314 Krenters—Ondhe Classification of Carbon-Compounds. 
are connected with but one other carbon atom. The methylene 
hydrogen atoms are connected with a carbon atom which has 
but two of its affinities saturated by hydrogen and is connected 
with two other carbon atoms. The possibility of two mono¬ 
hydroxy substitution products of propane thus becomes appar¬ 
ent. The one can be formed by substituting a hydroxy group 
in place of one of the six methyl hydrogens, the other by simi¬ 
lar substitution of one of the two methylene hydrogens, thus: 
ch 2 oh ch 3 
CH s or CH OH. Of di-substitution products there are 
I i 
CH S CH 3 
four, etc. Applying these principles of substitution and of 
dehydration, the accompanying table will explain itself: 
If comparisons are now made it will be seen that we can gen¬ 
eralize and at the same time classify the mono-substitution 
products or alcohols, according to the following type-formulas, 
R' being equal to the univalent saturated radicle (CnH^i-f-j)' : 
R' — CH 2 . OH or primary alcohols, 
R' 3 = C H. O H or secondary alcohols, 
R' 3 =C .OH or tertiary alcohols. 
The di-substitution products having the hydroxy groups con¬ 
nected with two different carbon atoms are. glycols of the ethy¬ 
lene glycol type, with two primary, or one primary and one 
secondary, or two secondary, or one primary and one tertiary, 
etc., alcohol groups. Upon dehydration they yield oxides. 
The di-substitution products, in which the two hydroxy 
groups are connected with the same carbon atom, are glycols of 
the ethyledene glycol type and readily break up into water and 
either aldehydes, characterized by the general formula 
TT T?'\. 
R'— Cc^q ; or ketones, characterized by the formula jj/ C=0. 
It is evident why primary alcohols yield aldehydes and why 
secondary alcohols yield ketones upon oxidation. The tertiary 
alcohols can form neither, i. e., with the same number of car¬ 
bon atoms, because the carbon atom with which the alcohol 
group (O—H)' is connected has none of its affinities saturated 
by hydrogen that could be oxidized to a hydroxy group. 
The tri-hydroxy substitution products having all three 
