Thermal Decomposition Mechanism for Ethanethiol.

Area of Science:

• Chemical Kinetics
• Physical Chemistry
• Combustion Science

Background:

• Understanding the thermal decomposition of sulfur-containing organic compounds is crucial for combustion and industrial processes.
• Previous studies on ethanethiol decomposition have lacked detailed identification of initial products.

Purpose of the Study:

• To investigate the initial unimolecular decomposition pathways of ethanethiol (CH3CH2SH) at high temperatures.
• To identify the primary molecular and radical products formed during ethanethiol pyrolysis.

Main Methods:

• Utilized a pulsed silicon carbide (SiC) microtubular reactor with short residence times (≤100 μs) and temperatures ranging from 300-1700 K.
• Employed photoionization mass spectrometry and IR spectroscopy to probe the molecular beam exiting the reactor.
• Entrained ethanethiol in Argon or Helium carrier gas for controlled reaction conditions.

Main Results:

• Identified three distinct unimolecular decomposition pathways for ethanethiol.
• Pathway 1: CH3CH2SH → CH3CH2 + SH (ethyl radical and thiyl radical).
• Pathway 2: CH3CH2SH → CH3 + H2C═S (methyl radical and thioformaldehyde).
• Pathway 3: CH3CH2SH → H2C═CH2 + H2S (ethylene and hydrogen sulfide).

Conclusions:

• The experimental results align well with theoretical electronic structure calculations.
• This research provides a comprehensive understanding of the initial steps in ethanethiol thermal decomposition.
• The identified pathways offer valuable data for modeling combustion and atmospheric chemistry involving sulfur compounds.