Methamphetamine synthesis from P2P by NaBH4 reduction. Medium-Scale.

[btcboss2022]

Introduction.​

I represent to BB audience Methamphetamine synthesis method of 1-phenyl-2-propanon (P2P) reduction by NaBH4. Following method allows obtaining and large batches of product. The hardest problem of this method is the heat generating during exothermic reaction of imine reduction. Extremely important keep temperature in described frames and keep all reagent and reaction atmosphere dry (use drying tubes with CaCl2). Also, manipulations with NaBH4 is quite dangerous and take a lot of attention because this reagent has toxic effects, reacts with water and alcohols with releasing enormous amount of hydrogen and form the corresponding borate, it may cause an explosion, burns and injuries. You have to use chemical glass, gloves, chemical coat and respirator.​

Equipment and glassware:​

• Ceramic mortar;​
• 2 L (x2), 0.5 L (x2) and 200 ml (x2) beakers;​
• 2 L (x2) and 10 L Erlenmeyer flask;​
• Measuring cylinder for 100 ml;​
• 2 L three-necked round bottom flask with plugs;​
• 2 L round bottom flask with vacuum quickfit or Schlenk flask;​
• 0.5 L Simple dropping funnel with Claisen flask and drying tube or 0.5 L equal pressure dropping funnel;​
• 1 L Separator funnel;​
• 2 L Evaporation flask;​
• Pyrex dish 0.5 L;​
• Magnetic stirrer with heating plate;​
• Retort stand and clamp for securing apparatus;​
• Silicone-oil bath;​
• Icecubes/methanol bath (-10 °C) or Mashed ice with salt (-10 °C);​
• Laboratory scale (1 g-1 kg is suitable);​
• Oven;​
• Laboratory grade thermometer (-20 °C to 200 °C) with three-necked flask adapter;​
• Aspirator;​
• HCl laboratory generator;​
• Drying tube x2;​
• Rotavap machine with water bath;​
• Filter paper.​

Reagents:​

• 138 gram P2P (1 mole) (1-phenyl-2-propanone);​
• 10% Methylamine in Methanol (w/w) - 1000 ml with 100 g MeNH2 (~3 moles);​
• Magnesium Sulfate - 36 g (MgSO4·7H2O, oven dry at 300 °C for 2h MgSO4·1H2O) [For drying MeOH/MeNH2 solution];​
• Silica Gel (3-5 mm balls) - 200 ml (dry at 300 °C/2h, they will darken!) [For absorbing 2 mol H2O during rxn];​
• 15 gram NaBH4 as a reducing agent for the formed (water-free!) imine;​
• 5-7 L distilled water + ~5 L distilled water to filling rotavap machine bath;​
• 1 L Dichloromethane (DCM);​
• 0.5 L Acetone.​

Important: the reaction is very sensitive to any water (fluid or vapour in the air!).

Note: hold all manipulations in pull out probe or under exhaust hood; methylamine is a rather toxic substance, do not let its vapors enter the respiratory tract. Using respiratory mask is required. Inhalation of methylamine causes severe skin irritation, eyes and upper respiratory tract. Firstly, leads to excitement and then to depression of the central nervous system. Death can occur from respiratory arrest.​

Procedure.​

Precursors drying.
First quickly crunch your pre-dried (oven, 300 °C, 3 hrs.) dry MgSO4 to pop corn shaped rocks in a mortar, sieve the powder out, and directly put the rocks under max. mixing in the Methanol/Methylamine mix (1000 ml) and close the pot to let no water from the air in. Keep mixing for 10 minutes, then all the water will be taken up to the MgSO4. Let stand and wait till all the MgSO4 is on the bottom. Now quickly tap off the now dry MeOH/methylamine (MA) mix in a 2 L three-necked round bottom flask and close that one. Wash directly your empty pot with lots of water, to remove the smell of methylamine, so you can safely store it.
​

Synthesis.

Now add the 200 ml (measure in beaker, neglect the free spaces) dry Silicagel beads (2-5 mm) and a magnetic mixer bar also in the 2 L flask and close again. Keep 2 L flask in Silicone-oil bath at 20 °C. Silicone-oil only slowly warms up! Do not apply heat now, it's only meant as a cooling medium in this stage. Now add slowly via a dropping funnel the 138 g P2P to the 2 L flask under strong mixing. The temperature rises to 23 °C during the (water-free) Imine forming. The water from this reaction is taken up by the dried Silicagel! This takes 30 minutes. Let, then mix for another hour. The reaction mix color changes from light yellow to coffee+milk color. Temp 23 °C.​

View attachment 2944 ​

Stop mixing after this 1 hour and pour the fluid off into a 2 L glass erlenmeyer with flat bottom and add a mixbar. The remaining Silicagel is washed 3 times with 50 ml dried (use silicagel) methanol, to catch the remaining Imine, and those 2 x 50 ml is also poured into the 2 L erlenmeyer. Now put the 2 L erlenmeier on magn.mixer, in an icecubes/methanol bath (-10 °C) (or mashed ice with salt) and start strong mixing. Put a drip funnel on top of 2 L erlenmeier, in rubber ring. Now start adding, every 5 min., a teaspoonfull (flat off!) of NaBH4 in minimum methanol, wash it from funnel with minimum methanol amount. After every spoonfull, stopper the funnel loosely with a rubber stopper. This takes 2.5 hrs. Do not exceed a temp of more than 20 °C! You can add the next spoon at ±8 °C. Solution color is light clear orange/brown. Let mix in total for 8.5 h (could perhaps be lot fewer hours).​

View attachment 2945 ​

The total volume is ~1900 ml. Add then the mix to 5 L distilled water into a 10 L flask, under magn.mixing. The pH=12. Add then 500 ml DiChloroMethane (DCM) and mix strongly for 30 min. Let oil precipitate and a dark, honey-coloured layer of DCM+oil settle onto the bottom. Decant the water part with an aspirator + siliconetube. Fill the rest (water+DCM+oil) in a seperatory funnel and tap off only the DCM+oil = 550 ml. (DCM b.p. 40 °C). The leftover MgSO4 and boro salts stayed nicely in the waterpart. Then dry the DCM+oil with some dry MgSO4 and decant in 2l erlenmeier. Wash this MgSO4 with some fresh, DRY DCM and add the DCM washings to the now dry DCM+oil. Total volume DCM+oil =1000 ml, colour is honey/red.​

Producing methamphetamine hydrochloride.

Start now bubbling this 1000 ml with HCl-gas via 2 L Schlenk flask (or round bottom flask with vacuum quickfit), while this 2 L flask stands in ice bath on magn. mixer and blends vigorously. Check pH frequently, proceed until pH 6. Pour the now acidified 1000 ml in a 2 L evaporation flask and put on Rotavap machine. Spee~100 rpm, t° = 80 °C, little vacuum=0.8 bar (water-jet aspirator is enough), to hold the flask. After distillating off nearly all the DCM, suddenly the contents of the flask turns from dark honey colour to creamy milk color, and it dries out to a round cake on the bottom. Remove the ~0.5 L DCM, now in the collector flask, and hang that empty flask on again. Now put full vacuum on to remove the last traces of water.

Cleaning by 3 x recrystallization: put minimum quantity of hot (40 °C) dry DCM (or dry 98%+ ethanol) in the flask until the last remains of the dry stuff dissolves, and add 4x this DCM-quantity in the form of dry acetone. Close with stopper and put 1 hr in freezer. A solid dirty-white crystal mass is formed with a layer of dark red fluid on top of it. Decant the fluid and repeat this step another 2x and 2 hrs. You have, the last time, snow-white crystals of racemic methamphetamine hydrochloride. Dry Weight = 141.5 g, close to quantitative yield.

Methamphetamine purification.
You can use this technique or follow next advices to produce ICE meth: melt this crystal mass in an alu flat bottom pot on a heater plate at 170-175 °C. Then let this melt, very slowly, and do not go higher than necessary to melt it, or its starts smoking (you have your first quick-test then: enjoy!). Cool down to 150 °C again, really slowly, 1 °C/30 min. (regulate with your temp controller!), and you got ICE, after you let it very slowly again cool down to room temperature (with a closed lid on it!, its hygroscopic!). Advantage: you removed all the water in this process!

