# Catalytic hydrogenation FAQ



## G.Patton (Jun 12, 2022)

*Introduction*​Hydrogenation is a chemical process which involves introducing elemental hydrogen gas (H2) to a liquid solution containing a catalyst. The catalyst latches onto the H atoms then gives them up, to bond with the molecules in solution. Coincidentally, this process can be utilized in the manufacture of drugs like Amphetamine, Methamphetamine and other substances, which are produced from nitro-compounds via reduction.​*Catalyst*​The catalyst consists of a metal in powder form which has been sifted into a buffer like Carbon, it is all very fine powder, black and nasty, shouldn't be inhaled and gets all over everything if you're not careful, leaving your fingerprints for all to see. Catalysts come in different concentrations. For example: 10% Palladium on Carbon would be 90% carbon and 10% Palladium by mass, and is expressed: <10% Pd/C>. This procedure describes the use of Pd/C as the catalyst. Other catalysts are used in hydrogenation, such as PtO2. The catalyst is always settled and filtered out after the process, it is then washed with distilled water, dried, and is reusable up to around 20 times. With this in mind, it's not too expensive.​





PtO2 and Pd/C​
*Hydrogen gas*​The hydrogen is supplied from a pressure tank. A fresh Hydrogen tank contains extreme pressure. For this reason, a pressure regulator is required, fitting a simple valve to the tank is potentially catastrophic. Even pressuring a Parr shaker requires a regulated or low pressure feed.

A regulator for a cutting torch is the obvious and best choice. You have to use the regulator and gauge set from the oxygen side of the torch set-up, since it is designed for high pressures. Once you have used a regulator and hoses for hydrogen, NEVER use them for anything else, hydrogen is absorbed into materials and this limits their safe usage with other gases. Smaller gas containers can be obtained from scientific supply houses, they are referred to as 'those little tank things' or 'watchamacallits' and may require different hook-ups. I am unfamiliar with these, but I'm sure it's all worked out.

I guess everyone knows that Hindenburgers are char-broiled, or is at least familiar with ledZeppellin album covers...hydrogen is very flammable, doggone explosive, even.

Hydrogen lines have configurations of two types: fixed hose or detachable hose.​*Fixed hose configuration:*​


*Detatchable hose configuration:*​


*Important:* other than the regulator, there are no brass fittings allowed here. This prevents production of weird cupric toxins. Stainless or specialized plastic, teflon, etc. must be utilized. Hose must be psi rated and neoprene is best.​*Pressure reaction vessel*​Where the gas and liquid get together with the catalyst. It must be able to contain (for our purposes) 60 psi (4.14 barr), capable of a gas supply hose connection, and an access opening at least the size of a quarter; silver dollar or larger is better, any opening larger than 4" and I would do a lot of dry run pressure testing before using, to make sure it will hold.

Stainless Steel is the only thing I would use. Examples of SS containers which are easily converted: Stove top milk steamer devices as used at home. Cappuccino synthesis as well as some types of stove top espresso makers. They have cool little SS valves already configured in. Soda fountain equipment. For larger batches, or mandatory life sentence quantities, the refillable containers that soda fountain syrup comes in are excellent (they're about 6 gals/22 L), also the tank on the CO2 maker. These systems are phasing out right now commercially, and components are surplus everywhere. You have to be able to wire or clamp a stopper and design a hose barb that won't pop out, and guess at the psi capacity. There is Sci-glass spec'ed for this.​

​Chemical resistant polymer constructed pump garden sprayers aren't bad and almost ready to go like they are. Come in all sizes, psi rated.

Very economical, I always worry about polymers in the presence of benzene, diethyl ether, etc., but haven't actually had any bad experiences. Polymer gasoline containers are also used, but hose connection takes some doing, not preferred.​*Shaker*​The Pressure Reaction Vessel is fastened to this mechanical device. Imagine a paint shaker. The paint can is your pressure reaction vessel. That's it. There are as many home hydrogenator designs as there are ambitious speedfreaks. In deciding on, or tweaking out your own shaker device, there are a few things you should know.

As mentioned, the contents of your reaction vessel are a liquid solution, which is flammable, and a solid catalyst in powder form. The catalyst is potentially EXPLOSIVE. Into this, you are preparing to pump in HYDROGEN and shake it?!! Proper understanding of handling the catalyst is required. The catalyst is dangerous when dry and floating around in the air like dust, especially around oxygen. Keeping the catalyst wet throughout the entire procedure is key to survival. This is also why the Pressure reaction Martini is 'shaken, not stirred'. Those of you who have utilized mechanical or magnetic stirs, know that the liquid occasionally sloshes up pretty high on the inside of the vessel, the catalyst could easily slosh up there, dry out, then dust...you know the rest. With an effective shaker, the whole inside of the vessel is constantly washed with solution so this cannot happen. Therefore, this is the minimum level of activity required to prevent incident. Shakers also create the most desirable exposure of catalyst surface area to the gas, increasing efficiency and uniformity of the reaction.​*Here are some approaches to shaker devices.*​*Straightforward approach *- Go out and buy a paint shaker, then design a reaction vessel to fit it. (fixed or detachable hose config.)

