Suberic

Methanol and n-hexane of analytical grade were obtained from PENTA (Praha, Czech Republic). The toluene (analytical-grade) was purchased from Sigma-Aldrich (St. Louis, MO, USA). Further, the 3-(Trifluoromethyl)phenyltrimethylammonium hydroxide (TFTMAH), 5% w/v in methanol (known as MethPrep II), was supplied by Tokyo Chemical Industry Co., Ltd. (Nihonbashi-honcho, Chuo-ku, Tokyo, Japan). The fatty acid standards—azelaic (C9), suberic (C8), sebacic (C10), palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3), and cholesta-3,5-diene-7-one—were purchased from Sigma-Aldrich. Individual stock standard solutions were prepared for fatty acids in n-hexane and cholesta-3,5-diene-7-one in 2-propanol at a concentration of 1 mg·mL⁻¹ and stored in a refrigerator at 5 °C.

All dicarboxylic acids (oxalic, succinic, suberic, and sebacic), methanol, 1-decanol, and tetradecanol were acquired from Sigma Aldrich (St. Louis, MO, USA) with high purities (≥98%) as synthesis precursors. Dimethyl oxalate was purchased from Sigma Aldrich with purity ≥ 99% and was used for comparison with the self-synthesized one for validation of the synthesis procedure. 1-Pentanol was purchased by Roth GmbH (Karlsruhe, Germany) with purity ≥ 98%. The synthesis procedure was the same as reported by Ravotti et al. [18 (link)]; thus, concentrated sulfuric acid (H₂SO₄) was used as the acid catalyst (Sigma Aldrich, ≥99%), sodium sulfate anhydrous (Na₂SO₄) was used as a water-absorbing agent (Sigma Aldrich, ≥99%) for the elimination of water, and ethyl acetate (EtOAc) was used as the organic solvent for extraction (Sigma Aldrich, ≥99%). Cylohexane (Sigma Aldrich, GC quality, ≥99.9%) was used as the solvent for the Gas Chromatography coupled with Mass Spectrometry (GC-MS) analysis. All chemical materials listed above were used without any prior purification.