Xanthydrol

Filthy conditions, due to rodent or insect population, may be observed in a grain warehouse. The inspector notes rat-chewed flour sacks and sacks contaminated with rat excrement. He removes a sample of sacking and flour from such contaminated areas and submits them to the analyst. Urine fluoresces under ultraviolet light. Where rodent urine is to be confirmed, the xanthydrol test is one of several that may be used. Excreta pellets may be moistened with water or an appropriate clearing solution and crushed for observation under the compound microscope. The presence of striated hair fragments indicates rodent excrement. 

More experimental work has been done with DDT than with all the other five chlorinated hydrocarbons combined, probably because DDT was the first of the group found to have insecticidal value. Carter (10) has summarized the several colorimetric methods for DDT. The one proposed by Stiff and Castillo (51), as modified by Claborn (14), and the one by Schechter and Haller (47) have probably been most widely used. In the Stiff and Castillo method, when the DDT is heated in pyridine solution containing xanthydrol and potassium hydroxide, a red color develops which is proportional to the quantity of DDT present. The reaction is sensitive to 10 micrograms. As TDE does not give a color with this reagent, Claborn (14) has proposed the reaction for the determination of DDT in the presence of TDE. He has also shown that for the development of the color the amount of water in the pyridine is critical. 

The pyridine-xanthydrol method of Stiff and Castillo (4) and Claborn (1) will indicate the presence of methoxychlor, but it has a low order of sensitivity and does not distinguish between methoxychlor and DDT. 

Our laboratories10 have developed a system separating erythromycin estolate, erythromycin base, and anhydroerythromycin on a silica gel 60 F-254 plate utilizing ethanol, methanol, triethylamine, 170 30 1. Visualization is made by spraying with 0.15% xanthydrol and 7.5% acetic acid in water. Table V summarizes the Rf s. 

Methylcarbazole reacted with 2,6-dimethyl-4-pyrone in the presence of phosphorus oxychloride generating the pyrylium salt 170. Xanthydrol and thiaxanthydrol condensed with carbazole and 9-methylcarbazole under acid catalysis and sulfuric acid oxidation to give the colored salts 171 (X = O or S) the process has been used for the colorimetric determination of carbazole. ... 

It is difficult to synthesize 9-[l-(2,4,6-cycloheptatrienyl)]-9-xanthydrol [347] from xanthone by a simple addition, considering the potential nucleophile, cyclohepta-trienide anion, is antiaromatic. An umpolung strategy works well in that reversed roles are given to the two reactants. 

Four Milk, ACN/Na2CO3 extn. 15 Silica gel BUOH/H2O/HOAC Vis/Xanthydrol or 20 ppb/ 143... 

It was first prepd by treating xanthydrol with perchloric add in eth (Ref 3) or nitrobenzene (Ref 2). It has also been prepd by the oxidation of xanthene with triphenyl methyl perchlorate, and the product recrystd from acet to giver bronze plates (Ref 6) The refs consider the compd to be an expl... 

Some pseudo-bases do not ring open the xanthylium ion (210) gives xanthydrol (211) which can be isolated or oxidized with dilute nitric acid to xanthone (212). 

Xanthene shows maxima at 250, 278 and 292 nm (51BSF693, 53JA3333) and in xanthydrol (104) the latter peaks show a red shift but the first moves towards the blue. The ESR spectra of the radical anion of xanthene and several of its derivatives have been measured. It is suggested that the ion is not symmetrical but that the electron is localized on one of the aromatic rings and jumps rapidly between the two sites (75JCS(P1)1652). 

Xanthydrol is oxidized by potassium persulfate (56MI22400), whilst xanthydryl chloride yields xanthone on reaction with silver nitrate (59JCS458). 

Xanthydrol is employed as a reagent for the determination of urea, with which it forms an insoluble condensation product. The material obtained is entirely satisfactory for this purpose if desired, however, it may be recrystallized from alcohol, whereupon the melting point is raised by about i°. 

Xanthydrol was first prepared by reducing xanthone by means of zinc dust in the presence of boiling alcoholic sodium hydroxide 1 it was later shown by Fosse that it could be conveniently prepared by the action of a low percentage sodium amalgam upon xanthone in alcohol. The method is based upon the directions of Fosse.2... 

Pyronines. Pyronines are diphenylmethane derivatives synthesized by the condensation of m-dialkylaminophenols with formaldehyde, followed by oxidation of the xanthene derivative to the corresponding xanthydrol. W hich in the presence of acid forms the dye (5). If R is methyl, the dye is pyronine G (Cl 45005) if R is ethyl, pyronine B (Cl 45010) is obtained. 

Xanthates, with azothiazoles, 111 Xanthine, mesoionic, 55, 60 Xanthydrol, 117... 

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