US EPA

1353772 

Book/Book Chapter 

Liquid sulfur 

Steudel, R 

2003 

TOPICS IN CURRENT CHEMISTRY 

230 

81-116 

10.1007/b12111 

WOS:000187853100002 

The molecular composition as well as the physical properties
(including spectra) of liquid sulfur are reviewed starting with a historic Introduction to
explain the terms pi-sulfur and mu-sulfur. At all temperatures the melt contains homocyclic rings
of between 6 and at least 35 atoms with S-8 as the majority species as well as polymeric sulfur
(S-infinity) which becomes a major component only above 170 degreesC. The polymer probably
consists of very large rings at temperatures below 157 degreesC but above this temperature very
long diradicalic chains occur in addition. At temperatures above 300 degreesC highly colored
small molecules like S-3 and, at even higher temperatures, S-4 can be detected spectroscopically.
According to quantum-chemical calculations branched rings (clusters) will be minor components at
temperatures near the boiling point only. The temperature dependence of the composition is
explained and the various polymerization theories for the transformation of S-8 into S-infinity
as well as the molecular nature of the polymer are discussed. In addition, the various analytical
techniques applied to solve the composition problem of liquid sulfur are described. 

sulfur rings; sulfur chains; branched rings; thermodynamics; polymerization; photochemistry