You can better make the sulfate salt following logical method: Let 10% H2SO4/Ethanol mix acidifying a 1:4 mix of freebase Meth/Ethanol. This is not so hygroscopic. Filter and dry the crystals.​

G.PattonHello,

After many tests using Methylamine HCL based on this method I will share the best way that I found to obtain Methamphetamine freebase in big scale:

• 966 gr P2P​
• 14 liters Methanol
• 1183 gr Methylamine HCL​
• 638gr NaOH​
• 452 gr Anhydrous Sodium Sulfate​
• 105 gr NaBH4​
• 35 L distilled water​
• 7 Liters DCM​

- Fill the reactor with the 14 L of Methanol
- With stirring dissolve the Methylamine HCL
- Put the reactor temp at 0C(not the mixture temp) and add the NaOH, the temp will increase
- Once the temp come back to 20C add the P2P, the temp will increase stir it during 45min-1 hour
- Add 252gr of anhydrous sodium sulfate
- When the mixture temp arrives to 8C start adding portionwise the NaBH4 not exceeding the 20C
- Once all the NaBH4 has been added let it mixing under 20C during aprox 2 hours until the mixture stops bubbling
- Add the water and continue mixing during 5 min
- Add the DCM and mix it during 10 min
- Stop stirring and let layers get separated
- Keep the bottom layer and discard the upper one( not profitable to extract this aqueous phase)
- Add 200gr of anhydrous sodium sulfate to the saved layer and mix it
- Filter it in Buchner Funnel
- Evaporate the DCM
- Clean and smelly Methamphetamine freebase obtained

;-)

 

[Doubleboil]

Hello,

After many tests using Methylamine HCL based on this method I will share the best way that I found to obtain Methamphetamine freebase in big scale:

• 966 gr P2P​
• 14 liters Methanol
• 1183 gr Methylamine HCL​
• 638gr NaOH​
• 452 gr Anhydrous Sodium Sulfate​
• 105 gr NaBH4​
• 35 L distilled water​
• 7 Liters DCM​

- Fill the reactor with the 14 L of Methanol
- With stirring dissolve the Methylamine HCL
- Put the reactor temp at 0C(not the mixture temp) and add the NaOH, the temp will increase
- Once the temp come back to 20C add the P2P, the temp will increase stir it during 45min-1 hour
- Add 252gr of anhydrous sodium sulfate
- When the mixture temp arrives to 8C start adding portionwise the NaBH4 not exceeding the 20C
- Once all the NaBH4 has been added let it mixing under 20C during aprox 2 hours until the mixture stops bubbling
- Add the water and continue mixing during 5 min
- Add the DCM and mix it during 10 min
- Stop stirring and let layers get separated
- Keep the bottom layer and discard the upper one( not profitable to extract this aqueous phase)
- Add 200gr of anhydrous sodium sulfate to the saved layer and mix it
- Filter it in Buchner Funnel
- Evaporate the DCM
- Clean and smelly Methamphetamine freebase obtained

;-)

btcboss2022and @G.Patton
Can I get some help please. I can’t get it to crystallise. Here’s what I’ve done more then a couple times.
methylamine hcl dissolved in Meoh
Naoh added and salt appears.
p2p added temp up and back down.
nabh4 on ice.
mgso4 normal
Water added and turns kinda foamy like milk
Dcm added
Separate take dcm layer. Color yellowish
MgSO4 and filter
Now this dcm layer has many small bubbles inside. (Air and product)?
Dcm is evaporated leaving a light golden oil.
Ph adjusted to 7 ( I’ve tried with ph 6 and 5 also)
Acetone added by
-3 to 1 ratio and freezer
-3 to 1 ratio air dry
-1 to 1 ratio and freezer
-1 to 1 ratio air dry


All of them failed. No crystals. Any insight would be appreciated. Thanks!

 

[mithyl2]

what can be used in place of Dichloromethane?

 

[Sciencenutz]

what can be used in place of Dichloromethane?

mithyl2Toluene will be ok but it will be on the top layer then

 

[mithyl2]

Toluene will be ok but it will be on the top layer then

Sciencenutzdo you think there would any adjustments to quantity I would need when using toluene?

 

[Sciencenutz]

do you think there would any adjustments to quantity I would need when using toluene?

mithyl2Quantity as in volume needed to extract it all? I would just use same quantity as DCM and just keep extracting untill your toluene has no color therefore you extracted all the oil

 

[w2x3f5]

And if the synthesis is slightly changed, take water by desitylation of the alcohol / water azeotrope during the production of imine, and then use zeolite for better drying?

Why the color of coffee with milk? I always have a yellow color, I never got a brown color, not at the stage of imine formation, not at the stage of reduction with borohydride.

