クロロ酢酸

外観

白色, 結晶及び塊

定義

本品は、次の化学式で表される有機化合物である。

溶解性

水と混和, エタノール, エーテルに易溶。水にきわめて溶けやすく、エタノール及びジエチルエーテルに溶けやすい。水にきわめて溶けやすく、エタノール及びジエチルエーテルに溶けやすい。

解説

酢酸の塩素置換体に相当し，その程度によって異なる3種類のものがある．一般にはモノクロロ酢酸をさす．【Ⅰ】モノクロロ酢酸：C2H3ClO2(94.50)．CH2ClCOOH．酢酸を少量の硫黄，ヨウ素などの存在下で塩素化するか，トリクロロエテンを硫酸で処理すると得られる．無色の潮解性結晶．d²⁰₂₀1.58．3種類の形があり，それぞれの融点はα形：63 ℃，β形：55～56 ℃，γ形：50 ℃．沸点189 ℃，104 ℃(2.66 kPa)．水，エタノール，ベンゼン，クロロホルム，エーテルに可溶．水溶液は酢酸より強酸である．pKa 2.85，Ka 1.55×10－2(25 ℃)．アンモニアと反応してグリシンに，またシアン化カリウムと反応してシアン酢酸になる．種々の有機合成の原料になる．[CAS 79-11-8]【Ⅱ】ジクロロ酢酸：C2H2Cl2O2(128.95)．CHCl2COOH．モノクロロ酢酸を塩素化すると得られる．液体．融点9.7 ℃，沸点193～194 ℃，102 ℃(2.6 kPa)．d²⁰₄"1.563．水，エタノール，エーテルに易溶．加水分解するとグリオキシル酸になる．刺激臭を有する．[CAS 79-43-6]【Ⅲ】トリクロロ酢酸：C2HCl3O2(163.39)．CCl3COOH．クロラールを硝酸酸化するか，ジクロロ酢酸をさらに塩素化すると得られる．無色の潮解性結晶．融点57～58 ℃，沸点197 ℃，142 ℃(3.3 kPa)．d²⁰₄"1.629．水，エタノール，エーテルに易溶．モノクロロ酢酸，ジクロロ酢酸より強酸である．pH 1.2．希アルカリで加水分解されてクロロホルムと二酸化炭素になる．また，濃アルカリではギ酸になる．腐食剤，角質溶解剤などのほか，生体のリン酸化合物，タンパク質，脂質などの分画分析に用いられる．強い腐食性を有する．[CAS 76-03-9]　三者とも皮膚，粘膜などをおかすのでとくに注意が必要である．
森北出版「化学辞典（第2版）

用途

除草剤、医薬品原料、有機合成用

用途

カルボキシメチルセルロース原料、2,4-ジシクロフェノキシ酢酸原料、チオグリコール酸及び両性界面活性剤原料 (NITE初期リスク評価書)

用途

有機合成原料。

用途

有機合成原料(医薬、農薬、可塑剤、香料等)。

化粧品の成分用途

pH調整剤、剥離剤

効能

腐食剤

使用上の注意

極めて潮解性が強く液化しやすい。腐食性大。

説明

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.

化学的特性

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.

使用

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.

定義

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.

調製方法

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.

一般的な説明

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.

空気と水の反応

Water soluble.

危険性

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

健康ハザード

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.

火災危険

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

安全性プロファイル

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.

職業ばく露

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.

環境運命予測

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.

輸送方法

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

純化方法

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.]

不和合性

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.

廃棄物の処理

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.