Chemical synthesis and characterization of single-chain C 18 -chloroparaffin materials with defined degrees of chlorination

• Published in: Chemosphere (Oxford) 2022-03, Vol.291 (Pt 2), p.132938
• Main Authors: Knobloch, Marco C, Sprengel, Jannik, Mathis, Flurin, Haag, Regula, Kern, Susanne, Bleiner, Davide, Vetter, Walter, Heeb, Norbert V
• Format: Article
• Language: English
• Subjects: China; Environmental Monitoring; Halogenation; Hydrocarbons, Chlorinated - analysis; Mass Spectrometry; Paraffin - analysis
• ISSN: 1879-1298
• DOI: 10.1016/j.chemosphere.2021.132938

Technical chlorinated paraffins (CPs) are produced via radical chlorination of n-alkane feedstocks with different carbon chain-lengths (∼C -C ). Short-chain CPs (SCCPs, C -C ) are classified as persistent organic pollutants (POPs) under the Stockholm Convention. This regulation has induced a shift to use longer-chain CPs as substitutes. Consequently, medium-chain (MCCPs, C -C ) and long-chain (LCCPs, C ) CPs have become dominant homologues in recent environmental samples. However, no suitable LCCP-standard materials are available. Herein, we report on the chemical synthesis of single-chain C -CP-materials, starting with a pure n-alkane and sulfuryl chloride (SO Cl ). Fractionation of the crude product by normal-phase liquid-chromatography and pooling of suitable fractions yielded in four C -CP-materials with different chlorination degrees (m  = 39-52%). In addition, polar side-products, tentatively identified as sulfite-, sulfate- and bis-sulfate-diesters, were separated from CPs. The new single-chain materials were characterized by LC-MS, H-NMR and EA. LC-MS provided Relative retention times for different C -CP homologues and side-products. Mathematical deconvolution of full-scan mass spectra revealed the presence of chloroparaffins (57-93%) and chloroolefins (COs, 7-26%) in the four single-chain C -CP-materials. Homologue distributions and chlorination degrees were deduced for CPs and COs. H-NMR revealed chemical shift ranges of mono-chlorinated (δ = 3.2-5.3 ppm) and non-chlorinated (δ = 1.0-3.2 ppm) hydrocarbon moieties. The synthesized C -single-chain standard materials and respective spectroscopic data are useful to identify and quantify LCCPs in various materials and environmental samples. CP- and CO-distributions resemble the ones of existing SCCP and MCCP reference materials and technical mixtures. Furthermore, these materials now allow specific studies on the environmental fate and the transformation of long-chain chloroparaffins and chloroolefins.