Chloroacetic acid

Description

Chloroacetic acid (CAA) is a monohalogenated acetic acid (m-HAA) that is used as a photosensitizing agent and in industrial synthesis of certain organic chemicals such as indigoid dyes. The m-HAAs are a major class of drinking water disinfection by-products during chlorination of drinking water.

Chemical properties

colourless or white crystals

Chemical properties

Chloroacetic acid is a colorless to white crystalline solid. It has a strong vinegar-like odor and an Odor Threshold of 0.15 milligram per cubic meter.

The Uses of Chloroacetic acid

Chloroacetic acid behaves as a very strong monobasic acid and is used as a strong acid catalyst for diverse reactions. The Cl function can be displaced in base-catalyzed reactions.

The Uses of Chloroacetic acid

Herbicide, preservative, bacteriostat, intermediate in production of carboxymethylcellulose; ethyl chloroacetate, glycine, synthetic caffeine, sarcosine, thioglycolic acid, EDTA, 2,4-D, 2,4,5-T.

The Uses of Chloroacetic acid

CAA is one of these agents used in the topical treatment of warts in most European countries and also as an herbicidal agent and a bleaching agent for silkworm cocoons. It can be found in wines and beers using static headspace extraction coupled with gas chromatography–mass spectrometry. CCA is the main toxic metabolite of vinyl chloride. CAA and volatile organochlorines are suspected to contribute to forest dieback and stratospheric ozone destruction.

What are the applications of Application

Chloroacetic acid is a standard laboratory chemical

Definition

ChEBI: A chlorocarboxylic acid that is acetic acid carrying a 2-chloro substituent.

Definition

A colorless crystalline solid made by substituting one of the hydrogen atoms of the methyl group of ethanoic acid with chlorine, using red phosphorus. It is a stronger acid than ethanoic acid because of the electron-withdrawing effect of the chlorine atom. Dichloroethanoic acid (dichloroacetic acid, CHCl₂COOH) and trichloroethanoic acid (trichloroacetic acid,CCl₃COOH) are made in the same way. The acid strength increases with the number of chlorine atoms present.

Production Methods

Chloroacetic acid can be synthesized by the radical chlorination of acetic acid, treatment of trichloroethylene with concentrated H2SO4, oxidation of 1,2-dichloroethane or chloroacetaldehyde, amine displacement from glycine, or chlorination of ketene.

General Description

Chloroacetic acid, solution is a colorless solution of the white crystalline solid. The acid concentration can be up to 80%.It is used in manufacturing dyes and in medicine. Chloroacetic acid is toxic by inhalation, ingestion and skin contact. Chloroacetic acid is corrosive to metals and tissue. Chloroacetic acid is used as an herbicide, preservative and bacteriostat.

Air & Water Reactions

Water soluble.

Reactivity Profile

These organic compounds donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic. Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat. Neutralization between an acid and a base produces water plus a salt. Soluble carboxylic acid dissociate to an extent in water to yield hydrogen ions. The pH of solutions of carboxylic acids is therefore less than 7.0. Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt. Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry. Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in Chloroacetic acid to corrode or dissolve iron, steel, and aluminum parts and containers. Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide. The reaction is slower for dry, solid carboxylic acids. Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions.

Hazard

Use in foods prohibited by FDA. Irritating and corrosive to skin. Upper respiratory tract irritant. Questionable carcinogen.

Health Hazard

Inhalation causes mucous membrane irritation. Contact with liquid causes severe irritation and burns of the eyes and irritation and burns of skin. Ingestion causes burns of mouth and stomach.

Fire Hazard

Special Hazards of Combustion Products: Toxic gases, such as hydrogen chloride, phosgene and carbon monoxide, may be generated.

Flammability and Explosibility

Non flammable

Safety Profile

Poison by ingestion, inhalation, subcutaneous, and intravenous routes. A corrosive skin, eye, and mucous membrane irritant. Questionable carcinogen with experimental tumorigenic data. Mutation data reported. Combustible liquid when exposed to heat or flame. To fight fire, use water spray, fog, mist, dry chemical, foam. When heated to decomposition it emits toxic fumes of Cl-. See also CHLORIDES.

