Chemical synthesis and characterization of single-chain C18-chloroparaffin materials with defined degrees of chlorination

Marco C Knobloch; Jannik Sprengel; Flurin Mathis; Regula Haag; Susanne Kern; Davide Bleiner; Walter Vetter; Norbert V Heeb

doi:10.1016/j.chemosphere.2021.132938

Chemical synthesis and characterization of single-chain C₁₈-chloroparaffin materials with defined degrees of chlorination

Chemosphere. 2022 Mar;291(Pt 2):132938. doi: 10.1016/j.chemosphere.2021.132938. Epub 2021 Nov 16.

Authors

Marco C Knobloch¹, Jannik Sprengel², Flurin Mathis³, Regula Haag⁴, Susanne Kern⁵, Davide Bleiner⁶, Walter Vetter², Norbert V Heeb⁴

Affiliations

¹ Laboratory for Advanced Analytical Technologies, Swiss Federal Institute for Materials Science and Technology Empa, Überlandstrasse 129, 8600, Dübendorf, Switzerland; Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland. Electronic address: marco.knobloch@empa.ch.
² University of Hohenheim, Institute of Food Chemistry (170b), Garbenstrasse 28, 70599, Stuttgart, Germany.
³ Laboratory for Advanced Analytical Technologies, Swiss Federal Institute for Materials Science and Technology Empa, Überlandstrasse 129, 8600, Dübendorf, Switzerland; Zürich University of Applied Sciences ZHAW, Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland.
⁴ Laboratory for Advanced Analytical Technologies, Swiss Federal Institute for Materials Science and Technology Empa, Überlandstrasse 129, 8600, Dübendorf, Switzerland.
⁵ Zürich University of Applied Sciences ZHAW, Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland.
⁶ Laboratory for Advanced Analytical Technologies, Swiss Federal Institute for Materials Science and Technology Empa, Überlandstrasse 129, 8600, Dübendorf, Switzerland; Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.

PMID: 34798110
DOI: 10.1016/j.chemosphere.2021.132938

Abstract

Technical chlorinated paraffins (CPs) are produced via radical chlorination of n-alkane feedstocks with different carbon chain-lengths (∼C₁₀-C₃₀). Short-chain CPs (SCCPs, C₁₀-C₁₃) 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, C₁₄-C₁₇) and long-chain (LCCPs, C_>₁₇) 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 C₁₈-CP-materials, starting with a pure n-alkane and sulfuryl chloride (SO₂Cl₂). Fractionation of the crude product by normal-phase liquid-chromatography and pooling of suitable fractions yielded in four C₁₈-CP-materials with different chlorination degrees (m_Cl,EA = 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, ¹H-NMR and EA. LC-MS provided Relative retention times for different C₁₈-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 C₁₈-CP-materials. Homologue distributions and chlorination degrees were deduced for CPs and COs. ¹H-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 C₁₈-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.

Keywords: Chlorinated olefins (COs); Chlorinated paraffins (CPs); Long-chain chlorinated paraffins (LCCPs); Single-chain CPs; Standard materials.

MeSH terms

China
Environmental Monitoring
Halogenation
Hydrocarbons, Chlorinated* / analysis
Mass Spectrometry
Paraffin / analysis

Substances

Hydrocarbons, Chlorinated
Paraffin