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Marvin "Popcorn" Sutton

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We'll consider mephedrone (4MMC) synthesis in this article. Dichloromethane (DCM) is used as a solvent. It has a low boiling point (~40 °C) and synthesis procedures take a little time.

Work conditions:
  • Air temperature 20-24 ºC;
  • Relative humidity <60%;
  • Well-ventilated room (with air intake/exhaust hood);
  • Access to water and electricity;
Main stages:
1. Bromination;
2. Methylamination;
3. Separation/cleaning of the free base;
4. Acidification;

Bromination
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1. 4'-Methylpropiophenone (cas 5337-93-9) 1000g and DCM 3000 ml is placed into a 10 l flask, stirred until a homogeneous solution is obtained.
2. A portion of bromine (Br2) 1000 g, 330 ml is poured into a drip funnel.
It is important to know: Work with bromine takes special safety measures because the substance is very corrosive and toxic. Every surface, which has contact with bromine, will be completely spoiled. It is better to use long graduated pipette or graduated cylinder in order to measure volume of this substance. Bromination have to be carried out outside or in a well-ventilated room by reason that bromine is very volatile. The procedure isn't tricky but takes an attention. All glassware, which will be used for manipulations with bromine, must be cooled and absolutely dried.

3. Hydrochloric acid (HCl 36% aq) 50 mL is added into the reaction mixture. It is the catalyst of bromination reaction. A weak stirring is turned on and bromine addition is started.
4. The first portion of bromine ~50 ml is added. The solution is turned brown and eventually is discolored. It means that the bromination reaction is taken place. You have to wait this moment, and not pour out all bromine in a one portion to avoid a violent exothermic reaction with a subsequent boiling off of the solution.
5. Bromine is added from the drip funnel to the solution dropwise, when the first Br2 portion is discolored, in order to a smooth reaction course. If the solution begins to boil, the addition of bromine have to be stopped until the solution is cooled to 30-35 ºC.

It is important to know: Hydrogen bromide is released during bromination. It is the caustic white gas (acid). It takes respiratory organs and eyes protection (full face mask) and well ventilated exhaust fumes hood.

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6. It is necessary to make sure that the reaction has been completed after all the bromine has been poured in: reaction temperature is stopped to rising, the solution is stopped to discoloring. Then, the reaction mixture is stirred for 30-60 min.

7. Obtained solution is washed from remaining bromine, it positively influence on the final product quality. The reaction mixture is washed with an equal volume of sodium thiosulfate (Na2S2O3) 10% solution or sodium bicarbonate (NaHCO3) 10% solution. The solutions is stirred well for 10 min, layers are clearly separated. The lower organic layer is taken for further manipulations. The top layer is disposed.

8. Next, the reaction mixture is washed with an equal volume of water to
neutral pH. The washing procedure of the organic layer can be repeated several times, if it is necessary. The reaction 2-Bromo-4'-methylpropiophenone (cas 1451-82-7) yield is ~1400g, which is already dissolved in DCM.

Methylamination
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9. Methylamine 40% aqueous solution is added to the solution from previous reaction. This reaction is also exothermic, so that methyl amine is added at slow rate in order to avoid the solution boiling. This influences on the reaction yield. Methylamine is taken in excess by reason that it is partially evaporated during the reaction. The average proportion is 2 ml per 1g of 2-Bromo-4'-methylpropiophenone. Methylamine 40% aqueous solution 2800 ml is added to 2-Bromo-4'-methylpropiophenone 1400 g. Methylamine is added via drip funnel in a thin flow or It is divided to 2-3 portions and poured in equal portions with a moderate stirring without splashing.

10. The reaction mixture is stirred for 2 h at 40 ºC.

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Free base separation and purification
11. After the mixture from the previous part is processed, the free base is washed and separated. The lower organic layer is separated from the upper aqueous layer. The organic layer is washed as described in step 7 (same procedures), the upper layer is scrapped. The organic layer washing is repeated several times until methylamine smell is disappeared.
1

12. The mephedrone (4-MMC) free base DCM solution yield is ~3000 ml. If the organic layer is too small after methylamination, pour DCM 1-2 L. This will help to extract 4-MMC free base better. Then, layers are separated and an aqueous layer is disposed.