 

[Multivitamin]

hey i am newbie attempting this synthesis.I was wondering if my calculations are right.I want to scale it down to start only from 60grams of p2p oil.
These are my calculations:

p2p 60g
434ml methanol with 43g of MeNH2
15.6g magnesium sulfate
86,9 ml of silica gel
6,5g NaBH4
2 liters of water
434ml of DCM
0.2 l of acetone

Thank you for your time guys this forum is awesome.

 

[G.Patton]

hey i am newbie attempting this synthesis.I was wondering if my calculations are right.I want to scale it down to start only from 60grams of p2p oil.
These are my calculations:

p2p 60g
434ml methanol with 43g of MeNH2
15.6g magnesium sulfate
86,9 ml of silica gel
6,5g NaBH4
2 liters of water
434ml of DCM
0.2 l of acetone

Thank you for your time guys this forum is awesome.

MultivitaminHello, correct. It isn't necessary to use exactly 15.6 MgSO4. You can use also Na2SO4.

 

[w2x3f5]

Hello, correct. It isn't necessary to use exactly 15.6 MgSO4. You can use also Na2SO4.

G.PattonBetter MgSO4, Na2SO4 not so fast work (

 

[mygodson]

Introduction.​

I represent to BB audience Methamphetamine synthesis method of 1-phenyl-2-propanon (P2P) reduction by NaBH4. Following method allows obtaining and large batches of product. The hardest problem of this method is the heat generating during exothermic reaction of imine reduction. Extremely important keep temperature in described frames and keep all reagent and reaction atmosphere dry (use drying tubes with CaCl2). Also, manipulations with NaBH4 is quite dangerous and take a lot of attention because this reagent has toxic effects, reacts with water and alcohols with releasing enormous amount of hydrogen and form the corresponding borate, it may cause an explosion, burns and injuries. You have to use chemical glass, gloves, chemical coat and respirator.​

Equipment and glassware:​

• Ceramic mortar;​
• 2 L (x2), 0.5 L (x2) and 200 ml (x2) beakers;​
• 2 L (x2) and 10 L Erlenmeyer flask;​
• Measuring cylinder for 100 ml;​
• 2 L three-necked round bottom flask with plugs;​
• 2 L round bottom flask with vacuum quickfit or Schlenk flask;​
• 0.5 L Simple dropping funnel with Claisen flask and drying tube or 0.5 L equal pressure dropping funnel;​
• 1 L Separator funnel;​
• 2 L Evaporation flask;​
• Pyrex dish 0.5 L;​
• Magnetic stirrer with heating plate;​
• Retort stand and clamp for securing apparatus;​
• Silicone-oil bath;​
• Icecubes/methanol bath (-10 °C) or Mashed ice with salt (-10 °C);​
• Laboratory scale (1 g-1 kg is suitable);​
• Oven;​
• Laboratory grade thermometer (-20 °C to 200 °C) with three-necked flask adapter;​
• Aspirator;​
• HCl laboratory generator;​
• Drying tube x2;​
• Rotavap machine with water bath;​
• Filter paper.​

Reagents:​

• 138 gram P2P (1 mole) (1-phenyl-2-propanone);​
• 10% Methylamine in Methanol (w/w) - 1000 ml with 100 g MeNH2 (~3 moles);​
• Magnesium Sulfate - 36 g (MgSO4·7H2O, oven dry at 300 °C for 2h MgSO4·1H2O) [For drying MeOH/MeNH2 solution];​
• Silica Gel (3-5 mm balls) - 200 ml (dry at 300 °C/2h, they will darken!) [For absorbing 2 mol H2O during rxn];​
• 15 gram NaBH4 as a reducing agent for the formed (water-free!) imine;​
• 5-7 L distilled water + ~5 L distilled water to filling rotavap machine bath;​
• 1 L Dichloromethane (DCM);​
• 0.5 L Acetone.​

Important: the reaction is very sensitive to any water (fluid or vapour in the air!).

