Comparative online coupled TG-FTIR and TG/DTA-MS analyses of the evolved gases from thiourea complexes of SnCl2.

Abstract

Identification and monitoring of gaseous species released during thermal decomposition of title compound 1, Sn-2(tu)(5)Cl(4)(.)2H(2)O (tu stands for thiourea (NH2)(2)C=S)) in flowing air atmosphere have been carried out up to 600 degreesC by both online coupled TG-EGA-FTIR and simultaneous TG/DTA-EGA-MS apparatuses. The first gaseous products of the dehydrated 1, evolved around 190 degreesC, are carbonyl sulphide (COS), carbon disulfide (CS2), and cyanamide (NH2CN). At 240 degreesC isothiocyanic acid, HNCS becomes the main product, accompanied by CS2, ammonia (NH3) a small amount of hydrogen cyanide (HCN) and traces of hydrogen chloride (HCI), according to EGA-FTIR spectroscopic analysis. At 250 degreesC formation of sulphur dioxide (SO2) has been observed by EGA-mass spectrometry. SO2 as air oxidation product of tin sulphides, formed in the previous stages, occurs also around 430 degreesC, while gaseous oxidation products of the organic residues, such as CO2 and NH2CN are released at 515 degreesC. Both oxidation processes are accompanied by an exothermic heat effect. All species identified by FTIR gas cell are also confirmed by mass spectrometry, except HNCS. (C) 2004 Elsevier B.V. All rights reserved