Large-Scale Methamphetamine Manufacture

4.4 Reduction of 1-phenyl-2-nitropropene to 1-phenyl-2-propanone

4.4.1 Equipment construction

This procedure is the most difficult described. Not because the reaction is difficult to perform, but because of the equipment one must build in order to make it workable. The problem is one of scale; A two-mole reduction can be performed in 5000ml glassware using a heating mantle and standard stirring equipment. To reduce a 20-mole batch requires ten times the volume, 50 liters, a controllable heat source, and scaled-up stirring equipment. Additionally, we will perform a steam-distillation in order to extract and purify the final product, which will require a large condenser. We will want this condenser to also operate in the reflux mode during the reaction in order to keep the acid from boiling off and killing everything. To make matters worse, we will be working with 15 liters of muriatic acid, which means everything must be made of stainless-steel. Fortunately, this equipment is neither difficult nor expensive to construct. One needs to either own and be proficient with a TIG welder or find a shop that can do the work. If one must use shops, spread the work around. They will all ask what it's for-simply tell them that you have a non-disclosure agreement and would lose your job or contract if you told them. Or make up your own story.

Our reaction vessel will be a 50-liter stainless stock-pot found at the kitchen/restaurant supply. It must be stainless, and not aluminum. High-quality stainless pots have aluminum-clad bottoms for better heat transfer-this is good. They will all be fabricated of thin-wall stainless, but look for the most heavy-duty pot you can find. This pot is the weak point in our equipment because the boiling hydrochloric acid will eat through the wall of the pot in 5-7 reactions, after which a new pot must be purchased.
In order to seal the pot, a flange must be welded onto the pot rim and provision made for attaching and sealing a top. This is done by carefully measuring the diameter of the pot rim and fabricating a flange to fit. We will be using a 3/16" polypropylene "O" ring for a seal and a series of bolts on the outside to accomplish the sealing and attaching. The ring should be about 2" wide, with the bolts(3/8" stainless hardware) on the outside and a 1/16" x 3/16" groove machined into the flange face about ¾" from the inside rim. Polypropylene O-ring material can be found at most good hydraulics shops and machine shops. We will be using 1/8" diameter or 3/16" diameter O-ring material, whichever is available. Buy enough for several rings, as they wear out. Our flange must also be flat to within 1/16" so the top isn't warped. Do not weld the flange to the pot until the top-plate has been fabricated.
We also have a requirement for knowing the temperature of the reaction at all times. In order to do this, one must either weld a stainless bushing into the side of the pot that fits an industrial thermometer or create a fitting in the top through which one can insert a thermometer long enough to reach the reaction solution. Good luck finding a thermometer that long. This writer chose the bushing-in-the-side method with mixed results-the temperature indication worked great but the boiling acid eats the thermometers and the bushing weld creates a weak point which the acid attacks and eats through after only three reactions. Covering the weld completely with fast-drying J-B Weld after each use doubled the lifespan of the pot to six reactions. I'm sure someone out there can think of something better. A Teflon- coated pot would be nice.
Now that we have the beginnings of a reaction vessel, we will need a heat source. Fortunately, one can find propane- powered barbeques almost anywhere, including the heavy-duty one pictured, which is more than adequate. A 30lb propane tank is good for about three reactions.

