Rate Constants for the Gas-Phase Reactions of the OH Radical with Selected Carbamates and Lactates

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• 作者：Eric S. C. Kwok ; Sara M. Aschmann ; and Roger Atkinson
• 刊名：Environmental Science & Technology
• 出版年：1996
• 出版时间：January 1996
• 年：1996
• 卷：30
• 期：1
• 页码：329 - 334
• 全文大小：312K
• 年卷期：v.30,no.1(January 1996)
• ISSN：1520-5851

文摘

Using a relative rate method, rate constants havebeen measured for the gas-phase reactions of the volatilecarbamates CH₃NHC(O)OCH₃,CH₃NHC(O)OCH₂CH₃,CH₃CH₂NHC(O)OCH₃andCH₃CH₂NHC(O)OCH₂CH₃andthe lactatesCH₃CH(OH)C(O)OCH₃, andCH₃CH(OH)C(O)OCH₂CH₃ with the OH radical at 296± 2 K of (in unitsof 10^-12 cm³molecule^-1 s^-1) 4.3± 1.2, 8.3 ± 2.2,10.5 ± 2.9, 14.4 ± 3.7, 2.8 ± 0.8, and 3.9 ± 1.1,respectively,where the error limits include the estimated overalluncertainties in the rate constants for the referencecompounds. Rate constants were also measuredfor the reactions of the carbamates with NO₃radicalsand O₃, with respective NO₃ radical andO₃ reactionrate constants (in cm³ molecule^-1s^-1 units) ofCH₃NHC(O)OCH₃, (8.5 ± 3.2) ×10^-16 and <4 ×10^-20; CH₃NHC(O)OCH₂CH₃, (9.4 ± 3.5) ×10^-16 and <4 ×10^-20;CH₃CH₂NHC(O)OCH₃,(1.8 ± 0.8) × 10^-15 and <6×10^-20; andCH₃CH₂NHC(O)OCH₂CH₃,(2.6 ± 1.3) × 10^-15and <3 × 10^-20. The OH radicalreaction rateconstants for the carbamates have been used to extenda previously developed estimation method to carbamates of the structureR₁NHC(O)OR₂ (whereR₁ andR₂ are alkyl groups only), allowing OH radicalreactionrate constants and hence tropospheric lifetimes tobe calculated for carbamates used in agriculture forwhich experimental data are not available.