The science of Breaking Bad: Sunset

Breaking Bad : Season 3 : Episode 6 : “Sunset”

Walt and Jesse make a mortal enemy out of Hank.

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.

You can read more about this episode at AMC, IMDb and the A.V. Club.

Random thoughts

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

Quinic acid

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.

Preparation of phenylacetone from phenylacetic acid and acetic acid

Benzene

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.

Diethyl ether

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

Breaking	Bromine
Bad	Barium
Created	Chromium
Bryan Cranston	Bromine
AnNa Gunn	Sodium
AAron Paul	Argon
DeaN Norris	Nitrogen
Betsy Brandt	Beryllium
RJ MitTe	Tellurium
BOb Odenkirk	Oxygen
Giancarlo Esposito	Einsteinium
David Costabile	Cobalt
Michael ShAmus Wiles	Americium
MAtt Jones	Astatine
Tom KiEsche	Einsteinium
Larry Hankin	Lanthanum
Luis Moncada	Lutetium
Daniel Moncada	Molybdenum
KelleY Dixon	Yttrium
Mark FreeboRn	Radon
MiChael Slovis	Carbon
Dave Porter	Polonium
Sharon Bialy	Sulfur
SherrY Thomas	Yttrium
Diane MerCer	Cerium
Moira Walley-Beckett	Molybdenum
Thomas SchnAuz	Gold
George Mastras	Germanium
PeTer Gould	Tellurium
Sam Catlin	Calcium
John ShiBan	Barium
Melissa Bernstein	Beryllium
MicHelle MacLaren	Helium
Mark JOhnson	Oxygen
StewArt A. Lyons	Argon
John Shiban	Sulfur
Vince Gilligan	Vanadium