Trimethylsilanol

Structural formula
General
Surname	Trimethylsilanol
other names	Hydroxytrimethylsilane Trimethylhydroxysilane MOH
Molecular formula	C 3 H 10 OSi
Brief description	colorless clear liquid
External identifiers / databases
CAS number 1066-40-6 EC number 213-914-1 ECHA InfoCard 100.012.650 PubChem 66110 Wikidata Q416218
properties
Molar mass	90.20 g mol −1
Physical state	liquid
density	0.95 g cm −3
Melting point	−4.5 ° C
boiling point	98 ° C
Vapor pressure	21 mbar (20 ° C)
solubility	35–43 g · l −1 in water
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 225-332 P: 210
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Trimethylsilanol ( TMS ) is a chemical compound and belongs to the group of silanols . It is a derivative of silane and the silicon analogue of tert- butanol .

Presentation and extraction

Simple hydrolysis of the chlorotrimethylsilane tends to lead to the etherification product hexamethyldisiloxane because of the by-product hydrochloric acid .

${\displaystyle \mathrm {2\ ClSi(CH_{3})_{3}{\xrightarrow[{-2\ HCl}]{+2\ H_{2}O}}\ 2\ HOSi(CH_{3})_{3}\ {\xrightarrow[{-H_{2}O}]{\ }}\ (CH_{3})_{3}Si{-}O{-}Si(CH_{3})_{3}} }$

Trimethylsilanol is accessible through a weakly basic hydrolysis, since dimerization can be avoided in this way. Trimethylsilanol can also be obtained by the basic hydrolysis of hexamethyldisiloxane .

properties

Trimethylsilanol is a volatile organic liquid with a boiling point of 98 ° C. The heat of vaporization is 45.64 kJ · mol ⁻¹ , the entropy of vaporization 123 J · K ⁻¹ · mol ⁻¹ . According to Antoine, the vapor pressure function results from log ₁₀ (P) = A− (B / (T + C)) (P in bar, T in K) with A = 5.44591, B = 1767.766 and C = −44.888 in the temperature range from 291 K to 358 K. Below the melting point at −4.5 ° C, the compound solidifies in a monoclinic crystal lattice. Trimethylsilanol is provided with a pK _a value of 11, a weak acid. The acid strength is comparable to that of orthosilicic acid , but much higher than that of alcohols such as. B. tert -butanol (pK _a 19).

use

TMS is used for the hydrophobic coating of silicate surfaces. It reacts with the silanol groups (R ³ SiOH) of the substrate , creating a layer of methyl groups . TMS usually occurs as a contaminant in spaceships because it outgasses from the silicone- based materials.

Like other silanols, TMS is being studied for use as an antimicrobial agent.

TMS is a possible hydrolysis product of PDMS chain end groups .

See also

• Dimethylsilanediol
• Methylsilanetriol

Individual evidence

1. ↑ ^{a b} Trimethylsilanols. Retrieved November 7, 2009.
2. ↑ ^{a b} Batuew et al. in Doklady Akademii Nauk SSSR 95 (1954) 531.
3. ↑ ^{a b} Stepovik, LP; Kazakina, SV; Martynova, IM in Russian Journal of General Chemistry - English Version 70 (2000) 1371-1377 or Zhurnal Obshchei Khimii 70 (2000) 1459-1461.
4. ↑ ^{a b c} Grubb, WT; Osthoff, RC: Physical Properties of Organosilicon Compounds. II. Trimethylsilanol and triethylsilanol in J. Am. Chem. Soc. 1953, 75: 2230-2232; doi : 10.1021 / ja01105a061 .
5. ↑ SM Mazzoni, S. Roy, S. Grigoras: Eco-Relevant Properties of Selected Organosilicon Materials . In: G. Chandra (Ed.): The Handbook of Environmental Chemistry - Organosilicon Materials . Springer-Verlag, Berlin / Heidelberg 1997, ISBN 3-540-62604-2 (Vol. 3, Part H).
6. ↑ ^{a b} Entry on trimethylsilanol in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
7. ↑ Trimethylsilanol data sheet from Sigma-Aldrich , accessed on January 13, 2020 ( PDF ). .
8. ^ Didier Astruc: Organometallic Chemistry and Catalysis. Springer Science & Business Media, 2007, ISBN 978-3-540-46129-6 , p. 331 ( limited preview in Google book search).
9. ↑ JA Cella, JC Carpenter: Procedures for the preparation of silanols in J. Organomet. Chem. 480: 23-23 (1994); doi : 10.1016 / 0022-328X (94) 87098-5
10. ↑ M. Lovric, I. Cepanec, M. Litvic, A. Bartolincic, V. Vinkovic: Croatia Chem. Acta 80 (2007), 109-115.
11. ↑ Entry on silanol, trimethyl- (phase change data). In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD, accessed May 2, 2013.
12. ↑ R. Minkwitz, S. Schneider: The low temperature crystal structure of trimethylsilanol. In: Journal of Nature Research B . 53, 1998, pp. 426-429 ( PDF , free full text).
13. ↑ ^{a b} T. Kagiya, Y. Sumida, T. Tachi: An Infrared Spectroscopic Study of hydrogen bonding interaction. Structural Studies of Proton-donating and -accepting Powers in Bull. Chem. Soc. Japan, 43: 3716-3722 (1970).
14. ^ Trimethylsilanol , Harold L. Kaplan, Martin E. Coleman, and John T. James Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants , Volume 1 (1994).
15. Jump up ↑ Yun-mi Kim, Samuel Farrah, Ronald H. Baney: Silanol - A novel class of antimicrobial agent . In: Electronic Journal of Biotechnology . 9, No. 2, 2006, p. 176. doi : 10.2225 / vol9-issue2-fulltext-4 .

Web links

• Entry on trimethylsilanol in the GESTIS substance database of the IFA (JavaScript required)