Tetraethylene glycol thermooxidation and the influence of certain compounds relevant to conserved archaeological wood

The degradation of tetraethylene glycol (TEG) was studied at 70 °C under dry air and nitrogen. Degradation products were detected using gas chromatography-mass spectrometry (GC–MS). They were mono-, di- and tri-ethylene glycol, mono- and di-formates of mono-, di-, tri- and tetra-ethylene glycol and formic acid. The rate of TEG degradation was significantly decreased by approximately 10 mmol/l KI, FeCl₃, Cu(CH₃COO)₂, MnO₂ and CuSO₄, small amounts of fresh oak wood sawdust and gypsum-containing scrapings from the wood surface of the Vasa ship in Stockholm. Thus certain salts and natural components of archaeological wood are able to inhibit oxidative degradation of TEG. NaFe₃(SO₄)₂(OH)₆ (Natrojarosite), FeS₂ (pyrite), FeSO₄, Fe₂(SO₄)₃, NiCl₂, NiSO₄, Fe, Cu, Fe₂O₃, CuO, NaHSO₄ and natrojarosite-containing scrapings from the Vasa had no major effect on the rate of oxidation.