4mmc freebase turns red with few acid

[scalpere]

hi,

my 4MMC synth has a problem, i always have mid/good results (always about 50% yield but for me its good bc its for myself), but since some months, when im trying to acidify my freebase, it becames red after some drops, do u know why? the pH isnt even low, i dont rlly think its bc of the temperature bc its not hot

for example, i failed some hours ago this :

50g 2B4M
300ml EA
100ml M40% (from coinstantylious777)
i dissolved 2B4M in EA and added M40%, i used a magnetic stirrer and waited 40min (bc the reaction didnt finished yet after 20min, the temperature was about 40°C so i let the solution cooled after 40min), the top (4MMC freebase) was trouble, but a good yellow color, i washed 3 times and after, i put 250ml acetone in freebase whil stirring to begin the acidification, i mesured pH before acidifying and it was about 7, i added some drops (with acetone) and the freebase becames orange then red.. i waited and i was that 4mmc started to precipitate, i filtred the solution and my 4mmc was white/red and now after drying, its white and a little blue..

anyone knows why my freebase doesnt have a high pH before acidification and why it turns red after 5,6 drops? i dont drop them quickly, about 1 sec per drop, if someone can helps me it will be cool

 

[handle]

Yeah i had that same experience... dont know why either?

 

[scalpere]

idk if this is bc the extend the reaction (40min-1h instead of 20min) bc the reaction didnt finish, i can see it bcof the temperaature of the rm and the colour which isnt yellow/orange enough, and for the amount of EA, its 300ml and maximum 500ml when 2B4M doesnt dissolves good ( i have some 2B4M rocks so i shake and sometimes, i add a little more EA)

an important information : i use a magnetic stirrer and idk why but i dont think this is the best stuff to do the methylamination, i have the impresion that the reaction turns at the middle only, maybe the colour of my freebase is less yellow than before bc i use more EA? (before i used 200ml for 100g so i think its logic that my freebase was more yellow), maybe i can try to wait 20min only? but the freebase is always at 7 pH so i cant use 50ml of HCl, i heard about acidification in water, how does it works? i add demineralized water (approx. the same amount of freebase?) and i add HCl until pH 4-5? i need to stir it? or i let the 4MMC falls?

 

[scalpere]

other information : i use flat bottom flask of 2000ml, maybe its too large for this 100g of 2B4M? maybe i need to use a 2000ml bottle? so the bottle will be long and not large and maybe the reaction will be stirred better?

 

[dnBQByvHb8Zkawbjpx]

Had this happen to me once (I faced issues on other cooks too, but got different colors not red).

Acidification in water (in aqueous environment) is criminally little studied and discussed on this forum. You get your free base and flush excess methylamine like normal. Then, instead of adding cold acetone, you go straight in with HCl acid (which is the solution of HCl gas in water). As you add HCl acid you turn the free base into 4-MMC hydrochloride salt which is very soluble in water and will dissolve in the water that came with the acid. Depending on the concentration of your HCl you may need to add a small amount of water to dissolve all 4-MMC.HCl, the exact calculation is easy if you can count with molar mass. You stop at pH 5 as usual, separate layers in a funnel, put the organic layer into the freezer to crash out any remaining product and the aqueous layer goes straight into crystallization. Wash crystals with acetone and recrystallize with fresh distilled water.

Avoiding the use of acetone could be very beneficial in preventing unwanted reactions in the RM, such as aldol condensation. I recommend you try it.

 

[scalpere]

habitually,; i use acetone, for 100g i put 250ml to prevent temperature increase and while adding HCl i put 250ml too (maybe its not enough? habitually for 100g i use 1L) (this is what i read here), but i dont think this is a temperature question? how did u solved this problem? the weird thing, is that before, when i started 4MMC, for 10g of 2B4M, i used 5ml of HCl and i didnt have this problem, and the worst, before i putted all the HCl in one drop, not slowly, and i have never burnt my freebase, maybe i will wait only 20min instead of 40min - 1 hour, and i remember that once, i let my freebase while like 12 hours and she becames red, if i remember its bc of the oxydation, maybe 40min-1hour is too much for EA so she oxydate when i add HCl? im not a chimist, im a noobie and i am sure that some ppl here already have this probleme once.. :-(

 

[Dr. MMX]

There is a lot of ways for side reactions. 1stly the purity of 2b4m, dibromine can react in the amination later on, even if its pure with only some residues, its the 2b4m which is protonated by water, while its not our dream in the reaction, methylamine can react with this what a already could happen, wont mention if its 100% methytlamine or some other amines, ethyl acetate as well do reacts with methylamine so its one big boom and in the end acetone self condenses with hcl

 

[scalpere]

oh and another question, how do know when the acidification is finished? how much time u need to wait? i see the 4MMC precipited but maybe its not completed u know?

 

[dnBQByvHb8Zkawbjpx]

Use pH test strips and stop when pH drops to 5.

 

[scalpere]

i talk about when u finish the acidification, how do know all 4MMC precipited?

 

[dnBQByvHb8Zkawbjpx]

Stop at the pH of 5, then put the solution into the freezer overnight. All 4-MMC will precipitate at the low temperature.