Study on Association Between o-methoxy-benzylidene-paminoaniline with phenols

Abstract

The interactions of o-methoxy-benzylidene-p-aminoaniline (MBAA) with phenol,
p-methoxyphenol ,and p-chlorophenol in n-hexane are studied by using UV
spectroscopy . The study led to the formation of hydrogen bond species of types
O – H·····O and O – H ····· N between MBAA with phenol and p-methoxyphenol .
The last is appeared from the UV spectra record of MBAA with phenols stated at
relative concentrations ratio of phenol / MBAA and p-methoxy phenol / MBAA of
values 4/1 and 4/1 respectively. Similar result is obtained on using p-chlorophenol at
relative concentration ratio of p-chlorophenol / MBAA of a value 4/1 , with additional
appearance of two UV protonated bands at a wavelengths of 463 nm and 474 mm .
These can be of type nitrilium ion N H or oxonium ion O ,or both of
H
them . The equilibrium constants for hydrogen bond formations of MBAA with
phenols stated are included . The interactions of systems under study are confirmed by
thermodynamic method . These show that ΔH and ΔS have a negative signs , as
well as their values which support hydrogen bondings . Moreover , the processes of
non spontaneous hydrogen bonding as observed and evident from the positive values
of ΔG are included . These final abnormal results are unexpected and discussed in
details .