ORGANIC ACIDS, ACID SALTS, AND ESTERS 125 



linked together through one or more alkyl carbon atoms, are 

 also possible, and a few typical ones (as 



COOH 



I 

 HOOC-CH 2 -COH-CH 2 -COOH, citric acid) 



are found in fruits and other plant tissues. 



The H atom of the COOH group may be replaced by metals, in 

 exactly the same way as it is replaceable in inorganic acids, pro- 

 ducing either neutral or acid salts, depending upon whether all or 

 only a part of the acid H atoms are replaced by the basic element. 



Thus, with sulfuric acid: 



OH /ONa 



(H 2 S0 4 )+ NaOH = S0 2 < (NaHS0 4 )+H 2 O 

 H X OH 



Sulfuric acid Acid sodium sulf ate 



OH /ONa 



or, SO 2 < (H 2 SO 4 )+2NaOH = SO< (Na 2 SO 4 ) +2H 2 

 XMH x ONa 



Sulfuric acid Neutral sodium sulfate 



Similarly, with oxalic acid; 



COOH COOK 



(H 2 C 2 4 )+KOH = | +H 2 O 



COOH COOH 



Oxalic acid Acid potassium oxalate 



or, COOH COOK 



(H 2 C 2 O 4 )+2KOH = | +2H 2 O 



COOH COOK 



Oxalic acid Neutral potassium oxalate 



Similarly, the acid H atom of either an organic or an inorganic 

 acid may be replaced by the alkyl group of an alcohol, producing 

 " ethereal salts," or " esters." 



Thus, with nitric acid; 



N0 2 OH(HN0 3 ) +C 2 H 5 OH = N0 2 OC 2 H 5 (C 2 H 5 N0 3 ) +H 2 O 



Nitric acid Ethyl alcohol Ethyl nitrate 



And, with acetic acid; 

 CH 3 COOH(H 4 C 2 2 ) +C 2 H 5 OH = CH 3 COOC 2 H 5 +H 2 



Acetic 'acid Ethyl acetate 



With dibasic or polybasic acids, either one or more of the 

 carboxyl H atoms may be replaced with an alcohol radical, so that 



