1,2-Dioxane

{{Chembox

|ImageFile = 1,2-Dioxane.svg

|ImageSize = 100px

| PIN = 1,2-Dioxane

| OtherNames = o-Dioxane

| Section1 = {{Chembox Identifiers

| CASNo = 5703-46-8

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = DK6UQU3A2W

| PubChem = 138570

| ChemSpiderID = 122188

| SMILES = C1CCOOC1

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| Section2 = {{Chembox Properties

| C=4|H=8|O=2

| Appearance = colorless liquid

| Density =

| MeltingPt =

| BoilingPtC = 116-117

| Solubility =

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| Section3 = {{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

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1,2-Dioxane or o-dioxane is an organic compound with the molecular formula (CH{{sub|2}}){{sub|4}}O{{sub|2}}, classified as a cyclic peroxide. Its synthesis was reported in 1956 by Criegee and Müller, who prepared it by reacting butane-1,4-diol bis(methanesulfonate) with hydrogen peroxide and distilled it as a colorless liquid. Acids and bases decompose it to gamma-hydroxybutyraldehyde.{{cite journal|first=Rudolf|last=Criegee|first2=Gerhard|last2=Müller|author-link1=Rudolf Criegee|title=1,2-Dioxan|journal=Chem. Ber.|year=1956|volume=89|issue=2|pages=238–240|doi=10.1002/cber.19560890209}}

Substituted 1,2-dioxanes have also been prepared, and some have been isolated from natural sources.{{cite journal|title=Endoperoxide Synthesis by Photocatalytic Aerobic [2 + 2 + 2] Cycloadditions|author1=Parrish, Jonathan D. |author2=Ischay, Michael A. |author3=Lu, Zhan |author4=Guo, Song |author5=Peters, Noel R. |author6=Yoon, Tehshik P.|journal=Organic Letters|year=2012|volume= 14|issue=6|pages=1640–1643|doi=10.1021/ol300428q|pmc=3306464|pmid=22372647}}