Dichloroacetic acid
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| Dichloroacetic acid | |
|---|---|
 |
 |
| IUPAC name | |
| Other names | Dichloroethanoic acid |
| Identifiers | |
| CAS number |
79-43-6  Y |
| PubChem | 6597 |
| MeSH | Dichloroacetate |
| RTECS number | AG6125000 |
| SMILES | |
| Properties | |
| Molecular formula | C2H2Cl2O2 |
| Molar mass | 128.94 g/mol |
| Appearance | colorless liquid |
| Density | 1.5634 g/cm3 (20 °C) |
| Melting point | 13.5 °C |
| Boiling point | 194 °C |
| Solubility in water | miscible |
| Solubility | miscible with ethanol, diethyl ether[1] |
| Acidity (pKa) | 1.25[2] |
| Thermochemistry | |
|
Std enthalpy of formation ΔfH |
-496.3 kJ·mol-1[3] |
| Hazards | |
| MSDS | MSDS (jtbaker) |
| R-phrases | R35, R50 |
| S-phrases | (S1/2), S26, S45, S61 |
| NFPA 704 |
1
3
0
|
| Related compounds | |
| Related chloroacetic acids |
Chloroacetic acid Trichloroacetic acid |
| Related compounds |
Acetic acid Difluoroacetic acid Dibromoacetic acid |
|
Y (what
is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Dichloroacetic acid, often abbreviated DCA, is a chemical compound, an acid, and an analogue of acetic acid in which two of the three hydrogen atoms of the methyl group have been replaced by chlorine atoms, it has the chemical formula CHCl2COOH. The salts and esters of dichloroacetic acid are called dichloroacetates.
Contents[hide] |
[edit] Chemistry and occurrence
The chemistry of dichloroacetic acid is typical for halogenated organic acids. It is a member of the chloroacetic acids family. The dichloroacetate ion is produced when dissolved in water. As an acid with a pKa of 1.48,[4] pure dichloroacetic acid is very corrosive and extremely destructive to tissues of the mucous membranes and upper respiratory tract.[5]
DCA does not occur in nature. It is a trace product of the chlorination of drinking water and is produced by the metabolism of various chlorine-containing drugs or chemicals.[6] It is typically prepared by the reduction of trichloroacetic acid.
[edit] Therapeutic use
Owing to the highly corrosive action of the acid, only the salts of dichloroacetic acid are used therapeutically, including its sodium and potassium salts, sodium dichloroacetate and potassium dichloroacetate.
[edit] Lactic acidosis
The dichloroacetate ion stimulates the activity of the enzyme pyruvate dehydrogenase by inhibiting the enzyme pyruvate dehydrogenase kinase.[7] Thus, it decreases lactate production by shifting the metabolism of pyruvate from glycolysis towards oxidation in the mitochondria. This property has led to trials of DCA for the treatment of lactic acidosis in humans.[8][9][10][11]
A randomized controlled trial in children with congenital lactic acidosis found that while DCA was well tolerated, it was ineffective in improving clinical outcomes.[9] A separate trial of DCA in children with MELAS (a syndrome of inadequate mitochondrial function, leading to lactic acidosis) was halted early, as all 15 of the children receiving DCA experienced significant nerve toxicity without any evidence of benefit from the medication.[10] A randomized controlled trial of DCA in adults with lactic acidosis found that while DCA lowered blood lactate levels, it had no clinical benefit and did not improve hemodynamics or survival.[11]
Thus, while early case reports and pre-clinical data suggested that DCA might be effective for lactic acidosis, subsequent controlled trials have found no clinical benefit of DCA in this setting. In addition, clinical trial subjects were incapable of continuing on DCA as a study medication owing to progressive toxicities.