Now we must design our top-plate, which is fairly complex. The first step is to have a matching circle of 3/16" thick stainless-steel cut and drilled to fit the flange so they can be bolted together. Next, we must provide for a Teflon bearing in the middle. This writer designed a bearing machined from 3" Teflon round stock. Since the gearmotor used to turn the stirrer has a ½" driveshaft, the bearing consisted of a ½" hole in the middle and a ¾" wide outside shoulder machined down to ½" depth. This results in a ½" thick bushing wall, which has held up without problem. Using these dimensions, a center-hole of 1.5" diameter and four 10-32 threaded holes on the outside rim are required. It is advisable to have the Teflon bushing machined first and then fitted to the top. A shaft clearance of 0.003-5 works well. Unfortunately, one must know the diameter of the motor driveshaft in order to design the bearing. Many motors have 5/8" driveshafts which will operate perfectly with the above bushing design by simply enlarging the center hole, leaving a 3/8" bushing wall. The stirring shaft should be standard 316 stainless round stock with a flat machined at one end to make attaching the vanes easy.
The importance of vigorous stirring cannot be overemphasized. If too much iron remains on the bottom, it can cause a runaway reaction, which you will regret. To avoid this, keep the iron in suspension and the reactants moving. This writer has determined experimentally that about 150 rpm is a good speed for stirring, but this can vary depending upon the effectiveness of the stirring vanes. The vanes on the reaction vessel shown were a simple plate welded onto the bottom of the shaft, insuring that it did not contact the thermometer shaft inserted through the pot wall.
Now that we have a bearing and driveshaft, we must design a bracket that will hold our gearmotor firmly in line with the bearing and driveshaft. The picture above shows the gearmotor without the bracket, as the unit has been disassembled for storage. The reader will be left to his own devices in this bracket design since there is little chance that your gearmotor will be exactly like mine. Since there are two more attachments which must be placed on the top cover, one should locate an adequate gearmotor early on in the design and then wait until the end to fit the motor and bracket. The motor should have a shaft speed of about 150 rpm and a torque of 32 inch-pounds or better, keeping in mind that the more reaction mixture being turned, the more torque is required.
A 2" stainless nipple must be welded to the top plate to accommodate the condenser and it's fittings. In addition, a threaded ¼" hole must be placed in a location near the outside of the top plate. A ¼" NPT stainless nipple screws in here and is attached to 5/16 Tygon tubing leading to the acid reservoir. This is where the acid enters the reaction vessel.

The condenser and its fittings are fairly straightforward. Four 5' sections of ½" thinwall stainless tubing are grouped within a 2" diameter circle and welded into a flat flange with outside boltholes. Use ½" bolts for strength and a thick rubber gasket. The outside waterjacket is 4" thinwall truck exhaust tubing which is light and cheap. It is fitted with ¼ " NPT bushings at each end for water circulation. It is sealed at the end with another flange, leaving 6-9" of tubing sticking out the end. The waterjacket should be 4' long. Use dishwasher hoses found at the hardware store that have ¼" NPT thread on one end and hose thread on the other for circulating water through the system. The condenser will need to be supported with chains due to it's weight when full of water. In order to use the condenser in both distillation and reflux modes, another flange must be fabricated which can be moved around in combination with standard pipe fittings. A combination of 2" stainless "T" , a 2" plug, and a 6" long nipple with an angled flange of about 20°C on the end worked well for this writer. The adapter flange must mate well with the condenser flange to avoid leaks.

The following diagrams show how the condenser is configured for both distillation and reflux modes:
A container to hold and dispense the muriatic acid is required. This writer uses a small(5gal) plastic garbage can with a Tygon tubing siphon hole drilled just above the acid line. A 1/8" stainless-steel flow valve is required to control the flow of acid into the reaction. These valves may be found at industrial supply houses like W.W. Grainger, etc. One should use only Tygon tubing as most other types will soon harden and crack.

