Sublimation study of triphenyl boron and the bond-dissociation enthalpy of B-C6H5

Article abstract of DOI:10.1016/0021-9614(84)90053-3

The sublimation pressures of triphenyl boron, B(C6H5)3, in the temperature range 340 to 380 K have been determined from simultaneous measurements of the rate of mass effusion and torsional recoil.The measured vapor pressures expressed by the equations: log₁₀(p_K/p⁰) = (9.52 +/- 0.07) - (5.326 +/- 0.026)*10³(K/T), log₁₀(p_τ/p⁰) = (10.08 +/- 0.06) - (5.518 +/- 0.022)*10³(K/T) where p_K and p_τ are the pressures measured by the Knudsen effusion and torsional recoil techniques, respectively, and p⁰ = 101.325 kPa, confirm that triphenyl boron is a monomer in the vapor phase in the temperature range of the measurements.The mean standard molar enthalpy and entropy of sublimation (p⁰ = 101.325 kPa) derived from these equations are: Δ_subH⁰_m = (103.8 +/- 2.5) kJ*mol^-1 and Δ_subS⁰_m = (187.6 +/- 7.6) J*K^-1*mol^-1.The mean molar bond-dissociation enthalpy (B-C6H5) is calculated to be (459 +/- 11.6) kJ*mol^-1.

Full text of DOI:10.1016/0021-9614(84)90053-3

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