Crotonic acid

From Wikipedia, the free encyclopedia
(Redirected from Crotonate)
Jump to navigation Jump to search

Template:Chembox

Crotonic acid ((2E)-but-2-enoic acid) is a short-chain unsaturated carboxylic acid described by the formula CH3CH=CHCO2H. The name crotonic acid was given because it was erroneously thought to be a saponification product of croton oil.[1] It crystallizes as colorless needles from hot water. With a cis-alkene, Isocrotonic acid is an isomer of crotonic acid. Crotonic acid is soluble in water and many organic solvents. Its odor is similar to that of butyric acid.

Production

Crotonic acid produced industrially by oxidation of crotonaldehyde:[2][3]Template:Rp

Template:Chem2

A number of other methods exist, including the Knoevenagel condensation of acetaldehyde with malonic acid in pyridine:[2]Template:Rp

Synthesis of crotonic acid by the Knoevenagel condensation of acetaldehyde and malonic acid

The alkaline hydrolysis of allyl cyanide followed by the intramolecular rearrangement of the double bond:[4][5]

Alkaline hydrolysis of allyl cyanide

Furthermore, it is formed during the distillation of 3-hydroxybutyric acid:[6]

Synthesis of crotonic acid from 3-hydroxybutyric acid

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]

Hydrogenation of crotonic acid

Upon treatment with chlorine or bromine, crotonic acid converts to 2,3-dihalobutyric acids:[8]

Chlorination of butenoic acid

Crotonic acid adds hydrogen bromide to form 3-bromobutyric acid.[8][9]

Reaction of crotonic acid with hydrogen bromide.

The reaction with alkaline potassium permanganate solution affords 2,3-dihydroxybutyric acid.[8]

Reaction of crotonic acid with alkaline potassium permanganate solution.

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:

Preparation of 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]

Reaction of crotonic acid into 2-chloro-3-hydroxybutanoic acid and subsequent reactions

Crotonic acid reacts with ammonia at the alpha position in the presence of mercury(II) acetate. This reaction provides [[threonine|Template:Sc-threonine]].[12]

Use

Crotonic acid is mainly used as a comonomer with vinyl acetate.[13] The resulting copolymers are used in paints and adhesives.[3]

Crotonyl chloride reacts with N-ethyl-2-methylaniline (N-ethyl-o-toluidine) to provide crotamiton, which is used as an agent against scabies.[14]

Crotamiton synthesis
Crotamiton synthesis

Safety

Its LD50 is 1 g/kg (oral, rats).[3] It irritates eyes, skin, and respiratory system.[13]

See also

References

<templatestyles src="Reflist/styles.css" />

  1. ↑ Template:Cite EB1911
  2. ↑ a b Script error: No such module "citation/CS1".
  3. ↑ a b c Template:Ullmann
  4. ↑ Script error: No such module "Citation/CS1".
  5. ↑ Script error: No such module "Citation/CS1".
  6. ↑ Script error: No such module "citation/CS1".
  7. ↑ Script error: No such module "Citation/CS1".
  8. ↑ a b c d Script error: No such module "Citation/CS1".
  9. ↑ Script error: No such module "Citation/CS1".
  10. ↑ Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".; Script error: No such module "citation/CS1"..
  13. ↑ a b Template:RömppOnline
  14. ↑ Script error: No such module "citation/CS1".

Script error: No such module "Check for unknown parameters".

Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=Crotonic_acid&oldid=2083786"