13. It is very important to separate the organic layer from the water. To be sure, you can put the DCM solution in the freezer, the remaining water will freeze and easy to separate. Also, you can dry your solution by anhydrous magnesium sulphate (MgSO4). If the water is left, problems with precipitation in the next step can happen during acidification.

Acidification
14. The resulting mephedrone free base in the DСM is treated with hydrochloric acid. The best way salt production is HCl gasification. A 35-38% HCl hydrochloric acid water solution in acetone or isopropanol is also used in the ratio of 1 ml of hydrochloric acid per 10 ml of solvent (1:10).

The acid is added in small portions with a constant stirring. If the reaction mass become to thick, it is diluted with acetone. The mixture should be liquid enough in order to acidify 4-MMC free base evenly. White gas (HCl) is actively released during this procedure. Respiratory organs and eyes protection have to be used. In order to minimize the release of gas, it is recommended to cool the solution. During the acidification process, it is important to control the pH. At 5.5-6 pH, the acidification is stopped. The mixture is put into a freezer for several hours. After that, the product is filtered and dried. pH is controlled with
pH indicator paper.
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Hans-Dietrich

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Bromination would be easier to do in a flask with a side neck, from which gaseous acid must enter the container with the absorber. For methylamination, you can use a HDPE canister with a tight-fitting stopper. Methylamine can be safely added in a trickle, the main thing is that the reaction mass does not start to boil. After adding all the methylamine, it is necessary to close the stopper and stir until the reaction mixture cools down. Then the synthesis can be considered complete. The emerald green color in the third picture indicates that there is too much unreacted 2-bromo-4-methilpropiophenone. In this case, it is necessary to distill the reaction mass with steam and separate the unreacted 2-bromo-4-methilpropiophenone, if this is not done, the product will acquire a color that will be difficult to wash. This will also get rid of the remaining methylamine. When laying 1.4 kg 2-bromo-4-methilpropiophenone you will not be able to simply take a glass rod and stir the acid in the base. A top drive agitator or similar device must be used. It is desirable to cool the reaction mass. A separatory funnel can then be used to supply the acid.
 

Hans-Dietrich

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There is no doubt that this is a real synthesis )) I just expressed my comments on the process based on my experience. Welcome )))
 

Marvin "Popcorn" Sutton

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Thank you for your comment, your additions are very important. I'm glad that there are interested persons who contribute to the topic.
This synthesis is described directly by the chemist who performed it, I communicated with him online during the whole process and recorded. This is a first-person report of how everything happened in the lab.
This is one of the many syntheses the two of us have put together. It is a classic technique that has been worked out many times with different solvents.
For a 10L flask, this is the perfect calculated reagents charge. It is better not to distill the free base, but just to warm it at a boiling point solvent (watch the boiling point of the solvent in which the reaction takes place), although there may be different opinions here. Acidification was done in a PP bucket, adding acid from a chemical cup, and stirred with a Teflon stirrer attached to a electric screwdriver.
This is 100% real synthesis, which was carried out by me including))))
 
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Hans-Dietrich

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Distilling the reaction mass with steam and distilling the freebase are two different processes. For steam distillation, additional water or steam is used. It looks like this: Water is added to the flask with the reaction mixture, about half of the volume of the reaction mixture and brought to a boil. The steam takes particles of the reaction mass with it and carries a receiver into the flask. The unreacted ketone will be transferred to the vapor receiver first. Green particles will be visible in the condenser. At some point, the freebase will go with steam. Then you need to change the receiver or stop the process altogether and start the salt release. Water will need to be added as it evaporates. By the way, the resulting ketone can be reused ))) You do not need to distill the entire content of the source. Something in the flask must come off. There it will be seen when the process needs to be completed. By the way, I also mixed the substance with a screwdriver and a Teflon stirrer. The screwdriver eventually burned out )))
 
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Marvin "Popcorn" Sutton

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I decided that distilling halogen ketone with water vapor is not the end of the matter.:) Thanks for the explanation. But I still do it differently, I just heat the reaction mixture at the level of boiling solvent. Some of the solvent escapes with the remaining ketone and methylamine, the reaction mixture changes color and smell(DANGER! Do not inhale!).
Especially useful for those who make large volumes, so as not to look for bulky containers, you can do with enameled buckets and an electric stove and pick up the desired level of heating. But it is necessary to observe safety precautions and to carry out this procedure under a good hood or in the open air.
In order not to break the electric mixer, you need to keep the mixture liquid enough, adding acetone when it thickens. It is not necessary to acidify the entire volume, you can do it in portions.
 
