Structure of Simpler Organic Compounds. 107 



Succinic acid, CO -OH melting point, 185 

 CH 2 

 CH, 



COOH 



Glutaric acid, CO- OH or, more shortly, COOH(CH 2 ) 3 COOH 

 | melting point, 97'5C. 



CH 2 



CH 3 

 I 

 COOH 



Adipic acid, CO-OH(CH 2 ) 4 -COOH melting point, 148 



Various isomerides of these substances exist, but the long- 

 chain substances are of more importance. The isomeride 

 of succinic acid is 



x 

 CH- 



CH 3 



300H 

 or methyl malonic acid. 



These substances can form acid and neutral salts, 

 according to whether the hydrogen of one or both carboxyl 

 groups is replaced by a metal. The two sodium oxalates 



COONa NO ONa 



would have the formulae | and | 



COOH CO ONa 



In the same way acid and neutral esters can be obtained, 

 such as the acid and neutral ethyl oxalates 



CO-OC a H 5 CO.OC 2 H 5 



| and | 



COOH COOC 2 H 6 



