Large-Scale Methamphetamine Manufacture

3.5 Reductive amination of P2P using Adam's catalyst

While the catalyst is pre-reducing, the chemist must prepare a Schiff's base from his P2P and methylamine solution.
For a 1-mole test batch using 1g of catalyst, one pours 150ml of 37-40% methylamine solution into a 1000ml beaker along with a stirring bar. With stirring, 134g(1mole) of 1-phenyl-2-propanone is added. This should be done inside the fume cabinet to avoid the strong smell of decaying fish that accompanies methylamine solutions. Cover the beaker with a clean shop rag while stirring continues. In a separate container, measure out 250ml of 95% ethanol. 95% ethanol can be purchased as very strong vodka under various brand names (Everclear?), but my favorite source of ethanol is found in almost every supermarket and drugstore. It is called Rubbing Alcohol Compound. This is very different from Rubbing Alcohol, which is the trade name for isopropyl alcohol. Rubbing Alcohol Compound has replaced isopropyl alcohol on grocery shelves because the ethanol subsidies provided by the feds allow the use of cheap subsidized ethanol instead of the more expensive isopropyl alcohol. Rubbing Alcohol Compound is 93% ethanol along with 2% ethyl acetate or some other denaturant that makes you sick if you drink it. Fortunately, the denaturants do not affect our reaction and now one has an inexpensive source of reaction solvent upon which no liquor taxes are paid. This writer has tried every brand available in my area and they all worked just fine. In a serious pinch, the chemist can use methanol instead of ethanol, although the reaction will take three times as long to complete with a similar yield. When the catalyst is ready, slowly add, with stirring, enough ethanol to clarify the solution. This should take about 125ml for a 1-mole batch, leaving 125ml to use in retrieving the catalyst from the pre-reduction vessel. Add the clarified P2P/methylamine solution to the reaction vessel and rinse the beaker with a dash of ethanol, adding the rinse to the reaction. One should now have a reaction vessel containing 20ml of water, 250ml of ethanol, 150ml of methylamine solution, and 135ml of P2P for a total volume of about 550ml. Keep this number in mind when designing a larger reaction vessel. Seal the reaction vessel, pull a 25" vacuum using a water aspirator, pressurize to 5psi with hydrogen, pull another 25" vacuum, and then pressurize to 25-30psi with hydrogen. Do not pull a vacuum harder than 25"Hg or the methylamine will boil off. Check for leaks. If no leaks are found, begin the agitation by turning up the stirring to full blast.
Agitation is important because it creates surface area. For the reaction to take place, the catalyst, a molecule of our Schiff's base, and an atom of hydrogen must come into contact simultaneously. Since we are dealing with solid, liquid, and gas phase materials, this can be difficult. The splash, or agitation, is the single most important physical variable affecting this reaction. The more surface area one can create, the better the chances are of our three reactants meeting and making meth.
At this point, one would like to know if the reaction is proceeding correctly and at what rate so one knows when the reaction is done. Our pressure/vacuum gauge along with our gas valve will provide this information. Once the reaction vessel is pressurized to 30psi, close the hydrogen valve and begin the agitation; the reading on the pressure gauge should drop over a short period of time. In my test vessel, a pressure drop of 10psi occurs in 11-16 minutes, depending upon how good the agitation is. Yours may be different. Once the pressure has dropped 10psi, open the hydrogen valve again and re-pressurize to 30psi. By precisely recording the amount of time it takes to cause a pressure drop of 10psi, the chemist can tell whether the reaction is proceeding or stopped for some reason, how well (quickly) the reaction is going, and when it is done. This can be vital information if something is going wrong. Typically, a 1-mole reaction in this writer's test vessel will use a 10psi gulp of hydrogen every 13 minutes for 10 gulps, and then begin to slow down as the reaction begins to have difficulty finding unused reactants. A total of 18 10psi gulps of hydrogen are required to complete a 1-mole batch in my test vessel. The last hydrogen gulp takes well over an hour to finish, with a total elapsed time of about 4-6 hours to complete the reaction. Using a known volume and pressure, one can calculate how many pressure drops it will take to use up a mole of hydrogen.

With the reaction done, the chemist pours the reaction solution into a 1000ml beaker and rinses the vessel out with a little ethanol, adding the rinse to the beaker. One must now remove the catalyst before processing. This is accomplished by using a small(2") Buchner along with Qualitative 5 filter paper and filtering into a 1000ml filter flask. Capture the remaining particles of catalyst in the beaker with ethanol. At this point, the chemist must be on his toes because the catalyst in the Buchner will catch the alcohol on fire if it is not quickly quenched. This is done by pouring a layer of distilled water over the catalyst and allowing the vacuum suction to pull it through, taking the alcohol with it.
One must always keep in mind that this catalyst is very pyrophoric, meaning it will burst into flames or explode at the slightest provocation. Things one should never do with this catalyst at any time, but especially once it has been pre- reduced, are; 1) allow it to fall freely through the air for more than a few inches, 2) allow it to come into intimate contact with flammable solvents such as ethanol, methanol, etc., and, 3) expose it to open flame. We have forced hydrogen atoms into the lattice structure of the platinum dioxide crystals, and that hydrogen reacts with oxygen both in the air and the platinum dioxide (reducing it over time to platinum), and this reaction creates heat which will catch things on fire. A static charge of sufficient intensity, such as that picked up when falling freely through dry air, will cause the catalyst to explode, although not with an intensity that will damage anything but one's dignity.

