The use of naphthalene derivatives in inorganic analysis : Part IV. The nitronaphthylamines as fluorimetric reagents for stannous tin

Thirteen of the theoretically possible fourteen nitronaphthylamines have been tested and found to be of use as fluorimetric reagents for stannous tin. The presence of strong hydrochloric acid in the reagent solution is necessary for maximum sensitivity of test. This indicates that the nitronaphthylamines are not as versatile as their corresponding nitroaminonaphthalene monosulphonic acids as reagents for tin. Present evidence confirms the original postulate that the species responsible for the fluorescence is the excited state of the naphthylammonium ion.     

The use of napthalene derivatives in inorganic analysis: The nitronaphthols as fluorimetric reagents for stannous tin

Thirteen nitronaphthols have been examined and found to be of use in the fluorimetric detection of stannous tin. The reagents were capable of detecting 10^-4 to 10^-5 g stannous tin whilst the nitro derivatives of 2-naphthol produced more intense fluorescence than the corresponding derivatives of 1-naphthol. Of the series examined, 8-nitro-1 -naphthol was the least reactive, and this was attributed to the presence of intramolecular hydrogen bonding between the nitro and hydroxyl groups in this compound.     

The use of naphthalene derivatives in inorganic analysis : A new reagent for the fluorimetric detection of tin

The use of 6-nitro-2-hydroxy-naphthalene-8-sulphonic acid as a new fluorimetric reagent for the detection of tin has been reported. This reagent is capable of detecting 10^-8 g stannous tin under the conditions of the test and is slightly more sensitive for this purpose than the previously recommended 6-nitro-2-aminonaphthalene-8-sulphonic acid.     

The use of naphthalene derivatives in inorganic analysis : The nitroaminonaphthalene monosulphonic acids as spot tests for stannous tin

Three new reagents, viz 8-nitro-2-aminonaphthalene-6-sulphonic acid (ammonium salt) and the two nitroaminonaphthalene sulphonic acids (potassium salts) prepared by the mononitration of 2-aminonaphthalene-5-sulphonic acid have been developed as spot tests for stannous tin. Each reagent produces a strong fluorescence under ultraviolet light, less than one microgram of stannous tin being detected under the conditions of test. The application of the reagents to the quantitative estimation of tin is also indicated.     

The use of naphthalene derivatives in inorganic analysis : The effect of substituents in the naphthalene nucleus on the fluorimetric detection of tin

Fourteen substituted nitronaphthalene derivatives have been examined as reagents for the fluorimetric detection of tin. The compounds investigated included dinitronaphthalenes, dinitronaphthylamines, halogen substituted mononitronaphthylamines, mononitroso- and dinitro-naphthols and their sulphonic acid derivatives. Four of these reagents have been found to exhibit strong fluorescence and another four to give moderate fluorescence with stannous tin. All reagents are capable of detecting l0^-4 g stannous tin and with four of them, 10^-5 g is capable of detection in 0.01 ml of solution. The results indicate that two of the most important factors relating structure of reagent to intensity of fluorescence are (a) the position of the nitro group in the naphthalene nucleus, i.e., whether it is α- or β- or whether it is sterically hindered and (b) the electropositive or electronegative character of other substituent groups in the reagent     

The use of naphthalene derivatives in inorganic analysis : V. further applications of the nitroamino-naphthalene monosulphonic acids to the flourimetric detection of stannous tin

Three new reagents, viz 5-nitro-1-aminonaphthalene-2-sulphonic acid,4-nitro-1-aminonaphthalene-5-sulphonic acid and 4-nitro-1-aminonaphthalene-6-sulponic acid, have been found to be of use as fluorimetric spot tests on filter paper for stannous tin. The orientation of the sulphonic acid group does not appear to appreciably affect the sensitivity of the test, approximately one microgram of stannous tin being capable of detection by all isomers     

The use of quinoxaline-2-carboxylic acid and its derivatives as analytical reagents

Quinoxaline-2-carboxylic acid and 3-chloro and 3-hydroxy derivatives have been studied as analytical reagents. The solubility products of the metal salts, the optimum pH range for complete precipitation and the thermal behaviours of the metal complexes have been established. Quinoxaline-2-carboxylic acid allows the gravimetric determination of Cu(II), Cd(II), Zn(II), Co(II), Ni(II) and Pd(II); with the 3-chloro and 3-hydroxy derivatives, only palladium(II) could be precipitated quantitatively.     

