Breaking Bad : Season 3 : Episode 6 : “Sunset”
Just as the super-lab begins production of the Best Meth Ever, the RV lab finally meets its end. Also, watch out for Hank turning into the Incredible Hulk sometime soon. In this post, I’ll be talking about Gale’s coffee and the large-scale cooking process.
Gale’s comment about no added toxins or adulterants refers to a common issue with buying drugs on the street – as there is no quality control or dealer trustworthiness to speak of, what you’re buying could be mixed with just about anything (this practice is generally referred to as cutting).
Gale’s coffee house
Gale’s perfect coffee equipment looks to be a fairly overcomplicated vacuum reflux/distillation set-up, which is not currently under vacuum (there is no pump running, and a reflux condenser is not sealed into its flask). His quinic acid theory, however, is sound – it is known to contribute to the bitterness/acidity of coffee, but there are many other contributing factors.
Boiling a chemical under a mild vacuum is a common method of distilling or refluxing without strong heating, especially for things like water that have a relatively high boiling point. For the water to boil at 92 °C, the pressure would have to be about 0.75 bar (normal atmospheric pressure is 1 bar), which is roughly equivalent to an elevation of 2440 m, which can be experienced at the summit of El Capitan.
The bromance montage
During Walt and Gale’s first co-cooking session in the industrial-scale lab, we can see lots of shiny and hard-to-identify equipment and a few cute exchanges between the pair (in reality, one’s lab partners are rarely so easy to get along with). We begin with some serious pestle and mortar grinding – these are as common in the laboratory as they are in the kitchen, but are normally only used for small amounts of material (once procedures get scaled up, machines not unlike coffee or flour grinders are used). Aluminium foil still plays a part, which means that even Gus has difficulty getting hold of pseudoephedrine.
The shot where Walt adds drops of a red liquid to various test tubes looks like some kind of quality control stage, perhaps to measure pH or the concentration of some intermediate chemical (despite their ubiquity in the public image of science, test tubes aren’t used very much in the laboratory). Similarly, when Gale hands Walt a small, thin glass tube (called a capillary tube) it is almost certainly for use in thin layer chromatography (TLC) – a common technique used to check the progress of a reaction. In TLC, a small (typically 8 cm x 4 cm) piece of thick foil (usually aluminium) is coated with a thin layer of silica (around 0.2 mm). The sample is added as a small dot (using the capillary tube) around 1 cm from the bottom edge, and the entire piece is placed vertically in a jar containing a small amount of solvent. The solvent rises up the silica layer, carrying the sample with it. Different components of the sample will move at different rates, and hence separate out over time. By taking samples over the course of a reaction, it is possible to see quite quickly when the various reactants and products are used up or created, and hence when to stop or change the conditions.
Gale’s curiosity about the phenylacetic acid addition rate (a possible ploy to steal Walt’s secrets before throwing him to the Cousins) prompts Walt to talk about synthesis efficiency. Recall from A No-Rough-Stuff-Type Deal that the “blue meth” process converts phenylacetic acid, which is partially soluble in water, into phenylacetone, which is insoluble in water. If the reaction vessel contains both aqueous and organic components, then it will form two distinct non-mixing layers (i.e. oil and water). Phenylacetic acid will be present in the aqueous layer, and when phenylacetone is formed it will migrate into the organic layer – the organic layer can then be drawn off, neatly separating the product from any water-soluble chemicals.
The problem with this is that phenylacetic acid will also be partially soluble in the organic layer (due to the non-polar benzene ring), so any unreacted acid will end up in the product and complicate later reaction steps. If the aqueous layer is made “oilier”, then phenylacetic acid will be more soluble in it and will be less likely to contaminate the product (though how reducing the amount of acid makes this happen is not clear). Gale mentions “benzene extraction” – benzene is almost insoluble in water, and would naturally be present in the organic layer with the phenylacetone – but even if the aqueous phase is made oilier, any benzene should still prefer the organic phase. Gale may simply be referring to the benzene (or phenyl) group in phenylacetic acid, or there could be a benzene-producing side-reaction that our chemists want to avoid.
When Walt says that he “prefers ether”, he is probably referring to diethyl ether – a common laboratory solvent often used for liquid-liquid extractions (generally called solvent extractions). Diethyl ether forms an organic layer above an aqueous layer, so Walt could have been mooting it as a potential solvent for the reaction if phenylacetic acid turned out to be less soluble in it than whatever solvent they were currently using. Interestingly, solvent extraction with diethyl ether is also used to produce freebase cocaine.
Elements in the credits
|Michael ShAmus Wiles||Americium|
|StewArt A. Lyons||Argon|