Phenylacetone | |
|---|---|
| IUPAC name | 1-phenylpropan-2-one |
| Other names | benzyl methyl ketone; methyl benzyl ketone; phenyl-2-propanone; Phenylacetone 1-phenylpropan-2-one, 1-Phenyl-2-propanone, Cas 103-79-7, Benzyl methyl ketone, Methyl benzyl ketone, Phenyl-2-propanone, 1-Phenylacetone, 2-Propanone, 1-phenyl-3-Phenyl-2-propanone, Phenylmethyl methyl ketone, phenyl acetone, 1-phenyl-propan-2-one, NSC 9827 |
| Identifiers | |
| CAS number | 103-79-7 |
| Properties | |
| Density | 1.006 g/mL |
| Melting point | −15 °C |
| Boiling point | 214 — 216 °C |
Phenylacetone, sometimes abbreviated P2P is an organic compound. It is a clear oil with a refractive index of 1.5168. This chemical is used in the manufacture of methamphetamine and amphetamine. Due to the illicit uses in clandestine chemistry, it was made a controlled substance in 1979.
Preparation
There are many methods in the scientific literature to prepare Phenylacetone, and due to its controlled nature there is crossover into popular literature such as works by Uncle Fester and Alexander Shulgin. Not surprisingly there is also a fair amount of data available on the Internet relating to the preparation of phenylacetone.
A conceptually simple, although low-yielding, example of phenylacetone organic synthesis is the Friedel-Crafts alkylation of benzene with chloroacetone. The reaction is low yielding because the monoalkylation product is activated towards additional substitution at the ortho and para positions.
Phenylacetone can also be produced from many other chemicals. For example, phenylacetic acid is distilled with lead acetate to yield phenylacetone. Another is, benzaldehyde is reacted with nitroethane yielding phenyl-2-nitropropene, which is reduced, usually in the presence of acid, to phenylacetone.
Standard Synthesis
In the original variation, (S)-pseudoephedrine is extracted from decongestant. This involves the use of different organic solvents at various stages. It is key that the pure isomer (S)-pseudoephedrine, the diastereomer of (R)-ephedrine, is extracted. This is further converted by reduction (e.g. by the traditional way involving iodine and red phosphorus, as shown in Breaking Bad) into (S)-N-methylamphetamine.
Blue-Meth Synthesis
A possible alternative route is based on phenyl acetic acid and acetic acid, e.g., acetic acid anhydride, and leads initially to phenyl acetone through reduction with supported thorium oxide, from thorium nitrate, as catalyst in a tube furnace [11]. This synthesis route is probably that followed by Walter and Jesse and is very demanding, not least due to the preparation of radioactive thorium.
There then follows the reaction of phenyl acetone with methylamine and the subsequent reduction of the resulting N-methylimine. These two steps can take place as a multistep or one-pot reaction. Mercury aluminium amalgam can be used as catalyst for the reduction, as discussed by Walter and Jesse. Episode (IV-1), however, only shows how aluminium granulate is added to the reactor. Sodium amalgam or lithium aluminium hydride would also be possible catalysts