Oxygen → 1-Decanol

Participants

Reaction Steps

The kinetic product is a polyhomologated trialkylborane 6 (Scheme 1-6a). Following consumption of the salt, the reaction is exposed to the atmosphere during isolation of the product. During this time, organoborane 6 may be partially oxidized and hydrolyzed in basic aqueous solution to a mixture of boronic and boric acids/esters, and their hydroxy complexes. Although no formal oxidation-hydrolysis step was carried out after the polyhomologation reaction, the oxidation-hydrolysis was confirmed by both IR and NMR spectra, which indicate the existence of oxygen-carbon bonds and hydroxy groups in polymer 5. Solid state 11B NMR spectrum of polymer 5 also shows the characteristic signals for boronic and boric acids/esters, and their hydroxy complexes. The air oxidation of organoboranes is well-known. Furthermore, semicrystalline PE has good O2 permeability, which would facilitate air oxidation of the solid, boron-containing polymer. A model reaction with tridecylborane confirmed the spontaneous oxidation and hydrolysis. After stirring a DCM solution of tridecylborane with 50% NaOH solution in air, 80% of decanol was obtained. However, because the polymerization workup does not involve an exhaustive oxidation-hydrolysis, polymethylene 5 contains polymethylene boronic and boric acids/esters/complexes. These species can contribute to the relatively broad molecular weight distributions. If the as-synthesized polymethylene 5 is subjected to a formal oxidation-hydrolysis with trimethylamine N-oxide dihydrate in toluene at 80° C., all the boron species are fully oxidized and hydrolyzed. The resultant polymethylene product exhibits no boron signal on solid state 11B NMR spectrum, as shown in FIG. 11. Specifically, FIG. 11 shows a solid state 11B NMR spectra of as-synthesized polymethylene 5 (black) produced from trimethylsulfoxonium iodide 1 using trihexylborane as the initiator/catalyst in 50% NaOH aqueous solution/DCM mixture (Table 1-1, entry 1), and polymethylene (blue) produced after a formal oxidation-hydrolysis of polymethylene 5 with trimethylamine N-oxide dihydrate in toluene at 80° C. Trialkylboranes BR3 are typically in the range of 80-90 ppm, borinic acids/esters are in the range of 40-60 ppm, boronic acids/esters are in the range of 25-40 ppm, boric acids/esters are in the range of 10-25 ppm, tetracoordinated boron complexes are in the range of −10 to 10 ppm.

Provenance & Evidence