Homogeneous gas-phase formation of polychlorinated naphthalene from dimerization of 4-chlorophenoxy radicals and cross-condensation of phenoxy radical with 4-chlorophenoxy radical: Mechanism and kinetics study

Quantum Chemical and Kinetic Study on Polychlorinated Naphthalene Formation from 3-Chlorophenol Precursor

“…The error correction of the kinetic calculation may be mainly from the SCT method [ 51 , 52 , 53 , 54 ]. The reliability and accuracy of the CVT/SCT method was verified in our recent studies [ 47 , 48 , 49 , 50 , 55 , 56 , 57 , 58 ]. For example, the CVT/SCT rate constants of C 6 H 5 OH + H → C 6 H 5 O + H 2 and C 6 H 5 OH + OH → C 6 H 5 OH + H 2 O are in good agreement with the corresponding experimental values [ 49 , 50 ], respectively.…”

“…Comparison of the formation of PCNs from the 3-CP with our previous studies of PCN formation from 2-CP and 4-CP precursors [ 47 , 48 ] shows that the position of chlorination affects each elementary step involved in the PCN formation. On the one hand, the isomer patterns of PCNs products are completely different from the three CPs.…”

“…In Kim’s mechanism, the chloro-dihydrofulvene occurs intramolecular rearrangement of 1,5-sigmatropic shifts of H/Cl to the ortho -carbon of cyclopentadiene ring before ortho -carbon H/Cl atom is abstracted by H, OH and Cl radicals. However, this deduction has been refused in our previous study on PCN formation from 2-CP and 4-CP [ 47 , 48 ], owning to the high potential barrier of 1,5-sigmatropic shift step. Similarly, theoretical calculation of 1,5-sigmatropic H shift mechanism of IM10 is shown in Figure 5 .…”

“…By In addition, dimerization of CPRs is barrierless and is the initial step of PCN formation. The dimerization of 3-CPRs (−23.42, −23.25 and −23.60 kcal/mol) is approximately 10 kcal/mol more exothermic than those of 2-CPRs (−17.63 and −10.29 kcal/mol) and 4-CPRs (−16.20 kcal/mol) [ 47 , 48 ]. Thus, 3-CP have stronger PCN formation potential than that of 2-CP and 4-CP [ 46 , 47 ], which is consistent with the experimental result wherein 3-CP produced the highest PCN yield [ 32 , 33 ].…”

“…Due to the high toxicity of PCNs and the lack of efficient detection schemes for intermediate radicals, the specific formation mechanism of PCNs from CPs remains unclear. Our previous studies have systematically investigated the homogeneous gas-phase formation mechanism of PCNs from 2-CP and 4-CP precursors [ 47 , 48 ]. As a ongoing study of this field, it is important to continue study the PCN formation mechanism from 3-CP in order to compare the contributions and effects of ortho -, meta- , and para- chlorine of monochlorophenol on the formation potential and isomer distributions of PCN products.…”