4.4.2 Iron Reduction of 1-phenyl-2-nitropropene to 1-phenyl-2-propanone

Pour 15 liters of clean tap water into the vessel. Follow this with 4000g of catalytic iron, 3400g (20mol) of 1-phenyl- 2-nitropropene and 40-50g of ferric chloride. Assemble the top with the condenser in the reflux mode, start the water running through the condenser, begin stirring, and fire up the propane burner. Watch the thermometer and turn off the heat when the temperature reaches 90°C. Slowly add muriatic acid in small doses over a 2-hour period. Watch the top of the condenser for signs things are getting out of hand. This reaction needs to be performed in a small shed or other outbuilding with good ventilation. Install a heavy-duty (500+cfm) exhaust fan in the shed. The reason for this is that the fumes from this reaction are very corrosive and if the reaction goes into runaway, one will want to abandon the shed for awhile as the fumes clear out. A total of 15 liters of muriatic acid is added. Once all of the acid has been added, allow the stirring to continue for another 2 hours before going on to the next step.
We now must extract our P2P from the nasty black mess inside the reaction vessel. We will do this through steam distillation. Disconnect the condenser, flange, and "Tee", leaving the 2" nipple open. The stirrer should remain turning. Next, quickly pour in about 4 liters of saturated lye solution that has cooled off overnight. Some heat and steam will be generated as the lye neutralizes the muriatic acid. Assemble the Tee, flange, and condenser in the distillation mode and start the water flowing through the condenser. Place a 20 liter bucket under the end and fire up the propane burner to high. Discontinue stirring. Distill over the water and P2P until the bucket is full, then turn off the heat.
The yield for this reduction is 75% no matter how badly one thinks he has blown it, so we should expect to obtain 15 moles, or a little over 2000g of P2P. Since P2P has a density close to that of water, this works out to about 2 liters of product.
We must now extract the P2P from the water, purify it, and store it for later use. This is accomplished by pouring 3000ml of water/P2P into each of two 4000ml separatory funnel. One then adds about 300ml of saturated lye solution to each and shakes vigorously for 3-5 minutes. This is done to insure there is no residual acid which can, and will, poison the catalyst when used. After a thorough shaking, 400ml of methylene chloride is added to each separatory funnel and shaken vigorously for 2-3 minutes. Methylene chloride is an easily obtainable solvent for most plastics. Check the plastics supply shops that sell buckets, sheet plastic, etc. Since methylene chloride is heavier than water, it will pick up the P2P and carry it to the bottom of the sep funnel. This takes some time, however, so one must not get in a hurry. This writer allows the separation to sit for 6 hours before draining the bottom layer into a one-gallon wine bottle, or even better, an amber glass bottle. Cut a square out of a plastic baggie and use it for a seal between the bottle-top and the cap. Add another 400ml of methylene chloride, shake vigorously, and let it settle out again for 6 hours before draining. This is good enough, go on to the next batch. When finished, one should have 3-4 gallons of methylene chloride/P2P solution.

We will now recover our methylene chloride solvent for reuse and distill the P2P. Use a 5000ml round-bottom vessel and distill over the methylene chloride from 39 to 60°C. Return the solvent to it's container and continue until there is only about 2000ml of P2P left in the vessel. Add boiling stones and vacuum distill over the remnants of the methylene chloride and water until it is clear that only P2P is left. Using a clean receiver and fresh boiling stones, distill over the P2P at 105-115°C. Do not distill at a temperature lower than 105°C or the P2P will carry contaminants over with it, the contaminants being darker colored. P2P is a clear, pale-yellow liquid that smells like cat piss. P2P will auto- oxidize over a period of weeks if left at room temperature, so put it in the freezer until ready for use.
One can use toluene to extract the P2P from the water, but it must be vacuum-distilled and the separation will be to the top instead of the bottom like methylene chloride. It takes about the same amount of time to separate as when using methylene chloride.

4.4.3 Alternative reduction procedure

For those unable or unwilling to construct the admittedly large number of mechanical items described above, there is an alternative reduction procedure that the reader may or may not find more convenient. This reduction, gleaned from Dr. Alexander Shulgin's wonderful book PIKHAL, uses glacial acetic acid instead of muriatic acid to create hydrogen by reacting with catalytic iron. It also cleans up with water and eliminates the steam distillation step used above. The downside is that, as described, it takes a much larger volume of acid to reduce an equivalent amount of nitropropene. It may be possible to reduce the amount of acid required, and I leave it those interested to develop it further.
Place a 1000ml Pyrex beaker into a pan of water and rest this on a hotplate. Add 140ml of glacial acetic acid and 32g of 80-100 mesh catalytic iron. Heat to about 85°C, just below the point where white salts begin to appear, then add 10-15g of 1-phenyl-2-nitropropene crystals dissolved in 75ml of glacial acetic acid. Add slowly, allowing a vigorous reaction free from excessive frothing. Continue heating for 1.5 hours after the addition. The surface will crust up, turn whitish, and climb the walls of the beaker. Remove from heat, mix into 2000ml of clean water. Add enough concentrated lye solution to neutralize the acid, then extract with methylene chloride and distill exactly as above. One can scale this up by using a bucket made from polypropylene (try Chevron Delo 400 oil buckets). These tough buckets will stand up to 100°C temperatures without deforming. Or one can use a stainless pot either plain or Teflon coated. Glacial acetic acid has a strong vinegar smell which disperses rapidly when heated, making for an odor problem hard to disguise. But since there is no power required, one can do this in the woods somewhere. This procedure was designed by Dr. Shulgin to reduce the nitrostyrene associated with MDMA, so it can be used for both Meth and Ecstasy if one can find a supply of piperonal. The reader will find that most of the procedures described herein apply to the manufacture of both products. This writer has tried this procedure with excellent results, obtaining a 75% yield of a very pure and colorless P2P.