Propadiene

{{Short description|1=Organic compound (H2C=C=CH2)}}

{{Chembox

| Verifiedimages = changed

| Watchedfields = changed

| verifiedrevid = 464215747

| ImageFileL1 = Propadiene structure.svg

| ImageFileL1_Ref = {{chemboximage|correct|??}}

| ImageNameL1 = Stereo structural formula of propadiene with explicit hydrogens

| ImageFileR1 = Allene3D.png

| ImageFileR1_Ref = {{Chemboximage|correct|??}}

| ImageNameR1 = Spacefill model of propadiene

| ImageFile2 = Allene-CRC-IR-3D-balls.png

| ImageFile2_Ref = {{Chemboximage|correct|??}}

| ImageSize2 = 160

| ImageName2 = Ball and stick model of propadiene

| PIN = Propadiene{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = The Royal Society of Chemistry | date = 2014 | location = Cambridge | page = 375 | doi = 10.1039/9781849733069 | isbn = 978-0-85404-182-4 | quote = The name allene, for {{chem2|CH2\dC\dCH2}}, is retained for general nomenclature only; substitution is allowed, but not by alkyl or any other group that extends the carbon chain, nor characteristic groups expressed by suffixes. The systematic name, propadiene, is the preferred IUPAC name. | last1 = Favre | first1 = Henri A. | last2 = Powell | first2 = Warren H. }}

| OtherNames = Allene
Propadiene

|Section1={{Chembox Identifiers

| CASNo = 463-49-0

| CASNo_Ref = {{cascite|correct|CAS}}

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

| UNII = 4AV0LZ8QKB

| PubChem = 10037

| ChemSpiderID = 9642

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| EINECS = 207-335-3

| UNNumber = 2200

| MeSHName = Propadiene

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChEBI = 37601

| ChEMBL = 116960

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| Beilstein = 1730774

| Gmelin = 860

| SMILES = C=C=C

| StdInChI = 1S/C3H4/c1-3-2/h1-2H2

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = IYABWNGZIDDRAK-UHFFFAOYSA-N

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

}}

|Section2={{Chembox Properties

| C=3 | H=4

| Appearance = Colorless gas

| MeltingPtC = -136

| BoilingPtC = -34

| LogP = 1.45}}

|Section3={{Chembox Hazards

| ExternalSDS = [http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=52 External MSDS]

| GHSPictograms = {{GHS flame}}{{GESTIS|ZVG=13750 |CAS=463-49-0 |Name=Allene |Date=17 November 2020}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|220}}

| PPhrases = {{P-phrases|210|377|381|410+403}}

| NFPA-H = 0

| NFPA-F = 4

| NFPA-R = 3

| ExploLimits = 13%}}

}}

Propadiene ({{IPAc-en|p|r|oʊ|p|ə|ˈ|d|aɪ|iː|n}}) or allene ({{IPAc-en|ˈ|æ|l|iː|n}}) is the organic compound with the formula {{chem2|H2C\dC\dCH2}}. It is the simplest allene, i.e. a compound with two adjacent carbon double bonds.{{GoldBookRef | title = allenes | file = A00238}} As a constituent of MAPP gas, it has been used as a fuel for specialized welding.