CuO oxidation

The polyester domains of suberized walls can also be depolymerized using chemical and/or enzymatic approaches similar to those used for cutin. The aromatic domains are far more difficult to depolymerize as C-C and C-O-C crosslinks are probably present in such domains. Therefore, more drastic degradation procedures such as nitrobenzene, CuO oxidation, or thioglycolic... 

Tsutsuki, K., Esaki, I. and Kuwatsuka, S. (1994). CuO-oxidation products of peat as a key to the analysis of the paleo-environmental changes in a wetland. Soil Science and Plant Nutrition 40 107-116. 

Figure 3. CuO oxidation products for soil humic acid Farmer (7) and Steelink (13)...

Figure 9.45 Eleven dominant phenolic monomers, yielded from the oxidation of lignin using the CuO oxidation method these compounds can be separated into four families p-hydroxyl, vanillyl (V), syringyl (S), and cinnamyl (C) phenols. (Modified from Hedges...

Alberts, J.J., Filip, Z., Price, M.T., Hedges, J.I., and Jacobsen, T.R. (1992) CuO-oxidation products, acid hydrolysable monosaccharides and amino acids of humic substances occurring in a salt marsh estuary. Qrg. Geochem. 18, 171-180. 

Hatcher, P.G., Nanny, M.A., Minard, R.D., Dible, S.C., and Carson, D.M. (1995) Comparisons of two thermochemolytic methods for the analysis of lignin in decomposing wood The CuO oxidation method and the method of thermochemolysis with TMAH. Org. Geochem. 23, 881-888. 

The other axis of this property/property plot is the C/V lignin ratio (Fig. 15.15b), which is the weight ratio of total cinnamyl phenols to total vanillyl phenols. This tracer is based on the general relationship that cinnamyl phenols are obtained from the CuO oxidation of nonwoody plant tissues, whereas vanillyl phenols are produced by all vascular plant tissues, including woods. Phytoplankton do not produce either cinnamyl or vanillyl phenols, and hence have no effect on C/V ratios. Woods produce only trace amounts of cinnamyl... 

Miltner A. and Emeis K. C. (2001) Terrestrial organic matter in surface sediments of the Baltic Sea, Northwest Europe, as determined by CuO oxidation. Geochim. Cosmochim. Acta 65, 1285-1299. 

Figure 2. Yields of organic acids obtained from the CuO oxidation of coals (Samples 1-6) plotted against the % C in the coal.

High-temperature cupric oxide (CuO) oxidation of vascular plant lignins yields the eight simple phenols illustrated here as major reaction products. These reaction products comprise monomethoxylated (vanillyl) and dimethoxylated (syringyl) phenols, which occur primarily as aldehydes, along with smaller amounts of the corresponding ketones and acids. Two cinnamyl phenols (p-coumaric and ferulic acid) are also produced that retain the three-carbon side chain of the original structural units and terminate in a carboxyl. 

The bulk chemical composition of seawater DOM (Table 8.8), however, is not consistent with a predominant riverine origin. In particular, seawater DOM is depleted in C and enriched in C and compared with most DOM discharged by rivers (with the Amazon being taken here as an example). Seawater DOM is also depleted in aromatic carbon (as measured by C NMR) and lignin phenol structural units (as determined by CuO oxidation), possibly as a consequence both of the low phenol content of marine plankton, and of selective alteration of aromatic carbon by photodegradation. Thus all evidence to date, including elevated total concentrations in surface marine waters (Fig. 8.19), indicates that seawater DOM is largely... 

In addition to the analyses of lignin products by PGCMS as discussed here, one sample of estuarine sediment, comparable to sample S-15, was analyzed for lignin oxidation products by the CuO oxidation method (22). The distribution of various types of phenolic compounds In the sediment Is compared to that of Spartlna... 

From the infrared spectroscopy of adsorbed CO it appears that aging treatments, as low as 923 K, lead to a migration of the active isolated copper ions to inaccessible sites. In these conditions an agglomeration is not detected but, after aging at 1173 K, an agglomeration is evidenced both by XRD and by the infrared bands of CO adsorbed on partially reduced bulk CuO oxide. These accessible copper oxide crystallites are probably located at the external surface of the zeolite and are inactive. In fact, the activity remains correlated to the number of Cu VCu isolated ions deduced from the infrared spectra of adsorbed CO and located in the zeolite structure. This correlation holds whatever the treatment and whatever the Si/Al ratio (Table 4). 

Goni M.A., EglintonT.I. (1996) Stable carbon isotopic analyses of lignin-derived CuO oxidation products by isotope... 

Hyotylainen J, Knuutinen J, Malkavaara P, Siltala J (1998a) Pyrolysis-GC-MS and CuO-Oxidation-HPLC in the characterization of HMMs from sediments and surface waters downstream of a pulp mill. Chemosphere 36, 291-314. 

Iledge.s, J. I., Blanchette, R. A., Weliky, K., and Devol, A. II. (1988). Effects of fungal degradation on the CuO oxidation products of lignin A controlled laboratory study. Geodiim. C.osmodiim. Acta 52, 2717-2726. 

Kogel-Knaber, 1., Hempfling, R., and Schulten, H.-R., Decomposition in forest humus layers studied by CPMAS C NMR, pyrolysis-field ionization-MS and CuO oxidation, Sci. Total Environ., 62, 111-113, 1987. 

Let us recall that the admission of CO at 298 K on Cu-ZSM5 zeohthes treated in the same conditions as the C11/AI2O3 solids leads to the appearance of a unique and very intense band at 2150-60 cm l band that we have ascribed to CO adsorbed onto isolated Cu ions [22, 23], From literature data [24-32] it is possible to consider that the 2190-2200 cm" band is associated with CO adsorbed on isolated Cu2+ ions or to A13+ surface ions. The 2135, 2125 and 2110 cm 1 bands may be due to CO adsorbed on Cu+ and Cu ions arising from the partiel reduction of an CuO oxide ie., on non-isolated copper Cu" " and (or) Cu ions. CO is more strongly adsorbed on Cu and Cu" " than on Cu". ... 

Chart II. Chemical structures of simple phenols that are released by the CuO oxidative degradation of lignins. 

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