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Methylamine Synthesis

by ChemHack

The way I figure it, Hexamine is a lot less nasty (fume-wise) to make then Ammonium Chloride and just as easy.

The Hexamine and the Ammonium Chloride procedures are essentially the SAME. Adding HCl to Hexamine causes it to degrade into Ammonium Chloride and Formaldehyde and is not a nasty reaction AT ALL, just raises the temp a little bit.

If you want methylamine.hcl the easy way then follow my advice. Make your hexamine the way that you have been. Boil away all the water in a stovetop safe glass frying pan. (a Teflon pan coated regular pan will also work) This produces a buttload of nasty fumes but in my opinion the smell of ammonium is not as bad as having HCl gas in the air as you would if you just made ammonium chloride directly. You want to do it in a separate room with a window if you don't have a fume hood. The fumes of formaldehyde are worse than HCl so make sure that the solution you are boiling away has excess ammonium instead of excess formaldehyde.

Once you boil all the liquid away you will be left with white hexamine powder. Add the HCl and stir it around real good. Some heat will be evolved. Let it sit overnight and in the morning there will be a buttload of Ammonium Chloride crystals sitting in the bottom of your flask.

Rig up a large reflux device by attaching a long hose to the top of a large glass bottle. Now put the bottle in a pot and add cooking oil. If you put to much oil in then the thing will float so be careful. Now just heat the oil up until the thing starts bubbling. Turn off the heat and swirl it around. Notice how it continues bubbling even after it is no longer boiling? Tiny bubbles? That is CO2 being released.

Now heat it again and this time let it keep bubbling. Swirl it around a lot to make sure the evolved gas can get out. I like to use a big-ass hose as the "reflux" area and then stick a smaller hose through it down into the solution. Attach the smaller hose to a fish tank bubbler and let the bubbler do the stirring for you. This will also help blow the evolved CO2 out of there. To make sure your little bubbler hose wont melt or distort because of the heat, test it in boiling water first.

After a couple of hours the thing will no longer bubble when it is not boiling. The boiling point will go up from 100 to about 108. This is a good sign that the reaction is done. For 340g of hexamine I let it go 5 or 6 hours total but some of that time was just heating it up.

Oh yeah, heat and cool slowly when using a regular bottle because the glass can't take quick temperature swings when it is that hot. The last thing that you want is a bunch of nasty formaldehyde/methyamine/ammonium water boiling below a layer of hot oil!

When your heating is done allow it to slowly drop to room temperature on its own. Maybe best to just leave it overnight again. A bunch of ammonium chloride will fall out of solution again. Filter this off and set it aside for later.

Using the same frying pan, evaporate the liquid solution. Again, there will be nasty fumes. If you have boiling flasks and an aspirator you may choose to use that instead because you suck those fumes right down the drain. Personally, I don't have any 2 liter boiling flasks and I don't wanna wait to do successive smaller amounts. I just boil them away in the spare bedroom with the windows open. Go back and check often because you don't wanna boil all the water away and scorch your goodies.

At some point during the evaporation, more ammonium chloride will start to come out. Remove it from the heat and cool quickly. Then filter out the crystals and set them aside with the others.

Put it back on the heat and let it go all the way until it is mushy. It won't get completely dry but don't worry about it. Take it off the heat and it will get nice and solid. Scrape this stuff up and combine it with the other crystals. You now have a much of methylamine and ammonium chloride.

Get two large flasks with pouring spouts. Pyrex measuring cups work great. Put the crystals in the larger one. Pour a couple hundred mls of hardware store denatured alcohol in the other one and heat it to boiling in the microwave. Add the boiling alcohol to the crystals and stir like mad for a few seconds. The alcohol will probably take on a yellowish tint. The less yellow the better because that means you have fewer by-products but don't worry if it is bright yellow. You can worry if it is orange.

Pour the hot alcohol off into a separate container. Put this container in the freezer and go smoke a cigarette. When you come back to the freezer you will see magic crystals!

Keep repeating the procedure with fresh alcohol until you don't get any more crystals. Then do it one more time for good measure. The bright white crystals left in the measuring cup are ammonium chloride. Load them up in funnel with a coffee filter and pour one last bit of hot alcohol over them. Add the alcohol to the other and spread the ammonium chloride out on a plate to dry.

Now put all of the alcohol extracts (even the ones that solidified) back into your frying pan and evaporate. Be extra careful to notice when no more alcohol is coming over because it might still be slushy even though all the alcohol is gone. These are the liquidy impurities. Once all the alcohol is gone the temperature in the frying pan will go way up so pay attention!

Purification:

Once the alcohol is all gone remove it from the heat and allow it to cool down and get nice and solid again. If you have any chloroform then now is a good time to use it. It dissolves the di-methylamnine impurities but leaves the good stuff behind.

