Sulfinylmethane or sulfine is an organic compound with molecular formula H<sub>2</sub>CSO. It is the simplest sulfine. Sulfines are chemical compounds with the general structure XY=SO. IUPAC considers the term 'sulfine' obsolete, preferring instead thiocarbonyl S-oxide; despite this, the use of the term sulfine still predominates in the chemical literature.
The parent sulfine H<sub>2</sub>CSO is very labile, whereas substituted derivatives are more conveniently isolated.
One route is a variant of ketene synthesis, in which a sulfinyl halide reacts with a hindered base. For example, syn-propanethial-S-oxide, responsible for eye-watering effects of cutting onions, is produced so from allicin.
Another route is oxidation, as with thiobenzophenone from diphenylsulfine: