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Environmental fate & pathways

Phototransformation in air

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Description of key information

t1/2 = 9.8 hours or 0.82 days (12h daylight) at 298 K

Key value for chemical safety assessment

Half-life in air:
0.82 d

Additional information

Wallington (1991) investigated the atmospheric fate of diethyl ether, particularly by reaction with hydroxyl radicals, after concluding that rates of photolysis, and reaction with ozone and NO3 radicals, were negligibly slow. The experimentally identified degradation products, after hydroxyl radical attack, were primarily ethyl formate (92 ±6%) with some formaldehyde.

The reaction rate of the hydroxyl radical with diethyl ether was experimentally determined by Atkinson (1989) to be kOH = 1.33x10^-11 cm3/molecule/s. Other reported values vary by about 10% (Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, Vol. III, Oxygen Containing Compounds, 2nd Ed., 2006, CRC Press, p2267 - 8).

Using the equations and default hydroxyl concentration values (Atkinson, R., etal, Environ. Sci. Technol., 1990, 24, 1326 - 1332) presented in AOPWIN v1.92 (US EPA, EPISuite, v4.0), the half-life in the troposphere can be estimated:

t1/2 = 0.693 / kOH . [OH], where kOH = 1.33x10^-11 cm3/molecule/s and [OH] = 1.5x10^6 radicals/cm3/12h daylight.

t1/2 = 0.693 / 1.33x10^-11 . 1.5x10^6

t1/2 = 9.8 hours or 0.82 days (12h daylight) at 298 K

AOPWIN was not used itself for the above half-life calculation (although the result is the essentially the same: t1/2 = 10.4 h), because it's primary use is as a QSAR for the generation of unknown reaction rate constants. As an experimental value is available, this was used instead.

The available experimental data and calculated half-life indicate rapid hydroxyl-radical degradation of diethyl ether in the atmosphere, to form ethyl formate.