ANALYTICAL AND PREPARATIVE SEPARATION OF FUNCTIONAL CARBOSILANES AND PHOSPHANES BY MEANS OF SFC (SUPERCRITICAL FLUID CHROMATOGRAPHY)

Analytical and preparative separations of functional silanes, carbosilanes and phosphanes by means of SFC (supercritical fluid chromatography) using CO2 or CF3Cl as mobile phases are reported. The detecting system (an IR high pressure cell) of the apparatus which was developed by us is depicted. The separation of mixtures containing silanes with strongly polarizing groups proceeds successfully with Nucleosil-C18 and CO2 according to the molecular weights. Large differences in the polarity of the compounds give rise to a separation according to molecular weights, smaller ones to the types of compounds. The advantages of a separation by SFC are demonstrated using a mixture of 1,3,5-trisilacyclohexanes with SiH, CCl2 and SiF groups. The preparative separation is demonstrated using a mixture of 4 different groups of a toral 22 carbosilanes. Eight fractions were obtained each of which containing the compounds with the same number of Si atoms. The final separation was achieved by means of a pressure program (Nucleosil-C18, CO2). The preparative isolation of a cyclic phosphinoborane from a mixture of three components of the same type as well as the isolation of (Me3Si)3P from a mixture of P-rich silylphosphanes is reported.