Vapor-Liquid Equilibria and Chemical Equilibria in the System (Formaldehyde plus Water plus Isoprenol)

Isoprenol (3-methyl-3-buten-1-ol) is an important intermediate in the chemical industry and is used, for example, in the production of various scent and flavor chemicals. Isoprenol is produced from aqueous formaldehyde and isobutene and is separated by distillation from mixtures containing formaldehyde, water, and isobutene in the process. As formaldehyde forms oligomers with both water and isoprenol, these mixtures are complex reacting systems, which are not easy to separate. Hence, for understanding and modeling the process, information on the vapor-liquid equilibria and the chemical equilibria in the system (formaldehyde + water + isoprenol) is essential. However, only very limited data on this system are available in the literature. Therefore, in the present work, vapor-liquid equilibria were measured in the following systems: system (water + isoprenol) at 20 and 90 kPa, system (formaldehyde + isoprenol) at 373 and 393 K, and system (formaldehyde + water + isoprenol) at 373 K. Furthermore, the chemical equilibria of the oligomerization reactions of formaldehyde and isoprenol were studied with C-13-NMR spectroscopy at temperatures ranging from 283 to 353 K. The experimental data were used to extend a physico-chemical model of the system (formaldehyde + water) from the literature to include isoprenol.