NMR Analysis of Mixed Pentaerythritol, Dipentaerythritol, and 1, 1, 1-Trirnethylolpropane Esters

摘要

Benzene solutions of mixed pentaerythritol, dipentaerythritol, and 1,1,1-trimethylolpropane esters may be quantitatively assayed by proton NMR spectroscopy with an absolute accuracy of ±5 mole-% for each of the ester types. Higher accuracies are possible if a cali¬bration curve is used. Average acid chain length and the approxi¬mate degree of chain branching are also obtained.nThe NMR method can be used for monitoring base stocks, check¬ing blend compositions, and determining constancy of formulation of oils qualified under specification MIL-L-23699. NMR analyses of a group of commercial esters and of several aircraft engine lubricant formulations have been made. Results were obtained on both the Varian A-60 and HA-100 spectrometers, with comparable accuracy. The A-60 is felt to be the preferred instrument, however, because its integrals are simpler to process.