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Hans-Dietrich

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Yes, there is logic in your words. Is that making large syntheses in a buckets is not entirely professional )). I think if the drug chemist has grown up to the production of industrial batches of the substance, then the equipment must correspond to the level )))

And I almost forgot ... When the reaction mixture boils after synthesis, the solvent will partially fly away, yes, and completely fly away methylamine, and the color will change unconditionally, but the ketone will not go anywhere. In any case, something more serious than banal evaporation must be done. Alternatively, add IPA and evaporate the reaction mixture 1-2 times. Maybe something else ...
 

MadHatter

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I'm sorry ... which article? Do I miss something?
 

Marvin "Popcorn" Sutton

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You didn't miss anything, it's just beginning:)
 
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rickyrick

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What is in your opinion best bromine synthesis method?(cost effective,medium scale)
 

Hans-Dietrich

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There is no better thing. There is more or less smelly.
 

hlebsladky2

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In this article, we will look at one of the options for the synthesis of mephedrone (4MMC). We will use dichloromethane (DCM) as the solvent. It has a low boiling point and the whole synthesis goes quickly.

Conditions for the work:
Air temperature 20-24ºC
Relative humidity <60%
Well-ventilated room (with air intake/exhaust)
Access to water and electricity

Main steps:
1. Bromination
2. Methylamination
3. Separation/cleaning of the free base
4. Acidification
View attachment 904
In a 10l flask place 1000g of 4-methylpropiophenone and 3000ml of DCM, stir until a homogeneous solution is obtained.
A portion of bromine is measured in a dropping funnel: 1000g ~ 330ml.
It is important to remember: Work with bromine requires special care because the substance is very corrosive and smelly. Everything to which bromine touches cannot be recovered. It is best to dose bromine with a long graduated pipette by volume. Bromination should be done outside or in a well-ventilated room, as bromine is very volatile. The procedure is simple, but requires the utmost care. The container with bromine should be cooled with ice.
In a flask with a solution of 4-methylpropiophenone, 50 mL of hydrochloric acid is added, which is the catalyst for the bromination reaction. Turn on weak stirring and start adding bromine. The first portion of bromine is ~50ml, the solution will turn brown and will eventually discolor, this will mean that the bromination reaction has taken place. You should wait for this moment, and not pour out all the bromine at once to avoid a strong exothermic reaction, followed by boiling out of the solution. After the first portion of bromine has discolored, the bromine should be added from the funnel drop by drop, thus giving a smooth course of the reaction. If the solution begins to boil, the addition of bromine should be stopped until the solution cools to a comfortable temperature of 30-35ºC.
In the process of bromination actively released hydrogen bromide - a caustic white gas (acid), you must take care of the respiratory organs and eyes, to protect them, as well as have a good hood.
View attachment 714
After all the bromine has been poured in, it is necessary to make sure that the reaction has been completed: the temperature in the flask has stopped rising, the solution has stopped discoloring. It makes sense to hold the reaction mass for some time on stirring for 30-60 min. After completion of the reaction, the obtained solution should be washed of the remaining bromine, which will positively influence the quality of the final product. To do this, wash the reaction mixture with an equal volume of 10% sodium thiosulfate solution (or 10% sodium bicarbonate solution). Stir the solutions well in the flask for ~10min, let the layers stand clearly, select the lower organic layer for further work and dispose of the upper layer. Then wash the solution with an equal volume of water. The operation of cleaning the organic layer can be repeated several times if necessary.
The yield of this reaction is ~1400g, of bromoketone (4-methyl-alpha-bromopropiophenone) dissolved in DCM.
View attachment 905
To the solution obtained in the previous reaction, we add methylamine (40% aqueous solution). This reaction is also exothermic, so methyl amine should be added at such a rate that the solution does not boil, this affects the yield. Methyl amine is taken in excess, since some of it escapes during the reaction. The average proportion is 2ml per 1g of bromoketone. We had 1400g of bromoketone, so we take 2800ml of methyl amine. To prevent the solution from boiling, add methyl amine in a thin stream from a drop funnel or divide the addition of methyl amine into 2-3 parts and pour in equal portions on moderate stirring without splashing. After all the methyl amine has been added, keep stirring for two hours at 40ºC.
View attachment 716View attachment 715
After the mixture from the previous part is processed, we proceed to cleaning and separating the free base. First, we separate the lower organic layer from the upper aqueous layer. The organic layer goes further to work, the upper layer is scrapped. Repeat all cleaning steps as after bromination: wash the reaction mass with equal volume of 10% sodium thiosulfate solution (or 10% sodium bicarbonate solution). Stir well the solutions in the flask for ~10 min, let the layers stand clearly, select the lower organic layer for further work and dispose of the upper layer. Then rinse with an equal volume of water. The operation of cleaning the organic layer can be repeated several times until the smell of methyl amine disappears.
View attachment 771

