Supplementary material to "Mechanistic insight into the kinetic fragmentation of Norpinonic Acid in the gas phase: An experimental and DFT study"

Synthesis of investigated compound Synthesis protocolThe commercially available (1S)-(-)-verbenone (CAS Registry No. 1196-01-6, ≥ 94%, Sigma-Aldrich) was used as starting material.The protocol for the synthesis of norpinonic acid covered one step -the oxidative cleavage of the double C=C bond using RuCl3×H2O (CAS Registry No. 14898-67-0, Sigma-Aldrich, ≥99.98%).Other chemicals used in cis-norpinonic acid synthesis were as follows: sodium periodate (CAS Registry No. 7790-28-5, Sigma-Aldrich, ≥ 99.8%), carbon tetrachloride (CAS Registry No. 56-23-5, Sigma-Aldrich, ≥ 99.5%), acetonitrile (CAS Registry No. 75-05-8, POCH, ≥ 99.9%), hexane (CAS Registry No. 110-54-3, POCH, ≥ 99.9%), ethyl acetate (CAS Registry No. 60-29-7, POCH, ≥ 99.9%), magnesium sulfate (CAS Registry No. 7487-88-9, POCH, ≥ 98.5%).To the stirred solution of (1S)-(-)-verbenone (2.5 mL, 16 mmol) in 2:2:3 carbon tetrachlorideacetonitrile-water (130 mL), catalytic RuCl3 hydrate (120 mg) and NaIO4 (13.4 g, 63 mmol) were added.The resulting mixture was stirred overnight at the room temperature, then diethyl ether (100 mL) was added and stirring for the next 5 min.Then mixture was extracted with diethyl ether (3×100 mL).The combined organic extracts were dried (MgSO4) and concentrated under reduced pressure.Norpinonic acid was isolated as white crystals after crystallization from diethyl ether (yield: 80%).The structural identification of the final product based on IR, ESI-HR-MS, 1 H , 13 C and 2D NMR analytical spectra proved the presence of cis-norpinonic acid stereoisomeric form. Copies of 1H and 13C NMR spectra of isolated compound 2. Experimental procedures Breakdown CurvesCollision spectra were recorded by varying the collision energy in incremental steps.Collision mass spectra were recorded with an energy resolution of 8-30 eV in the lab frame and 2-10 minutes of collection time at each step.Creation of the total breakdown curves was performed using absolute peak heights.Breakdown curves at five different argon pressures are presented in.