Trichloro (methyl) silane

Structural formula
General
Surname	Trichloro (methyl) silane
other names	Trichloromethylsilane Methyltrichlorosilane Methylsilyl trichloride Methyl silicone trichloride
Molecular formula	CH 3 Cl 3 Si
Brief description	highly flammable, colorless liquid with a pungent odor
External identifiers / databases
CAS number 75-79-6 EC number 200-902-6 ECHA InfoCard 100,000,821 PubChem 6399 Wikidata Q1814764
properties
Molar mass	149.48 g mol −1
Physical state	liquid
density	1.29 g cm −3 (20 ° C)
Melting point	−90 ° C
boiling point	66 ° C
Vapor pressure	179 hPa (20 ° C) 274 hPa (30 ° C) 406 hPa (40 ° C) 585 hPa (50 ° C)
solubility	reacts violently with water
Refractive index	1.4106 (20 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 225-315-319-335 EUH: 014 P: 302 + 352-304 + 340-305 + 351 + 338-403 + 235
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Trichlor (methyl) silane is a colorless, clear liquid with a pungent odor. It belongs to the group of halogenated silanes and is a basic chemical in organic chemical synthesis, especially in protecting group chemistry .

Extraction and presentation

Trichloro (methyl) silane is produced together with dichlorodimethylsilane and chlorotrimethylsilane via the Müller-Rochow synthesis . Powdered silicon reacts with chloromethane at 350 ° C in the presence of powdered copper and copper oxide as a catalyst to initially form dichlorodimethylsilane, which disproportionates to chlorotrimethylsilane and trichloromethylsilane under the reaction conditions :

The product mixture can be separated by distillation due to the different boiling points of its components. Traces of hydrogen chloride , which may be present in the chlorotrimethylsilane due to hydrolysis , can be removed by distillation with the addition of a little quinoline .

properties

Physical Properties

Trichloromethylchlorosilane is a colorless, pungent smelling liquid that smokes heavily in the air due to the splitting off of hydrogen chloride. The compound boils at 66 ° C. under normal pressure . The heat of vaporization at the boiling point is 30.7 kJ mol ⁻¹ . According to Antoine, the vapor pressure function results from ln (P) = A− (B / (T + C)) (P in bar, T in K) with A = 3.997033, B = 1167 and C = −47 in the temperature range of 287 to 337.5 K. The heat capacity at 25 ° C is 163.1 J mol ⁻¹ K ⁻¹ or 1.09 J g ⁻¹ K ⁻¹ .

Chemical properties

Violent hydrolysis occurs with water. The connection is very corrosive.

Safety-related parameters

Trichloromethylchlorosilane forms highly flammable vapor-air mixtures. The compound has a flash point of −15 ° C. The explosion range lies between 7.6% by volume (470 g · m ⁻³ ) as the lower explosion limit (LEL) and 10.4% by volume as the upper explosion limit (UEL). The ignition temperature is above 500 ° C. The substance therefore falls into temperature class T1.

use

Trichlor (methyl) silane is a raw material for the production of fumed silica and high-purity silicon carbide , whereby it has to be heated to 1110 ° C to 1900 ° C:

${\displaystyle \mathrm {CH_{3}SiCl_{3}\longrightarrow SiC+3\,HCl} }$

safety instructions

Since the vapors are heavier than air, explosive mixtures can form on the floor. In contact with water and humidity, hydrochloric acid forms , which can lead to chemical burns.

Individual evidence

1. ↑ ^{a b c d e f g h i j k l m n} Entry on trichloromethylsilane in the GESTIS substance database of the IFA , accessed on April 17, 2020(JavaScript required) .
2. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-378.
3. ↑ Entry on trichloro (methyl) silane in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
4. ↑ Rugina, T .; Gaspar, M .; Sacarescu, L .: Liquid-vapor equilibrium for a binary system of dichlorodimethyl-silane with trichloromethylsilane, chloromethylsilane and silicon tetrachloride in Rev. Chim. (Bucharest) 38 (1987) 680.
5. ↑ Golubkov, YV; Lapidus, II; Nisel'son, LA: in Russ. J. Phys. Chem. 41 (1967) 1122.
6. ↑ Jenkins, AC; Chambers, GF: Vapor Pressures of Silicon Compounds in Ind. Eng. Chem. 46 (1954) 2367-2369, doi : 10.1021 / ie50539a043 .
7. ↑ Samorukov, OP; Kostryukov, VN: Thermodynamics of organic derivatives of chlorosilanes. Low-temperature heat capacities, melting points, heats of fusion, and thermodynamic functions of the condensed phases of trichloromethylsilane and dichloromethylsilane in Russ. J. Phys. Chem. 45 (1971) 747-748.
8. ↑ Entry on methylchlorosilanes. In: Römpp Online . Georg Thieme Verlag, accessed on April 17, 2020.
9. ↑ E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.