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Environmental fate & pathways

Phototransformation in air

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Description of key information

- Phototransformation in air: k = (1.5 +/- 0.4) x 10 -11 cm3 molecule-1 s-1 (sensitizer: OH radical).
- Tropospheric lifetime estimated to be 20 hours - no estimate of half-life available.
- Transformation proucts: diacetone alcohol, acetone, and peroxyacetyl nitrate.
- Estimated photochemical ozone creation potential (POCP) reported to be 47 (ethylene = 100).
- Expected to be oxidised at the local or regional scale.

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Additional information

The OH-initiated oxidation of hexylene glycol was studied in 2 photoreactors: a 140 L Teflon bag irradiated by lamps at CNRS-Orléans and the 200 m3 European photoreactor, EUPHORE, irradiated by sunlight. The OH-initiated oxidation of hexylene glycol resulted in the formation of diacetone alcohol, acetone, and peroxyacetyl nitrate (PAN), and the estimated photochemical ozone creation potential (POCP) of hexylene glycol was reported to be 47 (POCP ethylene = 100).

The rate constant for the reaction of hexylene glycol with OH was measured relative to 4 reference substances of known photolysis, and determined to be k = (1.5 +/- 0.4) x 10-11cm3molecule-1s-1. From this, the tropospheric lifetime was estimated to be 20 hours, assuming [OH] = 10-6molecules cm-3 - no estimate of half-life available. Hexylene glycol is expected to be oxidised at the local or regional scale.