Chloroacetic acid

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Chloroacetic acid
Chloroacetic-acid-2D-skeletal.png
Chloroacetic-acid-3D-vdW.png
Names
Preferred IUPAC name
Chloroacetic acid
Systematic IUPAC name
Chloroethanoic acid
Other names
2-Chloroacetic acid
2-Chloroethanoic acid
Identifiers
3D model (JSmol)
3DMet
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.072 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 201-178-4
KEGG
PubChem CID
RTECS number
  • AF8575000
UNII
  • InChI=1S/C2H3ClO2/c3-1-2(4)5/h1H2,(H,4,5) Yes check.svgY
    Key: FOCAUTSVDIKZOP-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C2H3ClO2/c3-1-2(4)5/h1H2,(H,4,5)
    Key: FOCAUTSVDIKZOP-UHFFFAOYAR
  • ClCC(O)=O
Properties
ClCH2CO2H
Molar mass 94.49 g·mol−1
AppearanceColorless or white crystals
Density 1.58 g/cm3
Melting point 63 °C (145 °F; 336 K)
Boiling point 189.3 °C (372.7 °F; 462.4 K)
85.8 g/(100 mL) (25 °C)
Solubility Soluble in methanol, acetone, diethyl ether, benzene, chloroform, ethanol
log P 0.22
Vapor pressure 0.22 hPa
Acidity (pKa)2.86 [1]
−48.1×10−6 cm3/mol
1.4351 (55 °C)
Structure
Monoclinic
Thermochemistry
144.02 J/(K·mol)
−490.1 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
alkylating agent
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-skull.svg GHS-pictogram-pollu.svg
Danger
H301, H311, H314, H331, H400
P260, P261, P264, P270, P271, P273, P280, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P312, P321, P322, P330, P361, P363, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
1
0
Flash point 126 °C (259 °F; 399 K)
470 °C (878 °F; 743 K)
Lethal dose or concentration (LD, LC):
76 mg/kg. [2]
Safety data sheet (SDS) External MSDS
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Chloroacetic acid, industrially known as monochloroacetic acid (MCA), is the organochlorine compound with the formula Cl C H 2CO 2H. This carboxylic acid is a useful building block in organic synthesis. It is a colorless solid. Related compounds are dichloroacetic acid and trichloroacetic acid.

Contents

Production

Chloroacetic acid was first prepared (in impure form) by the French chemist Félix LeBlanc (1813–1886) in 1843 by chlorinating acetic acid in the presence of sunlight, [3] and in 1857 (in pure form) by the German chemist Reinhold Hoffmann (1831–1919) by refluxing glacial acetic acid in the presence of chlorine and sunlight, [4] and then by the French chemist Charles Adolphe Wurtz by hydrolysis of chloroacetyl chloride (ClCH2COCl), also in 1857. [5]

Chloroacetic acid is prepared industrially by two routes. The predominant method involves chlorination of acetic acid, with acetic anhydride as a catalyst:

H3C−COOH + Cl2 → ClH2C−COOH + HCl

This route suffers from the production of dichloroacetic acid and trichloroacetic acid as impurities, which are difficult to separate by distillation:

H3C−COOH + 2 Cl2 → Cl2HC−COOH + 2 HCl
H3C−COOH + 3 Cl2 → Cl3C−COOH + 3 HCl

The second method entails hydrolysis of trichloroethylene:

ClHC=CCl2 + 2 H2O → ClH2C−COOH + 2 HCl

The hydrolysis is conducted at 130–140 °C in a concentrated (at least 75%) solution of sulfuric acid. This method produces a highly pure product, unlike the halogenation route. However, the significant quantities of HCl released have led to the increased popularity of the halogenation route. Approximately 420,000 tonnes are produced globally per year. [2]

Uses and reactions

Most reactions take advantage of the high reactivity of the C−Cl bond.

In its largest-scale application, chloroacetic acid is used to prepare the thickening agent carboxymethyl cellulose and carboxymethyl starch.

