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Updated: May 26, 2026

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates
Published on: January 15, 2018
Overlooked Dichloroacetonitrile Formation from Ammonia and Phenolic Compounds during UV-Activated Mixed
Xiaoyu Tan1, Xiao Li1, Guiying He2
1State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, Harbin Institute of Technology, Shenzhen 518055, China.
Abstract:
To evaluate the role of inorganic nitrogen and nitrogen-free organic matter in forming nitrogenous disinfection byproducts (N-DBPs), this study investigated dichloroacetonitrile (DCAN) formation during mixed chlorine/chloramine (MCC) processes with and without ultraviolet (UV) irradiation. Results showed that ammonia and phenol yielded higher DCAN (0.036%) than representative dissolved organic nitrogen precursors, including nitrobenzene (0.012%) and aminobenzene (0.016%), under identical nitrogen, carbon, and chlorine dosages, indicating that inorganic nitrogen can be a dominant contributor to N-DBPs formation. Among UV-based processes, DCAN yields followed the order UV/chlorine (0.256%) > UV-activated MCC (0.099%) ≫ UV/monochloramine (0.011%), while MCC without UV generated less DCAN. For phenolic compounds, DCAN formation decreased with increasing number of hydroxyl groups (-OH) and varied by substitution position. A quantitative structure-activity relationship model (R2 = 0.842) identified acid dissociation coefficient (pKa) and chemical softness (S, a measure of a molecule's susceptibility to electrophilic attack) as dominant descriptors. Transformation products analysis revealed two parallel DCAN formation pathways in the UV-activated MCC process: (i) nitrogen incorporation after oxidative cleavage and (ii) amination before aromatic ring opening. These results demonstrate that ammonia can be converted into DCAN via multiple pathways, highlighting an overlooked route for N-DBPs formation during the water disinfection process.
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