Rate constants for the gas‐phase reactions of O3 with a series of monoterpenes and related compounds at 296 ± 2 K

Abstract

Rate constants for the gas‐phase reactions of O 3 with a series of monoterpenes and related compounds have been determined at 296 ± 2 K and 740 torr total pressure of air or O 2 using a combination of absolute and relative rate techniques. Good agreement between the absolute and relative rate data was observed, and the rate constants obtained (in units of 10−17 cm 3 molecule−1 s−1) were: α‐pinene, 8.7; β‐pinene, 1.5; Δ 3‐carene, 3.8; 2‐carene, 24; sabinene, 8.8; d‐limonene, 21; γ‐terpinene, 14; terpinolene, 140; α‐phellandrene, 190; α‐terpinene, 870; myrcene, 49; trans‐ocimene, 56; p‐cymene, <0.005; and 1,8‐cineole, <0.015. While these rate constants for α‐ and β‐pinene and sabinene are in good agreement with recent absolute and relative rate determinations, those for the other monoterpenes are generally lower than the literature data by factors of ca. 2–10. The measured rate constants for the monoterpenes are reasonably consistent with predictions based upon the number and positions of the substituent groups around the 〉CC〈 bond(s).