Now that the catalyst is removed, pour the filtrate into a 1000ml round-bottom (RB) flask and distill the ethanol and methylamine off until the temperature reaches 90-92°C. Turn off the heat, attach an empty receiving vessel, then slowly apply a vacuum by gradually closing the bleeder valve on the water-aspirator system. When the temperature has dropped and the vacuum is down to 28-29"Hg, turn on the heat again and vacuum distill off the residual water until the condenser is clear, which will occur between 50-60°C. Remove the heat and allow the remaining meth base to cool a little. With fresh boiling stones and a clean receiver that has been weighed, reapply the vacuum and distill the meth base over a 10°C range. Adjust the vacuum using the bleeder valve so that the meth base distills over at 95-105°C. Meth base is a clear, colorless liquid. If it is anything but clear and colorless, it contains contaminants. The accompanying picture shows the result of a 6.5 mole batch, which produces about 900g of meth base.
A one-mole batch of P2P with 100% conversion would result in 149g (one mole) of methamphetamine base, but the typical yield is 90-93%, resulting in 134-140g of base. Meth base will quickly react with carbon dioxide in the air to form the carbonate, so it is advisable to crystallize the base as soon as possible. Crystallization is performed by adding 450g(3 moles) of meth base to a 1000ml Pyrex beaker and placing the beaker on a stirring hotplate. Carefully drop in a Teflon- coated stirring bar and begin stirring. One now adds 37% hydrochloric acid in 15ml portions. A graduated 15ml test-tube makes an ideal dispenser. A great deal of heat is generated as the acid reacts with the meth base and will result in boiling if added too quickly. Add 15ml of acid at intervals of 1 minute until 19 portions (285ml) have been added, then add acid in smaller portions and watch the color carefully. If the meth base was clean to begin with, it will turn light pink when the pH reaches 3-4. Test with pH strips(Colorphast 0-14 strips) or a meter. Stop adding acid when the pH reaches 3.

Now we must boil off the water contained in the acid, as water solvates meth very efficiently. Turn the heat on the hotplate to 4.5 while stirring continues and place a thermometer that reaches 150°C into the beaker on the bottom. Over the next 1.5 hours, the temperature will climb to 110°C where boiling begins, then gradually rise as the water is boiled off. When the temperature reaches 130°C, turn off the heat and remove the thermometer. Using a dishtowel, grip the beaker with both hands and quickly pour it into a 5000ml plastic bucket containing 4.5 liters of acetone which has been frozen for 2 weeks. Retrieve the stir-bar with a chaser, replace the lid and return to the deep freeze for 1 week to allow complete crystallization. Clean, freshly distilled acetone will retain about ¼ lb of product the first time it is used, which is why one should recycle one's acetone. Alternatively, one can pour the hot methamphetamine hydrochloride into a 5-gal plastic bucket containing 4.5-gal of acetone that has been frozen for about a month (it takes a long time to pull the heat out of a large mass). The meth will crystallize the instant it hits the frozen acetone, although about 25% will remain in the acetone and must be frozen to crystallize.

Paradoxically, dirty meth crystallizes better than pure meth because the crystals quickly grow around a particle of impurity, forming nice large, hard crystals. The meth crystals are filtered out using a large Buchner, two 4000ml filter flasks, and a high-volume vacuum aspirator. An 18cm porcelain Buchner will hold a little over 1 lb of filtered product. Do not use Qualitative 5 filter paper for this filtration. This writer has found that the filters used in milk processing equipment are ideal for meth harvesting. A lot of money has been spent by the dairy industry over the years figuring out how to quickly filter solids out of mixed-phase solutions. These filters will allow liquids, both water and oils, to pass freely while trapping the finest solids, making them ideal for rapid filtering. The problem with the fine paper filters is that oil-water mixtures plug them up very quickly. Milk filters do not have this problem and they are easy to find, cheap, and suspicionless. One will need to cut-to-fit, but this is a small inconvenience. A suitable high-volume filtering setup can be easily made using 5 and 20-liter buckets, a round plastic plate, and some glue. This writer was fortunate enough to discover a large Buchner being used as a planter by a nice lady in my neighborhood. Happily paying the lady for a replacement, the retrieved treasure holds over 2lb of product and makes the chemist's life much easier. The point is that one can find useful equipment almost anywhere. Pure meth is more difficult to crystallize, and results in a light, flaky white product with a mild scent of marzipan (actually benzaldehyde). Empty the product into a large cake tray and let the acetone evaporate in the fume cabinet for a day or two, separating it as it dries.
This product may be cut with powdered niacinamide (vitamin B3) at a 4:1 ratio (20% cut) to make a product that burns clean and is water-soluble. Do not use vitamin B-3 tablets which contain insoluble buffers that burn dirty.