. Now, your HCl is ever so slightly stronger (32 % vs my 31 %), so you're going to need a little bit less. 20 ml looks like the theoretical maximum you'd want to use, or perhaps a bit less than that if you account for any free base lost during flushing before the acidification (because some EA dissolves in water that is discarded). Anyway, overshooting the pH is not the end of the world. You rinse off the excess with acetone and further remove it during crystallization.

Looking good, I think you're out of the woods and on the right path to some nice product.

 

[animeboro]

HCl 37% he use about 11ml to 13ml on 100g 2b4m then he get ph5

 

[William D.]

This is not enough. Here need to check the synthesis or check the quality of the BK4.