Positive ion reactions in the high energy irradiation of gaseous acetic acid

The gas-phase positive ion reactions in pure acetic acid and in the mixtures with various reactant gases have been studied over the pressure range 0.1-5 torr and the temperature range 210-380 K using high-pressure mass spectrometry. The formation of the species H ⁺·(CH ₃COOH) _n, n⪕9, CH ₃CO ⁺·(CH ₃COOH) _n, n⪕7, H ⁺·(CH ₃COOH) _n·H ₂O, 5⪕n⪕9, (CH ₃COOH) ₂⁺, C ₄H ₉⁺·(CH ₃-COOH) _n, n⪕2 and C ₃H ₃⁺·(CH ₃COOH) _n, n⪕2, have been observed, and the solvation enthalpies for the major clusters H ⁺·(CH ₃COOH) _n, 2⪕n⪕7, and CH ₃CO ⁺·(CH ₃COOH) _n, 1⪕n⪕6 are derived from appropriate van't Hoff plots. The stabilities of the H ⁺·(CH ₃COOH) _n clusters were compared with those of H ⁺·(H ₂O) _n.