Reuters sheds a new light on the Druzhba contamination case:
The substance that brought one of Russia’s longest oil pipelines to a halt in April was carbon tetrachloride, a lethal chemical meant to be tightly controlled by an international agreement, according to the results of three separate, undisclosed tests seen by Reuters.
“Lethal” sounds a couple of notches too strong for CCl4. Once it was a common dry cleaning agent and fire extinguisher liquid. All the four chloromethanes have been used as solvents. All are toxic to some degree but CCl4 appears to be the most toxic of them and, worse, is both an ozone-depleting substance and (as vapor) a greenhouse gas. It’s no longer produced on a large scale thanks to the so-called Montreal Protocol of 1987, which Russia has ratified. Actual compliance is a different issue:
…[F]our oil traders… told Reuters they regularly obtain carbon tetrachloride to bulk up more expensive bona fide oil products.
The traders… said producers of the chemical often give it away or even pay third parties to take it away, making it lucrative to mix with oil and sell the resulting mixture on at a profit.
Back in May, it was reported that the contaminant was a chloroethane, namely 1,1- or 1,2-dichloroethane, C2H4Cl2. But since it is “at least ten times more expensive than crude oil,” according to Vitaly Yermakov at the OIES, what would anyone gain by mixing it with crude? Now we seem to have the answer. It’s a different compound and can be obtained for free.
On the other hand, it’s non-combustible… Update. That’s the problem with CCl4: a spark won’t inflame it at street temperature but once it’s heated to 250-300C, it reacts with O2 in the air to form phosgene, a highly poisonous gas.