2-fluoroethyl fluoroacetate high toxicity

On p. 129 it was shown that 2-fluoroethyl fluoroacetate was about twice as toxic as methyl fluoroacetate (M.F.A.) by inhalation. By analogy then it seemed that 2-fluoroethyl-5-fluoropentanecarboxylate (III) might be a compound of exceptionally high toxicity. This proved to be correct, for its l.d. 50... 

Ethyl 9 fluorononanecarboxylate (VII) was found to be even more toxic than ethyl 5 fluoropentanecarboxylate by injection into rabbits, the l.d. 50 for a propylene glycol solution of (VII) being 0-2 mg./kg. Mice and rats were sbghtly more resistant, but exhibited convulsions of the general fluoroacetate type. On account of the high boiling-point of the material, no inhalation experiments were attempted. 2 Fluoroethyl 9 fluorononanecarboxylate (VIII) was found to be no more toxic than the corresponding ethyl ester by injection into mice. Each had a l.d. 50 of about 10 mg./kg. This anomaly is discussed later. 

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