Decomposition of multifunctionalized α-alkoxyalkyl-hydroperoxides derived from the reactions of Criegee intermediates with diols in liquid phases

• Published in: Physical chemistry chemical physics : PCCP 2022-05, Vol.24 (19), p.11562-11572
• Main Authors: Endo, Yasuyuki, Sakamoto, Yosuke, Kajii, Yoshizumi, Enami, Shinichi
• Format: Article
• Language: English
• Subjects: Adducts; Aerosols; Alcohols; Atmosphere; Atmospheric models; Butanediol; Carbonyls; Decomposition; Decomposition reactions; Diols; Fog; Hydrogen bonding; Hydrogen Peroxide; Liquid phases; Mass spectrometry; Oxidation; Phase decomposition; Reaction time; Temperature dependence; Terpineol; VOCs; Volatile organic compounds; Water; Water chemistry
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d2cp00915c

The oxidation of volatile organic compounds in the atmosphere produces organic hydroperoxides (ROOHs) that typically possess not only -OOH but also other functionalities such as -OH and -C(&z.dbd;O). Because of their high hydrophilicity and low volatility, such multifunctionalized ROOHs are expected to be taken up in atmospheric condensed phases such as aerosols and fog/cloud droplets. However, the characteristics of ROOHs that control their fates and lifetimes in liquid phases are poorly understood. Here, we report a study of the liquid-phase decomposition kinetics of multifunctionalized α-alkoxyalkyl-hydroperoxides (α-AHs) that possessed an ether, a carbonyl, a hydroperoxide, and two hydroxy groups. These ROOHs were synthesized by ozonolysis of α-terpineol in water in the presence of 1,3-propanediol, 1,4-butanediol, or 1,5-pentanediol. Their decomposition products were detected as chloride anion adducts by electrospray mass spectrometry as a function of reaction time. Experiments using H 2 18 O and D 2 O revealed that hemiacetal species were α-AH decomposition products that further transformed into other products. The result that the rate coefficients ( k ) of the decomposition of C 15 α-AHs increased exponentially from pH 5.0 to 3.9 was consistent with an H + -catalyzed decomposition mechanism. The temperature dependence of k and an Arrhenius plot yielded activation energies ( E a ) of 15.7 ± 0.8, 15.0 ± 2.4, and 15.9 ± 0.3 kcal mol −1 for the decomposition of α-AHs derived from the reaction of α-terpineol CIs with 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol, respectively. The determined E a values were compared with those of related ROOHs. We found that alkyl chain length is not a critical factor for the decomposition mechanism, whereas the presence of additional -OH groups would modulate the reaction barriers to decomposition via the formation of hydrogen-bonding with surrounding water molecules. The derived E a values for the decomposition of the multifunctionalized, terpenoid-derived α-AHs will facilitate atmospheric modeling by serving as representative values for ROOHs in atmospheric condensed phases. The ozonolysis of alpha-terpineol with C 3 -C 5 diols produced multifunctionalized ROOHs that decomposed into hemiacetals and H 2 O 2 in acidic aqueous organic media.