In this study, 4-benzyloxyphenol was introduced as an α-O-4 dimeric lignin model compound to explore the pyrolysis mechanism of α-O-4 linkage in lignin. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), density functional theory (DFT) calculations, and collision theory were employed to illustrate the pyrolysis process experimentally and theoretically. The results suggest that the pyrol...

ion from the –CH2– groups in a-position to a C@C double bond (C7–H in D-sterols, C23–H in the two avenasterols and D-fucosterol, C6–H in D-sterols, or C23–H in D-gramisterol, D-episterol and D-citrostadienol). In the case of 2-propene, the experimentally determined BDE for CH2@CH–CH2–H bond (370 ± 2) kJ mol 1 was practically identical with the C6H5CH2–H BDE for toluene due to the conjugation in...

A model was used to predict the photodebromination of the BDE-203, 197, 196, and 153, the major components of the octa-polybrominated diphenyl ether (PBDE) technical mixture, as well as BDE-47, and the predicted results were compared to the experimental results. The predicted reaction time profiles of the photodebromination products correlate well with the experimental results. In addition, the...

This paper investigates the pyrolysis of PODEn (n = 3, 4, 5) using ReaxFF molecular dynamics simulation. A large-scale model, which contains 2000 molecules, is simulated at 3000 K. The higher frequencies initial decomposition reaction α or β C-O bond show that in not easy to break, approximately half number other type dissociation. Furthermore, dissociation energies (BDEs) are calculated method...

CX (X = F, Cl, Br, I) and CE bonding (E = O, S, Se, Te) was investigated for a test set of 168 molecules using the local CX and CE stretching force constants k(a) calculated at the M06-2X/cc-pVTZ level of theory. The stretching force constants were used to derive a relative bond strength order (RBSO) parameter n. As alternative bond strength descriptors, bond dissociation energies (BDE) were ca...

The reaction mechanisms by which antioxidants can exert their activity are: hydrogen atom transfer (HAT), proton coupled electron transfer (PCET), sequential proton loss electron transfer (SPLET), single electron transfer proton transfer (SET-PT), radical adduct formation, and sequential proton loss hydrogen atom transfer. The antioxidative activity of different compounds (flavones, flavonols, ...

A quantitative understanding of the thermochemistry of cyclohexadienyl radical and 1,4-cyclohexadiene is beneficial for diverse areas of chemistry. Given the interest in these two species, it is surprising that more detailed thermodynamic data concerning the homolytic C-H bond enthalpies of such entities have not been forthcoming. We thus undertook an experimental and computational evaluation o...

Correlations of various indices of the stability and reactivity of carbon-centered radicals with ESR hyperfine splitting constants have been examined. For a large number of monoand disubstituted radicals there is a moderately good linear correlation of R-proton hyperfine splitting constants (a(HR)) with radical stabilization enthalpies (RSE) and with BDE(C-H), the C-H bond dissociation energies...

The negative ion chemistry of five azine molecules has been investigated using the combined experimental techniques of negative ion photoelectron spectroscopy to obtain electron affinities (EA) and tandem flowing afterglow-selected ion tube (FA-SIFT) mass spectrometry to obtain deprotonation enthalpies (Δ(acid)H(298)). The measured Δ(acid)H(298) for the most acidic site of each azine species is...