Note: hold all manipulations in pull out probe or under exhaust hood; methylamine is a rather toxic substance, do not let its vapors enter the respiratory tract. Using respiratory mask is required. Inhalation of methylamine causes severe skin irritation, eyes and upper respiratory tract. Firstly, leads to excitement and then to depression of the central nervous system. Death can occur from respiratory arrest.​

Procedure.​

Precursors drying.
First quickly crunch your pre-dried (oven, 300 °C, 3 hrs.) dry MgSO4 to pop corn shaped rocks in a mortar, sieve the powder out, and directly put the rocks under max. mixing in the Methanol/Methylamine mix (1000 ml) and close the pot to let no water from the air in. Keep mixing for 10 minutes, then all the water will be taken up to the MgSO4. Let stand and wait till all the MgSO4 is on the bottom. Now quickly tap off the now dry MeOH/methylamine (MA) mix in a 2 L three-necked round bottom flask and close that one. Wash directly your empty pot with lots of water, to remove the smell of methylamine, so you can safely store it.
​

Synthesis.

Now add the 200 ml (measure in beaker, neglect the free spaces) dry Silicagel beads (2-5 mm) and a magnetic mixer bar also in the 2 L flask and close again. Keep 2 L flask in Silicone-oil bath at 20 °C. Silicone-oil only slowly warms up! Do not apply heat now, it's only meant as a cooling medium in this stage. Now add slowly via a dropping funnel the 138 g P2P to the 2 L flask under strong mixing. The temperature rises to 23 °C during the (water-free) Imine forming. The water from this reaction is taken up by the dried Silicagel! This takes 30 minutes. Let, then mix for another hour. The reaction mix color changes from light yellow to coffee+milk color. Temp 23 °C.​

View attachment 2944 ​

Stop mixing after this 1 hour and pour the fluid off into a 2 L glass erlenmeyer with flat bottom and add a mixbar. The remaining Silicagel is washed 3 times with 50 ml dried (use silicagel) methanol, to catch the remaining Imine, and those 2 x 50 ml is also poured into the 2 L erlenmeyer. Now put the 2 L erlenmeier on magn.mixer, in an icecubes/methanol bath (-10 °C) (or mashed ice with salt) and start strong mixing. Put a drip funnel on top of 2 L erlenmeier, in rubber ring. Now start adding, every 5 min., a teaspoonfull (flat off!) of NaBH4 in minimum methanol, wash it from funnel with minimum methanol amount. After every spoonfull, stopper the funnel loosely with a rubber stopper. This takes 2.5 hrs. Do not exceed a temp of more than 20 °C! You can add the next spoon at ±8 °C. Solution color is light clear orange/brown. Let mix in total for 8.5 h (could perhaps be lot fewer hours).​

View attachment 2945 ​

The total volume is ~1900 ml. Add then the mix to 5 L distilled water into a 10 L flask, under magn.mixing. The pH=12. Add then 500 ml DiChloroMethane (DCM) and mix strongly for 30 min. Let oil precipitate and a dark, honey-coloured layer of DCM+oil settle onto the bottom. Decant the water part with an aspirator + siliconetube. Fill the rest (water+DCM+oil) in a seperatory funnel and tap off only the DCM+oil = 550 ml. (DCM b.p. 40 °C). The leftover MgSO4 and boro salts stayed nicely in the waterpart. Then dry the DCM+oil with some dry MgSO4 and decant in 2l erlenmeier. Wash this MgSO4 with some fresh, DRY DCM and add the DCM washings to the now dry DCM+oil. Total volume DCM+oil =1000 ml, colour is honey/red.​

Producing methamphetamine hydrochloride.

Start now bubbling this 1000 ml with HCl-gas via 2 L Schlenk flask (or round bottom flask with vacuum quickfit), while this 2 L flask stands in ice bath on magn. mixer and blends vigorously. Check pH frequently, proceed until pH 6. Pour the now acidified 1000 ml in a 2 L evaporation flask and put on Rotavap machine. Spee~100 rpm, t° = 80 °C, little vacuum=0.8 bar (water-jet aspirator is enough), to hold the flask. After distillating off nearly all the DCM, suddenly the contents of the flask turns from dark honey colour to creamy milk color, and it dries out to a round cake on the bottom. Remove the ~0.5 L DCM, now in the collector flask, and hang that empty flask on again. Now put full vacuum on to remove the last traces of water.

Cleaning by 3 x recrystallization: put minimum quantity of hot (40 °C) dry DCM (or dry 98%+ ethanol) in the flask until the last remains of the dry stuff dissolves, and add 4x this DCM-quantity in the form of dry acetone. Close with stopper and put 1 hr in freezer. A solid dirty-white crystal mass is formed with a layer of dark red fluid on top of it. Decant the fluid and repeat this step another 2x and 2 hrs. You have, the last time, snow-white crystals of racemic methamphetamine hydrochloride. Dry Weight = 141.5 g, close to quantitative yield.