Chloroacetic acid is also used in the production of phenoxy herbicides by etherification with chlorophenols. In this way 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) are produced. It is the precursor to the herbicide glyphosate and dimethoate. Chloroacetic acid is converted to chloroacetyl chloride, a precursor to adrenaline (epinephrine). Displacement of chloride by sulfide gives thioglycolic acid, which is used as a stabilizer in PVC and a component in some cosmetics. [2]

Illustrative of its usefulness in organic chemistry is the O-alkylation of salicylaldehyde with chloroacetic acid, followed by decarboxylation of the resulting ether, producing benzofuran. [6] [7]

Safety

Chloroacetic acid burns Image-Chloracetic Acid Burns.jpg
Chloroacetic acid burns

Like other chloroacetic acids and related halocarbons, chloroacetic acid is a hazardous alkylating agent. The LD50 for rats is 76 mg/kg. [2]

It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities. [8]

See also

Related Research Articles

<span class="mw-page-title-main">Carboxylic acid</span> Organic compound containing a –C(=O)OH group

In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO2H, sometimes as R−C(O)OH with R referring to an organyl group, or hydrogen, or other groups. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.

In organic chemistry, an acyl chloride is an organic compound with the functional group −C(=O)Cl. Their formula is usually written R−COCl, where R is a side chain. They are reactive derivatives of carboxylic acids. A specific example of an acyl chloride is acetyl chloride, CH3COCl. Acyl chlorides are the most important subset of acyl halides.

In chemistry, halogenation is a chemical reaction which introduces of one or more halogens into a chemical compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, drugs. This kind of conversion is in fact so common that a comprehensive overview is challenging. This article mainly deals with halogenation using elemental halogens. Halides are also commonly introduced using salts of the halides and halogen acids. Many specialized reagents exist for and introducing halogens into diverse substrates, e.g. thionyl chloride.

<span class="mw-page-title-main">Acyl halide</span> Oxoacid compound with an –OH group replaced by a halogen

In organic chemistry, an acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group.

In organic chemistry, the chloroacetic acids (systematic name chloroethanoic acids) are three related chlorocarbon carboxylic acids:

<span class="mw-page-title-main">Trichloroacetic acid</span> Chemical compound

Trichloroacetic acid is an analogue of acetic acid in which the three hydrogen atoms of the methyl group have all been replaced by chlorine atoms. Salts and esters of trichloroacetic acid are called trichloroacetates.

Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds containing at least one covalently bonded atom of chlorine. The chloroalkane class includes common examples. The wide structural variety and divergent chemical properties of organochlorides lead to a broad range of names, applications, and properties. Organochlorine compounds have wide use in many applications, though some are of profound environmental concern, with TCDD being one of the most notorious.

<span class="mw-page-title-main">Aluminium chloride</span> Chemical compound

Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms a hexahydrate with the formula [Al(H2O)6]Cl3, containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are colourless crystals, but samples are often contaminated with iron(III) chloride, giving them a yellow colour.

<span class="mw-page-title-main">Manganese(II) chloride</span> Chemical compound

Manganese(II) chloride is the dichloride salt of manganese, MnCl2. This inorganic chemical exists in the anhydrous form, as well as the dihydrate (MnCl2·2H2O) and tetrahydrate (MnCl2·4H2O), with the tetrahydrate being the most common form. Like many Mn(II) species, these salts are pink, with the paleness of the color being characteristic of transition metal complexes with high spin d5 configurations.

<span class="mw-page-title-main">Acetyl chloride</span> Organic compound (CH₃COCl)

Acetyl chloride is an acyl chloride derived from acetic acid. It belongs to the class of organic compounds called acid halides. It is a colorless, corrosive, volatile liquid. Its formula is commonly abbreviated to AcCl.

<span class="mw-page-title-main">Thionyl chloride</span> Inorganic compound (SOCl2)

Thionyl chloride is an inorganic compound with the chemical formula SOCl2. It is a moderately volatile, colourless liquid with an unpleasant acrid odour. Thionyl chloride is primarily used as a chlorinating reagent, with approximately 45,000 tonnes per year being produced during the early 1990s, but is occasionally also used as a solvent. It is toxic, reacts with water, and is also listed under the Chemical Weapons Convention as it may be used for the production of chemical weapons.

In organic chemistry, the Wurtz reaction, named after Charles Adolphe Wurtz, is a coupling reaction whereby two alkyl halides are treated with sodium metal to form a higher alkane.

In organic chemistry a halohydrin is a functional group in which a halogen and a hydroxyl are bonded to adjacent carbon atoms, which otherwise bear only hydrogen or hydrocarbyl groups. The term only applies to saturated motifs, as such compounds like 2-chlorophenol would not normally be considered halohydrins. Megatons of some chlorohydrins, e.g. propylene chlorohydrin, are produced annually as precursors to polymers.

