Linear α-Olefins from Linear Internal Olefins by a Boron-Based Continuous Double-Bond Isomerization Process

Abstract

Linear α-olefins (LAOs) find industrial use as high-value chemical intermediates. Most of the LAO production is based on ethylene oligomerization and does not yield a market-related product distribution. Various non-ethylene-based LAO production routes have been evaluated and it was found that a process based on boron chemistry was the most likely to be successfully commercialized. Process flow diagrams for a low-temperature (150−200 °C) continuous boron-based process to produce LAOs from linear internal olefins are presented, showing that it can be designed with or without a solvent in the boron cycle. Experimental data are presented to illustrate progress made in understanding the chemistry associated with such a process. It is shown that (a) solvent exchange competes with hydroboration and is rate-controlling by regulating borane availability, (b) reactivity of substituted boranes is determined by the availability of the empty p z orbital of boron, (c) steric effects influence the rate of hydroboration and isomerization, (d) alkylborane isomer distribution is temperature-dependent and back-isomerization of terminally bonded alkylboranes is possible, and (e) thermal dehydroboration is more efficient than olefin liberation by displacement.