Methamphetamine purification.
You can use this technique or follow next advices to produce ICE meth: melt this crystal mass in an alu flat bottom pot on a heater plate at 170-175 °C. Then let this melt, very slowly, and do not go higher than necessary to melt it, or its starts smoking (you have your first quick-test then: enjoy!). Cool down to 150 °C again, really slowly, 1 °C/30 min. (regulate with your temp controller!), and you got ICE, after you let it very slowly again cool down to room temperature (with a closed lid on it!, its hygroscopic!). Advantage: you removed all the water in this process!

You can better make the sulfate salt following logical method: Let 10% H2SO4/Ethanol mix acidifying a 1:4 mix of freebase Meth/Ethanol. This is not so hygroscopic. Filter and dry the crystals.​

G.PattonAn additional route, 3-phenyl-2-propanol and methansulfonyl chloride, and then react with methylamine can also yield the target product

 

[G.Patton]

An additional route, 3-phenyl-2-propanol and methansulfonyl chloride, and then react with methylamine can also yield the target product

mygodsonCan you describe this method with details in detached new post? Or share a link please.

 

[mygodson]

Can you describe this method with details in detached new post? Or share a link please.

G.PattonAn additional route, 3-phenyl-2-propanol and methansulfonyl chloride,
Triethylamine as alkali, in dichloromethane, raw material: methansulfonyl chloride: triethylamine mole ratio of 1:1.05:1.1, after treatment directly washing, steam can be directly to the next step.
Crude and tetrahydrofuran solution of methylamine reflux, the mole amount of methylamine should be at least twice, and then steam under reduced pressure, add dichloromethane or ethyl acetate, and then water, reduced pressure to remove the solvent can directly get the target product。

 

[Stretcher5335]

An additional route, 3-phenyl-2-propanol and methansulfonyl chloride,
Triethylamine as alkali, in dichloromethane, raw material: methansulfonyl chloride: triethylamine mole ratio of 1:1.05:1.1, after treatment directly washing, steam can be directly to the next step.
Crude and tetrahydrofuran solution of methylamine reflux, the mole amount of methylamine should be at least twice, and then steam under reduced pressure, add dichloromethane or ethyl acetate, and then water, reduced pressure to remove the solvent can directly get the target product。

mygodsonMr mPatton or any expert please validate this claim. I dont know enough to say it is or it isnt but what i can say is it looks like the all to familiar cutting agent methylsulfonylmethane (MSM)

 

[G.Patton]

An additional route, 3-phenyl-2-propanol and methansulfonyl chloride,
Triethylamine as alkali, in dichloromethane, raw material: methansulfonyl chloride: triethylamine mole ratio of 1:1.05:1.1, after treatment directly washing, steam can be directly to the next step.
Crude and tetrahydrofuran solution of methylamine reflux, the mole amount of methylamine should be at least twice, and then steam under reduced pressure, add dichloromethane or ethyl acetate, and then water, reduced pressure to remove the solvent can directly get the target product。

mygodsonIt is quite messy description. Nobody can repeat procedure by this manual =/

 

[mygodson]

It is quite messy description. Nobody can repeat procedure by this manual =/

G.Patton This is feasible.

 

[mygodson]

Can you describe this method with details in detached new post? Or share a link please.

G.Pattontell me your e-mail,I will tell you more about the operation process.

 

[G.Patton]

tell me your e-mail,I will tell you more about the operation process.

mygodsonYou can write me in DM here. If you want, you can encrypt this chat.

 

[mygodson]

You can write me in DM here. If you want, you can encrypt this chat.

G.Pattonhow encrypt this chat

 

[mygodson]

 The by-product is methylamine mesylate，washed with water,then
can be removed

 

[w2x3f5]

The synthesis technique works, but constant problems with water, or silica gel takes part of the product.
The idea is to obtain an imine with simultaneous distillation of an azetropic mixture of IPA alcohol with water. Additionally, get rid of excess methylamine. An azeotropic mixture of IPA alcohol and water boils lower than absolute alcohol. And to dry imine add absolute alcohol, a small amount of silica gel, then borohydride.

