2-Hydroxyisobutyric acid → Trioctylammonium

Participants

Reaction Steps

A trioctylammonium salt solution was prepared by mixing 2-hydroxyisobutyric acid (2-HIB) with trioctylamine (TOA). For this, 10 g of 2-hydroxyisobutyric acid were weighed in and dissolved in 90 g of TOA. This initial weight results in a stoichiometric ratio of TOA/2-hydroxyisobutyric acid of 2.64. 50.6 g of this trioctylammonium salt solution were initially introduced in a rotary evaporator. For the thermal salt splitting, an absolute pressure of 27 mbar was established by means of a vacuum pump. The oil bath used for the thermal treatment of the initial charge was adjusted to 180° C. and kept constant. After about 20 min, white crystals crystallized out on the cool glass sections. After ca. 4 h, the experiment was terminated. Final weighing of the initial charge following thermal splitting revealed a mass reduction of 3.5 g. The white crystals located on the glass were washed with water and analysed by means of HPLC. This analysis showed that these crystals are 2-hydroxyisobutyric acid. Using elemental analysis (C, H, N, O), the samples were analysed both before the start of the experiment, and also after the end of the experiment. On the basis of these analyses, it was possible to calculate the concentrations and the quantitative amounts of the respective substances. 98.4% of the yielded TOA amount was still found in the initial charge after the experiment; 34.4% of the initial quantitative mass of the 2-hydroxyisobutyric acid were found at the end of the experiment also as trialkylammonium salt in the initial charge. 65.6% of the weighed-in 2-hydroxyisobutyric acid mass could be thermally split from the salt and partly be returned as crystals to the cool glass sections.

Provenance & Evidence