Acylthioketene-thioacylketene-thiet-2-one rearrangements

Area of Science:

• Organic Chemistry
• Thermochemistry
• Spectroscopy

Background:

• 1,3-dioxine-4-thiones are precursors to reactive intermediates.
• Understanding the thermolytic behavior of heterocyclic compounds is crucial.

Purpose of the Study:

• To investigate the reaction pathways of 6-aryl-1,3-dioxine-4-thiones under flash vacuum thermolysis (FVT).
• To characterize the transient intermediates and final products using spectroscopic methods.

Main Methods:

• Flash vacuum thermolysis (FVT) was employed to induce thermal decomposition.
• In-situ characterization using Ar matrix infrared (IR) spectroscopy.
• On-line tandem mass spectrometry was used for intermediate identification.

Main Results:

• FVT of 6-aryl-1,3-dioxine-4-thiones yielded acylthioketenes.
• Acylthioketenes rearranged to thioacylketenes, which cyclized to 3-aryl-thiet-2-ones.
• Thiet-2-ones decomposed via CO extrusion to arylthioketenes or cycloreversion to COS and arylacetylene.

Conclusions:

• Flash vacuum thermolysis provides a route to generate and study acylthioketenes and thiet-2-ones.
• The study elucidates the complex reaction cascade initiated by thermal decomposition of dioxine-thiones.
• Spectroscopic techniques are vital for characterizing short-lived intermediates in high-temperature reactions.