Heteroatom Tuning of Bimolecular Criegee Reactions and Its Implications

Abstract

High-level quantum-chemical calculations have been performed to understand the key reactivity determinants of bimolecular reactions of Criegee intermediates and H X (X=O, S, Se, and Te). Criegee intermediates are implicated as key intermediates in atmospheric, synthetic organic, and enzymatic chemistry. Generally, it is believed that the nature and location of substituents at the carbon of the Criegee intermediate play a key role in determing the reactivity. However, the present work suggests that it is not only the substitution of the Criegee intermediate, but the nature of the heteroatom in H X that also plays a crucial role in determining the reactivity of the interaction between the Criegee intermediate and H X. The barriers for the reactions of Criegee intermediates and H X satisfy an inverse correlation with the bond strength of X-H in H X, and a direct correlation with the first pK of H X. This heteroatom tuning causes a substantial barrier lowering of 8-11 kcal mol in the Criegee reaction barrier in going from H O to H Te. An important implication of these results is that the reaction of the Criegee intermediate and H S could be a source of thioaldehydes, which are important in plantery atmospheres and synthetic organic chemistry. By performing the reaction of Criegee intermediates and H S under water or acid catalysis, thioladehydes could be detected in a hydrogen-bonded complexed state, which is significantly more stable than their uncomplexed form. As a result, simpler aliphatic thioaldehydes could be selectively synthesized in the laboratory, which, otherwise, has been a significant synthetic challenge because of their ability to oligomerize.

Elucidating the molecular mechanisms of Criegee-amine chemistry in the gas phase and aqueous surface environments

“…N-H bonds in both CH 3 NH 2 and NH 3 (Scheme 2). Both OH radical and H O 2 forming paths from bimolecular Criegee reactions have previously been shown to involve similar energetic demands, [74][75][76] and thus, are equally likely to occur in the troposphere. Since the H 2 O 2 forming pathway requires the presence of two polar N-H bonds in a given amine, such a mechanistic option in the case of the Criegee-(CH 3 ) 2 NH reactions will not be available.…”

“…The bond dissociation energy for the O-OH bond in Criegee-derived hydroperoxides is $40 kcal mol À1 . [74][75][76] Considering that the adduct in the Criegee-amine reactions is formed with an additional energy of 38.5-51.9 kcal mol À1 , the O-OH bond breakage in C(CH 3 )(H)(OOH)(CH 3 NH)-type adducts may occur under tropospheric conditions, which makes these Criegeeamine chemistries a potential source of the tropospheric OH radical. The C(CH 3 )(H)(OOH)(CH 3 NH) adduct formed from the Criegee-CH 3 NH 2 /NH 3 reaction may also decompose into H 2 O 2 and C(CH 3 )(H)(CH 3 N)/C(CH 3 )(H)(H 2 N) due to the presence of two polar Scheme 2 Plausible mechanism for the formation of low-volatility oligomers containing stabilized Criegee intermediates as repeat units during the olefin ozonolysis.…”

Criegee intermediate-hydrogen sulfide chemistry at the air/water interface

“…However, it has recently been suggested that the gas-phase reaction between Criegee intermediate or a carbonyl compound and hydrogen sulfide (H 2 S) under water or acid catalysis could account for the atmospheric formation of thioaldehydes and provide useful guidelines for efficiently synthesizing thioaldehydes within laboratory environment. 7 , 9 Criegee intermediates are formed in the cycloaddition reactions between ozone and olefins. 10 Ever since Criegee intermediates have directly been detected in the gas phase, 11 understanding their chemistry using experimental and theoretical means has become an important avenue of atmospheric research.…”

Criegee intermediates: production, detection and reactivity

“…Various computational studies have shown that Criegee intermediates react with organic and inorganic molecules containing polar covalent bonds with hydrogen as shown in Scheme 3 [68,93,110,[117][118][119][120][121][122]. The kinetics of insertion reactions of Criegee intermediates have been measured by various research groups using direct methods such as multiplexed photoionization mass spectrometry (MPIMS) and UV absorption spectroscopy, and the resulting rate coefficient values are summarized in a previous review (see Table 2 and Table 6 in Khan et al [26]).…”