:Isomalathion
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 424828408
| ImageFile=Isomalathion.png
| ImageSize=200px
| ImageFile1 = Isomalathion 3D ball.png
| ImageSize1 = 220
| ImageAlt1 = Ball-and-stick model of the isomalathion molecule
| PIN=Diethyl {[methoxy(methylsulfanyl)phosphoryl]sulfanyl}butanedioate
| OtherNames=S-Methylmalathion
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo=3344-12-5
| UNII_Ref = {{fdacite|changed|FDA}}
| UNII = 9XEP5P83AO
| PubChem=91529
| SMILES=CCOC(=O)CC(C(=O)OCC)SP(=O)(OC)SC
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 82649
| InChI = 1/C10H19O6PS2/c1-5-15-9(11)7-8(10(12)16-6-2)19-17(13,14-3)18-4/h8H,5-7H2,1-4H3
| InChIKey = LPQDGVLVYVULMX-UHFFFAOYAO
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/C10H19O6PS2/c1-5-15-9(11)7-8(10(12)16-6-2)19-17(13,14-3)18-4/h8H,5-7H2,1-4H3
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = LPQDGVLVYVULMX-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| Formula=C10H19O6PS2
| MolarMass=330.36 g/mol
| Appearance=
| Density=
| MeltingPt=
| BoilingPt=
| Solubility=
}}
|Section3={{Chembox Hazards
| MainHazards=
| FlashPt=
| AutoignitionPt =
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Isomalathion is an impurity found in some batches of malathion. Whereas the structure of malation is, generically, RSP(S)(OCH3)2, the connectivity of isomalathion is RSPO(SCH3)(OCH3). It arises by heating malathion. Being significantly more toxic to humans than malathion, it has resulted in human poisonings.{{Cite journal | doi=10.1021/jf00083a030|title = Investigation of some factors influencing isomalathion formation in malathion products| journal=Journal of Agricultural and Food Chemistry| volume=36| issue=5| pages=1025–1030|year = 1988|last1 = Rengasamy|first1 = S.| last2=Parmer| first2=Balraj S.}}
In 1976, numerous malaria workers in Pakistan were poisoned by isomalathion.{{cite journal |author=Baker EL |title=Epidemic malathion poisoning in Pakistan malaria workers |journal=Lancet |volume=1 |issue=8054 |pages=31–4 |year=1978 |pmid=74508 |doi= 10.1016/S0140-6736(78)90375-6|name-list-style=vanc|author2=Warren M |author3=Zack M |display-authors=3 |last4=Dobbin |first4=RD |last5=Miles |first5=JW |last6=Miller |first6=S |last7=Alderman |first7=L |last8=Teeters |first8=WR|s2cid=24973326 }} It is an inhibitor of carboxyesterase.