MOLAR HEAT-CAPACITIES OF ALKANOLAMINES FROM 299.1 TO 397.8 K - GROUP ADDITIVITY AND MOLECULAR CONNECTIVITY ANALYSES

The molar heat capacities of 14 alkanolamine compounds have been measu red at five separate temperatures in the range 299.1 to 397.8 K. These compounds were monoethanolamine (MEA), monomethylethanolamine (MMEA), dimethylethanolamine (DMEA), monoethylethanolamine (MEEA), diethyleth anolamine (DEEA), n-propylethanolamine (n-PEA), diisopropylethanolamin e (di-PEA), diethanolamine (DEA), methyldiethanolamine (MDEA), ethyldi ethanolamine (EDEA), n-butyldiethanolamine (n-BDEA), tert-butyldiethan olamine (tert-BDEA), triethanolamine (TEA) and 2-amino-2-methylpropan- 1-ol (AMP). Molar heat capacities of these compounds show a structural dependence, where the molar heat capacity of one molecule may be cons idered as the sum of various group contributions. Hence, the reported molar heat capacity data have been used as input to a group additivity analysis that yields estimates of CH2, OH, NH and N group contributio ns to molar heat capacities at each investigated temperature. The addi tivity principle has been explored in more detail by using molecular c onnectivity indexes to obtain a simple five-term equation that models the molar heat capacities of the investigated alkanolamines over the e ntire experimental temperature range.