94 Messrs Sell and Dootson, On the synthesis of 



stopped. The distillate contained a small quantity of the un- 

 changed tetrachloro pyridine, but consisted mainly of ethyl malo- 

 nate, more than half of the quantity employed being thus 

 recovered. Tn view of this result experiments were tried with a 

 smaller proportion of sodiomalonic ester, when the yield was found 

 to be perceptibly diminished. After some hours the dark-coloured 

 residual liquid remaining in the flask became solid. This was 

 moistened with alcohol, drained at the pump and washed with 

 small quantities of the solvent, until almost colourless crystals 

 remained. On purification from alcohol these separated in colour- 

 less massive forms which melted sharply at 63 — 64° (uncorr.). 



This substance on analysis was found to be ethyl trichloro- 

 pyridylmalonate having the formula 



C 5 HC1 3 NCH (COOC 2 H 5 ) 2 . 



It is readily soluble in alcohol, ether and the usual organic 

 solvents. It dissolves in dilute solutions of the caustic alkalies, 

 and is reprecipitated on acidifying. If to its solution in aqueous 

 caustic potash a strong solution of this reagent be added, a 

 potassium salt separates in colourless crystals which may be re- 

 crystallised from a hot moderately strong solution of the alkali. 

 A potassium determination confirmed the formula 



C 5 HCl 3 NCK(COOC 2 H 5 ) 2 . 



Now it was found, by a long series of experiments, that the <y 

 position alone, in the tetrachloropyridine used, was replaced under 

 any of the conditions tried. Therefore in the trichloropyridyl- 

 malonic ester above described the malonic residue must be regarded 

 as occupying the 7 position. This ester, on treatment with 

 80 per cent, sulphuric acid, is converted into trichloropyridyl- 

 acetic acid, slowly at 100° C, and more rapidly as the temperature 

 approaches the boiling point. This substance is precipitated 

 from the sulphuric acid solution on dilution, and may be purified 

 by recrystallisation from water. Thus obtained it forms tabular 

 colourless crystals which melt at 144 — 145° (uncorr.) and which 

 are represented by the formula 



C 5 HCl 3 NCH 2 COOH. 



The silver salt of the acid is a white granular substance 

 sparingly soluble in boiling water. The calcium salt is soluble. 

 The barium salt, in presence of ammonia, slowly separates in long 

 needles. 



On heating to its melting point, or a higher temperature, 

 trichloropyridylacetic acid decomposes, carbon dioxide being 

 freely evolved. If the operation be carried out in vacuo, trichloro- 

 methylpyridine distils over. The yield of the latter substance 



