[1184-90-3] C₁H₄N₂O₃S (MW 124.13)

InChI = 1S/CH4N2O3S/c2-1(3)7(4,5)6/h(H3,2,3)(H,4,5,6)

InChIKey = AOPRFYAPABFRPU-UHFFFAOYSA-N

(parent compound and its derivatives guanylate amines; some derivatives give triazoles with azide and aminoiminoethanenitriles with cyanide as nucleophile)

Alternate Name: formamidinesulfonic acid.

Physical Data: mp 131–131.5 °C when highly pure; around 125 °C with dec before purification.

Solubility: sol water; slightly sol methanol, ethanol; insol ether.

Preparative Methods: by the oxidation of thiourea or aminoiminomethanesulfinic acid (formamidinesulfinic acid) with Peracetic Acid. Many substituted aminoiminomethanesulfonic acids can be prepared in the same way.^{1, 2} Others have utilized Hydrogen Peroxide with sodium molybdate as a catalyst to oxidize the corresponding thioureas to a variety of monosubstituted aminoiminomethanesulfonic acids; the substituents include phenyl, 2-methylphenyl, 4-fluorophenyl, n-propyl,³ cyclohexylmethyl, S-α-methylbenzyl, cyclooctyl, and benzhydryl.⁴

Purification: recrystallize from glacial acetic acid.

Handling, Storage, and Precautions: stable for at least a few weeks at room temperature. After drying, it remains stable for at least 5 months if kept in a freezer. Thiourea and its metabolites (probably oxidized thiourea) are tumorigenic and cause lung edema. All direct contact with the compound should be avoided; for example, a dust mask should be worn. All residues should be destroyed with strong bleach solution. Many substituted thioureas and their metabolites are also biologically active. Use in a fume hood.