*Bizarre approach* - The Milwaukee Skateboard-> You will need: A variable speed SAWZALL, a skateboard, a C-clamp, four 1x4's 12" long, A workbench with a sturdy vice, electricity. Place the body of a Sawzall in a vice so that it is parallel to the bench and turned sideways, put two blades in the Sawzall by stacking them (short blades). C-clamp the blade tips to the stern of the skateboard, which rides on the benchtop. Nail the 1x4's together so as to imitate two lengths of angle iron, each a foot long. Lay the wooden angle pieces on the bench on the port and starboard sides of the skateboard and parallel and not so snugly so as to prevent travel. Tack them to the bench. You now have a little bobsledTunnel sortaThing for the skateboard to run back and forth within. Attach the reaction vessel (a cylinder) to the skateboard by laying down on it's side and duct taping it on. Set the sawzall speed, then use the trigger lock. (detachable hose config.)

*The aerobic approach* - Fasten a rope to the pressure vessel, hang it from the ceiling, shake it back & forth by hand on the dangle...tiring, need partner for shift work, not recommended. (fixed or detachable hose config.)

*The high dollar approach* - Buy a Parr shaker. For about three grand. I held on to one of these for an ex-partner/friend who took a mandatory retirement in Folsum for 3 to 5...and had some occasion to try it out. They're bulletproof, precision machined, over built. These are designed for mini-yield experimentation, not production. The model I'm familiar with had a meager 1L capacity yet weighed approx 200 lbs (90 kg) and took up 42"x27" of floor space. The bottle clamp was not tweakable to greater capacity...the motor was NOT sparkless, the exhaust valve seat was way too small and clogged with catalyst every single time. Before returning it to the owner, I had to change all the bolts from carbon to stainless myself, after minimal acidic exposure rusted them out. Totally unimpressed. (fixed hose config.)​

​*Bathtub sailorman approach* - I thought this one up myself, it is fairly intuitive, so I'm sure others have too. Buy a bunch of those suction cup rubber mats and stick them on the sides and bottom of a bathtub. Fill the tub. After pressuring the reaction vessel, detach the hose, orient the cylindrical vessel horizontally, float it, then spin it, rocking end to end slightly.(detachable hose config.)

*Standard hydrogenation methodology*
1. First combine ingredients of reaction mixture in a safe container.
2. In a separate beaker, carefully add dry catalyst, then moisten with a non-reactive solvent, Hexane is common.
3. Introduce 1/3rd reaction mixture to catalyst 'paste', stir briskly, quickly transfer to pressure vessel. Repeat. Repeat. Pressure vessel
should never exceed 2/3rds full to allow for slosh About.
4. Seal pressure container, a fix hydrogen feed line, and pressurize container to 40 psi (2.76 bar). Now realign valves and release the pressure into a
safe exhaust. This is called 'purging', and is done three times.
5. Now pressurize to 60 psi (4.14 bar), cut off H feed then shake (or spin)
6. Continuously monitor the pressure gauge and when the pressure within the vessel falls below 20 psi (1.38 bar), re-pressurize to 60 psi (4.14 bar). When uptake of hydrogen ceases (after 3x's is average) reaction is finished.
7. Remove pressure vessel from shaker and orient in a vertical position, let rest about 15 minutes, then slowly release pressure into safe exhaust...it is not unusual for the contents of the container to aerosol out with the gas resulting in loss of product and temper, for this reason, I recommend you design a simple liquid trap (aspirator) which is a fixed along the exhaust line at this point.​*Troubleshooting*​The hydrogen is not being taken up.​
Not using enough catalyst, check recipe.​
Catalyst is old or no good.​
Your recipe is no good, or you've goofed the chemistry.​
Have you cut off hydrogen feed b-4 shaking as mentioned in step 5?​
Your psi gauge is malfunctioning or is fouled with catalyst.​
Line or valve is fouled with catalyst.​
The hydrogen is endlessly being taken up.​
You have a leak!​
*Filtering catalyst from reaction mixture*​Methanol is used as a solvent/carrier in this description, appropriate substitution where necessary. Combine contents of aspirator and pressure container into a glass vessel which can be stoppered. Rinse containers with methanol and add. The holding vessel should then be filled to the top with methanol to purge the air and prevent any weird oxidation catastrophes, then stoppered.

