This group of substances includes esters of fluoroacetic acid and esters of higher fluorocarboxylic acids, of the general formula :
F(CH2)nCOOR
also other fluorine compounds - e.g. fluoroalcohols, fluoroacetamide and their derivatives. All these substances are usually called fluoroacetates because they resemble methyl fluoroacetate, with which they are often compared, in their toxic properties. During the Second World War, these substances were counted on as a means of contaminating water. They are very permanent in aqueous solutions and are tasteless and odourless.
They are toxic if they enter the body through the respiratory organs or are injected intravenously or splashed on the skin.
However, they have no irritant effects.
From the data available, the following relationships between their chemical structure and toxicity can be deduced:
1.) compounds capable of forming the radical FCH2CO - by oxidation or hydrolysis, are toxic. Substitution in this group reduces or completely suppresses toxicity.
2.)esters of the type F(CH2)nCOOC2H5 are toxic as long as >n< number is odd. As long as the >n< number is even, the compounds have virtually no toxic properties.
3.)An increase in >n< at higher esters results in an increase in toxicity, the maximum occurring at n = 5, thereafter toxicity decreases.
4.)For this type of ester, toxicity increases as long as the >n< number is odd and less than >9< - when the ethyl group is replaced by a 2 fluoroethyl group.
Fluoroacetic acid and its derivatives
C2H3FO2 ( l.m.: 78 g/mol ) Boiling point: 168 °C
Chemical name (IUPAC): 2-fluoroacetic acid. Derivatives of sodium fluoroacetate (sodium salt) and fluoroacetamide (amide); English: fluoroacetic acid; sodium fluoroacetate; fluoroacetamide. Not used in the Slovak Republic, in some countries preparations labelled "1080" (baits containing 0.1 - 0.25% sodium fluoroacetate) and "1081" (baits containing 1 - 2% fluoroacetamide).
Fluoroacetic acid forms colourless or white crystals, melting point 35,2 °C, boiling point 165 °C, weak vinegar odour; sodium fluoroacetate forms a white, hygroscopic powder, melting point 200-202 °C, odourless, very soluble in water, slightly soluble in alcohols and insoluble in non-polar organic solvents; fluoroacetamide is a colourless or white crystalline powder, melting point 108 °C, odourless, freely soluble in water, soluble in alcohols and acetone, slightly soluble in non-polar solvents.
Fluoroacetic acid or its anion, fluoroacetate, is an extremely violent poison to all warm-blooded animals and some arthropods; the mechanism of toxic action is the metabolisation of fluoroacetate to fluorcitrate in the Krebs cycle and the blockage of the Krebs cycle by the competitive inhibition of the enzyme aconitase; the metabolism of all the cells of the organism is thereby severely disturbed to the point of cessation, with concomitant accumulation of citrate and lactate, leading to metabolic acidosis and disruption of the internal environment. The heart and central nervous system are particularly affected. Death occurs within 45 minutes to 18 hours after ingestion of the poison due to cardiac arrest or paralysis of the respiratory centre.
Toxicity of fluoroacetate and substances metabolised to fluoroacetate (fluoroacetamide, 2-fluoroethanol, 18-fluorostearate, etc.The acute LD50 for the rat is 0,22 mg/kg p.o., for the mouse 0,5 mg/kg p.o. The dog is particularly sensitive, the LD50 is only 0,066 mg/kg p.o. (data valid for sodium fluoroacetate). Toxicity to man is also quite high, in addition there is no specific antidote and developed severe poisoning is virtually impossible to reverse. For this reason, as well as the high risk to non-target animals, the use of fluoroacetate as a rodenticide is banned in most countries.
Methyl fluoroacetate
FCH2COOCH3 ( m.h.: 92.0 )
It is one of the most important of these substances.
Physical properties :
It is a colourless liquid, practically odourless ( not perceptible even when diluted 1 : 1000 ) t.v. : 105°C.
It is soluble in water up to 15% and is miscible with most organic solvents, also with yperite.
Chemical properties :
In water, methyl fluoroacetate hydrolyses very slowly according to the equation :
FCH2COOCH3 + H2O -> FCH2COOH + CH3OH
At normal temperature, only 2.5% of methylene fluoride is hydrolysed in 60 h. The hydrolysis is catalysed more by alkalis than by acids. The fluorine atom is considerably inert. After boiling for 20 hours with reflux condenser, only 50 % of potassium chloride is released.
Dilute sodium hypochlorite solution does not decompose methyl fluoride, but it is decomposed by vigorous oxidising agents ( chromic acid, sulphuric acid ) into water, hydrogen fluoride and carbon dioxide.
Evidence :
It can be converted indirectly by proof of fluorine after decomposition of the molecule by some common method.
Physiological effects :
Acts similarly to the esters of fluorophosphoric acid, has no irritant effects.
