Hobbs, Patrick T (1994) Synthesis and use of an immobilized catalyst for the n-oxidation of 2-chloropyridine. Master of Science thesis, Dublin City University.
Abstract
N-oxides were defined, their history and chemistry
surveyed. Conventional N-oxidising reagents, such as the
aliphatic and aromatic percarboxylic acids were examined.
Immobilized catalysts, their applications and synthesis
were extensively reviewed and examples noted. Immobilized
percarboxylic acids or carboxylic acids in conjunction with hydrogen peroxide were identified as potential N-oxidising reagents. The literature survey yielded eight routes which have been utilized for introduction of a carboxyl group into polystyrene. A number of these routes were
investigated experimentally. Two routes proved useful,
(i) modification of Merrifield resin to carboxylated resin
and (ii) chloroacylation of polystyrene , then formation of
the phenyl pyridinium chloride derivative followed by
cleavage afforded carboxylated polystyrene.
The criteria for a useful support resin were reviewed and a
porous macroreticular polystyrene-divinylbenzene
crosslinked resin was found to offer a number of advantages
over convensional gel-type resins. A sample of such a
resin, XE-305 was procured from a commercial company and
used for synthesis. The carboxylated derivative with
carboxylate loading from 42% to 88% were used to oxidise
2-chloropyndine to its N-oxide in the presence of excess
hydrogen peroxide and mineral acid. Yields of the order of
33-35% were achieved. 2-Chloropyridine-N-oxide is used for
the manufacture of a number of commercially important
antifungal and anti- bacterial biocides.
Despite numerous changes and modifications to the reaction
conditions, including the use of a peroxide stabiliser, the
yield could not be increased above 33-35%. For commercial
success, yields greater than 60% would have to be achieved
inorder to compete with existing processes such as the
peracetic acid process reported in the literature. A mass
balance examination showed that up to 24% of the initial
2-chloropyridine was unaccounted for at the end of
oxidation. A further study of 2-chloropyndine and its
N-oxide stability, demonstrated that product N-oxide and
not 2-chloropyridine was unstable and decomposed under
conditions likely to prevail m the oxidations. No way was
found to prevent this decomposition and so it was
concluded that this process using immobilized catalyst
could not compete with existing batch processes utilising
peracetic or acetic acid/hydrogen peroxide.
Metadata
Item Type: | Thesis (Master of Science) |
---|---|
Date of Award: | 1994 |
Refereed: | No |
Supervisor(s): | Pratt, Albert |
Uncontrolled Keywords: | Peroxidase; N-oxides |
Subjects: | Physical Sciences > Chemistry |
DCU Faculties and Centres: | DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences |
Use License: | This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License |
ID Code: | 18851 |
Deposited On: | 20 Aug 2013 13:12 by Celine Campbell . Last Modified 25 Apr 2017 14:24 |
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