In order to investigate the relative merits of a selective oxidant for the degradation of natural polymers, humic acid extracts from three Alberta soil sites and three British Columbia soil sites, and two Kraft's prepared wood lignins were oxidized with 1.6 N NaOCl at room temperature (23°C) for 5 days. The oxidation products included CO₂, highly volatile acids and organic solvent soluble (OSS) products with the relative size of each fraction determined by carbon content. OSS products were characterized by Infrared (IR), Thin Layer Chromatography (TLC) and Nuclear Magnetic Resonance (NMR) techniques and identified after methylation and separation by Gas Liquid Chromatography (GLC) methods involving co-injecting authentic compounds and matching elution time and temperature of some of the components with that of the authentic compounds.
Proceeding from the known chemistry of the NaOCl reaction, the CO₂ and highly volatile acid products could only be derived from the aliphatic chain or saturated ring components of humic acids or lignin and represented 66 to 82% of the products assuming no destruction of aromatic structure. Benzene carboxylic acid products were derived from the aromatic component of the starting materials. Estimates of the degree of aromaticity of the starting materials, using GLC and potentiometric titration data, were substantially less than those calculated from proposed model humic acid and lignin structures in the soils literature. An unidentified oily component was found
in the oxidation products of two of the humic acid preparations.
The results of this study indicated humic acid and lignin
are composed of a mixed aliphatic-aromatic compound system. The
relatively more mature humic acid preparations were found to be
of greater aromaticity than the less mature samples. It was found
2
that NaOCl was not totally selective in differentiating Sp² from Sp³ carbon hybrids; as a result the total discrimination between aliphatic and aromatic structures was not a safe assumption. It is postulated that aromatic ring opening may occur at sites of hydroxyl group substitution on the ring structures resulting in an apparent less aromaticity and the generation / Land and Food Systems, Faculty of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/21328 |
| Date | January 1977 |
| Creators | Herman, William Allan |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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