Isoprene nitrates: preparation, separation, identification, yields, and atmospheric chemistry 1Department of Chemistry, Purdue University, 560 Oval Dr. West Lafayette, IN 47907, USA
2Department of Earth and Atmospheric Sciences, Purdue University, 560 Oval Dr. West Lafayette, IN 47907, USA
*currently at: Clarion University of PA, Dept. of Chemistry and Biochemistry, 840 Wood St., Clarion, PA 16214, USA
Received: 08 April 2010 – Published in Atmos. Chem. Phys. Discuss.: 22 April 2010 Abstract. Isoprene is an important atmospheric volatile organic compound involved in
ozone production and NOx (NO+NO2) sequestration and transport.
Isoprene reaction with OH in the presence of NO can form either isoprene
hydroxy nitrates ("isoprene nitrates") or convert NO to NO2 which can
photolyze to form ozone. While it has been shown that isoprene nitrate
production can represent an important sink for NOx in forest impacted
environments, there is little experimental knowledge of the relative
importance of the individual isoprene nitrate isomers, each of which has a
different fate and reactivity. In this work, we have identified the 8
individual isomers and determined their total and individual production
yields. The overall yield of isoprene nitrates at atmospheric pressure and
295 K was found to be 0.070(+0.025/−0.015). Three isomers, representing
nitrates resulting from OH addition to a terminal carbon, represent 90%
of the total IN yield. We also determined the ozone rate constants for three
of the isomers, and have calculated their atmospheric lifetimes, which range
from ~1–2 h, making their oxidation products likely more important
as atmospheric organic nitrates and sinks for nitrogen.
Revised: 24 June 2010 – Accepted: 25 June 2010 – Published: 08 July 2010
Citation: Lockwood, A. L., Shepson, P. B., Fiddler, M. N., and Alaghmand, M.: Isoprene nitrates: preparation, separation, identification, yields, and atmospheric chemistry, Atmos. Chem. Phys., 10, 6169-6178, doi:10.5194/acp-10-6169-2010, 2010.