Thermodynamic Characteristics of Alkali Metal Pivalates (CH3)3CCOOM (M = Li, Na, K, Rb, Cs)

Abstract

The thermodynamic properties of alkali metal pivalates (CH3)3CCOOM, where M = Li, Na, K, Rb, Cs, were studied by mass spectrometry, thermogravimetric analysis, and differential scanning calorimetry. The sublimation of the compounds was determined to be congruent. The saturated vapor contains oligomeric forms MnPivn (n = 1–6), which are dominated by dimeric and tetrameric molecules in the case of Na and K pivalates and by monomeric and dimeric molecules in the case of Rb and Cs pivalates. The partial pressures of the main components of the gas phase, their temperature dependence, and their standard enthalpies of sublimation were calculated. The enthalpies of dissociation of dimeric and tetrameric molecules were found. The standard enthalpies of formation MPiv(solid) and MPiv(gas) were estimated.