Thermochemistry of Oxygen-Containing Organosilane Radicals and Uncertainty Estimations of Organosilane Group-Additivity Values

Si–C–H–O-containing
radicals are important
intermediates during the combustion and pyrolysis of precursors applied
for the gas-phase synthesis of silica nanoparticles. Despite the industrial
importance of silica nanoparticles, a comprehensive thermodynamics
database of organosilane species is still missing. This work presents
thermochemical data of 91 Si–C–H–O radical species.
Quantum-chemical calculations and isodesmic reaction schemes are used
to determine the standard enthalpy of formation, entropy, and heat
capacities covering the 298–2000 K temperature range. In addition,
90 group-additivity values (GAVs) are calculated, which cover all
relevant group increments. A combinatorial approach is used to ensure
that all possible group increments are considered. The theoretically
calculated species are used as a training set to derive 90 GAVs of
Si–C–H–O radical species for the first time.
In addition, uncertainty contributions of GAVs were estimated. These
uncertainty estimates also comprise GAVs that were previously derived
to compute thermochemical data of stable Si–C–H species
and radicals as well as stable Si–C–H–O compounds.
Therefore, uncertainty contributions of GAVs for a whole set of 243
group increments used to predict thermochemical data of Si-organic
species are reported.

含Si-C-H-O的自由基是用于气相合成二氧化硅纳米颗粒的前驱体在燃烧与热解过程中的关键中间体。尽管二氧化硅纳米颗粒具有重要的工业应用价值，但目前仍缺乏一套完整的有机硅物种热力学数据库。本工作提供了91种含Si-C-H-O自由基的热化学数据。
本研究采用量子化学计算与等键反应方案，测定了298~2000K温度区间内各物种的标准生成焓、熵与热容。此外，本研究还计算了覆盖所有相关基团增量的90个基团加和参数（group-additivity values, GAVs），并通过组合方法确保所有可能的基团增量均被纳入考量。本研究首次以理论计算得到的物种作为训练集，推导得到了含Si-C-H-O自由基的90个GAVs。
此外，本研究还估算了GAVs的不确定性贡献。该不确定性估算范围不仅涵盖此前用于计算稳定Si-C-H物种、自由基以及稳定Si-C-H-O化合物热化学数据的GAVs，同时还报道了可用于预测有机硅物种热化学数据的整套243个基团增量对应的GAVs不确定性贡献。