but it can be obtained pure as a dark-red liquid by fractional distillation in presence of some PCl5, which stabilizes SCI2.
Sulfur chlorides are solvents for sulfur, giving dichlorosulfanes up to about S100Cl2, Which are used in the vulcanization of rubber. They are also used as mild chlorinating agents.
Thionyl chloride, SOCl2, is obtained by the reaction
It is colorless fuming liquid (bp 80o) readily hydrolyzed by water
Because of this reaction in which the volatile products are easily removed. SOCI2 can often be used to prepare anhydrous chlorides. Examples are:
Thionyl chloride has a pyramidal structure with sulfur using a set of roughly sp3 hybrid orbitals , one of which holds the lone pair. SOCl2 can hence act as a weak Lewis base.
Sulfuryl chloride, SO2Cl2, is obtained by the reaction
in presence of a catalyst such as FeCl3,. It is a colorless liquid fuming in moist air and is used for chlorinating organic compounds. It is readily hydrolyzed by water.
19-5 Oxides and Oxo Acids
The dioxides are obtained by burning the elements in air. Sulfur dioxide is produced when many sulfides are heated in air. Selenium and tellurium dioxides are also obtained by treating the metals with hot nitric acid to form H2SeO3 and 2TeO2∙HNO3, respectively, and then heating these to drive off water or nitric acid
Sulfur dioxide is a gas with a pungent smell. The molecule is angular. Liquid SO2 dissolves many organic and inorganic substances and is used as a solvent for nmr studies as well as in preparative reactions. The liquid does not undergo self- ionization and Its conductivity is mainly a reflection of the purity.
Sulfur dioxide has lone pars and can act as a Lewis base. However, it also acts as a Lewis acid giving complexes, for example, with amines as in Me3NSO2 and with electron-rich transition metal complexes. In the crystalline compound SbF5 ∙SO3, which is of interest because of the use of SO2 as a solvent for superacid systems (page 177), the SO2 is bound as in (19-III). The bonding in