Crotonic acid
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| Names | |
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| Preferred IUPAC name
(2E)-But-2-enoic acid | |
| Other names
(E)-But-2-enoic acid
(E)-2-Butenoic acid Crotonic acid trans-2-Butenoic acid β-Methylacrylic acid 3-Methylacrylic acid | |
| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.003.213 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C4H6O2 | |
| Molar mass | 86.090 g·mol−1 |
| Density | 1.02 g/cm3 |
| Melting point | 70 to 73 °C (158 to 163 °F; 343 to 346 K) |
| Boiling point | 185 to 189 °C (365 to 372 °F; 458 to 462 K) |
| Acidity (pKa) | 4.69 [1] |
| Hazards | |
| Safety data sheet (SDS) | SIRI.org |
| Related compounds | |
Other anions
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crotonate |
Related carboxylic acids
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propionic acid acrylic acid butyric acid succinic acid malic acid tartaric acid fumaric acid pentanoic acid tetrolic acid |
Related compounds
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butanol butyraldehyde crotonaldehyde 2-butanone |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Crotonic acid ((2E)-but-2-enoic acid) is a short-chain unsaturated carboxylic acid, described by the formula CH3CH=CHCO2H. It is called crotonic acid because it was erroneously thought to be a saponification product of croton oil.[2] It crystallizes as colorless needles from hot water. The cis-isomer of crotonic acid is called isocrotonic acid. Crotonic acid is soluble in water and many organic solvents. Its odor is similar to butyric acid.
Production
Crotonic acid may be obtained by several methods:
- by oxidation of crotonaldehyde:[3]: 230
- by Knoevenagel condensation of acetaldehyde with malonic acid in pyridine:[3]: 229
- or by alkaline hydrolysis of allyl cyanide after the intramolecular rearrangement of the double bond:[4][5]
- Furthermore, it is formed during the distillation of 3-hydroxybutyric acid:[6]
Properties
Crotonic acid crystallizes in the monoclinic crystal system in the space group P21/a (space group 14, position 3) with the lattice parameters a = 971 pm, b = 690 pm, c = 775 pm and β = 104.0°. The unit cell contains four formula units.[7]
Reactions
Crotonic acid converts into butyric acid by hydrogenation or by reduction with zinc and sulfuric acid.[8]
Upon treatment with chlorine or bromine, crotonic acid converts to 2,3-dihalobutyric acids:[8]
Crotonic acid adds hydrogen bromide to form 3-bromobutyric acid.[8][9]
The reaction with alkaline potassium permanganate solution affords 2,3-dihydroxybutyric acid.[8]
Upon heating with acetic anhydride, crotonic acid converts to the acid anhydride:[10]
Esterification of crotonic acid using sulfuric acid as a catalyst provides the corresponding crotonate esters:
Crotonic acid reacts with hypochlorous acid to 2-chloro-3-hydroxybutyric acid. This can either be reduced with sodium amalgam to butyric acid, can form with sulfuric acid 2-chlorobutenoic acid, react with hydrogen chloride to 2,3-dichlorobutenoic acid or with potassium ethoxide to 3-methyloxirane-2-carboxylic acid.[11]
Crotonic acid reacts with ammonia at the alpha position in the presence of mercury(II) acetate. This reaction provides DL-threonine.[12]
Use
Crotonic acid is mainly used as a comonomer with vinyl acetate.[13] The resulting copolymers are used in paints and adhesives.[14]
Crotonyl chloride reacts with N-ethyl-2-methylaniline (N-ethyl-o-toluidine) to provide crotamiton, which is used as an agent against scabies.[15]
Crotamiton synthesis
Safety
Its LD50 is 1 g/kg (oral, rats).[14] It irritates eyes, skin, and respiratory system.[13]
See also
References
- ^ Dawson, R. M. C.; et al. (1959). Data for Biochemical Research. Oxford: Clarendon Press.
- ^ Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica. Vol. 7 (11th ed.). Cambridge University Press. p. 511.
- ^ a b Beyer, Hans; Walter, Wolfgang (1984). Organische Chemie (in German). Stuttgart: S. Hirzel Verlag. ISBN 3-7776-0406-2.
- ^ Rinne, A.; Tollens, B. (1871). "Ueber das Allylcyanür oder Crotonitril" [On allyl cyanide or crotononitrile]. Justus Liebigs Annalen der Chemie. 159 (1): 105–109. doi:10.1002/jlac.18711590110.
- ^ Pomeranz, C. (1906). "Ueber Allylcyanid und Allylsenföl" [On allyl cyanide and allylic mustard oil]. Justus Liebigs Annalen der Chemie. 351 (1–3): 354–362. doi:10.1002/jlac.19073510127.
- ^ Beilstein, F. (1893). Handbuch der organischen Chemie (in German). Vol. 1 (3rd ed.). Verlag Leopold Voss. p. 506.
- ^ Shimizu, S.; Kekka, S.; Kashino, S.; Haisa, M. (1974). "Topochemical Studies. III. The Crystal and Molecular Structures of Crotonic Acid, CH3CH=CHCO2H, and Crotonamide, CH3CH=CHCONH2". Bulletin of the Chemical Society of Japan. 47 (7): 1627–1631. doi:10.1246/bcsj.47.1627.
- ^ a b c d Heilbron (1953). "Crotonic acid". Dictionary of Organic Compounds. 1: 615.
- ^ Lovén, J. M.; Johansson, H. (1915). "Einige schwefelhaltige β-Substitutionsderivate der Buttersäure" [Some sulfur-containing β-substitution derivatives of butyric acid]. Berichte der deutschen chemischen Gesellschaft. 48 (2): 1254–1262. doi:10.1002/cber.19150480205.
- ^ Clover, A. M.; Richmond, G. F. (1903). "The Hydrolysis of Organic Peroxides and Peracids". American Chemical Journal. 29 (3): 179–203.
- ^ Beilstein, F. (1893). Handbuch der organischen Chemie (in German). Vol. 1 (3rd ed.). Verlag Leopold Voss. p. 562.
- ^ Carter, H. E.; West, H. D. (1955). "dl-Threonine". Organic Syntheses; Collected Volumes, vol. 3, p. 813.
- ^ a b Entry on Butensäuren. at: Römpp Online. Georg Thieme Verlag, retrieved January 7, 2020.
- ^ a b Schulz, R. P.; Blumenstein, J.; Kohlpaintner, C. (2005). "Crotonaldehyde and Crotonic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_083. ISBN 978-3527306732.
- ^ Kleemann, A.; Engel, J. Pharmazeutische Wirkstoffe: Synthesen, Patente, Anwendungen. Vol. 5 (2nd rev. and updated ed.). Stuttgart & New York: Georg Thieme Verlag. p. 251. ISBN 3-13-558402-X.