The yield from this step is ~3000ml of DCM solution with mephedrone base (approximately equal to the volume of DCM added first to the bromination synthesis), but may be less. The DCM volatilizes well, especially if the reaction mixture was boiling hard or the layers were not separated well.
If the organic layer is too small after methylamination, it makes sense to pour 1-2L of DCM, this will help extract the free base better. And only then separate the layers and dispose of the aqueous fraction.
At this stage, it is very important to separate the organic layer from the water. To be sure, you can put the DCM solution in the freezer, the remaining water will freeze and easy to separate. If the water is left behind, there may be problems with precipitation in the next step, during acidification.
The resulting free base in the DСM must be treated with hydrochloric acid. The best gas to use is chlorohydrogen, which can be obtained by the effect of sulfuric acid on table salt in a gas generator. But more often a mixture of 35-38% acid (water solution) in acetone or isopropanol is used in the ratio of 1ml of hydrochloric acid per 10ml of solvent.
The acid is added in small portions, stirring the mixture constantly. If the mass begins to thicken, it is diluted with acetone. The mixture should be liquid enough for the oxidation to proceed evenly.
White gas (HCl) may be actively released during this procedure, so observe safety precautions and protect your respiratory organs and eyes. In order to minimize the release of gas, it is recommended to use cooled solutions.
During the acidification process, it is important to control the pH factor, and at a level of 5.5-6 pH, stop the acidification, and put the mixture in the freezer for several hours. After that the product is filtered and dried.
The pH-factor is controlled with indicator paper or an electronic pH meter for acids and corrosive media.

View attachment 767View attachment 768View attachment 769View attachment 770
Instructions for purification and crystallization:
Hello! How will adding DCM during methylamination help the freebase extract from the water? btw will it even work if bromination was done in a different way(peroxide, hydrobromide acid) ?
 

Marvin "Popcorn" Sutton

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DCM does not need to be added during methylamination. It is used during bromination as a solvent for 4-methylpropiophenone. Then it also dissolves the resulting brominated bromo ketone. And at the end of the methylamination, it is the extractor of the mephedrone base. If a lot of DCM evaporates during the reactions and the free base does not form an organic layer after the methylamination, a portion of DCM is added to extract the free base.
 

Venom2021

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you can see that an error has been made, the flask should be closed immediately after adding methylamine so that the gas does not escape and the solution does not overheat immediately. The color of the mephedrone freebase should be amber or yellow like morning urine. Here is red, this phenomenon is well known to me, so here we get a small quantity of 4mmc and very poor quality. This synthesis can be done in a water bath in a jar or vodka bottle. Pour methylamine all at once and mix it for 10 minutes until the solution starts to heat up to 35 ° then put the bottle in the water bath and shake the bottle every 10 minutes vigorously for 30 seconds and so for 2 hours every 10 minutes each time, thank you
 

rafael1985

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How much you put HCl for one kg ketone or You only check with pH papers
 

Venom2021

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On 1kg bk4 you use about 550ml to 600ml acid 37%
 

rafael1985

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Ok but how is with 2 bromo 3 chloro one liter is 1,5 kg is the same for 1 kg like for 2 bromo 4 methylo?
 

KWasd

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I have a question from a different point of view. Suppose you have a completely airtight room, where fresh air is forced in on one side and a high-powered fan pulls it out of the centre of the room on the other.

How do you deal with the filtration of the odour in the air? Do you use any purifiers, if so, what kind and with what kind of cartridge, or is it enough to give a high-capacity carbon filter with activated carbon on the exhaust as is used in cannabis cultivation. If such a filter would do the job, which activated carbon is best, CTC or ordinary carbon?

How is the air and odours filtered in the laboratories? Regards
 
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