Naringin 3360 1639 41" " Flavanone-flavonoid values.noutrin, robinin, and rutin, have carbonyl absorption bands between 1652 cm.-1 and 1658 cm.-1 as shown in the table. The difference ( cm.-1) of the parent flavone minus the flavonoid is very small for the flavones and considered to be within the experimental error of the parent flavone carbonyl frequency. The flavones listed in Table I have hydroxyl group at the C-5 position adjacent to the carbonyl group with the exception of the parent compound, flavone. The lack of difference of the naturally occurring flavone carbonyl frequencies from the parent flavone would suggest the lack of hydrogen bonding in these substances. This does not seem reasonable, nor can it be rationalized on the basis of the shifts observed for hydrogen bonding for similar substituted substances.9-11 The interpretation of these anomalies by Hergert and Kurth appears to be sufficient. r The flavonols differ from the flavones by having a hydroxyl or glycosidic linkage at the C-3 position. This added opportunity for hydrogen bonding of the C-3 hydroxyl group with the carbonyl for the flavonoids, isorhamnetin, quercetin, and chrysosplenetin, did not make itself apparent. Likewise the C-5 hydroxyl containing flavonols do not reveal an appreciable difference-( cm.-1) between the flavonol carbonyl frequency and the parent flavone.
It is shown that only Schiff's method is suitable for the determination of formaldehyde in methylated cellulose formals. These are intermediates in the elucidation of the structure of cotton cross-linked with formaldehyde. Some modifications of the usual procedure are recommended to obtain an accuracy of 3% relative to the amount of formaldehyde present. The modified Schiff's method was standardized with cellulose formals containing C 14 -formaldehyde whose activity was determined by ionization chamber assay after combustion to CO 2 . A routine determination of C 14 -formaldehyde in cellulose formals by the liquid scintillation method is also described..
18 Mitteilung uber textilchemische Untersuchungen [I] Summary.(1) A method is described which allows the elucidation of the structure of cotton cross-linked with formaldehyde. I t consists of a pcrmethylation process (5 methylations with dimethyl sulphate and sodium hydroxide in dimethyl sulphoxide, followed by two exchange methylations of the formalised sodium cellulosate with methyl iodide in z-butanol), hydrolysis of the product in 72% sulphuric acid to the respective methylated glucoses, reduction of the mixture of glucoses to the respective sorbitols, blocking of all free hydroxyl groups by acetylation, trifluoroacetylation or formation of trimethylsilyl ethers, and vapour phase chromatographic separation of the derivatives.(2) It is shown that after permethylation practically no free hydroxyl groups can be detectcd and that scarcely any replacement of methylene or oxyniethylene cross-links by methyl groups has taken place. With the exception of losses in filtration of the permethylation product, all stages of the process proceed on an almost quantitative basis.
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