Premium
The Exhaustive Alkaline Cupric Oxide Oxidation of Humic Acid and Fulvic Acid
Author(s) -
Neyroud J. A.,
Schnitzer M.
Publication year - 1974
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1974.03615995003800060022x
Subject(s) - chemistry , permanganate , humic acid , alkaline hydrolysis , benzene , oxide , hydrolysis , carboxylic acid , potassium permanganate , organic chemistry , fertilizer
A humic acid and a fulvic acid were subjected to successive oxidations with alkaline cupric oxide at 170C for 3 hours until identifiable degradation products were no longer formed. Resistant humic acid and fulvic acid residues were then oxidized with alkaline permanganate. Following each oxidation, the degradation products were extracted into ethyl acetate, methylated, separated by column, thin‐layer and gas‐chromatography and identified by mass spectrometry and micro‐IR spectro‐photometry. The exhaustive alkaline cupric oxide oxidation of 1.0 g of humic acid yielded 109.0 mg of aliphatic compounds (mainly succinic acid and the n ‐C 16 and n ‐C 18 fatty acids), 94.9 mg of phenolic acids and 36.2 mg of benzene‐carboxylic acids. Oxidation of 1.0 g of fulvic acid produced 104.7 mg of aliphatic compounds, 146.7 mg of phenolic acids and 35.1 mg of benzene‐carboxylic acids. The resistant humic and fulvic acid residues yielded on further oxidation with alkaline permanganate additional amounts of benzene‐carboxylic acids. Compared to other degradation methods, alkaline cupric oxide oxidation of humic substances was found to be an efficient procedure for the formation of relatively large amounts of aliphatic and phenolic degradation products but was less effective for degrading aromatic structures linked by C‐C bonds only. The main reaction governing the alkaline cupric oxide oxidation of the humic substances appeared to be alkaline hydrolysis. The data indicate general similarities in the chemical structures of the two humic materials but with the fulvic acid containing more phenolic structures than the humic acid.