Atmospheric Autoxidation of Organophosphate Esters br

摘要

Organophosphate esters (OPEs), widely used asflame retardants and plasticizers, have frequently been identified inthe atmosphere. However, their atmospheric fate and toxicityassociated with atmospheric transformations are unclear. Here, weperformed quantum chemical calculations and computationaltoxicology to investigate the reaction mechanism of peroxy radicalsof OPEs (OPEs-RO2 center dot), key intermediates in determining theatmospheric chemistry of OPEs, and the toxicity of the reactionproducts. TMP-RO2 center dot(R1) and TCPP-RO2 center dot(R2) derived fromtrimethyl phosphate and tris(2-chloroisopropyl) phosphate,respectively, are selected as model systems. The results indicatethat R1and R2canfollowanH-shift-drivenautoxidationmechanism under low NO concentration ([NO]) conditions, clarifying that RO2 center dot from esters can follow an autoxidationmechanism. The unexpected autoxidation mechanism can be attributed to the distinct role of the???(O)3P(???O) phosphate-estergroup in facilitating the H-shift of OPEs-RO2 center dot from commonly encountered???OC(???O)???and???ONO2ester groups in theatmosphere. Under high [NO] conditions, NO can mediate the autoxidation mechanism to form organonitrates and alkoxy radical-related products. The products from the autoxidation mechanism have low volatility and aquatic toxicity compared to theircorresponding parent compounds. The proposed autoxidation mechanism advances our current understanding of the atmosphericRO2 center dot chemistry and the environmental risk of OPEs