Potential Exposure

This haloacetic acid can be a byproduct of drinking water disinfection and may increase the risk of cancer. Monochloracetic acid is used primarily as a chemical intermediate in the synthesis of sodium carboxymethyl cellulose; and such other diverse substances as ethyl chloroacetate, glycine, synthetic caffeine, sarcosine, thioglycolic acid, and various dyes. Hence, workers in these areas are affected. It is also used as an herbicide. Therefore, formulators and applicators of such herbicides are affected.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. SeekChloroacetic acid 629medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water ormilk. Do not induce vomiting. Medical observation isrecommended for 24-48 h after breathing overexposure, aspulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consideradministering a corticosteroid spray.

Environmental Fate

CCA by inhibition of the pyruvate-dehydrogenase, aconitase, and a-ketoglutarate dehydrogenase that contribute in tricarboxylic acid cycle and also inhibition of glyceraldehyde- 3-phosphate dehydrogenase can impair production of cellular energy and conversion to anaerobic glycolysis, resulting in increasing acidosis with accumulation of glycolic acid, oxalate, and lactate production. CCA can also affect cellular components via sulfhydryl groups. Both of these effects may contribute to central nervous system (CNS), cardiovascular, renal, and hepatic effects. The metabolites glycolic acid and oxalate may contribute to CNS and renal toxicity (myoglobin and oxalate precipitation in the tubuli). Binding of calcium to oxalates probably causes the hypocalcemia, but hypocalcemia can be secondary to rhabdomyolysis. CAA by reduction of cellular glutathione can cause oxidative stress. Inhibition of mitochondrial aconitase causes hypoglycemia.

storage

Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Color Code—White: Corrosiveor Contact Hazard; Store separately in a corrosion-resistantlocation. Prior to working with chloroacetic acid youshould be trained on its proper handling and storage. Storein tightly closed containers in a cool, well-ventilated areaaway from metal, combustibles, strong oxidizers, strongbases, and reducing agents. Where possible, automaticallypump liquid from drums or other storage containers to process containers. Drums must be equipped with self-closingvalves, pressure vacuum bungs, and flame arresters. Useonly nonsparking tools and equipment, especially whenopening and closing containers of this chemical. Sourcesof ignition, such as smoking and open flames, are prohibited where this chemical is used, handled, or stored in amanner that could create a potential fire or explosionhazard.

Shipping

UN1750 (liquid) & UN1751 (solid) Chloroacetic acid, solid or liquid, Hazard class: 6.1; Labels: 6.1-Poison Inhalation Hazard, 8-Corrosive material.

Purification Methods

Crystallise the acid from CHCl3, CCl4, *benzene or water. Dry it over P2O5 or conc H2SO4 in a vacuum desiccator. Further purification is by distillation from MgSO4, and by fractional crystallisation from the melt. Store it under vacuum or under dry N2. [Bernasconi et al. J Am Chem Soc 107 3621 1985, Beilstein 2 IV 474.]

Toxicity evaluation

Occupational exposure to CAA can occur through inhalation and dermal contact with this compound at workplaces where it is produced or used. The general population can be exposed to CAA via ingestion of chlorinated or chloraminated drinking water.
The atmospheric photochemical oxidation of some volatile organochlorine compounds is one source of CAAs in the environment. CAA can be generated during water disinfection processes and during metabolic detoxification of industrial solvents such as trichloroethylene.

Incompatibilities

Compounds of the carboxyl group react with all bases, both inorganic and organic (i.e., amines) releasing substantial heat, water, and a salt that may be harmful. Incompatible with arsenic compounds (releases hydrogen cyanide gas), diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, sulfides (releasing heat, toxic, and possibly flammable gases), thiosulfates, and dithionites (releasing hydrogen sulfate and oxides of sulfur). The solution in water is a strong acid. Contact with strong oxidizers, strong bases; and strong reducing agents such as hydrides can cause violent reactions. Chloracetic acid decomposes on heating, producing toxic and corrosive hydrogen chloride, phosgene, and carbon monoxide gases. Attacks metals in the presence of moisture.

Waste Disposal

Incineration, preferably after mixing with another combustible fuel; care must be exercised to assure complete combustion to prevent the formation of phosgene; an acid scrubber is necessary to remove the halo acids produced.