Differential thermal analysis, higher order

Order of thermal stabiUty as determined by differential thermal analysis is sebacic (330°C) > a2elaic = pimelic (320°C) > suberic = adipic = glutaric (290°C) > succinic (255°C) > oxahc (200°C) > malonic (185°C) (19). This order is somewhat different than that in Table 2, and is the result of differences in test conditions. The energy of activation for decarboxylation has been estimated to be 251 kj/mol (60 kcal/mol) for higher members of the series and 126 kJ/mol (30 kcal/mol) for malonic acid (1). 

Most of the information about dehydration because of temperature increase has come from differential thermal analysis curves, which are deceptive with regard to the subsurface environment because of the rapid rate at which temperature is raised (water loss therefore occurs at a higher temperature than it would otherwise), and because the sample is surrounded by air at 0.101 MPa (1 atm.) pressure rather than a saline solution at elevated pressure. Nevertheless, these curves (e.g., Hendricks et at, 1940 Rowland et al., 1956) indicate a relative order of events. 

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