Use of organic reagents in inorganic analysis

Summary Paper chromatography of cobalt, palladium, uranium, thorium, and zirconium/1-nitroso-2-hydroxy-3-naphtholates which are quantitatively precipitated, has been studied. As most of the complexes were not soluble in organic solvents, their hydrochloric acid solutions and solution of the cobalt, palladium, and uranium complexes in ammonium hydroxide were used for spotting. A large number of developing solvents were tried both on plain and salt-impregnated papers. A solvent mixture containing 60% acetone, 38% isobutyl alcohol and 2% 12N HCl, by volume was found suitable for the resolution of a mixture of complexes of cobalt, palladium, and uranium on plain paper. Thorium and zirconium complexes, however, did not move appreciably with any of the solvent mixtures tried. The paper impregnated with salt solutions did not show any improvement in the separation. The effect of HCl in the above solvent mixture on the separation of cobalt, palladium, and uranium, was also studied. It was observed that a small amount of HCl was necessary in this developing solvent for the migration of the metals, a large excess of this acid, increases their R_f values and these are brought so close that the separation of the metals becomes difficult. The colour of the cobalt, palladium, and uranium spots on the developed chromatograms indicated that the metals migrated as their complexes. Similar experiments were done with free metals ions, which gave different R_f values and this confirmed the fact that it was the metal complexes that moved and these complexes were stable under the conditions of the experiment. Precipitation of Co, Pd and U with 1-nitroso-2-hydroxy-3-naphthoic acid is quantitative and the paper chromatographic experiment affords a convenient method of concentrating the metal ions.Part IV: See Z. anal. Chem. 155, 241 (1957).     

Use of organic reagents in inorganic analysis

Summary Thorium and zirconium have been determined gravimetrically with phenylglycine-p-carboxylic acid and zirconium alone with phenylglycine-o-carboxylic acid, almost within the same pH range. Better results are obtained when zirconium is precipitated in acetic acid solution in presence of a little ammonium acetate. A number of foreign ions may be separated from thorium and zirconium with these reagents. Iron and titanium cause heavy interference. The interference caused by iron, may however, be eliminated by adding a little ascorbic acid, before precipitation of the metals. The para acid can also extract thorium from a mixture of cerite earths and from monazite sands.Part V: See Z. anal. Chem. 158, 347 (1957).The author likes to thank Dr. B. N. Bose, Principal of the College and Dr. S. K. Sinha, the Head of the Department of Chemistry for their kind advice and encouragements.     

Use of organic reagents in inorganic analysis

Summary Seven anilic acids obtained from phthalic anhydride and aromatic amines were studied for their quantitative precipitating action on zirconium. The anilic acids from p-toluidine, m- and p-nitranilines and -naphthylamine were only found effective for the quantitative determination of zirconium. Zirconium is completely precipitated at a little lowerph value with these reagents, than thorium. Compositions of the zirconium salts of these acids are not definite, so ignition of the precipitates to zirconia is necessary. Separation of zirconium from common elements like Cu, Al, Cr, Mg, Zn, Ti etc. may be done with ease. But for iron, uranium, cobalt and nickel double precipitation is essential. A considerable amount of thorium has been separated from zirconium, by extraction with amylacetate.     

Use of organic reagents in inorganic analysis

Summary Eighteen anilic acids have been prepared from maleic anhydride and various aromatic amines and their properties and analytical reactions with various metal ions have been studied. The acid prepared from benzidine was insoluble in all common solvents and, hence, its application could not be studied. Most of these reagents, except those obtained from aniline, o- and p-chloroanilines, nitranilines, p-amino-acetanilide and o-phenylenediamine, produced more or less quantitative precipitations with both thorium and zirconium. Their actions towards thorium and zirconium were very much alike. They also gave precipitations with mercury(I), lead and cerium(IV), but such precipitations were not complete. Ferrous iron showed greyish turbidity with most of the reagents, but ferric iron produced colourations varying from brown to violet, such colours were, however, found to be unstable either on standing for a while or on heating. Gold and platinum underwent reduction in presence of these reagents.Part VIII: See Z. analyt. Chem. 163, 403 (1958).The work has been carried out in the chemical laboratories of Darjeeling Government College, Darjeeling. The author is grateful to the authorities of the College for the laboratory facilities.