Isocrotonic acid

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 428788971

| ImageFile = Isocrotonic acid.svg

| ImageSize = 130px

| ImageName = Skeletal formula

| ImageFile1 = Isocrotonic-acid-3D-balls.png

| ImageSize1 = 150px

| ImageName1 = Ball-and-stick model

| PIN = (2Z)-But-2-enoic acid

| OtherNames = (Z)-But-2-enoic acid
(Z)-2-Butenoic acid
cis-2-Butenoic acid
cis-β-Methylacrylic acid
(Z)-β-Methylacrylic acid

|Section1={{Chembox Identifiers

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 503-64-0

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

| UNII = 85GQ7GL1UM

| EINECS = 207-973-2

| PubChem = 643792

| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

| ChemSpiderID = 558890

| SMILES = C/C=C\C(=O)O

| InChI = 1/C4H6O2/c1-2-3-4(5)6/h2-3H,1H3,(H,5,6)/b3-2-

| InChIKey = LDHQCZJRKDOVOX-IHWYPQMZBE

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChI = 1S/C4H6O2/c1-2-3-4(5)6/h2-3H,1H3,(H,5,6)/b3-2-

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = LDHQCZJRKDOVOX-IHWYPQMZSA-N

| RTECS =

| MeSHName =

| ChEBI_Ref = {{ebicite|changed|EBI}}

| ChEBI = 36253

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|Section2={{Chembox Properties

| C=4 | H=6 | O=2

| Density = 1.03 g·cm⁻³ The Merck Index. An Encyclopaedia of Chemicals, Drugs and Biologicals. 14. Auflage, 2006, S. 894, {{ISBN|978-0-911910-00-1}}.

| MeltingPtC = 12.5-14

| MeltingPt_ref =

| BoilingPtC = 168 to 169

| BoilingPt_ref =

}}

|Section8={{Chembox Related

| OtherFunction_label = carboxylic acids

| OtherFunction = Crotonic acid (trans isomer)
Angelic acid
Senecioic acid

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Isocrotonic acid (also known as quartenylic acid; formally named (Z)-2-butenoic acid) is the cis isomer of crotonic acid. It is an oil, possessing an odor similar to that of brown sugar. At its boiling point of 171.9 °C, it converts into crotonic acid. The compound can be prepared from 1,3{{nbh}}dibromo-2{{nbh}}butanone via the Favorskii rearrangement.{{cite journal |doi=10.15227/orgsyn.053.0123 |title=cis-a,b-Unsaturated Acids: Isocrotonic Acid |journal=Organic Syntheses |year=1973 |volume=53 |page=123|author=C. Rappe }}