Isocrotonic acid

Isocrotonic acid
Names
	Preferred IUPAC name (2Z)-But-2-enoic acid
	Other names (Z)-But-2-enoic acid; (Z)-2-Butenoic acid; cis-2-Butenoic acid; cis-β-Methylacrylic acid; (Z)-β-Methylacrylic acid
Identifiers
CAS Number	503-64-0 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:36253 ;
ChemSpider	558890 ;
ECHA InfoCard	100.007.249
EC Number	207-973-2;
PubChem CID	643792;
UNII	85GQ7GL1UM ;
CompTox Dashboard (EPA)	DTXSID70880977 ;
	InChI InChI=1S/C4H6O2/c1-2-3-4(5)6/h2-3H,1H3,(H,5,6)/b3-2- Key: LDHQCZJRKDOVOX-IHWYPQMZSA-N ; InChI=1/C4H6O2/c1-2-3-4(5)6/h2-3H,1H3,(H,5,6)/b3-2- Key: LDHQCZJRKDOVOX-IHWYPQMZBE;
	SMILES C/C=C\C(=O)O;
Properties
Chemical formula	C4H6O2
Molar mass	86.090 g·mol−1
Density	1.03 g·cm−3
Melting point	12.5–14 °C (54.5–57.2 °F; 285.6–287.1 K)
Boiling point	168 to 169 °C (334 to 336 °F; 441 to 442 K)
Related compounds
Related carboxylic acids	Crotonic acid (trans isomer); Angelic acid ; Senecioic acid
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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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‑dibromo-2‑butanone via the Favorskii rearrangement.^[2]

Related compounds

Ethyl isocrotonate can be prepared by semihydrogenation of ethyl tetrolate.^[3]

Rudolph Fittig and Hugo Erdmann showed that the γ-phenyl structural analog of isocrotonic acid forms α-naphthol when dehydrated, an observation that provided useful evidence in understanding the nature of naphthalene.^[4]

(Z)-(C₆H₅)CH=CHCH₂COOH → α-naphthol + H₂O

References

^ ^a ^b The Merck Index. An Encyclopaedia of Chemicals, Drugs and Biologicals. 14. Auflage, 2006, S. 894, ISBN 978-0-911910-00-1.
^ ^a ^b C. Rappe (1973). "cis-a,b-Unsaturated Acids: Isocrotonic Acid". Organic Syntheses. 53: 123. doi:10.15227/orgsyn.053.0123.
^ Michael J. Taschner, Terry Rosen, Clayton H. Heathcock (1986). "Ethyl Isocrotonate". Organic Syntheses. 64: 108. doi:10.15227/orgsyn.064.0108.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Fittig, Rudolph; Erdmann, Hugo (1883). "Synthese des α-Naphtols" [Synthesis of α-Naphtol]. Ber. Dtsch. Chem. Ges. (in German). 16 (1): 43–44. doi:10.1002/cber.18830160115.

[MerckIndex-1] The Merck Index. An Encyclopaedia of Chemicals, Drugs and Biologicals. 14. Auflage, 2006, S. 894, ISBN 978-0-911910-00-1.

[OS-2] C. Rappe (1973). "cis-a,b-Unsaturated Acids: Isocrotonic Acid". Organic Syntheses. 53: 123. doi:10.15227/orgsyn.053.0123.

[3] Michael J. Taschner, Terry Rosen, Clayton H. Heathcock (1986). "Ethyl Isocrotonate". Organic Syntheses. 64: 108. doi:10.15227/orgsyn.064.0108.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[4] Fittig, Rudolph; Erdmann, Hugo (1883). "Synthese des α-Naphtols" [Synthesis of α-Naphtol]. Ber. Dtsch. Chem. Ges. (in German). 16 (1): 43–44. doi:10.1002/cber.18830160115.

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