C2H4S

C2H4S is the molecular formula for several simple sulfur-containing organic compounds. The formula corresponds to at least two structural isomers: thiirane, also known as ethylene sulfide (IUPAC name 1,2-epithiirane), and ethenyl mercaptan, commonly called vinyl thiol (CH2=CH-SH). These isomers illustrate how the same elemental composition can have different connectivities and properties.

Thiirane is a small, strained heterocyclic sulfide in which two carbon atoms and one sulfur atom form a three-membered ring. The ring strain in thiirane makes it more reactive toward nucleophiles and ring-opening reactions, and it is used as a reactive building block in organic synthesis. It is typically a volatile, colorless compound and is handled under standard precautions for reactive sulfur-containing materials.

Vinyl thiol features a vinyl group attached to a thiol group, with the structure CH2=CH-SH. As a thiol, it is characterized by a reactive –SH group and can participate in thiol-ene chemistry and other sulfur-containing transformations. Vinyl thiol is used in organic synthesis and polymer chemistry as a reactive monomer or crosslinking agent, but it is typically handled with care due to potential reactivity and odor.

In summary, C2H4S denotes a small family of compounds with two carbon atoms, four hydrogen atoms, and one sulfur atom, most notably thiirane and vinyl thiol, which differ markedly in structure and reactivity.