Rothe method

Table I. Comparative Study of C-Methyl Determinations on Normal and Corresponding Reduced Coals by Kuhn-Roth Method...

A correlation between the hydroaromatic carbon and the C-methyl carbon as determined by Kuhn>Roth method is shown in Figure 1. The relationship is more or less linear. It had been determined earlier (14) that the proportion... 

Figure I. Relation between the C-methyl content (Kuhn-Roth method) and the alicyclic carbon content of coal values from Kaiser et al. (14) ...

The apparent decrease in values of C-methyl content with increase in rank observed earlier (14) would now appear to be caused largely by progressive aromatization of methyl-substituted hydroaromatic structures rather than demethylation. Since the Kuhn-Roth method has limitations, an alternative method for assessing the C-methyl content in coals is desirable. 

Martin B. Neuworth The Kuhn-Roth method has a number of limitations. These were discussed by Brandenberger et al. (Anal. Chem. 33, 453 (1961)). The normal method for estimating C-methyl groups is based on a determination of total acidity calculated as acetic acid. Brandenberger has shown that other acids can be produced during the oxidation—e.g., benzoic acid, and these acids steam distil with the acetic acid. Therefore, when the classical Kuhn-Roth procedure is applied to a substance like coal, it would lead to methyl group values of questionable significance. 

We are aware that the Kuhn-Roth method is not specific for all types of methyl groups. This is exactly the point that we have made in our paper. 

W.J. Roth, Method of M41S Functionalization of Potentially Catalytic Heteroatom Centers into As-synthesized M41S with Concomitant Surfactant Extraction, US Patent No. 5 925 330 (1999). 

J. Roth, Methods for Assessing Immunologic and Biologic Properties of lodinated Peptide Hormones, in Methods in Enzymology, Vol. 37 (B. W. O Malley and J. G. Hardman, Eds.), Academic Press, New York, 1975, p. 223. 

Kuhn-Roth method for C-methyl determination. Oxidation of organic compounds with chromic and sulfuric acids in such a manner that the C-methyl groups are converted to acetic acid which can be assayed volumetrically. The method has been modified and extended (1) to saturated fatty acids and alcohols containing up to about 20 carbon atoms, and (2) to aliphatic long-chain compounds of very high molecular weight. 

Structure determination of NONA unfolded along similar lines (Blix et al., 1956). Glycolic acid was cleaved with base and identified as the calcium salt by X-ray diffraction. Quantitative acetylation revealed six free hydroxyl groups, one more than for NANA. The absence of C-methyl groups, determined by the Kuhn-Roth method, implied that the extra hydroxyl is located on the iV-acetyl group. Blix found a close similarity in the chemical reactions of NONA as compared to NANA, and included the observation that heating with methanolic-HCl gave... 

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