Thionyl chloride. Inorganic compound of formula SOCl 2 . It is a transparent liquid at pressure and room temperature, which decomposes around 140 ° C. It is frequently used as a chemical reagent in chlorination reactions.
Summary
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- 1 Physical properties
- 2 Chemical properties
- 3 Structure
- 4 Applications
- 1 In the industry
- 2 In organic chemistry
- 3 Other reactions
- 5 Obtaining
- 6 Safety and toxicology considerations
- 1 Health effects
- 7 Sources
Physical properties
Thionyl chloride is known by other names: Sulphurous Oxychloride, Sulphurous Dichloride, Sulfinyl Chloride, Sulfide Oxide, and Thionyl Dichloride Chloride. Its fundamental physical properties are:
- Physical state; Colorless to yellow or reddish steaming liquid, pungent odor.
- The vapor is heavier than air.
- Solubility in water: reacts
- Vapor pressure, kPa at 25 oC: 16
- Relative vapor density (air at 20 oC = 1): 4.1
- Density: 1.64 g / cm 3
- Boiling point: 74.6 oC
- Molar mass: 118.97 g / mol
- CAS number: 7719–09–7
- Viscosity 0.6 cP a? orC
- Exposure limits TLV: C 1 ppm (as STEL) (ACGIH 2003) MAK not established.
Chemical properties
- Occasionally SOCl 2is confused with sulfuryl dichloride , SO 2 Cl 2 , but the chemical properties of these compounds, S (IV) and S (VI), differ significantly.
- SOCl 2reacts with water releasing hydrogen chloride and sulfur dioxide .
H 2 O + O = S Cl 2 (g) → 2 H Cl (g) + SO 2 (g)
Since it has a high reactivity with water , SOCl 2 is not expected to occur in nature .
Structure
The SOCl 2 molecule is pyramidal, indicating the presence of a pair of electrons in the center of the S (IV): in contrast, COCl 2 is flat, with a 1.4 dipole.
Applications
In the industry
Thionyl chloride is used in the batteries of lithium-thionyl chloride as the positive active material and lithium as the negative. It is also used as a reagent for the production of other chemical compounds or materials.
In military use, thionyl chloride is used in the “di-di”, G-series nerve agent production method.
In organic chemistry
Thionyl chloride is generally used to convert carboxylic acids and alcohols into their corresponding acyl chloride and alkyl chloride, respectively. It is preferred to other reagents such as phosphorous pentachloride because the reaction products of thionyl chloride, HCl and SO2 are gaseous, simplifying the purification of the product. Excess thionyl chloride can be removed by distillation.
RC (O) OH + O = SCl 2 → RC (O) Cl + SO 2 + HCl
R-OH + O = SCl 2 → R-Cl + SO 2 + HCl
- Thionyl chloride reacts with sulfonic acid to produce thionyl dichloride.
- The substance decomposes when heated intensively above 140 ° C, producing toxic and corrosive fumes.
- Reacts violently with water to produce toxic fumes of sulfur dioxide and hydrogen chloride.
- Reacts with certain substances such as amines, bases, combustible substances and metals, creating a fire and explosion hazard.
Other reactions
Thionyl chloride reacts with the primary foramide to form isocyanides. Amides react with thionyl chloride to form “imidoyl chloride”. However, the primary amides heated with thionyl chloride continue to react to form nitriles.
Obtaining
The most important industrial synthesis is carried out by the reaction of sulfur trioxide and sulfur dichloride.
SO 3 + SCl 2 → SOCl 2 + SO 2
Other methods include:
SO2 + PCl5 → SOCl2 + POCl3
SO2 + Cl2 + SCl2 → 2 SOCl2
SO3 + Cl2 + 2 SCl2 → 3 SOCl2
The first of the three aforementioned reactions also produces phosphorous oxychloride, which resembles thionyl chloride in many of its reactions.
Safety and toxicology considerations
Industrial production is controlled under the Chemical Weapons Convention , where it is listed in Table 3 (these are chemicals that can be used as toxic chemical weapons by themselves or used in the manufacture of chemical weapons but also have large industrial applications legitimate).
Health effects
SOCl 2 is toxic, corrosive, and tear gas. Dangerous for inhalation to the eyes , skin and respiratory tract. Inhalation of the substance can cause pulmonary edema, leading to inflammation and blockage of the airways. Exposure well above LEP can lead to death. Effects may not appear immediately. Medical surveillance is recommended. By evaporating this substance at 20 o C, a harmful concentration in the air can be reached very quickly.