512 Drushel and Holden — Hydracrylic Esters. 



The hydracrylic acid thus prepared, in about 50 gram portions, 

 was extracted from the residue by the absolute alcohol to be 

 used in the subsequent esterifi cation process. 



The alcoholic solution of hydracrylic acid, about 200 cm ' in 

 volume, was treated with somewhat more than the theoretical 

 amount of anhydrous copper sulphate free from sulphur 

 trioxide. The reaction mixture was gently boiled with a reflux 

 condenser on a sand bath until 80 per cent to 90 per cent of 

 the hydracrylic acid had been esteritied. The course of the 

 esteriiication was followed by titrating from time to time l rm3 

 of the reaction mixture with decinormal barium hydroxide. 

 After the completion of the reaction the copper sulphate was 

 filtered off, the unesterified hydracrylic acid almost neutralized 

 with anhydrous sodium carbonate, the excess of alcohol 

 distilled off in a water or oil bath and the residue of hydra- 

 crylic ester subjected to fractional distillation under diminished 

 pressure, usually at 12 mm to 20™. The esters which were 

 prepared in this way and whose properties were then studied 

 are the methyl, ethyl, propyl, isopropyl, isobutyl and isoamyl 

 esters of hydracrylic acid. The densities of these esters were 

 determined at 0° and at 25° ; the values obtained are recorded 

 in Table I. 



Table I. 



0" 25° 



Methyl hydracrylate ..1-140 1-118 



Ethyl " ' .1-085 1-064 



Propyl " 1-052 1-043 



Isopropyl " 1-071 1-058 



Isobutyl " 1-013 1-003 



Isoamyl " ...0-988 0-976 



These density determinations are referred to water at 4° 

 and were made by means of a pycnometer * of a type which 

 was especially devised for use in the qualitative organic 

 analysis work in this laboratory. It consists of a capillary stem 

 about 7 cm in length, a bulb to contain approximately l cma and a 

 drawn out capillary about l c,n in length. The capillary stem 

 is graduated so that the pycnometer shall contain exactly one 

 cubic centimeter of water at 4°. This type of instrument ha6 

 the advantage that by a single weighing it gives fairly accurate 

 specific gravity data even in the hands of those not skilled in 

 the use of the more complicated types. 



All of the hydracrylic esters investigated boil with decompo- 

 sition at atmospheric pressure. Their boiling points were 

 therefore determined directly over a range of pressures of 15 mm 

 to about 100 mm and from the data obtained the boiling points 



* A cut of this type is published in the Journal of Industrial and Engineer- 

 ing Chemistry, vii, 187. 



