Chlorides 4,18,22-pentamethyl-5,9,13,17,21-tricosapentaenes) with vari
ous phenyl substituents were prepared, and solvolysis rates were measu
red in aqueous ethanol (phi = 95% and 80%) and in aqueous 2,2,2-triflu
oroethanol (omega = 97%). Hammett rho(+) values obtained are -1.86, -1
.81 and -1.56, respectively, suggesting concerted cyclization of at le
ast two double bonds in the rate determining step.