HOME

TheInfoList



OR:

Thioacetone is an
organosulfur compound Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulf ...
belonging to the -thione group called
thioketone In organic chemistry, thioketones (; also known as thiones or thiocarbonyls) are organosulfur compounds related to conventional ketones in which the oxygen has been replaced by a sulfur. Instead of a structure of , thioketones have the structure ...
s, with a
chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
(CH3)2CS. It is an unstable orange or brown substance that can be isolated only at low temperatures. Above , thioacetone readily converts to a polymer and a trimer, trithioacetone. It has an extremely potent, unpleasant odor, and is considered one of the worst-smelling chemicals known. Thioacetone was first obtained in 1889 by Baumann and Fromm, as a minor impurity in their synthesis of trithioacetone.William H. Sharkey (1979): "Polymerization through the carbon-sulfur double bond". ''Polymerization'', series ''Advances in Polymer Science'', volume 17, pages 73-103.


Preparation

Thioacetone is usually obtained by cracking the cyclic trimer trithioacetone, CH3)2CSsub>3. The trimer is prepared by pyrolysis of allyl isopropyl sulfide or by treating acetone with hydrogen sulfide in the presence of a
Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
. The trimer cracks at to give the thione. :


Polymerization

Unlike its oxygen analogue
acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscibl ...
, which does not polymerise easily, thioacetone spontaneously
polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
izes even at very low temperatures, pure or dissolved in
ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again ...
or
ethylene oxide Ethylene oxide is an organic compound with the formula . It is a cyclic ether and the simplest epoxide: a three-membered ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless and flammable gas with a faintly sw ...
, yielding a white solid that is a varying mixture of a linear polymer and the cyclic trimer trithioacetone. Infrared absorption of this product occurs mainly at 2950, 2900, 1440, 1150, 1360, and 1375 cm−1 due to the
geminal In chemistry, the descriptor geminal () refers to the relationship between two atoms or functional groups that are attached to the same atom. A geminal diol, for example, is a diol (a molecule that has two alcohol functional groups) attached t ...
methyl pairs, and at 1085 and 643 cm−1 due to the C–S bond. The 1H NMR spectra shows a single peak at x = 8.1. The mean molecular weight of the polymer varies from 2000 to 14000 depending on the preparation method, temperature, and presence of the
thioenol In organic chemistry, thioenols (also known as alkenethiols) are alkenes with a thiol group () affixed to one of the carbon atoms composing the double bond (i.e. ). They are the sulfur analogs of enols (hence the '' thio-'' prefix). Alkenes with ...
tautomer Tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hy ...
. The polymer melts in the range of about 70 °C to 125 °C. Polymerization is promoted by
free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Ailments of unknown cause Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabo ...
s and light. The cyclic trimer of thioacetone (trithioacetone) is a white or colorless compound with a melting point of , near room temperature. It also has a disagreeable odor.


Odor

Thioacetone has an intensely foul odor. Like many low molecular weight organosulfur compounds, the smell is potent and can be detected even when highly diluted. In 1889, an attempt to distill the chemical in the German city of
Freiburg Freiburg im Breisgau (; abbreviated as Freiburg i. Br. or Freiburg i. B.; Low Alemannic: ''Friburg im Brisgau''), commonly referred to as Freiburg, is an independent city in Baden-Württemberg, Germany. With a population of about 230,000 (as o ...
was followed by cases of vomiting, nausea and unconsciousness in an area with a radius of around the laboratory due to the smell. In an 1890 report, British chemists at the Whitehall Soap Works in
Leeds Leeds () is a city and the administrative centre of the City of Leeds district in West Yorkshire, England. It is built around the River Aire and is in the eastern foothills of the Pennines. It is also the third-largest settlement (by popul ...
noted that dilution seemed to make the smell worse and described the smell as "fearful". Thioacetone is considered a dangerous chemical due to its extremely foul odor and ability to render people unconscious, induce vomiting, and be detected over long distances. In 1967, Esso researchers repeated the experiment of cracking trithioacetone, at a laboratory south of Oxford, UK. They reported their experience as follows:


See also

* Thiobenzophenone, a thioketone that can be isolated as a solid *
Bromoacetone Bromoacetone is an organic compound with the formula . It is a colorless liquid although impure samples appear yellow or even brown. It is a lachrymatory agent and a precursor to other organic compounds. Occurrence in nature Bromoacetone is ...
*
Chloroacetone Chloroacetone is a chemical compound with the formula . At STP it is a colourless liquid with a pungent odour. On exposure to light, it turns to a dark yellow-amber colour. It was used as a tear gas in World War I. Synthesis Chloroacetone ma ...
*
Fluoroacetone Fluoroacetone is an organofluorine compound with the chemical formula . In contrast to trifluoroacetone, the compound has one fluorine atom. Under normal conditions, the substance is a colorless liquid. Fluoroacetone is also a highly toxic and fla ...
*
Iodoacetone Iodoacetone is an organoiodine compound with the chemical formula The substance is a colorless liquid under normal conditions, soluble in ethanol. Synthesis The reaction of acetone and iodine produces iodoacetone. The reaction is typically aci ...


References


External links


Thioacetone
NIST
Trithioacetone
Aldrich {{Chemical agents Thioketones Foul-smelling chemicals