If you don't have any chloroform then pour out about 100mls of alcohol and put it in the freezer until it is very cold. Add the cold alcohol to your methylamine and impurities and stir it around real good. Not very much of the solid will dissolve but the alcohol will take up a bunch of the yellow crap leaving the crystals much lighter. Decant off the cold yellow alcohol and repeat with fresh cold alcohol until you reach the point of diminishing returns. This is the somewhat subjective point where you are starting to get more of your good stuff than yellow stuff.

With this first round you can probably go until the cold alcohol coming off the crystals is completely clear. Put these crystals in an airtight container. They are the purest ones but you can still get lots more.

Now evaporate the yellow alcohol as before. You will get a somewhat more mushy yellow product than before. Repeat the purification with fresh cold alcohol as before but this time adjust the amount of alcohol down because you have fewer crystals to purify. If you are really careful then this second batch of crystals, although much smaller, will be almost as pure as the first batch. If so then put them with the first batch. Otherwise put them in a sealed "Not-So-Pure" contianer.

You can continue the process over and over again until you are left with an orange sludge that pretty much dissolves completely in the amount of alcohol needed to get the orange liquid away from the paltry amount of powder. It is probably a waste of time to take it this far because you've already got a load of perfecty good, relatively pure methylamine.hcl.

Next time you want to make more you'e already got a bunch of ammonium chloride to start with so you can skip the hexamine step and instead add the ammonium chloride to the formaldehyde and boil from there without any HCl.


force: "I did not dry it thoroughly- it seemed to be more like paste than powder, so i mixed this with HCL..."

Well this is the reason that you never got hexamine powder. If you would have been more patient you could have dried the hexamine out into a fluffy white powder.

Adding HCl to hexamine causes it to break down into formaldehyde and ammonium chloride! When you tried to "evaporate" this mixture...well everyone knows that when you heat formaldehyde and ammonium chloride together they react leaving methylamine hydrochloride, formic acid, carbon dioxide, and garbage. If the temp goes above say 110C you will also get some di-methylamine. It is the methylamine, not the hexamine, that is soaking up water from the air and melting.

If you are intent on ruining your hexamine this way (haha) then the best thing to do is heat the hexamine/HCl mixture under reflux for a few hours until the temp reaches 110C. If you just evaporate it straight away most of the formaldehyde will escape as gas before it can react to form methylamine. Be careful with the reflux because a lot of CO2 gas will be released causing the boiling flask to bubble over. If you don't see any bubbles by the time it reaches 102C then take off the reflux apparatus and stir it briefly with a glass rod (you could use a chopstick instead.) This should get you on the way with thousands of tiny gas bubbles. The gas bubbles generally look smaller and more numerous than bubbles from simple boiling. You WANT these bubbles to come out of solution so that the CO2 doesn't stay in solution.

If you donít already have a stirring solution then one nifty way to stir it while it is refluxing is to find some small hi-temp plastic hosing that you can run down through the condenser to the bottom of the boiling flask. Connect the hose to a fish tank bubbler to force bubbles into the solution to agitate it.

Anyway, depending on the size of your batch you should expect to heat it for several hours. Stop the heating when the temp goes above 110C. If its been over 100C for 4 to 5 hours but the temp is still sitting at 108 you can stop adding heat but continue to stir. If the tiny gas bubbles are no longer coming off even when stirred by hand then it is safe to assume that you are done. One interesting thing to note is that even though the gas bubbles probably won't start to come off until you reach about 100C, once they do start you can remove the heat and they will continue to come out until the temp drops into the 80s.

When you are done heating allow the mixture to slowly come to room temperature. Lots of little white crystals will fall out of solution. They are ammonium chloride and you should filter them off and put them in a big ass jar. Then evaporate the remaining liquid on a steam bath. You really don't want to just put it in a frying pan and heat on the stove because the temp will go to high. Also, if you have an aspirator I STRONGLY recommend that you use it because there are some seriously nasty fumes that come off and it is best if they are sucked down the drain. If you do it in open air then, in my opinion, the only acceptable way to do it is in a separate room of your house with the window open and a fan blowing. The fumes will burn your eyes and lungs and I'm not kidding one bit!

Don't cheat on the drying like you did with the hexamine and it will be much easier to purify your product. As you dry it out it will reach the point where it is a little mushy at 100C but quickly hardens as it cools. Now you have a bunch of white to beige-ish yellow chunks of methylamine and ammonium chloride. Scrape this stuff up and put it in the big jar.

