On February 3, 2023, a train derailed in the town of East Palestine, Ohio.^1-2 Five of the train cars were carrying vinyl chloride (Figure 1), a compound that is mostly used to make PVC.

Figure 1: Chemical structure of vinyl chloride, C₂H₃Cl

The vinyl chloride was combusted because of the accident, and also from controlled burning of vinyl chloride initiated by authorities.^1,2

Vinyl chloride is a carcinogen, and its combustion of vinyl chloride is known to release HCl, phosgene (COCl₂), and CO through a variety of pathways.³ For example, HCl can be formed through the reaction:

2 C₂H₃Cl(g) + 5 O₂(g) → 4 CO₂(g) + 2 H₂O(g) + 2 HCl(g)              Equation 1

Phosgene might be produced through the following reaction:

2 C₂H₃Cl(g) + 5 O₂(g) → COCl₂(g) + 3 CO₂(g) + 3 H₂O(g)                Equation 2

In addition, the combustion of vinyl chloride can release dioxins, which are particularly problematic.⁵

The release of these various substances likely caused various ailments reported by people close to the crash, including headaches, eye irritation, and skin rashes.^1,2 Fortunately, no one was killed, but people have reported that chickens, fish, and even a dog died.

I discussed these issues with students in my chemistry classes, introducing them to the chemical equations that could describe the formation of HCl and COCl₂ from vinyl chloride combustion (Equations 1 and 2). I also used diffusion of HCl(g) from concentrated HCl(aq) to illustrate how gas phase HCl could have potentially impacted people and animals close to the crash site. All these experiments were conducted in the HOOD (Video 1).

Video 1: Train Derailment Chemistry, Tommy Technetium YouTube Channel (accessed Feb. 28, 2023)

Have you discussed some of the chemistry involved in the recent train accident in Ohio? If so, what kinds of topics did you and your students explore? I’d love to hear any thoughts you might have on how to incorporate this issue into your chemistry classes.

References:

1. https://cen.acs.org/safety/Safety-questions-remain-Ohio-train/101/i6
2. https://cen.acs.org/safety/Ohio-train-derailment-raises-questions/101/web/2023/02
3. O’Mara, M. M.; Crider, L. B.; Daniel, R. L. Combustion Products from Vinyl Chloride Monomer. Amer. Ind. Hyg. Assoc. J. 1971, 32, 153-156.
4. Lutrell, W. E.; Sheaman, L. G. Vinyl chloride. Journal of Chemical Health & Safety, 2012, 19, 30-31.
5. https://news.cornell.edu/media-relations/tip-sheets/vinyl-chloride-highly-mobile-soils-and-water-east-palestine-area-farmers

Preview image: Drone footage shows the freight train derailment in East Palestine, Ohio, U.S., February 6, 2023 in this screengrab obtained from a handout video released by the NTSB. NTSBGov/Handout via REUTERS