NEW RATE CONSTANTS FOR 10 OH ALKANE REACTIONS FROM 300 TO 400 K - AN ASSESSMENT OF ACCURACY

OH alkane reactions play a central role in atmospheric and combustion chemistry, and accurate modeling requires accurate knowledge of their rate constants over a wide temperature range. We present data for 10 O H radical - alkane reactions over the temperature range 300-400 K and then combine our data with other literature data to find optimally est imated Arrhenius parameters using a modified Arrhenius form consistent with transition state theory. This modified form explicitly accounts for the loose modes in the transition state that cause curvature in Ar rhenius plots. It thus fits data over a wide temperature range in a re alistic manner, allowing precise comparison of data sets covering diff erent temperature ranges. By comparing our data with other published d ata, we establish that most of these rate constants are now known to b etter than 5% accuracy over the 300-400 K temperature range.