Kinetics and general reaction rule for hydrogen atom abstraction reactions from C4–C10 alcohols by a hydroxyl radical

Abstract

This study establishes a generalized reaction rule for hydrogen atom (H) abstraction from C4–C10 1-alcohols by hydroxyl radicals (HO˙), overcoming the fundamental limitations of bond dissociation energy (BDE) models. Through systematic kinetics analysis, this study reveals that hydrogen atoms on OH-proximal carbons (C1–C4) exhibit alcohol-specific asymmetric reactivity, starkly deviating from n-alkane behavior, whereas distal carbons (>C4) show convergence. Crucially, hydrogen bonding leads to distinct kinetics for OS (opposite-side, relative to the hydroxyl group) and SS (same-side, relative to the hydroxyl group) pathways by modulating the transition state geometries and energy barriers. By incorporating these asymmetric reactivities and secondary electronic effects, a chain-length-independent rate rule is established that categorizes ten unique reaction channels with unified kinetic parameters. Validated by high-precision ONIOM-based energy calculations against CCSD(T)/CBS benchmarks, this rule enables accurate mechanistic extrapolation for long-chain alcohol combustion. The work provides a fundamental framework for refining kinetic models of oxygenated fuels and advancing energy technologies.