 

[JuanoImano4378]

Introduction.​

I represent to BB audience Methamphetamine synthesis method of 1-phenyl-2-propanon (P2P) reduction by NaBH4. Following method allows obtaining and large batches of product. The hardest problem of this method is the heat generating during exothermic reaction of imine reduction. Extremely important keep temperature in described frames and keep all reagent and reaction atmosphere dry (use drying tubes with CaCl2). Also, manipulations with NaBH4 is quite dangerous and take a lot of attention because this reagent has toxic effects, reacts with water and alcohols with releasing enormous amount of hydrogen and form the corresponding borate, it may cause an explosion, burns and injuries. You have to use chemical glass, gloves, chemical coat and respirator.​

Equipment and glassware:​

• Ceramic mortar;​
• 2 L (x2), 0.5 L (x2) and 200 ml (x2) beakers;​
• 2 L (x2) and 10 L Erlenmeyer flask;​
• Measuring cylinder for 100 ml;​
• 2 L three-necked round bottom flask with plugs;​
• 2 L round bottom flask with vacuum quickfit or Schlenk flask;​
• 0.5 L Simple dropping funnel with Claisen flask and drying tube or 0.5 L equal pressure dropping funnel;​
• 1 L Separator funnel;​
• 2 L Evaporation flask;​
• Pyrex dish 0.5 L;​
• Magnetic stirrer with heating plate;​
• Retort stand and clamp for securing apparatus;​
• Silicone-oil bath;​
• Icecubes/methanol bath (-10 °C) or Mashed ice with salt (-10 °C);​
• Laboratory scale (1 g-1 kg is suitable);​
• Oven;​
• Laboratory grade thermometer (-20 °C to 200 °C) with three-necked flask adapter;​
• Aspirator;​
• HCl laboratory generator;​
• Drying tube x2;​
• Rotavap machine with water bath;​
• Filter paper.​

Reagents:​

• 138 gram P2P (1 mole) (1-phenyl-2-propanone);​
• 10% Methylamine in Methanol (w/w) - 1000 ml with 100 g MeNH2 (~3 moles);​
• Magnesium Sulfate - 36 g (MgSO4·7H2O, oven dry at 300 °C for 2h MgSO4·1H2O) [For drying MeOH/MeNH2 solution];​
• Silica Gel (3-5 mm balls) - 200 ml (dry at 300 °C/2h, they will darken!) [For absorbing 2 mol H2O during rxn];​
• 15 gram NaBH4 as a reducing agent for the formed (water-free!) imine;​
• 5-7 L distilled water + ~5 L distilled water to filling rotavap machine bath;​
• 1 L Dichloromethane (DCM);​
• 0.5 L Acetone.​

Important: the reaction is very sensitive to any water (fluid or vapour in the air!).

Note: hold all manipulations in pull out probe or under exhaust hood; methylamine is a rather toxic substance, do not let its vapors enter the respiratory tract. Using respiratory mask is required. Inhalation of methylamine causes severe skin irritation, eyes and upper respiratory tract. Firstly, leads to excitement and then to depression of the central nervous system. Death can occur from respiratory arrest.​

Procedure.​

Precursors drying.
First quickly crunch your pre-dried (oven, 300 °C, 3 hrs.) dry MgSO4 to pop corn shaped rocks in a mortar, sieve the powder out, and directly put the rocks under max. mixing in the Methanol/Methylamine mix (1000 ml) and close the pot to let no water from the air in. Keep mixing for 10 minutes, then all the water will be taken up to the MgSO4. Let stand and wait till all the MgSO4 is on the bottom. Now quickly tap off the now dry MeOH/methylamine (MA) mix in a 2 L three-necked round bottom flask and close that one. Wash directly your empty pot with lots of water, to remove the smell of methylamine, so you can safely store it.
​

Synthesis.

