ON THE STUDY OF HYDRO-AROMATIC SUBSTANCES, Hel bes: 
study of polymethylene derivatives in respect to the velocity of chemical 
change.! 
The formation of the closed polymethylene ring from an open chain of 
normal structure proceeds with increase of velocity, the maximum occur- 
ring in the formation of the pentamethylene ring, decreasing through 
the hexamethylene, to the minimum increase in the case of the hepta- 
methylene ring. The increase of velocity at the closing of the open 
chain is not a specific property of the polymethylene ring, but is observed 
in the formation of all rings, alicyclic and heterocyclic. The secondary 
polymethylene alcohols, in which the hydroxyl group is attached to the 
carbon atom of the ring, are typical secondary alcohols. Their esterifica- 
tion constants are higher than those of the normal saturated secondary 
alcohols ; derivatives of cyclopentanol giving the highest, cyclohexanol 
much lower, and cycloheptanol the lowest values. The esterification con- 
stants of polymethylene tertiary alcohols are very low, but esterification 
proceeds regularly. This is characteristic of phenols, and does not occur 
with saturated tertiary alcohols. When side chains are present in the 
ortho or diortho positions a great decrease in the esterification constants 
is observed, an effect commonly ascribed to the benzene ring alone, but in 
reality a general property of all chains. Side chains in positions 3 or 
4 of the polymethylene series produce an increase of the constants ; and 
as open chain compounds show no such increase of velocity, this provides 
an important characteristic of closed chains. When a hexamethylene 
ring is introduced into the open chain of an alcohol, the decrease of the 
esterification constants is much larger than is effected by the benzene 
ring. 
' Menschutkin, J.C.S., 1906, 89, 1532. 
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