sesquimustard sesquimustard sesquimustard (military code q) is the organosulfur compound with the formula (clch2ch2sch2)2. although it is a colorless solid, impure samples are often brown. the compound is a type of mustard gas, a vesicant used as a chemical weapon. from the chemical perspective, the compound is both a thioether and an alkyl chloride. sesquimustard names preferred iupac name 1,2-bisethane other names agent qtl-86one-and-one-half mustard identifiers cas number 3563-36-8 y 3d model (jsmol) interactive image chemspider 18025 pubchem cid 19092 unii 5y1nv229po comptox dashboard (epa) dtxsid7074793 inchi inchi=1s/c6h12cl2s2/c7-1-3-9-5-6-10-4-2-8/h1-6h2key: amgnhzvuzwilsb-uhfffaoysa-n smiles c(cscccl)scccl properties chemical formula c6h12cl2s2 molar mass 219.18 g·mol−1 appearance white solid (impure samples: pale brown) melting point 56.5 °c (133.7 °f; 329.6 k) solubility in water insoluble, slowly degrades solubility alcohols, hydrocarbons, lipids, ethers, thf except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references because sesquimustard is a solid at room temperature, it is not as easily deployed as related liquid mustards. it was only ever deployed as mixtures with the original mustard, with phosgene, or as a solution. since 1997, it has been listed under schedule i of the chemical weapons convention, as a substance with few uses outside of chemical warfare (although since then, it has been found to be useful in chemotherapy).