Fluoroacetic acid, sodium salt

Synonyms Compound 1080 fluoroacetic acid, sodium salt Fratol sodium monofluo-roacetate... 

Fluoroacetic Acid, Sodium Salt A159 Industrial 151... 

Ethylenimine Famphur Fluorine Fluoroacetanide Fluoroacetic acid, sodium salt Dithiopyrophosphoric acid, tetraethyl ester Endosulfan Endothall Endrin Epinephrine... 

SYNONYMS fluoroacetic acid sodium salt, furatol, sfa, sodium fluoroacetic acid, sodium monofluoroacetate. 

Class B Fluoroacetic acid and salts, e.g. sodium fluoroacetate, triethyl-lead fluoroacetate all simple esters of fluoroacetic acid fluoroacetamide and substituted amides fluoroacetamidine hydrochloride fluoroacetyl chloride and fluoride fluoro-ethanol and its simple esters fluoroacetaldehyde. 

Fluoroacetic acid [144-49-OJ, FCH2COOH, is noted for its high, toxicity to animals, including humans. It is sold in the form of its sodium salt as a rodenticide and general mammalian pest control agent. The acid has mp, 33°C bp, 165°C heat of combustion, —715.8 kJ/mol( —171.08 kcal/mol) (1) enthalpy of vaporization, 83.89 kJ /mol (20.05 kcal/mol) (2). Some thermodynamic and transport properties of its aqueous solutions have been pubHshed (3), as has the molecular stmcture of the acid as deterrnined by microwave spectroscopy (4). Although first prepared in 1896 (5), its unusual toxicity was not pubhshed until 50 years later (6). The acid is the toxic constituent of a South African plant Dichapetalum i mosum better known as gifirlaar (7). At least 24 other poisonous plant species are known to contain it (8). 

Chemically, fluoroacetic acid behaves like a typical carboxylic acid, although its acidity is higher K — 2.2 x 10 ) than the average (9). It can be prepared from the commercially available sodium salt by distillation from sulfuric acid (10). 

Sodium chlorodifluoroacetate is prepared from chlorodi-fluoroacetic acid (K K Laboratories) as follows To a cooled, stirred solution of 60.7 g. (1.52 moles) of sodium hydroxide in 700 ml. of methanol is slowly added a solution of 198 g. (1.52 moles) of chlorodifluoroacetic acid in 300 ml. of methanol, the temperature being kept below 40°. The methanol is removed under reduced pressure at 40°. The salt, which is pulverized and dried overnight at room temperature at 1 mm., is obtained in essentially quantitative yield. The salt is again dried in the same way immediately before use. 

Sodium chlorodifluoroacetate is prepared in quantitative yield by careful neutralization of 130.5 g. (1.00 mole) of chlorodi-fluoroacetic acid (available from Allied Chemical Corp.) in 300 ml. of ether with 53.0 g. (0.500 mole) of anhydrous sodium carbonate, removal of the solvent and water under reduced pressure, and drying over phosphorus pentoxide in a vacuum desiccator. Studies have shown that the best yield of olefin is obtained when a 100% excess of salt is used. 

Fluoroacetate (3), the sodium salt of monofluoroacetic acid, is also a substance of vegetable origin, reported to poison sheep and cattle repeatedly. It is the toxic substance of a South African plant called gifblaar (Dichapetalum cymostm) and of the Australian plant Acacia georginae (Marais, 1944). The compound is readily soluble in water and is very toxic. Its acute oral lDj for rats is 0.2-2 mg/kg. The compound is converted via the citrate cycle into fluorocitrate and this blocks the citrate cycle. 

Although amines do not have to be in the free-base form for acylation by perfluoroacyl anhydrides, and derivatize smoothly even as their salts, some workers have included bases for catalytic purposes, and also to remove acid formed during the reaction, in addition to a solvent. In one recipe, the amine is dissolved in benzene (500 y ) and trimethylamine is added (100 fi of a 0.05 M solution in benzene) followed by 10 1 of anhydride, and the reaction is allowed to go to completion at room temperature. With the low concentration of anhydride this may take some hours. Excess anhydride is removed by washing with 3M ammonium hydroxide and the benzene solution is dried before GC analysis (80, 81]. In a similar procedure, the rather uncommon chlorodi-fluoroacetic anhydride is used. Here the base, extracted from its biological matrix, is dissolved in chloroform (20 fi ) and derivatized with triethylamine (1.5 yl) and the anhydride (3 y ) at 50 °C for 30 min. Excess reagent is neutralized with alkali and the derivatives are concentrated to dryness and taken up in toluene for GC analysis [82]. Trichothecenes (250 mg) are treated with TFAA and about 10 mg of solid sodium bicarbonate for 30 minutes at 80 C [83]. Alternatively, 0.5 ml of 10% acetonitrile in toluene is added followed by 100 y of triethylamine and 100 ul of PFPA. The reaction is carried out at 60 C for 15 minutes, and the reaction solution is washed with two 0.5 ml portions of 5% aqueous ammonia and one 0.4 ml portion of water to remove the surplus reagents [84]. 

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