436 Dr. Atkinson on Monoacetate of Glycol, 



sul[)1iatc of baryta, which corresponds to 0-996 of an equivalent 

 of acetic acid*. 



These results, together with its physical properties, leave no 

 doubt that the substance in question is the monoacetate of 

 glycol. The analytical results would correspond equally well to 

 a mixture of equivalent quantities of glycol and acetate of glycol; 

 but, on the other hand, its evidently homogeneous nature, its 

 complete solubility in water (in which it differs from acetate of 

 glycol), its boiling-point, which, in various preparations made 

 with various quantities, was found to be constant between 181° 

 and 182° C. (which is 5 degrees lower than that of diacetate of 

 glycol and about 13 degrees lower than that of glycol), and the 

 agreement in the quantity of acetic acid found in specimens of 

 different preparation are all inconsistent with this assumption. 

 In its formation, the elements of water take part, thus : — 



Q2JJ4 -^ 



C2 H4Br2 + 2 f ^^ ^^'2 T O ) + ^^' = 2 Br K + C^H^ 1 0^ + C2 H" 0^. 

 Bromide of ^ , , ^-i, ^ Bromide of H 



ethylcue. ,Si potassium. ^ 



And part of this acetic acid forms acetic ether with the alcohol 

 present. 



The diatomic glycol stands in the same relation to the mono- 

 acetate of glycol as a bibasic acid (for example, oxalic acid) docs 

 to its acid salts, thus : — 



H J 



Monoacetate of frlvcol. 



Glycol. 



g:}o' 



C2 



Oxalic acid. 



K yo^ 

 "■J , 



Acul oxalate of potash. 

 And monoacetate of glycol stands to the diatomic alcohol, 

 glycol, in a similar relation to that in which Berthelot's mono- 

 acctinc and diacetine stand to the triatomic alcohol, glycerine. 



* The chloride may be substituted for the bromide of ethylene in the 

 preparation of monoacetate of glycol ; but as its action on the potash salt 

 is less energetic, it is necessary to continue the heating in tlic water-bath 

 somewhat longer. In other respects the preparation is the same. Tlie 

 experiment was not made on a sufficiently large scale to enable nic to state 

 with certainty what amount of product was obtained ; but as the equiva- 

 lent of the chloride of ethylene is little more than half that of the bromide 

 {90 : 188), its emi)loyment would, cmtcris paribus, be more advantageous. 

 l?romide of ethylene yiehls nearly three-fom-ths of the theoretical quantity 

 of pure monoacetate of glycol required by the equation. 



I 



