Theoretical and Experimental Study on the Reaction of tert-Butylamine with OH Radicals in the Atmosphere

Abstract

The OH-initiated atmospheric degradation of tert-butylamine (tBA), (CH)CNH, was investigated in a detailed quantum chemistry study and in laboratory experiments at the European Photoreactor (EUPHORE) in Spain. The reaction was found to mainly proceed via hydrogen abstraction from the amino group, which in the presence of nitrogen oxides (NO ), generates tert-butylnitramine, (CH)CNHNO, and acetone as the main reaction products. Acetone is formed via the reaction of tert-butylnitrosamine, (CH)CNHNO, and/or its isomer tert-butylhydroxydiazene, (CH)CN═NOH, with OH radicals, which yield nitrous oxide (NO) and the (CH)Ċ radical. The latter is converted to acetone and formaldehyde. Minor predicted and observed reaction products include formaldehyde, 2-methylpropene, acetamide and propan-2-imine. The reaction in the EUPHORE chamber was accompanied by strong particle formation which was induced by an acid-base reaction between photochemically formed nitric acid and the reagent amine. The tert-butylaminium nitrate salt was found to be of low volatility, with a vapor pressure of 5.1 × 10 Pa at 298 K. The rate of reaction between tert-butylamine and OH radicals was measured to be 8.4 (±1.7) × 10 cm molecule s at 305 ± 2 K and 1015 ± 1 hPa.

Atmospheric Chemistry of 2-Amino-2-methyl-1-propanol: A Theoretical and Experimental Study of the OH-Initiated Degradation under Simulated Atmospheric Conditions

“…The OH reaction with the related compound, tert -butylamine ( t BA), was previously examined in both M062X and MP2 calculations. 19 In addition, improved single point energies were obtained in the CCSD(T*)-F12a calculations. In general, the results of the t BA + OH reaction obtained in M062X, CCSD(T*)-F12a//M062X, and CCSD(T*)-F12a//MP2 agreed within 2 kJ mol –1 when the aug-cc-pVTZ basis set was employed.…”

“…The major product in atmospheric AMP photo-oxidation is predicted to be CH 3 C(NH 2 )(CH 3 )CHO. Experimental room-temperature rate coefficients for OH reactions with the substituted 2-methylpropanes (CH 3 ) 3 CCH 2 OH ( k OH = 5.2 × 10 –12 cm 3 molecule –1 s –1 ), 46 (CH 3 ) 3 CCHO ( k OH = 2.7 × 10 –11 cm 3 molecule –1 s –1 ), 47 and (CH 3 ) 3 CNH 2 ( k OH = 8.4 × 10 –12 19 and 1.2 × 10 –11 48 cm 3 molecule –1 s –1 ) show the −CHO group being around 5 times more reactive than the −CH 2 OH group and that there is no simple structure–activity model for substituted amines (note that the −CH 2 OH group is the proton donor in AMP, whereas the −NH 2 group is the proton donor in CH 3 C(NH 2 )(CH 3 )CHO). In any case, CH 3 C(NH 2 )(CH 3 )CHO is expected to react around twice as fast with OH radicals as AMP does and that H abstraction from −CHO and −NH 2 will be the dominant pathways Δ H ⊖ = −125: Δ H ⊖ = −72: …”

Airborne measurements of particulate organic matter by PTR-MS: a pilot study

“…aminium sulfates (or as aminium nitrates). Volatile amines may also be released as gases which rapidly form particles in the atmosphere via acid-base reactions with nitric and sulfuric acid (Tan et al, 2018). To the best of our knowledge, this is the first time that aminium particles have been detected in the atmosphere downwind of an industrial facility and not directly at the stack.…”

Realtime measurement of phase partitioning of organic compounds using a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer coupled to a CHARON inlet

“…Another potential advantage of CHARON-PTR-ToF-MS is that the chemical information of the collected particles can be studied qualitatively and quantitatively over a chemical composition level even at sub-nanogram mass concentrations per molecule owing to the well studied ion-molecule reaction chemistry in PTR-ToF-MS (Piel et al, 2019). CHARON has shown promising potential in the realtime analysis of the chemical composition and spatiotemporal distributions of aerosols with laboratory-, ground-, and aircraft-based platforms (Piel et al, 2019;Tan et al, 2018;Gkatzelis et al, 2018a;Gkatzelis et al, 2018b;Muller et al, 2017;Eichler et al, 2017;Eichler et al, 2015;Antonsen et al, 2017;Leglise et al, 2019;Piel et al, 2021). As a relatively new technique, the use of CHARON-PTR-ToF-MS to investigate the gas-particle partitioning of organic compounds is still quite limited.…”