Difference between revisions of "Thioglycolic acid"
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Thioglycolic acid is about 100 times stronger acid than [[acetic acid]], with a pKa of 3.83. | Thioglycolic acid is about 100 times stronger acid than [[acetic acid]], with a pKa of 3.83. | ||
| − | Thioglycolic acid is a reducing agent, especially at higher pH. | + | Thioglycolic acid is a reducing agent, especially at higher [[pH]]. |
Thioglycolic acid, usually as its dianion, forms complexes with metal ions. Such complexes have been used for the detection of [[iron]], [[molybdenum]], [[silver]] and [[tin]]. | Thioglycolic acid, usually as its dianion, forms complexes with metal ions. Such complexes have been used for the detection of [[iron]], [[molybdenum]], [[silver]] and [[tin]]. | ||
Latest revision as of 18:52, 22 May 2019
| Names | |
|---|---|
| IUPAC name
Sulfanylacetic acid
| |
| Other names
2-Mercaptoacetic acid
2-Sulfanylacetic acid Acetyl mercaptan Mercaptoacetic acid Thioglycolic acid Thiovanic acid | |
| Properties | |
| C2H4O2S HSCH2COOH | |
| Molar mass | 92.11 g/mol |
| Appearance | Colorless liquid |
| Odor | Unpleasant, sulfurous |
| Density | 1.3253 g/cm3 (20 °C)[1] |
| Melting point | −16 °C (3 °F; 257 K) |
| Boiling point | 96 °C (205 °F; 369 K) (at 5 mmHg) |
| Miscible | |
| Solubility | Reacts with amines Miscible with acetone, benzene, chloroform, diethyl ether, ethanol, formic acid, isopropanol, toluene Immiscible with aliphatic hydrocarbons |
| Vapor pressure | 10 mmHg (17.8 °C) |
| Acidity (pKa) | 3.83 |
| Thermochemistry | |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
261 mg/kg (rat, oral) |
| Related compounds | |
| Related compounds
|
Glycolic acid |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Thioglycolic acid (TGA) or mercaptoacetic acid (MAA) is an organic compound, carboxylic acid with a thiol group. It has the chemical formula C2H4O2S or HSCH2COOH.
Contents
Properties
Chemical
Thioglycolic acid is about 100 times stronger acid than acetic acid, with a pKa of 3.83.
Thioglycolic acid is a reducing agent, especially at higher pH.
Thioglycolic acid, usually as its dianion, forms complexes with metal ions. Such complexes have been used for the detection of iron, molybdenum, silver and tin.
Physical
Thioglycolic acid is a colorless liquid, with an unpleasant odor.
Availability
Thioglycolic acid and its esters are commonly used in hair removing products.
Some rust removers or car tar removers contain 5-10% sodium thioglycolate. To obtain the free acid, simply add a weak acid to the salt and purify the reaction product.
Thioglycolic acid is sold by chemical suppliers.
Preparation
Thioglycolic acid is prepared by reaction of sodium or potassium chloracetate with alkali metal hydrosulfide in aqueous medium.
It can be also prepared via the Bunte salt obtained by reaction of sodium thiosulfate with chloroacetic acid.
Projects
- Chemical depilation
- Hair permanent
- Make ammonium thioglycolate
- PVC stabilizer
- Make thioglycolate broth
Handling
Safety
Thioglycolic acid is harmful and its strong unpleasant odor may cause health problems.
Storage
Thioglycolic acid should be kept in dark amber bottles, which must be airtight, as the compounds oxidizes in air over time. It is known to oxidize faster in the presence of water.
Disposal
Should be neutralized with hydrogen peroxide or bleach to a less smelly form, then poured down the drain.
References
- ↑ Klason; Carlson; Chemische Berichte; vol. 39; (1906); p. 739
