90 S. L. MILLER 



concentration of ammonia decreased steadily during the run, mostly due to 

 decomposition of the ammonia to hydrogen and nitrogen in the discharge. The 

 hydrogen cyanide concentration rose to 4 x lo^^ m, and after 120 hours ap- 

 parentiy littie more was synthesized in the spark. Thereafter the hydrogen 

 cyanide present was hydrolysed to formic acid or decomposed in the spark. 

 The aldehyde concentration rose to about io~3 m and declined after 120 hours. 

 The concentration of amino acids rose during the run and levelled off after about 

 140 hours. 



Several repetitions of this experiment gave concentrations of these compounds 

 of the same order of magnitude, but the values were not reproducible in detail. 

 Probably the most important variable that could not be controlled was the 

 operation of the spark. 



Hydrolysis of Amino- and Hydroxynitriles — Run 4 



Hydrogen cyanide, aldehydes and ammonia are known to react to give amino- 

 and hydroxy-nitriles. There is a question of whether the conditions of this 

 experiment will hydrolyse these nitriles to the corresponding acid. A solution 

 of 63 m-moles NH3 (corresponding to 25 cm Hg pressure), 20 m-moles hydrogen 

 cyanide, 6-i m-moles formaldehyde, 3-64 m-moles acetaldehyde and i-i6 m-moles 

 propionaldehyde (in 325 ml H2O) was boiled in the apparatus for a week. The 

 glycine, glycohc acid, iminodiacetic acid and imino-aceticpropionic acid accounted 

 for 52% of the formaldehyde; alanine, lactic acid and imino-acetic-propionic acid 

 accounted for 58% of the acetaldehyde; a-amino-«-butyric acid and a-hydroxy- 

 butyric acid accoimted for 36% of the propionaldehyde. This experiment shows 

 that aminonitriles and hydroxynitriles can be hydrolysed in this system, and 

 further that the amino and hydroxy acids are formed in good yield from the 

 aldehyde. 



By titrating samples withdrawn from the U-tube for hydrogen cyanide during 

 the course of the run, the rate constant for hydrolysis of hydrogen cyanide to 

 formic acid is estimated to be o-i hr"i. Similarly by determining the amino acid 

 concentration in the 500 ml flask at various times, the rate constant for hydro- 

 lysis of the aminonitriles is estimated to be 0-2 hr"i. 



From these rate data and the concentrations in Fig. 2 the yield of formic acid 

 from hydrolysis of hydrogen cyanide is calculated to be 3-6 m-moles and the 

 yield of amino acids from hydrolysis of the aminonitriles is calculated to be 

 1-4 m-moles. These values agree within the experimental error with the observed 

 yields of 2-4 m-moles of formic acid and 1-2 m-moles of amino acids. Thus in 

 the case of the spark discharge, the rates of hydrolysis under the conditions of 

 the experiment are sufficient to account for the total yields of formic acid and 

 amino acids observed. 



The Ratios of Products 



Further evidence that the synthesis of the amino and hydroxy acids is through 

 the corresponding nitrile can be obtained by considering the ratios of products 

 predicted by tJiis mechanism. 



