130 CHEMICAL PROPERTIES AND COMPOSITION 



CC1 3 COH, which under the action of alkali yields 

 chloroform. 



Combination with nitrogen has a still stronger tendency 

 towards decomposition ; this follows the appearance of the 

 cyanogen group, since, e.g. acetonitril, CH 3 CN, is decomposed 

 by sodium, cyanogen, NCCN, by bases and cyanoformic acid, 

 NCCOOH, even spontaneously. The same is true of the 

 nitro group, and leads, e.g. to non-existence of nitroacetic 

 acid, O 2 NCH 2 COOH, which on saponification of its ethyl 

 ester breaks up into nitromethane and carbon dioxide. 



2. Spatial Influences, 

 (a) Action of Hydrogen during Ebterification. 



The accelerating influences so far considered come into 

 play at some linkage of carbon, either with another element 

 or with itself. The action of hydrogen we are about to 

 consider is during the formation of esters, taking place 

 according to the equation 



H 3 CCOOH + HOC 2 H 5 = H 2 + H 3 COOC 2 H 5 , 

 or generally 



XCOOH + HOCY = H 2 O + XCOOCY ; 



here the carbon combined with oxygen remains so com- 

 bined, though it may be to another atom, while the principal 

 change happens to the oxygen linkage. Presence of 

 hydrogen and absence of other groups at the point in 

 question produces a most remarkable accelerative action 

 on this reaction, which may be followed in detail, because 

 here in some instances the velocity has been measured 

 under comparable circumstances, and expressed by the 

 velocity constant (Part I, p. 187). 



Menschutkin first pointed out the fact, and the fol- 

 lowing table gives the initial velocities of esterification of 

 different alcohols by acetic acid, i. e. the percentage amount 



