Polysulfanes

Polysulphanes ( polysulphurous hydrogen ) are chain-like chemical compounds made from sulfur and hydrogen with the formula HS _n -H. The starting compound monosulfane with n = 1 is generally known under the name hydrogen sulfide . Connections with values ​​for n between 2 and 18 are known.

Extraction and presentation

When a solution of a polysulphide (e.g. sodium polysulphide ) reacts while cooling with hydrochloric acid

${\displaystyle \mathrm {Na_{2}S_{n}+2\ HCl\longrightarrow 2\ NaCl+H_{2}S_{n}} }$

or the decomposition of solid polysulphides with anhydrous formic acid , yellow crude sulphane is deposited , which consists of a mixture of polysulphanes (n <= 8), which can be broken down into its components by high vacuum distillation .

The conversion of dichloropolysulfanes with twice the stoichiometric amount of mono- or polysulfanes results in higher polysulfanes.

${\displaystyle \mathrm {S_{n}Cl_{2}+2\ H_{2}S_{m}\longrightarrow 2\ HCl+H_{2}S_{n+2m}} }$

properties

All polysulfanes are colorless to yellowish, pungent-smelling liquids that are easily soluble in carbon disulfide . They are thermodynamically unstable and break down into hydrogen sulfide and sulfur. Bases, as well as ammonia and quartz powder, act as decomposition catalysts, which is why polysulfanes are violently decomposed by alkaline solutions.

${\displaystyle \mathrm {H_{2}S_{n}\rightleftharpoons H_{2}S+(n-1)/8\ S_{8}} }$

They are weak acids.

Polysulfanes

Surname		formula	CAS	description	density	Melting temperature	Boiling temperature
Disulfane		H 2 S 2	13465-07-1	colorless liquid	1.376 g cm −3	−89.6 ° C	70.7 ° C
Trisulfan		H 2 S 3	13845-23-3	light yellow liquid	1.491 g cm −3	−53 ° C	90 ° C (decomposition)
Tetrasulfan		H 2 S 4		light yellow liquid	1.588 g cm −3	−85 ° C
Pentasulfane		H 2 S 5		light yellow liquid	1.660 g cm −3		40 ° C (decomposition)
Hexasulfane		H 2 S 6		yellow liquid	1.699 g cm −3
Heptasulfane		H 2 S 7			1.721 g cm −3
Octasulfane		H 2 S 8			1.747 g cm −3

use

Polysulfanes are important for condensation reactions for the synthesis of other chemical compounds, for example sulfur rings.

${\displaystyle \mathrm {H_{2}S_{6}+Cl_{2}S_{6}\longrightarrow S_{12}+2\ HCl} }$

Individual evidence

1. ↑ ^{a b c d e f g h} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 560.
2. ^ ^{A b c} Erwin Riedel , Christoph Janiak: Inorganische Chemie . Walter de Gruyter, 2011, ISBN 3-11-022566-2 , p. 446 ( limited preview in Google Book search).
3. ↑ Ralf Steudel : Chemistry of the non-metals: with atomic structure, molecular geometry and bond theory . Walter de Gruyter, 1998, ISBN 3-11-015902-3 , p. 284 ( limited preview in Google Book search).
4. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 364.