Methyl chavicol reactions with ozone, OH and NO3 radicals: Rate constants and gas-phase products

Abstract

The rate constants for methyl chavicol reactions with OH and NO3 radicals and O3 have been measured using the relative rate method at (298 ± 1) K and atmospheric pressure. The constants are kmethylchavicol+OH=(5.20±0.78)×10−11cm3molecule−1s−1, kmethylchavicol+NO3=(3.58±0.67)×10−14cm3molecule−1s−1 and kmethylchavicol+O3=(1.03±0.23)×10−17cm3molecule−1s−1. To more clearly understand the main atmospheric degradation mechanism of methyl chavicol, the products of the methyl chavicol + OH reaction were also investigated by thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS). The identified products were 4-methoxytoluene, 4-methoxybenzaldehyde, 4-methoxy benzene acetaldehyde and 4-methoxybenzeneacetic acid. A possible formation mechanism for the main products is also proposed. The results indicate that methyl chavicol could have an impact on atmospheric chemistry at the regional scale and could also contribute to the production of secondary organic aerosol.