I wasn't sure what section is best for this.

2,3-dimethyl-2,3-dinitrobutane. Used as a marking/tagging agent in explosives such as C-4, at a level of 0.1 to 0.5%.

Now, what if someone added the material to a bomb, constucted from any old explosive you choose? Would the use of a high-grade military RDX-based plastique such as C4 or Semtex be suspected, turning investigation more towards those with access to such materials, rather than an individual with synthesised RDX, AN or whatever your tastes run to?

I found a synth, i don't quite follow where the Br comes from though,

The following low-cost one-pound process developed by ARDEC may be used to scale-up the synthesis to the 100 pound scale to yield low cost DMNB with a purity of at leasst 98.00 weight percent. A) Preparation of 2-Bromo-2-nitropropane = 2-Nitropropane (commercial, 97% 2-NP; impurities; nitroethane and 1-nitropropane; 450.0g, 5.0 moles) was added in 30 minutes to a stirred solution of sodium hydroxide (220.0g, 5.5 moles) in water 2.5 liters) at 0-5 degrees C. The reaction solution was stored at 0-5 degrees C for 30 minutes and then brought to room temperature. After 30 minutes the lower layer, 2-bromo-2-nitropropane (829.9g, 98.8% yield), was separated. The crude 2-bromo-2-nitropropane contains small amounts of bromonitroethanes and bromo-1-nitropropanes but is quite satisfactory for preparation of 2,3-dimethyl-2,3-dinitrobutane without any purification. B) Preparation of 2,3 dimethyl-2,3-dinitrobutane from Sodium 2-propanenitronate and 2-Bromo-2-nitropropane = A mixture of 2-nitropropane (90.0g, 1.0 mole) and sodium hydroxide (56.0g, 1.4 mole) in methanol (500 ml) was stirred at room temperature for 30 minutes and then brought to reflux. 2-Bromo-2-nitropropane (168.0g, 1.0 mole) was added in 15 minutes. The reaction mixture was refluxed 24 hours and cooled to room temperature. The solid present, 2,3-dimethyl-2,3- dinitrobutane and sodium bromide, was filtered. Methanol and water were removed from the filtrate by reduced pressure distillation to yield a solid concentrate. The reaction solids were combined, stirred with cold water (250 ml), and filtered. The filtered solid was rinsed with cold methanol (150 ml) to give white 2,3-dimethyl- 2,3-dinitrobutane (140.6g, 79.0% yield), mp 209-210 degrees C. Evaporation of the methanol washings gave a yellow solid which was washed with water, filtered, and recrystallized to yield additional 2,3-dimethyl-2,3-dinitrobutane (2.70g, 2.5% yield) mp 202-210 degrees C. The total yield of white 2,3-dimethyl-2,3-dinitrobutane is 80.5%. When the above reaction is conducted on a 5 mole scale, addition of 2-bromo-2-nitropropane (840g, 5 moles) to 2-nitropropane (450g, 5 moles) and sodium hydroxide (280g, 7.0 moles) in refluxing methanol (2.5L) alleviates much of the problem in agitation. It is not yet known what volumes of solvent will be needed for effective agitation and satisfactory efficiencies on larger scale reactions. Secondly, on the larger scale reactions, washing the crude 2,3-dimethyl-2,3-dinitrobutane on a filter pad or plate with cold methanol is not satisfactory for removing all of the colored by-products from the desired material. The methanol passes over the solid product too quickly to wash out all of the surface impurities in the 2,3-dimethyl-2,3-dinitrobutane. Stirring the colored 2,3-dimetyl-2,3-dinitrobutane with cold ethanol in the initial reactor equipment improves the product greatly and lowers the overall yield to about 75%.

If I understand correctly, you're suggesting that adding the taggant 2,3-dimethyl-2,3-dinitrobutane to some explosive other than C4 would mislead investigators into thinking an explosion had been caused by C4 rather than the explosive actually used. What would be the point?

In the first place, specific taggants/markers are only incorporated in explosives manufactured by "official" makers, whereas improvised explosives would not ordinarily contain them. However, it isn't primarily on the presence of these taggants that the type of explosive used in a bombing is determined, they look at chemical residues left by the explosive itself as well as the type of damage. Thus, while it might be possible to mislead investigators into thinking that an explosion was caused by military C4 instead of an identical homemade version, it's naive at least to think that adding a "C4 taggant" to a batch of something else would mislead them at all.

Slightly OT, but I've wondered how long it'll take before some terrorist or prankster figures out that "salting" a secure area like a major airport with a substance known to trigger explosives detection equipment would cause almost as much chaos as an actual explosive device. To give one example, in the case of TNT, easy-to-make mononitrotoluene is the substance actually detected by explosives sniffers, so a giant slurpy cup of the stuff dropped in a parking lot or at a main entrance would ultimately contaminate the whole terminal (and everyone in it along with their baggage) thereby rendering detection equipment useless not to mention creating absolute bedlam. Similarly, if a gallon or so were sloshed across a roadway just upstream from a vehicle screening checkpoint where sniffers and/or bomb-detecting dogs were being used, it would paralyze the whole operation. Talk about pushbutton gridlock!

According to news reports, the new "airblast" sniffer/screeners are now being installed at hub airports across the country. There's likely to be plenty of bureaucratic egg-on-the-face trying to justify the billions they've already spent on systems so piss-easy to spoof or disable. Oh well, at least our security fixation is creating new jobs!

Yes, it would only be practical with DIY C4 or some similar RDX based comp, i really don't know what i was going on about before.