Title:Synthesis of
Potential Biologically Active Synthones from Cellulose Derivatives
Author : Georgina Nabil Samaan
Collection : M.Sc. Chemistry
Abstract:
In
this thesis the preparation reactions, antibacterial effects of some modified
cellulosic compounds were studied. The cellulosic host was used in the
dialdehyde form by the oxidation to give Di-Aldehyde Cellulose (OAC). The
cellulosic compounds were prepared by reaction of DAC with Ortho- Phenylene
Di-Amine (OPDA) and two of its analogs namely 3,4-Di-Methyl Ortho-Phenylene
Di-Arnine and 4,5-Di-Chloro Ortho-Phenylene Di-Amine. The reaction is a
condensation addition reaction. A study of the reaction mechanism was carried
out. It was also validated that the reaction produces a seven membered ring
product. The kinetic study of the reaction focused on the variables of pH (1,
1.5,3, and 4), temperature (room temp. and 60-65°C), time (3mins up to 4 days),
method of stirring (continuous and occasional), and the method of heating (heat
bath or microwave). The study was carried out for all three of the OPOA
analogs. The general deductions concern those experiments with bath heating and
microwave heating. In bath heating as temperature increases the yield and rate
of reaction increase. The pH of the medium had a negative effect on the yield
and reaction rate since the reaction proceeds via nucleophilic addition which
is faster in W rich conditions. However the prolonged exposure to high
temperatures and low pH values causes the degradation of the products thermally
and chemically. Continuous stirring caused increase in yield but destroyed the
fiber form of the product, thus occasional shaking was used instead to
eliminate this problem. In microwave heating the rate of the reaction was substantially
higher than with bath heating and yield as high as 50% were reached in only 4
mins. The effect of pH was positive on reaction rate and yield since the severe
heating by irradiation also increased the rate of degradation of the products
especially at low pH values. Thus prolonged irradiation at high pH increased
yield but decreased yield at low pH due to degradation. The biological activity
of reaction product was studied on gram positive and gram negative bacteria.
The highest biological effect was observed with DAC reacted with 340MOPOA, the
second best performance was with DAC reacted with OPOA. Both showed activity
with gram +ve and gram - ve bacteria. In case of OAC reacted with 45DCOPDA it
showed an activity with only gram -ve bacteria and was ranked the least among
the three compounds. However this could be considered as an advantage of
specific antibacterial functionality of this compound against E.coli which
caused a lot of common infection.
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