Go to the hardware store and buy a gallon of denatured alcohol for ~$10. Estimate the amount of alcohol that would be required to cover the crystals with about an inch of alcohol. Put this amount of alcohol in a microwave safe (pyrex) measuring cup and heat it to boiling in the microwave. Pour the boiling alcohol into the jar of crystals, replace the lid, and shake the hell out of it for a minute or two. Bright white crystals of ammonium chloride will quickly settle to the bottom. Carefully decant off the alcohol (which should still be fairly hot) into another container. The alcohol will have probably have taken on a yellowish color but it is actually good if it hasn't. Repeat the process with more boiling alcohol and add this alcohol to the first. For good measure do it one last time with about half as much alcohol. This time instead of merely decanting the alcohol, hot filter it. Sparkly crystals of ammonium chloride should be left behind in the filter cake.

Evaporate the combined alcohol extracts to leave methylamine.hcl. Make sure it is good and dry and then wash with chloroform to get rid of any di-methylamine that might be hanging around.

If there was any water in your product before you did the initial alcohol extraction then there is probably still a bit of ammonium chloride in your product. Add boiling alcohol with stirring and see if all dissolves. If it doesnít then this is the ammonium chloride that escaped with the water the first time... filter it out.

Once you get rid of all that ammonium chloride you can do a cool trick with your mehtylamine.hcl. Add just enough boiling alcohol to dissolve all of your product and then let it cool down slowly without stirring. It will crystallize into a huge chunk of fairly pure methylamine. Now put it in the freezer to reduce the solubility even more. When it is good and cold you can take it out and pour the small amount of methylamine laden alcohol into an evaporating dish. If you skipped the chloroform wash then this alcohol will contain mostly yellowish di-methylamine garbage and the solid chunk of crystals will be your clean stuff.

Points to remember:

  • Ammonium Chloride is not soluble in alcohol.
  • Methylamine.hcl is much more soluble in hot alcohol than cold.
  • Both are soluble in water. Minimizing water aids separation.
  • Methylamine.hcl is not soluble in chloroform.
  • The dimethylamine(?) impurities are more soluble in alcohol than methylamine.
  • If you read what people have written about the separation most will tell you that methylamine.hcl and ammonium chloride look different. This is really only true AFTER you separate them. In a homogenous mixture it is much more difficult to point to any particular grain and identify.
  • With a mixture of methylamine.hcl and ammonium chloride, leaving it exposed to the air results in a mushy mess.

Now for some clarifications on my previous post:

There is no reason that you need to totally dry your hexamine at the beginning except to know what your TRUE YIELD of hexamine really is. You want to know how much you actually have so that you don't add too much HCl. Any extra HCl you add will come back to haunt you if you plan on evaporating the stuff in the open air. It is easy to add too much based on the weight of the hexamine because it is capable of holding a HUGE amount of water. I evaporating to dryness the first time you make hexamine and keeping careful notes of how much formaldehyde and ammonium hydroxide was used. On subsequent runs you can use this information to more accurately estimate the amount of hexamine likely to have been produced and avoid the long wait for dryness.

"If its been over 100C for 4 to 5 hours but the temp is still sitting at 108 you can stop adding heat but continue to stir. If the tiny gas bubbles are no longer coming off even when stirred by hand then it is safe to assume that you are done."

To clarify, if you remove the heat but continue stirring and gas bubbles DO continue to come off then you are NOT yet done. Continue heating. You should be able to tell the difference between the tiny gas bubbles and the larger "boiling bubbles" without removing the heat but since the gas bubbles will continue to come off below the boiling point this is a good way to be certain.

I don't if there is an upper limit to the size of this reaction. The largest glass container for sale at my local supermarket is a 1.5 liter apple cider jar. The OceanSpray bastards have replaced all of their glass bottles with plastic ones so this cider bottle is all that is easily available to me. The cider jar easily withstands the heat if you do it slowly. Plunging a jar full of room temperature liquid into a pot of hot oil results in a cracked bottle and a nasty oil/water mess! The key is to start with everything at room temp and raise the temp slowly. Even starting at room temp, immediately cranking the power up to max results in a cracked bottle. Three feet of 1/2" inner diameter hose from the hardware store cemented into place through the lid of the bottle makes for a perfectly effective air-cooled condenser. This method makes it easy to remove the condenser for a quick manual stir to get the gas bubbles going and the tube is wide enough to run the small fish-tank bubbler hose down through the middle of it and into the liquid to provide bubble-agitation.

This setup is good for processing the hexamine from 4 packets of mildewcide with a yield of ~190g of very pure methylamine.hcl and quite a bit of unpure material that seemed like to much of a pain in the ass to recover.

Cost of materials:

  • 4 packets of mildewcide --> ~$6 (~$1.50 each)
  • Muriatic Acid --> ~$2/gallon (there will be lots left over)
  • Ammonium Hydroxide --> ~$10/gallon (lots left over)