Hochmolekulare Perchlorsiloxane

Abstract

Die Reaktion von SiCl4 mit O2 in der Gasphase verläuft nicht spontan zu den thermodynamisch begünstigten Endprodukten SiO2 und Cl2. Bei Reaktionstemperaturen um 1300 K lassen sich zahlreiche Zwischenstufen SinOmCl4n−2m (Perchlorsiloxane) nachweisen und isolieren. Massenspektrometrische Untersuchungen zeigen die Bildung von Chlorsiloxanen mit n = 2…65 und m/n = 0,5…1,7; es wurden Molmassen bis 7000 D nachgewiesen. Auch die sehr hochmolekularen Chlorsiloxane haben typisch molekulare Eigenschaften: Sie sind löslich in unpolaren Solventien wie Hexan und unzersetzt verdampfbar. Es ergaben sich keine Hinweise darauf, daß die SiO‐Gerüste in den gebildeten Siloxanen Ausschnitte aus einer der Strukturen der SiO2‐Modifikationen darstellen.

CVD in Hot Wall Reactors—The Interaction Between Homogeneous Gas-Phase and Heterogeneous Surface Reactions

“…[17] Another impressive example has recently been published; it is concerned with chemical vapor deposition of silicon dioxide from silicon tetrachloride and oxygen. [18] In this study chlorine-substituted, soluble polysiloxanes with a molecular mass of several thousand have been detected. The problem of complex gas-phase reactions in relation to the overall deposition process has been treated in several chapters of reference.…”

Reaction Mechanism of Chlorosiloxane Ring Formation from SiCl4 and O2

“…The reaction of SiCl 4 with O 2 is of great technological importance for the chemical vapor deposition (CVD) of solid SiO 2 films used in the microelectronics industry and synthesis of the ceramic powders. − The basic reaction occurs when the mixture of O 2 with SiCl 4 , in a tube of about 30 cm length, is heated above 1000 °C. , However, in the temperature range of 800−1000 °C, the resulting product consists of a multitude of chlorosiloxanes of the general formula Si x O y Cl z . , These chlorosiloxanes have a variety of shapes and sizes ranging from chains and rings to oligocyclic and polycyclic shapes. A large number of chlorosiloxanes were identified by mass spectrometry. − These chlorosiloxanes are intermediate compounds formed in the course of the reaction because of the partial replacement of Cl atoms in SiCl 4 by oxygen atoms.…”

“…5,6 However, in the temperature range of 800-1000 °C, the resulting product consists of a multitude of chlorosiloxanes of the general formula Si x O y Cl z . 6,7 These chlorosiloxanes have a variety of shapes and sizes ranging from chains and rings to oligocyclic and polycyclic shapes. A large number of chlorosiloxanes were identified by mass spectrometry.…”

“…A large number of chlorosiloxanes were identified by mass spectrometry. [6][7][8][9][10][11] These chlorosiloxanes are intermediate compounds formed in the course of the reaction because of the partial replacement of Cl atoms in SiCl 4 by oxygen atoms.…”

Nonclassical Pathways for Silsesquioxane Growth

“…The importance of siloxanes in chemical vapor deposition (CVD) processes has been repeatedly discussed. , In the combustion of SiCl 4 in O 2 , which leads to silicon dioxide, hundreds of intermediates of chlorosiloxanes have been detected. − Such cluster compounds can be considered as connecting links between molecules and solids. Among the siloxanes, the silsesquioxanes of composition Si n O 3 n /2 R n (R = Cl, H, or other substituents) are most interesting.…”