Let sit for half day until Pd/C settles out. Carefully suction out the reaction mixture without disturbing Pd/C sedimentation. To increase yield, refill container with methanol and repeat last step. Now, filter the solution until it is free of catalyst, adding more methanol to carry solution through filter cake as necessary. Vacuum or distill off Methanol leaving product. Wash catalyst w/ distilled H2O and air dry for re-use.​
*Catalytic hydrogenation MDP2P to MDMA*​If the clandestine chemist would make MDMA, he would use a low-pressure stainless-steel autoclave with 1/3-1/4 space for the Hydrogen gas, a mixer motor on top and the shaft made leakproof by a mechanical seal to stand 5.0 bar pressure and about 0.5 bar vacuum. In a large freezer, he should cool the big steel cylinder of methylamine gas as it condenses to a liquid (b.p. -6°C), and he should lift the cylinder with a (takel zoals gebruikt in garages) in a near horizontal position just till above the fridge. With a flexible stainless steel hose is the cylinder connected to the autoclave, between the sealing and the lift he would make a scale to be able to weigh the amount of gas he should use.

*Difficulty rating:* 7/10​
*Equipment and glassware:*​
Vacuum source;
Vacuum and pressure manometers;
HCl gas producing apparatus;
5 L Reaction autoclave;
Whatman no 401 filtering paper;
Laboratory grade thermometer (10 °C to 200 °C);
Distillation apparatus with vacuum;
Buchner flask and funnel [Schott filter may be used for small quantities].
*Reagents:*​
1500 ml MDP2P;
1000 ml Methanol;
1100 ml (990 g) anhydrous liquid MeNH2 (b.p. -6 °C);
10 g Platinum(IV)oxide (Adam's Catalyst);
HCl gas;
7-8 L Diethyl ether.

When those chemicals are in the autoclave, he will evacuate the autoclave to a vacuum of approx. 0.5 bar to get rid of the oxygen. Then he should open the hydrogen bottle for a short moment till approx. 1.0 bar, and then evacuate a second time to be absolute sure all the oxygen is out.​

​He should then start the mixer motor (brush-less type in case of a hydrogen leak) and then he should pressurize with hydrogen to approx. 3.5 bar. By adjusting the pressure between 2.5-4.0 bar, he could keep the temp. around 50 °C and never higher than 60 °C. After 2 hours the temp will possibly go down, to control the uptake of the hydrogen gas he should close the bottle and watch for a period of 10 minutes if the pressure in the autoclave gets lower. In that case, open up the hydrogen bottle for a few minutes more and otherwise the reaction is stopped, and he could after a couple of hours drains the autoclave. He should use a Buchner filter on a vacuum bottle with Whatman no 401 filtering paper, he expects that other type of filters makes this filtering of the Platinum powder an endless job. He would then distill off the MeOH, the MeNH2 and the water at atmosphere pressure. He then changes the receiving flask and at about 150-160 °C at 20 mm Hg vacuum the MDMA freebase oil will come over in approximately *90% yield* (depends on the purity of the MDP2P).​

For making the MDMA hydrochloride crystals, he bubbles dry HCl gas through a solution of 1000 mL freebase in 7-8 L chilled (4 °C) diethyl ether, and filters off the precipitated crystals to get 1100 g MDMA hydrochloride after drying.​
Note that this reaction is not possible to perform with 40% aqueous methylamine.



> *Hydrogen gas (H2) generators*​*Hydrogen gas (H2) laboratory preparation*


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## PepitoPistol

Great post!

How about using an aluminum fire extinguisher, with PtO2?


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## G.Patton

PepitoPistol said:


> Great post!
> 
> How about using an aluminum fire extinguisher, with PtO2?



PepitoPistolYes, I've seen this method as well. Nice idea.


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## PepitoPistol

Two more things:
- How about using ammonia instead of methylamine, and ethanol instead of methanol, same procedure and quantities would apply, right?
- What should be the shaker frequency?


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## G.Patton

PepitoPistol said:


> ammonia instead of methylamine, and ethanol instead of methanol



PepitoPistolDo you want to obtain MDA? Probably yes.


PepitoPistol said:


> quantities


You have to count in molar equivalent 


PepitoPistol said:


> - What should be the shaker frequency?


Medium 
Honestly, it is not so important. I mean that you have to use not so fast shaking, maybe 40-50 shake per minute (i'm not sure).


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