Structure of Simpler Organic Compounds. 109 



This reaction is sufficient to indicate its constitution. Its 

 constitution is also indicated by the following synthesis. 

 When acetic acid is treated with chlorine, it yields a series 

 of chlorine substitution products (see p. 90). The mono- 

 chlor derivative is CH 2 C1 CO OH. The potassium salt 

 of this acid on treatment with potassium cyanide yields 

 the potassium salt of cyanacetic acid 



C1CH 2 COOK + KCN = KC1 + (CN)-CH 3 COOH 

 This latter substance on hydrolysis undergoes the general 

 reaction of substances containing the (CN) group, which is 

 converted into the carboxyl group 



(CNJCHa-COOH + 21^0 = NH 3 + COOH-CH 2 COOH 

 and yields malonic acid. 



If the potassium cyanacetate is treated with hydro- 

 chloric acid gas in the presence of alcohol, it yields, instead 

 of malonic acid, its ethyl ester 

 (CNJCHa-COOK + 2HC1 + 2C 2 H 5 -OH 



y 



CH 



= CH 2 +KC1 + NH 4 C1 



In this way ethyl malonate is produced, which, on 

 account of certain characteristic reactions, has been largely 

 employed for the purpose of organic synthesis. 



SYNTHESIS BY MEANS OF ETHYL MALONATE. 



By virtue of a special property which it possesses, 

 ethyl malonate forms a basis from which a large number 

 of more complex substances can be built up. It has been 

 found that when the group of elements CH 2 is placed 

 between two carbonyl ( CO ) groups, as is the case in 

 ethyl malonate, the two hydrogens of the former group 

 can be replaced by an alkali metal such as sodium. This 

 reaction is carried out in the following way. One atomic 



