Large-Scale Methamphetamine Manufacture

2.0 Manufacture of Platinum Dioxide

2.1 Discussion

As those familiar with clandestine drug manufacture are aware, the traditional catalysts used in reductive amination procedures, Raney nickel and palladium-on-carbon, are no longer available due to essential-chemical prohibition by the anti-drug thugs. Thus the need for an alternative catalyst which can be manufactured utilizing common materials and equipment. Platinum dioxide has many advantages in it's application to reductive aminations:
It can be made using common materials and easily obtainable equipment.
Reactions are performed at room temperature and at low pressure (<30 psi), thus eliminating the requirement for simultaneous heating and agitation and opening the door to simple high-volume manufacturing. One can easily perform 25-30 mole reactions using a 5 gallon paint shaker for agitation.

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  The catalyst is reusable up to six times.
  
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  Requires a catalyst density of only 1g/mole of precursor.
  
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  Provides a product yield of approximately 1kg/g of catalyst, and a 75% mole-to-mole yield from precursor-to-product (the reaction yield is 90%, the balance being lost during processing and crystallization) when manufacturing methamphetamine.
  
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  Is used with common ethanol solvent, eliminating odd smells and fire hazards.
  
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  Platinum dioxide catalyst also performs well in the manufacture of methylenedioxymethamphetamine (MDMA), but under slightly different conditions.
  

2.2 Review of alternative procedures

We will focus upon the manufacture of methamphetamine due to the current high volume requirement and the increasing attention it is drawing from the government antidrug machine.

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  The best route for manufacturing methamphetamine is the direct reduction of the hydroxyl on the L-ephedrine sulfate sidechain in glacial acetic acid using 70% perchloric acid as a promoter and 5% palladium-on-carbon as the catalyst. Vigorous agitation, pressurization with hydrogen to 30 psi, and heating to 90°C results in an 85-90% yield of non-racemic methamphetamine, with a 70% yield-to-product. Due to it's non-racemic chirality, this meth is stronger than that produced by any other non-stereospecific reduction technique. Typically, this reaction is performed in a 4000ml filter flask placed into a 6 gal aluminum pot containing water. The pot is heated on a stirring hotplate and agitation is provided by a stirring bar magnetically coupled through the non-ferrous aluminum. A solution of 1.25 liters of glacial acetic acid, 120ml of 68-72% perchloric acid, 166g (one mole) of L-ephedrine sulfate, and 16g of 5% palladium-on-carbon is pressurized to 20-30psi with hydrogen gas and reduced for 2-3 hours. The catalyst is filtered out, the filtrate made basic with 50% lye solution then extracted with toluene and stripped of solvent, the base is purified by distillation and crystallized in acetone for the hydrochloride salt. Despite what has been written by others, this reaction does not work with ephedrine hydrochloride because the hydrochloride ion poisons the catalyst, whereas the sulfate ion may actually act as a promoter (I have not tried it, but in theory sulfuric acid may be substituted for perchloric acid as a promoter). This reaction will, however, perform well using any ephedrine base. Due to the requirement for simultaneous heating, stirring, and pressurization, this reaction is limited to 1-3 mole batches. In addition, the palladium-on-carbon catalyst is not reusable without processing.
  
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  The most common current method of meth production is the direct reduction of the ephedrine hydrochloride hydroxyl using 57% hydriodic acid and red phosphorous in a 4-1-1 formula (4 lb ephedrine, 1 gal 57% hydriodic acid, 1 lb red phosphorous). This is an inefficient method, yielding 55% d-methamphetamine at the very best, which has been exploited as far as it can go due to the attention paid to the precursor and essential chemicals used in this reaction and the increasing diversion of Chinese ephedrine supplies to our industrious neighbors in Mexico. In it's favor, however, is the fact that one person can manufacture 4 lb of very poisonous meth per day if they skip the purification step. This is a perfect example of Gresham's Law at work (the cheap bad stuff drives out the expensive good stuff).
  
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  The P2P reaction, for many years the preferred method for making methamphetamine, requires 1-Phenyl-2-Propanone (impossible to buy, easy to make), 40% methylamine solution (impossible to buy, easy to make), large amounts of Raney nickel (hard to buy, difficult to make) and approximately 2000 psi of hydrogen along with simultaneous agitation and heating. There are many limitations in this process, not least of which is equipment construction. [This is a very limited truth, as there are many other ways of reductively aminate P2P with methylamine which uses much more readily available materials than Raney-Nickel/hydrogen gas /Rhodium]
  
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  The lithium-in-ammonia reduction. This is an elegant, high-yield reduction, but it is gawdawful stinky and must be done a long way from civilization. The volume of anhydrous ammonia required per mole of ephedrine relegates this procedure to the low-volume category.