autoxidative

Autoxidative refers to processes that proceed by autoxidation, the spontaneous oxidation of substrates by molecular oxygen in the absence of enzymatic catalysts. The term is often used to describe reactions driven by oxygen under ambient or elevated temperatures, light, or trace metal catalysts that generate reactive oxygen species.

Autoxidation most commonly proceeds through a free radical chain mechanism. Initiation forms reactive radicals, typically via hydrogen abstraction or decomposition of hydroperoxides. Propagation follows as substrates react with O2 to form peroxyl radicals and hydroperoxides, which in turn generate additional radical species. Termination occurs when two radicals combine to yield stable products. The overall rate is influenced by substrate structure, degree of unsaturation, temperature, light exposure, and the presence of catalytic metals.

The phenomenon has wide relevance. In biology, lipid peroxidation is a major autoxidative process that can damage cell membranes and generate reactive aldehydes associated with oxidative stress. In food chemistry, autoxidation of polyunsaturated fats leads to rancidity and off-flavors, reducing nutritional value and shelf life; antioxidants are commonly added to retard the process. In polymers and rubbers, autoxidation can cause chain scission, crosslinking, and hardening or embrittlement, affecting mechanical properties and durability. In some chemical syntheses, autoxidation is exploited to form hydroperoxides, though it is often difficult to control.

Detection and control involve measuring peroxide formation, monitoring conjugated dienes, or using spectroscopic methods to track radical species. Strategies to slow autoxidative degradation include reducing exposure to light and heat, limiting metal contaminants, and incorporating antioxidants or stabilizers. See also autoxidation.