T.t.: - 33 °C
T.v.: 105 °C
Minimum concentration detectable by smell in mg/cubic metre : above 1000
Protection : mask and suit
F(CH2)nCOOR
also other fluorine compounds - e.g. fluoroalcohols, fluoroacetamide and their derivatives. All these substances are usually called fluoroacetates because they resemble methyl fluoroacetate, with which they are often compared, in their toxic properties. During the Second World War, these substances were counted on as a means of contaminating water. They are very permanent in aqueous solutions and are tasteless and odourless.
They are toxic if they enter the body through the respiratory organs or are injected intravenously or splashed on the skin.
However, they have no irritant effects.
From the data available, the following relationships between their chemical structure and toxicity can be deduced:
1.) compounds capable of forming the radical FCH2CO - by oxidation or hydrolysis, are toxic. Substitution in this group reduces or completely suppresses toxicity.
2.)esters of the type F(CH2)nCOOC2H5 are toxic as long as >n< number is odd. As long as the >n< number is even, the compounds have virtually no toxic properties.
3.)An increase in >n< at higher esters results in an increase in toxicity, the maximum occurring at n = 5, thereafter toxicity decreases.
4.)For this type of ester, toxicity increases as long as the >n< number is odd and less than >9< - when the ethyl group is replaced by a 2 fluoroethyl group.
Fluoroacetic acid and its derivatives
C2H3FO2 ( l.m.: 78 g/mol ) Boiling point: 168 °C
Chemical name (IUPAC): 2-fluoroacetic acid. Derivatives of sodium fluoroacetate (sodium salt) and fluoroacetamide (amide); English: fluoroacetic acid; sodium fluoroacetate; fluoroacetamide. Not used in the Slovak Republic, in some countries preparations labelled "1080" (baits containing 0.1 - 0.25% sodium fluoroacetate) and "1081" (baits containing 1 - 2% fluoroacetamide).
Fluoroacetic acid forms colourless or white crystals, melting point 35,2 °C, boiling point 165 °C, weak vinegar odour; sodium fluoroacetate forms a white, hygroscopic powder, melting point 200-202 °C, odourless, very soluble in water, slightly soluble in alcohols and insoluble in non-polar organic solvents; fluoroacetamide is a colourless or white crystalline powder, melting point 108 °C, odourless, freely soluble in water, soluble in alcohols and acetone, slightly soluble in non-polar solvents.
Fluoroacetic acid or its anion, fluoroacetate, is an extremely violent poison to all warm-blooded animals and some arthropods; the mechanism of toxic action is the metabolisation of fluoroacetate to fluorcitrate in the Krebs cycle and the blockage of the Krebs cycle by the competitive inhibition of the enzyme aconitase; the metabolism of all the cells of the organism is thereby severely disturbed to the point of cessation, with concomitant accumulation of citrate and lactate, leading to metabolic acidosis and disruption of the internal environment. The heart and central nervous system are particularly affected. Death occurs within 45 minutes to 18 hours after ingestion of the poison due to cardiac arrest or paralysis of the respiratory centre.
Toxicity of fluoroacetate and substances metabolised to fluoroacetate (fluoroacetamide, 2-fluoroethanol, 18-fluorostearate, etc.The acute LD50 for the rat is 0,22 mg/kg p.o., for the mouse 0,5 mg/kg p.o. The dog is particularly sensitive, the LD50 is only 0,066 mg/kg p.o. (data valid for sodium fluoroacetate). Toxicity to man is also quite high, in addition there is no specific antidote and developed severe poisoning is virtually impossible to reverse. For this reason, as well as the high risk to non-target animals, the use of fluoroacetate as a rodenticide is banned in most countries.
Methyl fluoroacetate
FCH2COOCH3 ( m.h.: 92.0 )
It is one of the most important of these substances.
Physical properties :
It is a colourless liquid, practically odourless ( not perceptible even when diluted 1 : 1000 ) t.v. : 105°C.
It is soluble in water up to 15% and is miscible with most organic solvents, also with yperite.
Chemical properties :
In water, methyl fluoroacetate hydrolyses very slowly according to the equation :
FCH2COOCH3 + H2O -> FCH2COOH + CH3OH
At normal temperature, only 2.5% of methylene fluoride is hydrolysed in 60 h. The hydrolysis is catalysed more by alkalis than by acids. The fluorine atom is considerably inert. After boiling for 20 hours with reflux condenser, only 50 % of potassium chloride is released.
Dilute sodium hypochlorite solution does not decompose methyl fluoride, but it is decomposed by vigorous oxidising agents ( chromic acid, sulphuric acid ) into water, hydrogen fluoride and carbon dioxide.
Evidence :
It can be converted indirectly by proof of fluorine after decomposition of the molecule by some common method.
Physiological effects :
Acts similarly to the esters of fluorophosphoric acid, has no irritant effects.
T.t.: - 33 °C
T.v.: 105 °C
Minimum concentration detectable by smell in mg/cubic metre : above 1000
Protection : mask and suit