<span class="mw-page-title-main">Sulfuryl chloride</span> Chemical compound

Sulfuryl chloride is an inorganic compound with the formula SO2Cl2. At room temperature, it is a colorless liquid with a pungent odor. Sulfuryl chloride is not found in nature, as can be inferred from its rapid hydrolysis.

<span class="mw-page-title-main">Phosphoryl chloride</span> Chemical compound

Phosphoryl chloride is a colourless liquid with the formula POCl3. It hydrolyses in moist air releasing phosphoric acid and fumes of hydrogen chloride. It is manufactured industrially on a large scale from phosphorus trichloride and oxygen or phosphorus pentoxide. It is mainly used to make phosphate esters.

The Blanc chloromethylation is the chemical reaction of aromatic rings with formaldehyde and hydrogen chloride to form chloromethyl arenes. The reaction is catalyzed by Lewis acids such as zinc chloride. The reaction was discovered by Gustave Louis Blanc (1872-1927) in 1923.

<span class="mw-page-title-main">Nitrosyl chloride</span> Chemical compound

Nitrosyl chloride is the chemical compound with the formula NOCl. It is a yellow gas that is commonly encountered as a component of aqua regia, a mixture of 3 parts concentrated hydrochloric acid and 1 part of concentrated nitric acid. It is a strong electrophile and oxidizing agent. It is sometimes called Tilden's reagent, after William A. Tilden, who was the first to produce it as a pure compound.

<span class="mw-page-title-main">Thiophosphoryl chloride</span> Chemical compound

Thiophosphoryl chloride is an inorganic compound with the chemical formula PSCl3. It is a colorless pungent smelling liquid that fumes in air. It is synthesized from phosphorus chloride and used to thiophosphorylate organic compounds, such as to produce insecticides.

In organic chemistry, dehalogenation is a set of chemical reactions that involve the cleavage of carbon-halogen bonds; as such, it is the inverse reaction of halogenation. Dehalogenations come in many varieties, including defluorination, dechlorination, debromination, and deiodination. Incentives to investigate dehalogenations include both constructive and destructive goals. Complicated organic compounds such as pharmaceutical drugs are occasionally generated by dehalogenation. Many organohalides are hazardous, so their dehalogenation is one route for their detoxification.

<span class="mw-page-title-main">Photochlorination</span>

Photochlorination is a chlorination reaction that is initiated by light. Usually a C-H bond is converted to a C-Cl bond. Photochlorination is carried out on an industrial scale. The process is exothermic and proceeds as a chain reaction initiated by the homolytic cleavage of molecular chlorine into chlorine radicals by ultraviolet radiation. Many chlorinated solvents are produced in this way.

References

  1. Dippy, J. F. J.; Hughes, S. R. C.; Rozanski, A. (1959). "498. The dissociation constants of some symmetrically disubstituted succinic acids". Journal of the Chemical Society. 1959: 2492–2498. doi:10.1039/JR9590002492.
  2. 1 2 3 4 Koenig, G.; Lohmar, E.; Rupprich, N. (2005). "Chloroacetic Acids". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a06_537. ISBN   978-3527306732.
  3. LeBlanc, Félix (1844) "Recherches sur les produits dérivés de l'éther acétique par l'action du chlore, et en particulier sur l'éther acétique perchloruré" (in French), Annales de Chimie et de Physique, 3rd series, 10 : 197–221 ; see especially p. 212.
  4. Hoffmann, Reinhold (1857) "Ueber Monochloressigsäure" (in German) (On mono-chloroacetic acid), Annalen der Chemie und Pharmacie, 102 (1) : 1–20.
  5. Wurtz, Adolphe (1857) "Note sur l'aldéhyde et sur le chlorure d'acétyle" (in French) (Note on aldehyde and on acetyl chloride), Annales de chimie et de physique, 3rd series, 49 : 58–62, see p. 61.
  6. Burgstahler, A. W.; Worden, L. R. (1966). "Coumarone". Organic Syntheses . 46: 28. doi:10.15227/orgsyn.046.0028 ; Collected Volumes, vol. 5, p. 251..
  7. Inglis, J. K. H. (1928). "Ethyl Cyanoacetate". Organic Syntheses. 8: 74. doi:10.15227/orgsyn.008.0074.
  8. 40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities (PDF) (1 July 2008 ed.), Government Printing Office, archived from the original (PDF) on 25 February 2012, retrieved 29 October 2011