Now add the 200 ml (measure in beaker, neglect the free spaces) dry Silicagel beads (2-5 mm) and a magnetic mixer bar also in the 2 L flask and close again. Keep 2 L flask in Silicone-oil bath at 20 °C. Silicone-oil only slowly warms up! Do not apply heat now, it's only meant as a cooling medium in this stage. Now add slowly via a dropping funnel the 138 g P2P to the 2 L flask under strong mixing. The temperature rises to 23 °C during the (water-free) Imine forming. The water from this reaction is taken up by the dried Silicagel! This takes 30 minutes. Let, then mix for another hour. The reaction mix color changes from light yellow to coffee+milk color. Temp 23 °C.​

View attachment 2944 ​

Stop mixing after this 1 hour and pour the fluid off into a 2 L glass erlenmeyer with flat bottom and add a mixbar. The remaining Silicagel is washed 3 times with 50 ml dried (use silicagel) methanol, to catch the remaining Imine, and those 2 x 50 ml is also poured into the 2 L erlenmeyer. Now put the 2 L erlenmeier on magn.mixer, in an icecubes/methanol bath (-10 °C) (or mashed ice with salt) and start strong mixing. Put a drip funnel on top of 2 L erlenmeier, in rubber ring. Now start adding, every 5 min., a teaspoonfull (flat off!) of NaBH4 in minimum methanol, wash it from funnel with minimum methanol amount. After every spoonfull, stopper the funnel loosely with a rubber stopper. This takes 2.5 hrs. Do not exceed a temp of more than 20 °C! You can add the next spoon at ±8 °C. Solution color is light clear orange/brown. Let mix in total for 8.5 h (could perhaps be lot fewer hours).​

View attachment 2945 ​

The total volume is ~1900 ml. Add then the mix to 5 L distilled water into a 10 L flask, under magn.mixing. The pH=12. Add then 500 ml DiChloroMethane (DCM) and mix strongly for 30 min. Let oil precipitate and a dark, honey-coloured layer of DCM+oil settle onto the bottom. Decant the water part with an aspirator + siliconetube. Fill the rest (water+DCM+oil) in a seperatory funnel and tap off only the DCM+oil = 550 ml. (DCM b.p. 40 °C). The leftover MgSO4 and boro salts stayed nicely in the waterpart. Then dry the DCM+oil with some dry MgSO4 and decant in 2l erlenmeier. Wash this MgSO4 with some fresh, DRY DCM and add the DCM washings to the now dry DCM+oil. Total volume DCM+oil =1000 ml, colour is honey/red.​

Producing methamphetamine hydrochloride.

Start now bubbling this 1000 ml with HCl-gas via 2 L Schlenk flask (or round bottom flask with vacuum quickfit), while this 2 L flask stands in ice bath on magn. mixer and blends vigorously. Check pH frequently, proceed until pH 6. Pour the now acidified 1000 ml in a 2 L evaporation flask and put on Rotavap machine. Spee~100 rpm, t° = 80 °C, little vacuum=0.8 bar (water-jet aspirator is enough), to hold the flask. After distillating off nearly all the DCM, suddenly the contents of the flask turns from dark honey colour to creamy milk color, and it dries out to a round cake on the bottom. Remove the ~0.5 L DCM, now in the collector flask, and hang that empty flask on again. Now put full vacuum on to remove the last traces of water.

Cleaning by 3 x recrystallization: put minimum quantity of hot (40 °C) dry DCM (or dry 98%+ ethanol) in the flask until the last remains of the dry stuff dissolves, and add 4x this DCM-quantity in the form of dry acetone. Close with stopper and put 1 hr in freezer. A solid dirty-white crystal mass is formed with a layer of dark red fluid on top of it. Decant the fluid and repeat this step another 2x and 2 hrs. You have, the last time, snow-white crystals of racemic methamphetamine hydrochloride. Dry Weight = 141.5 g, close to quantitative yield.

Methamphetamine purification.
You can use this technique or follow next advices to produce ICE meth: melt this crystal mass in an alu flat bottom pot on a heater plate at 170-175 °C. Then let this melt, very slowly, and do not go higher than necessary to melt it, or its starts smoking (you have your first quick-test then: enjoy!). Cool down to 150 °C again, really slowly, 1 °C/30 min. (regulate with your temp controller!), and you got ICE, after you let it very slowly again cool down to room temperature (with a closed lid on it!, its hygroscopic!). Advantage: you removed all the water in this process!

You can better make the sulfate salt following logical method: Let 10% H2SO4/Ethanol mix acidifying a 1:4 mix of freebase Meth/Ethanol. This is not so hygroscopic. Filter and dry the crystals.​

G.PattonHey G.Patton, what do you mean by "minimum methanol amount"? How do you determine the minimum here?

 

[G.Patton]

Hey G.Patton, what do you mean by "minimum methanol amount"? How do you determine the minimum here?

JuanoImano4378Hi, as minimum MeOH amount as possible to dissolve NaBH4 and wash out from drip funnel