Organosilanols

Structure of trimethylsilanol

As organosilanols a group of chemical compounds of silicon , respectively. More precisely, they are carbosilanes which are derivatized with at least one hydroxyl group on the silicon atom . Organosilanols are the silicon analogues of alcohols .

Manufacturing

Organosilanols can be obtained by hydrolysis of organohalosilanes such as chlorotrimethylsilane . Organosilanols can also be produced by the oxidation of organosilanes with oxidizing agents or by hydrolysis in an alkaline medium.

${\displaystyle \mathrm {(H_{3}C)_{3}SiCl+\ H_{2}O\longrightarrow (H_{3}C)_{3}SiOH+\ HCl} }$

${\displaystyle \mathrm {R_{2}SiCl_{2}+\ 2\ HgO{\xrightarrow[{-80\,{}^{\circ }C}]{Toluol}}R_{2}Si(OH)_{2}+\ 2\ Hg^{0}\ \ \ R=organischer\ Rest} }$

${\displaystyle \mathrm {R_{3}SiH+\ H_{2}O\longrightarrow R_{3}SiOH+\ H_{2}\ \ \ R=organischer\ Rest} }$

The hydrolysis of silyl ethers , on the other hand, is usually slow:

${\displaystyle \mathrm {(H_{5}C_{2})_{3}SiOC_{2}H_{5}+\ H_{2}O\longrightarrow (H_{5}C_{2})_{3}SiOH+\ HOC_{2}H_{5}} }$

The hydrolysis of organosilanes is a first-order reaction . The rate of hydrolysis of the Si-H bond depends on the type and number of organic residues. The hydrolysis of trialkylsilanes is significantly slower than that of triarylsilanes. This can be explained by a greater increase in the electron density on the silicon atom due to the alkyl groups. The reaction rate of the tri-n-alkylsilanes decreases accordingly in the series ethyl, propyl, butyl. In the case of trialkylsilanes, the silanes with n-alkyl radicals react 10 times faster than the analogous silanes with branched alkyl radicals.

Systematics

A further distinction can be made depending on the substitution pattern of the silicon atom. Compounds where on the silicon atom

• an organyl radical and three hydroxyl groups are linked as organosilanetriols
  • z. E.g .: methylsilanetriol , phenylsilanetriol
• two organyl residues and two hydroxyl groups are bound as organosilanediols
  • z. E.g .: dimethylsilanediol , diphenylsilanediol
• three organyl residues and one hydroxyl group are bound as organosilanols
  • z. E.g .: trimethylsilanol , triethylsilanol , triphenylsilanol

designated.

literature

• Paul D. Lickiss: The synthesis and structure of organosilanols. In: Advances in Inorganic Chemistry . 42, 1995, pp. 147-262, doi: 10.1016 / S0898-8838 (08) 60053-7 .

Web links

Commons : Organosilanols  - Collection of images, videos and audio files

Individual evidence

1. ↑ Entry on silanols . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.S05664 Version: 2.3.3.
2. ↑ ^{a b} Barry Arkles: Silanes. (PDF) Reprint from Kirk-Othmer Encyclopedia of Chemical Technology, Forth Edition, Volume 22, Page 38-69. In: Gelest. P. 50 , accessed on December 10, 2016 (English). 
3. ↑ G. Schott, C. Harzdorf: Silanes. I Alkaline solvolysis of triorganosilanes . In: Journal of Inorganic and General Chemistry . tape 306 , no. 3-4 , October 1960, pp. 180-190 , doi : 10.1002 / zaac.19603060306 .
4. ↑ R. Pietschnig, p Spirk: The Chemistry of Organo Silanetriols . Coord. Chem. Rev. 2016, pp. 87-106, doi: 10.1016 / j.ccr.2016.03.010 .