Mechanism and Thermochemistry of Radical Driven Partial Chain Oxidation of p‐Benzylphenol

The thermochemistry of radical driven chain oxidation of gaseous p‐benzylphenol is studied using the DFT (M062X,B3LYP,wB97XD,M08HX,MN15) approaches at 6‐311++G(d,p) level of theory. The values of Δ f H o (Y , MEAN) or Δ f H o (Y i ,MEAN) RHp , used for the determination of Δ Rx H o of considered reactions, are derived from the intersections of 3SE i intervals of values of Δ f H o (Y i, CORR) or Δ f H o (Y i ,CORR) RHp , determined, respectively, using the corrected thermochemistry of atomization (ra) or homodesmotic (RH p ) reactions. The linear calibration dependencies are used for the correction of their values of Δ ra H o (Y i ) and Δ RHp H o (Y i ), derived from the calculated values of H o . According to calculations, the most thermochemically favorable product is benzophenone,4‐ol (Δ f H o 298.15 (benzophenone,4‐ol)=−126.0±7.6(±2σ) kJ/mol), while, the formation of PhCHPhO (Δ f H o 298.15 =151.3±7.8 kJ/mol) and PhC(OH)PhO (Δ f H o 298.15 =39.6±6.5 kJ/mol) is thermochemically unfavorable. The formation of benzophenone,4‐ol is due the tautomerization or dissociation of O−O bond of PhC(O 2 • )HPhOH (Δ f H o 298.15 =47.9±4.8 kJ/mol), produced, respectively, OH or PhC(O • )HPhOH (Δ f H o 298.15 =53.0±7.1 kJ/mol) radicals. However, the formation of PhC(O 2 • )HPhOH is exoergic only at T <500 K . The formation of PhC(O 2 H)HPhOH (Δ f H o 298.15 =−104.2±5.9 kJ/mol) and PhC(OH)HPhOH (Δ f H o 298.15 =−177.8±5.3 kJ/mol) via transfer of H atom from p‐benzylphenol is also thermochemically favorable, but can only be important, respectively, at low ( T <800 K ) and at high T . In addition, the tautomerization of PhC(O⋅)HPhOH to PhC⋅ (OH)PhOH (Δ f H o 298.15 =−61.0±1.3 kJ/mol) is thermochemically favorable and slightly depends upon T .