Direct Synthesis of Methyl Chlorosilanes from Pd‐Mg‐SiO2 Substrates Using Mechanochemistry. Issue 5 (17th February 2021)

• Record Type: Journal Article
• Authors: Sparschu, Wendy; Larsen, Robert; Katsoulis, Dimitris
• Other Names: Brook Michael A. guestEditor.; Skov Anne L. guestEditor.
• Is Part Of: Macromolecular rapid communications. Volume 42:Issue 5(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-17
• Subjects: ball milling -- direct process -- mechanochemistry -- methyl chlorosilanes -- palladium silicide; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.202000684
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract: The direct reaction of methyl chloride with magnesium and palladium infused silica substrates to synthesize methyl chlorosilanes is reported. First, high energy ball milling on solid Mg‐SiO2 mixtures produces elemental silicon and MgO. When PdCl2 is infused into the mixture, after additional ball milling and high‐temperature reduction under H2, dipalladium silicide (Pd2 Si) is produced. The silicon of the Pd2 Si readily reacts with MeCl under Müller–Rochow reaction conditions, to produce methyl chlorosilanes at yield ratios analogous to those of the traditional process. The dominant product is Me2 SiCl2 (selectivity > 30%), followed by MeSiCl3 and Me3 SiCl, with minor amounts of the remaining chlorosilanes. Silicon conversion exceeds 20% for most of the substrates. The elemental palladium, which remains within the Pd‐Mg‐SiO2 contact mass is re‐converted to Pd2 Si at the next H2 /high‐temperature treatment and reacts again with MeCl to repeat the methyl chlorosilane production. In principle, the resulting cycle of the mechanochemically induced formation of Pd2 Si followed by the reaction with MeCl can be repeated until the starting SiO2 converts completely to methyl chlorosilanes. Abstract : Mechanochemistry enables the reduction of SiO2 by Mg to generate elemental Si, which in the presence of Pd and additional mechanical energy forms Pd2 Si at temperatures as low as 220 °C. Direct reaction of Pd2 Si with MeCl under Müller‐Rochow conditions (300 °C), produces Me2 SiCl2 and other methyl chlorosilanes.