1921.] Recent Advances in\Stereochemistry. © 40! 217 
On the other hand, the molecular rotatory power in the 
homogeneous state increases regularly by small increments as 
the chain grows. 
hen, however, the space occupied by the groups a, b and 
c is larger, the increase in molecular rotatory power as d 
increases, becomes less regular. In the “ Ethyl” series, C, H, 
CH (OH) RB, there are sudden increments when the “ growing ”’ 
chain contains 5, 10 and 15 carbon atoms. 
Normal Secondary Alcobols of the formula 
C, H, CH (OH) R. 
R. Homogeneous. 
(A normal alkyl state. Ethyl Alcohol. Benzene. 
group.) (M)a (M)a (M)a 
Methyl 19° 10°77° 10°44° 
Propyl “29 117 1:87 
Butyl 11-11 1117 10°80 
y 12°53 1447 13°26 
1 12°43 13°86 13°82 
Heptyl 12 26 9°81 12°11 
tyl 12°43 10°69 12:18 
onyl 12°86 11°35 12-48 
D 14 42 13°46 14:62 
Undecyl 14:55 13-38 15°60 
Dodecyl 14-59 12°44 15°32 
Tridecyl 14°32 12°75 15-44 
Tetradecyl ie Has not been prepared. 
Pentadecyl whe 14°83 12°91 16°63 
Besides, the sudden increments which occur when the 
growing chain contains 5 or a multiple of 5 carbon atoms, there 
is a gradual, though slow increment in the rotatory power 
If the space occupied by the groups 4, b and ¢ is still 
greater, the ‘‘ approximate maximum ”’ is reached when the 
growing chain contains fewer than five carbon atoms. Thus 
in the “ isopropyl” series of .carbinols (CH,), CH. CH (OH)R 
where the isopropyl! group (CHs), CH—is fairly large, the mem - 
ber containing four atoms in the “ growing chain” has the 
conspicuous value for the molecular send power, in the 
1 alc 
has the conspicuous value. 
1 + e)y Pi CH OH . R. 
Carbinols, (CH3), CH wey Alcoholic solu- 
R, Homogeneous state. tion. 
(A normal alkyl group.) (aa 
Methyl i 4:3° + 37° + ¢T 
on at 219 2797 
n-Propyl 247 
n-Butyl 333 29:1 35°97 
n-Amyl 32°9 28°7 38°24 
n-Hexyl 33-9 29 38°36 
