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Radiochlorine exchange reactions with sulfuryl chloride

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Title Radiochlorine exchange reactions with sulfuryl chloride
Names Teague, Jack Loren (creator)
Norris, T. H. (advisor)
Date Issued 1963-12-11 (iso8601)
Note Graduation date: 1964
Abstract As part of a continuing study of sulfur containing non-aqueous
solvents, the present investigation was undertaken in an effort to obtain
a better understanding of the solvent sulfuryl chloride. The
primary object of the investigation involved a study of the rate of
radiochlorine exchange between sulfuryl and thionyl chloride in mixtures
of the two, the radioisotopic tracer chlorine-36 being used.
The principal motivation for such experiments rested in the hope of
being able to find some evidence relative to the possible significance
of an ionic dissociation process for sulfuryl chloride. The system
was of particular interest in presenting analogies to at least two
related types of systems previously studied, namely the thionyl
chloride-thionyl bromide system (where rapid radiosulfur exchange
was observed) and the thionyl chloride-sulfur monochloride system
(where negligible radiochlorine exchange occurred). The system
was further of interest in the light of the previous observation of a
rapid chlorine exchange between sulfuryl chloride and the solute
pyridinium chloride (in chloroform solution). Another point of
some pertinence related to the fact that earlier research had shown
that, between these two substances, little if any radiosulfur exchange
occurred, and the suggestion had been made that a rapid radiochlorine
exchange might result if the two substances interacted in an acid-base
type of ionization equilibrium, thionyl chloride acting as a basic,
chloride ion donor.
It was found in this work that radiochlorine exchange between
thionyl chloride and sulfuryl chloride was, at best, very slow, with
an exchange half time, t1/2, of at least 35 days or more. The rate of
the exchange did not appear to vary greatly, at least in apparent order
of magnitude, over the concentration range from a five fold excess of
sulfuryl chloride to a two fold excess of thionyl chloride, the value
of the order of magnitude at 25°C being 10⁻¹ g-atoms 1⁻¹day⁻¹. The
obtaining of precise rate data was, however, hampered both by the
extreme slowness of the reaction and by the considerable difficulty in
a clean cut reactant separation at the end of each experiment, a
factor which resulted in a large and rather irreproducible apparent
zero time exchange.
A single experiment was done investigating the radiochloride
exchange between sulfuryl chloride and the initially labeled solute tetramethylammonium chloride. Despite incomplete solution of the
salt in the solvent, 84% exchange occurred in the time of the experiment
(14.75 hours). It appears most likely that, if solution had been
complete, exchange would also have been complete within the period
of the experiment, and in all probability in a far shorter time, probably
less than an hour.
The results are taken to imply that sulfuryl chloride neither
undergoes any significant chloride ion dissociation, nor any acid-base ionic interaction with thionyl chloride. They further suggest
that exchange of the solvent with ionic chloride solutes probably
occurs via either a rapid association equilibrium or a bimolecular
equilibrium. The results demonstrate the hazard of a too indiscriminate
application of the solvent systems interpretation of chemical
phenomena in non-aqueous systems. Many processes can be better
understood in less restricted terms, Lewis acid-base concepts, for
example, being particularly useful. Further investigations of sulfuryl
chloride exchange reactions, particularly with other basic and
some acidic solutes appear most inviting.
Genre Thesis/Dissertation
Topic Sulphuryl chloride
Identifier http://hdl.handle.net/1957/48827

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