Ab initio calculation of the proton transfer reaction rate coefficients to volatile organic compounds related to cork taint in wine

Abstract

We compute the proton transfer rates to a range of volatile organic compounds (VOCs) related to cork taint in wine. These rates are useful to support quantification in proton-transfer-reaction mass spectrometry (PTR-MS) and in selected-ion flow-tube mass spectrometry (SIFT-MS). We apply the average dipole orientation theory and the parameterized trajectory method to evaluate the rate coefficients for proton transfer occurring in ion-molecule collision, from both H 3 O + and NH + 4 to the VOCs. The main input ingredients for these methods are the electric dipole moment and polarizability of the VOC molecules, which we evaluate by means of quantum chemical calculations based on density functional theory. We provide new data for proton transfer rate coefficients of compounds responsible for cork taint and off-flavor in wine such as chloroanisoles, bromoanisoles, methylisoborneol, guaiacol, and terpenes.

Theoretical Investigation of Charge Transfer from NO+ and O2+ Ions to Wine-Related Volatile Compounds for Mass Spectrometry

“…Table reports these DFT-computed ingredients, namely, electric dipole moment and polarizability for the targeted molecules. The reported values are in close proximity to the values previously obtained using the Quantum Espresso suite . A few experimental/theoretical values of dipole moment and polarizability are also available for the investigated molecules: they are marked with their corresponding references in Table .…”

“…The above observations are in accordance with the Su theory for parametrized calculations. Previously reported proton transfer reactions rates with H 3 O + and NH 4 + ions at higher energies follow a similar trend. Spesyvyi and co-workers have reported an analogous behavior in rates at elevated interaction energies for ketones and isoprene .…”

“…The negative Δ H values indicate that all these reactions are predicted to be exothermic. Likewise, the listed molecules are likely to undergo non-dissociative charge transfer reactions with NO + and O 2 + ions because their IEs, as reported earlier, lie well below the corresponding IEs of NO and O 2 , respectively. Moreover, the majority of the polyatomic exothermic reactions proceed at or near their collision rate ( k = k c ).…”

“…The reported values are in close proximity to the values previously obtained using the Quantum Espresso suite. 65 A few experimental/theoretical values of dipole moment and polarizability are also available for the investigated molecules: they are marked with their corresponding references in Table 1. The adopted DFT method, B 3 LYP/ 6-31+(d,p), provides a good balance of computational cost and accuracy.…”

Gaussian Process Regression (GPR) Method for the Prediction of Rate Coefficients of Gas-phase Reactions in Chemical Ionization Mass Spectrometry

“…These quantities can be evaluated by using quantum chemical simulation methods. A broad range of molecules related to food and beverages are investigated and reported [32]. Langevin rates are given as,…”