Carbonyl sulfide

Structural formula
General
Surname	Carbonyl sulfide
other names	Carbon oxide sulfide Carbon oxysulfide COS
Molecular formula	COS
Brief description	colorless, malodorous gas
External identifiers / databases
CAS number 463-58-1 EC number 207-340-0 ECHA InfoCard 100.006.674 PubChem 10039 ChemSpider 9644 Wikidata Q412371
properties
Molar mass	60.07 g mol −1
Physical state	gaseous
density	2.72 g l −1 (0 ° C, 1013 hPa) 1.18 g cm −3 (liquid at boiling point)
Melting point	−138.81 ° C
boiling point	−50.2 ° C
Vapor pressure	1.13 MPa (20 ° C)
solubility	bad in water (1.45 g l −1 )
Refractive index	1.24 (−87 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 220-280-331-315-319-335 P: 210-261-305 + 351 + 338-311-410 + 403
Thermodynamic properties
ΔH f 0	−142.0 kJ / mol
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

Carbonyl sulfide is a colorless, flammable, poisonous gas with an unpleasant odor. Chemically pure COS should, however, be odorless. It plays an important role, especially in atmospheric chemistry.

history

It was discovered in 1867 by the Hungarian chemist Carl von Than . In 1868 von Than received the Lieben Prize from COS for his work on the absorption coefficients .

Occurrence

Carbonyl sulfide is mainly formed in the atmosphere. However, it is also found in natural gas , volcanic gases, biogas and as a by-product in the chemical industry.

Extraction and presentation

In the laboratory, carbonyl sulfide can be prepared from potassium thiocyanate and sulfuric acid . In addition to potassium hydrogen sulfate and ammonium hydrogen sulfate , gaseous COS with various impurities such as carbon dioxide , sulfur dioxide , hydrogen sulfide , carbon disulfide , formaldehyde and hydrocyanic acid is also produced . It must therefore be cleaned.

${\displaystyle \mathrm {KCNS+2\,H_{2}SO_{4}+H_{2}O\rightarrow KHSO_{4}+NH_{4}HSO_{4}+COS} }$

Another synthetic route consists in the reaction of carbon monoxide with sulfur vapor in glowing tubes:

${\displaystyle \mathrm {CO+S\longrightarrow COS} }$

Another possibility for the synthesis of COS is the incomplete oxidation of a stoichiometric mixture of carbon and sulfur with oxygen according to the following reaction equation:

${\displaystyle \mathrm {2\ C+2\ S+O_{2}\longrightarrow 2\ COS} }$

Linear molecular structure with indication of the bond lengths.

properties

The carbonyl sulfide molecule has a linear structure: the carbon atom is linked to sulfur and oxygen via a double bond . It is isoelectronic to carbon dioxide and carbon disulfide .

Combustion in air produces carbon dioxide and sulfur dioxide :

${\displaystyle \mathrm {2\ COS+3\ O_{2}\longrightarrow 2\ CO_{2}+2\ SO_{2}} }$

With water or steam it hydrolyzes to carbon dioxide and hydrogen sulfide :

${\displaystyle \mathrm {COS+H_{2}O\longrightarrow CO_{2}+H_{2}S} }$

Carbonyl sulfide has a critical temperature of 105.3 ° C, a critical pressure of 63.5 bar and a critical volume of 0.1351 m ³ kmol ⁻¹ . The compound forms highly flammable gas-air mixtures. The explosion range is between 6.5% by volume (160 g / m ³ ) as the lower explosion limit (LEL) and 29% by volume (730 g / m ³ ) as the upper explosion limit (UEL).

Atmospheric chemistry

Carbonyl sulfide is a gas that influences aerosol formation in the atmosphere (and thus the climate) and is the dominant sulfur gas in the atmosphere. The reason for this is its longevity in the atmosphere. Like nitrous oxide (laughing gas), it is not broken down in the troposphere and thus enters the stratosphere . There it is converted into sulfate aerosols , which reflect sunlight into space and thus help cool the earth .

In nature, it is mainly formed by the action of sunlight on sulfur-containing organic compounds (e.g. dimethyl sulfoxide and CS) in the upper layers of the oceans (especially coastal areas).

use

Carbonyl sulfide is used for container fumigation to control pests such as mice and rats. In organic synthesis it is used to produce thioacids , substituted thiazoles and thiocarbamates .

Biological importance

Many plants absorb carbonyl sulfide as an organic source of sulfur during the day. The compound also plays a role in the formation of protein chains from amino acids and is believed to have an important role in the origin of life.

Individual evidence

1. ↑ ^{a b c d e f g h i j} Entry on carbon oxide sulphide in the GESTIS substance database of the IFA , accessed on January 8, 2018(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. 3-88.
3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-20.
4. ↑ ^{a b c d} Entry on carbon oxide sulfide. In: Römpp Online . Georg Thieme Verlag, accessed on November 12, 2014.
5. ↑ ESPERE Climate Encyclopedia: Gases from Sea Water ( Memento from May 23, 2014 in the Internet Archive ).
6. ^ ^{A b} P. DN Svoronos, TJ Bruno: Carbonyl Sulfide: A Review of Its Chemistry and Properties. In: Ind. Eng. Chem. Res. 41, 2002, pp. 5321-5336, doi: 10.1021 / ie020365n .
7. ↑ Eberhart Breitmaier, Günther Jung: Organic chemistry - fundamentals, compound classes, reactions, concepts, molecular structure, natural substances, synthesis planning , sustainability. 7., revised. Edition. Georg Thieme Verlag, 2012, ISBN 978-3-13-541507-9 , p. 436.
8. ↑ E. Brandes, W. Möller: Safety-related parameters. Volume 1: Flammable Liquids and Gases. Wirtschaftsverlag NW - Verlag für neue Wissenschaft, Bremerhaven 2003.
9. ^ Max Planck Institute for Chemistry: Fascination Research ( Memento from April 6, 2011 in the Internet Archive ).