SILANES

1. SILANES Hydrides of silanes are known as silanes. Sin H2n+2 (n ups 7) Preparation By the action of acids on metallic silicides. Mg2 Si + 4 HCl 2 MgCl2 + SiH4 By reacting SiCl4 with LiAlH4 in ether at low temperature. SiCl4 + LiAlH4  SiH4 + LiCl + Alcl3 4bcL3 + LiAlH4  AlCl3 + LiCl + B2 H6 ii) All Silanes are prepared by the reduction of corresponding chlorides using Lithium Aluminum hydride in ether solution. 2Si2 Cl6 + 3 LiAlH4  2 Si2 H6 + 3LiCl + 3 AlCl3 Properties All the silanes are colourless volatile covalent compounds. The first two silanes are gases while other are liquids Action of alkali solution : Silanes are soluble in strong alkale solution in presence of air and evolve H2 2 SiH4 + 4 NaoH + O2  2 No2 SiO3 + 6H2 4. Action of Hcl & HBr SiH4 when treated with HCl or HBr at 1000 C in presence of a catalyst Al2 Cl3 results in the substitution of H-atom by Cl/Br atom. Al2 Cl3 SiH4 + 4 HCl SiH3Cl + H2

2. Silanes (also known as saturated hydrosilicons) are chemical compounds that consist only of hydrogen and silicon atoms and are bonded exclusively by single bonds (i.e., they are saturated compounds) without any cycles (or loops; i.e., cyclic structure). Silanes belong to a homologous series of inorganic compounds, analogous to alkanes, in which the members differ by a constant relative molecular mass of 30. Each silicon atom has 4 bonds (either Si-H or Si-Si bonds), and each hydrogen atom is joined to a silicon atom (H-Si bonds). A series of linked silicon atoms is known as the silicon skeleton or silicon backbone.

3. 5. Action of heat : when heated to v. high temperatures, silanes break into its elements 670k 470k SiH4 Si + 2H2 Si2 H6 2Si + 3H2 ∆ ∆ 6. Action of salts : Ag is pptd when SiH4 reacts with Agcl in heated flow reactor 200 0 C SiH4 + 2 Agcl SiH3Cl + HCl + 2 Ag Silanes have structure similar to alkanes i.e. to those of the corresponding saturated hydrocarbons. Difference between alkanes and silanes

4. Silanes (also known as saturated hydrosilicons) are chemical compounds that consist only of hydrogen and silicon atoms and are bonded exclusively by single bonds (i.e., they are saturated compounds) without any cycles (or loops; i.e., cyclic structure). Silanes belong to a homologous series of inorganic compounds, analogous to alkanes, in which the members differ by a constant relative molecular mass of 30. Each silicon atom has 4 bonds (either Si-H or Si-Si bonds), and each hydrogen atom is joined to a silicon atom (H-Si bonds). A series of linked silicon atoms is known as the silicon skeleton or silicon backbone.