Dichloro (dimethyl) silane

Structural formula
General
Surname	Dichloro (dimethyl) silane
other names	Dichlorodimethylsilane; Dimethyldichlorosilane; Repel silane; DMDCS;
Molecular formula	C 2 H 6 Cl 2 Si
Brief description	colorless, highly flammable liquid with a pungent odor
External identifiers / databases
EC number	200-901-0
ECHA InfoCard	100,000,820
PubChem	6398
Wikidata	Q416690
properties
Molar mass	129.06 g mol −1
Physical state	liquid
density	1.06 g cm −3
Melting point	−86 ° C
boiling point	70 ° C
Vapor pressure	150 h Pa (20 ° C); 232 hPa (30 ° C); 347 hPa (40 ° C); 504 hPa (50 ° C); 865 hPa (60 ° C);
solubility	violent decomposition in water
safety instructions
H and P phrases	H: 225-302-331-314
	EUH: 014-071
	P: 210-261-280-305 + 351 + 338-310
Toxicological data	6056 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Dichloro (dimethyl) silane is a colorless, caustic, highly flammable liquid that belongs to the group of silanes . It is mainly used for silylation . The resulting derivatives are generally more thermally stable and hydrophobic .

Extraction and presentation

Dichloro (dimethyl) silane is produced together with chloro (trimethyl) silane and trichloro (methyl) silane via the Müller-Rochow synthesis . Powdered silicon reacts with chloromethane at 350 ° C in the presence of powdered copper and copper (I) chloride as a catalyst to form dichloro (dimethyl) silane.

properties

Dichloro (dimethyl) silane is a colorless liquid that hydrolyzes in moist air or water to form polymeric methylsiloxanes. The compound decomposes at the boiling point of 70 ° C. According to Antoine, the vapor pressure function results accordingly:

{\ displaystyle \ log _ {10} (p) = 4.26844 - {\ frac {1328} {T-32}} ~~~ \ mathrm {(p ~ in ~ bar, ~ T ~ in ~ K)} }

in the temperature range of 301 K to 345 K. dichloro (dimethyl) silane at 25 ° C has a dynamic viscosity of 0.64 mPa · s .

Important thermodynamic quantities are given in the following table:

Compilation of the most important thermodynamic properties
property	Type	Value [unit]	Remarks
Heat capacity	c _p	171.5 J mol ⁻¹ K ⁻¹ (25 ° C) 1.33 J g ⁻¹ K ⁻¹ (25 ° C)	as a liquid
Critical temperature	T _c	520.4 K
Critical pressure	p _c	34.90 bar
Critical density	ρ _c	2.86 mol·l ⁻¹
Enthalpy of evaporation	Δ _V H	31.5 kJ mol ⁻¹	at 316 K
Enthalpy of fusion	Δ _F H	8.828 kJ mol ⁻¹

Safety-related parameters

Dichloro (dimethyl) silane forms highly flammable vapor-air mixtures. The compound has a flash point of −12 ° C. The explosion range is between 3.4% by volume (180 g / m ³ ) as the lower explosion limit (LEL) and> 9.5% by volume (> 510 g / m ³ ) as the upper explosion limit (UEL).) The The limit gap width was determined to be 0.98 mm. This results in an assignment to explosion group IIA. The ignition temperature is 425 ° C. The substance therefore falls into temperature class T2.

use

Dichloro (dimethyl) silane is a universal silylating agent (e.g. for the derivatization of alcohols , diols , carboxylic acids , (di) amines , amides , ketones , dithiols , etc.) and is mainly used as an intermediate in the production of silicones . Since the compound imparts hydrophobic properties to other compounds , it can be used (e.g. in food chemistry) to prevent clumping.

safety instructions

Dichloro (dimethyl) silane reacts with alcohols, amines, alkalis, acids and water.

Risk assessment

The toxicity to mammals is LC ₅₀ : 4.91 mg / l / 4 h ( inhalation , rat) and LD ₅₀ : 6060 mg / kg (oral, rat).

In 2012, dichloro (dimethyl) silane was included in the EU's ongoing action plan ( CoRAP ) in accordance with Regulation (EC) No. 1907/2006 (REACH) as part of substance evaluation . The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. The reasons for the uptake of dichloro (dimethyl) silane were concerns regarding high (aggregated) tonnage and the dangers arising from a possible assignment to the group of PBT / vPvB substances. The re-evaluation took place from 2014 and was carried out by the Czech Republic . A final report was then published.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s Entry on dichlorodimethylsilane in the GESTIS substance database of the IFA , accessed on May 23, 2017(JavaScript required) .
↑ Entry on dichloro (dimethyl) 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 .
↑ Data sheet dichloro (dimethyl) silane (PDF) from Merck , accessed on January 19, 2011.
↑ ^a ^b Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 707.
^ ^A ^b Arthur C. Jenkins, George F. Chambers: Vapor Pressures of Silicon Compounds. In: Ind. Eng. Chem. 46, 1954, pp. 2367-2369, doi: 10.1021 / ie50539a043 .
↑ ^a ^b O. P. Samorukov, VN Kostryukov: 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, pp. 747-748.
↑ ^a ^b ^c N. G. Stepanov, VF Nozdrev: Physical Properties of Certain Organic Derivatives of Chlorosilane in the Critical Region. In: Russ. J. Phys. Chem. (Engl. Transl.). 42, 1968, pp. 1300-1302.
↑ ^a ^b ^c ^d ^e E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.
^ European Chemicals Agency (ECHA): Substance Evaluation Report and Conclusion Document .
↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Dichloro (dimethyl) silane , accessed on March 26, 2019.

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s Entry on dichlorodimethylsilane in the GESTIS substance database of the IFA , accessed on May 23, 2017(JavaScript required) .

[CLP_100.000.820-2] Entry on dichloro (dimethyl) 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 .

[Merck-3] Data sheet dichloro (dimethyl) silane (PDF) from Merck , accessed on January 19, 2011.

[brauer-4] Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 707.

[Jenkins-5] A ^b Arthur C. Jenkins, George F. Chambers: Vapor Pressures of Silicon Compounds. In: Ind. Eng. Chem. 46, 1954, pp. 2367-2369, doi: 10.1021 / ie50539a043 .

[Samorukov-6] O. P. Samorukov, VN Kostryukov: 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, pp. 747-748.

[Stepanov-7] N. G. Stepanov, VF Nozdrev: Physical Properties of Certain Organic Derivatives of Chlorosilane in the Critical Region. In: Russ. J. Phys. Chem. (Engl. Transl.). 42, 1968, pp. 1300-1302.

[Brandes-8] E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.

[9] European Chemicals Agency (ECHA): Substance Evaluation Report and Conclusion Document .

[10] Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Dichloro (dimethyl) silane , accessed on March 26, 2019.