LABILITY AND ENERGY IN RELATION TO PROTOPLASM. 397 
nitro-group, however, we observe a somewhat different behaviour 
in regard to the influence of position ; thus 1. 3 dinitropropane is 
much less stable than the isomeric 1. 1 or 2. 2 dinitropropanes. (1) 
The stability of a compound against chemical attacks grows with 
the increase of the number of the CH 2 or alkyl groups. Thus, form¬ 
aldehyde enters much more easily into various reactions than its 
homologues ; acetone clicarboxylic ether is no longer attacked by 
phenylhydrazine after two methyl groups have been introduced 
and it even resists the action of phosphorus pentachloride after 
fotir methyl groups have entered. (2) 3 Also the relative position 
exerts an influence ; thus, a methyl group in para-position in 
diazobenzene leads to a greater stability than one in ortho-posi¬ 
tion/ 33 The i. 3 keto-aldehydes of the form R — CO —CH 2 —CHO 
are very unstable and undergo spontaneous condensation, while 
after the introduction of a second alkylic radical in <2 —position, 
a product R — CO —CHR'— CHO results that may even be dis¬ 
tilled unchanged. (4) On the other hand we must not omit an excep¬ 
tion observed with diazo-propionic ether, which is less stable 
than diazo-acetic ether. (5) 
CH-COOR 
/\ 
N = N 
■ "" *. 1 - v —--s 
Diazo-acetic ether 
The readiness with which an atom is replaced by another 
atom or by a radical, may, ceteris paribus , be considered as a 
measure of the lability of its position. Thus, the hydrogen atoms 
in ^-position to a keto or carboxylic group show a higher 
degree of lability than those in /3 or/-position, (6) 7 but still more 
labile are generally the hydrogen atoms of the amido-group. il) 
(1) V. Meyer , Ber. Chem. Ges. 25 , 1709. 
(2) Petrenko , Chemikerzeitung, I895, p. 1880. 
(3) Hirsch, Ber. Chem. Ges. 24 , 325. 
(4) Claisen, Bayr. Akad. Ber. 1890 p. 447. 
(5) Cur tins, Ber. Chem. Ges. 23 , 3037. 
(6) Very numerous are the observations on varying lability of hydrogen atoms and 
their substitutes in the benzene ring. Hydrogen atoms in a high degree of lability 
are easily attracting atomospheric oxygen (autoxidations). By the vicinity of negative 
groups as cyanogen, phenyl or carboxethyl, certain hydrogen atoms attached to 
carbon can acquire in special cases the property of being easily replaced by metals; this 
state, however, is not a genuine case of lability. 
(7) Also the cyanogen group linked to nitrogen is more labile than when linked to 
carbon (Ber. 28, 2074). 
ch 3 -c-cooh 
/\ 
N = N 
Diazo-propionic ether 
