Thermogravimetric and Gas Chromatographic Behaviors of Copper Chelate of Tropolone

Abstract

Numerous metal chelates are separated and analyzed by gas chromatography. In such cases, metal chelates of acetylacetone and its derivatives, which form inner complexes, are mainly used because of their thermal stability and high volatility. Metal tropolonates similarly to metal j9-diketonates form inner complexes and are expected to evaporate in molecular form.
Thermal stability and volatility of copper tropolonate (Cu (trp), ) were investigated by means of thermogravimetric analysis (TGA) and by comparing IR spectrum of solid chelate before vaporization with that of vaporized one. The weight of Cu (trp), begins to decrease at 246°C and reaches 72% weight loss, while the weights of copper pivaloyltrifluoroacetonate, trifluoroacetylacetonate, dipivaloylmethanate, acetylacetonate and benzoylpivaloylmethanate (Cu (bpm), ) begin to decrease at 72, 93, 128, 155 and 222°C, respectively and reach almost 100% weight loss, except the weight of Cu(bpm)which reaches 93% weight loss. As for copper β- diketonates, IR spectra of vaporized chelates are the same as those of solid chelates before vaporization, while as for Cu (trp)besides its own absorption bands, bands of free ligand appear in vapor phase. On the basis of these results, Cu(trp), is less volatile and partially decomposes befdre sublimation.
Gas chromatographic behaviors of Cu (trp), were also investigated and compared them with those of copper chelate of β-diketone, Cu (bpm), . Typical gas chromatogram of Cu (trp), was obtained by using stainless steel column packed with silanized glass microbeads, to which Siljcone F-50 being applied and by programmed column temperature. Retention time of Cu. (trip), was 3.1 min, while that of Cu(bpm), was 1.1 min. On the basis of these results, it is difficult to elute copper tropolonate.