Ion-selective electrodes in organic functional group analysis: microdetermination of nitrates and nitramines with use of the iodide electrode

A simple, selective and accurate method has been described for the rapid micro and submicro determination of organic nitrates and nitramines. It is based on reaction with mercury-sulphuric acid mixture for 5 min at room temperature followed by potentiometric titration of the mercurous ions released, a solid-state iodide-sensitive electrode being used. Three equivalents of potassium iodide as titrant are consumed per mole of nitrate or nitramine group. The results obtained, with sample sizes ranging from 1.0 to 50 mumole, are precise to +/- 0.2% and the average recovery is 99%. None of the other nitrogenous functional groups responds to this reaction.     

Mercurous nitrate as a reductimetric reagent : The determination of hydroxylamine and nitrates

Hydroxylamine can be determined indirectly using standard mercurous nitráte, by treating the test solution with an excess of standard ferric alum, and back titrating the excess.The same procedure cannot be recommended for the determination of hydrazine and hydroquinone. The results with hydrazine were irregular and generally low. With hydroquinone, the brown colour of the oxidation product masked the endpoint.An attempt was made to determine nitrate after reduction with ferrous ammonium sulphate, but the high acidity required is unfavourable for mercurous nitrate titration, and results are only accurate to about 1 per cent.     

Mercurous nitrate as a reductimetric reagent: The potentiometric titration of ferric iron in the presence of ions forming highly coloured thiocyanates

The reduction of ferric iron by means of mercurous salts in the presence of an excebs of ammonium, thiocyanate can be predicted on theoretical grounds. By consideration of the oxidation potentials involved it has been shown by calculation that quantitative reduction of the ferric iron is to be expected.—The titration may be effected potentiometrically using a bright platinum indicator electrode in conjunction with a silver/silver chloride electrode or a saturated calomel reference electrode. Ferric iron can be titrated in the presence of ions such as cobalt which form intensely coloured thiocyanate complexes.A possible method for the titration of molybdate by means of mercurous nitrate has been examined. The sensitivity of the method suffers from the instability of potential of the system under titration, but particularly since tungstate does not interfere, the method is worthy of further study.     

Mercurous nitrate as a reductimetric reagent : The determination of mercurous mercury

Mercurous mercury can be determined indirectly by allowing the test solution to react with an excess of standard ferric alum and back-titrating the unconsumed ferric iron with standard mercurous nitrate. The titration can be carried out in the presence of appreciable quantities of mercuric mercury.     

Sodium meta-vanadate as volumetric reagent : Iodine monochloride method

Sodium meta-vanadate has been used as an oxidising agent in hydrochloric acid medium for the volumetric estimations of potassium iodide, sodium arsenite, mercurous chloride, potassium thiocyanate, sodium sulphite, sodium bisulphite, sodium thiosulphate, ferrous sulphate and hydrazine sulphate, using iodine monochloride as a catalyst and preoxidiser. Chloroform is used as an indicator. It is coloured pink due to the liberation, of iodine during the titration and becomes light pale yellow at the end-point due to the formation of iodine monochloride.     

Mercurous nitrate as a reductimetric reagent : The determination of copper

It has been found that in the presence of excess thiocyanate ions, cupric copper will oxidise ferrous ions. Use has been made of this reaction to determine copper by titration of the ferric iron produced, with mercurous nitrate. Although this reaction is the reverse of that usually observed, where the cuprous ion reduces the ferric iron, it has been found that the large excess of thiocyanate is responsible for this effect.     

Studies in oxidation-reduction reactions: Oxidation with chloramine-b,iodine monochloride method

Chloramine-B has been used as an oxidizing agent in hydrochloric acid medium for the volumetric estimations of potassium iodide, arsenious oxide, tartar-emetic, mercurous chloride, stannous chloride, potassium thiocyanate, ferrous ammonium sulphate, hydrazine sulphate and hydroquinone, using iodine monochloride as a catalyst and pre-oxidizer. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point because of the formation of iodine monochloride.     

Volumetric studies in oxidation-reduction reactions: Oxidation with chloramine-t. iodine monochloride method

Chloramine-T has been used as an oxidizing agent in hydrochloric acid medium' for the volumetric estimations of potassium iodide, hydrazine sulphate, arscnious oxide, stannous chloride, mercurous chloride, tartar-emetic, potassium thiocyanate and ferrous ammonium sulphate, using iodine monochloride as a catalyst and pre-oxidizer. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes very pale yellow at the end-point because of the formation of iodine monochloride.     

Mercurous nitrate as a reductimetric reagent : The interference of the more common cations and anions in the determination of iron

The interfering effect of most of the more common cations and anions on the titration of ferric iron with mercurous nitrate has been examined. As would be expected, ions capable of oxidising ferrous iron interfere. Certain other cations and anions interfere, but in several cases this effect can be eliminated. Copper and thallium must be completely absent, and ions which give coloured products with thiocyanate ions, e.g., molybdenum.     

Nitroxide chemistry XXII. Oxidation of N,N-bis(trifluoromethyl)hydroxylamine

A number of cheap oxidising agents have been found to be effective for the conversion of N,N-bis(trifluoromethyl)hydroxylamine into bis(trifluoromethyl)nitroxide. The best of these are cerium(IV) salts either in the solid state or in aqueous acid solution. Efficient, self-indicating processes have been developed using either catalytic amounts of silver(II) picolinate and aqueous potassium persulphate solutions, or electrochemical oxidation with cerium(III) nitrate and sodium nitrate in dilute nitric acid.     

Potassium meta-periodate as volumetric reagent : Iodine bromide method

Potassium meta-periodate has been used as an oxidising agent in acid medium for the volumetric estimationss of potassium iodide, arsenious oxide, antimonous oxide, stannous chloride, mercurous chloride, sodium sulphite, sodium thiosulphate, sodium tetrathionate, ferrous sulphate, potassium thiocyanate, hydrazine sulphate, phenylhydrazine hydrochloride and hydroquinone by the iodine bromide method. Carbon tetrachloride is used as an indicator. It is coloured pink during the titration. and becomes colourless at the end-point due to the formation of stable iodine bromide complex IBr2-, which does not dissociate, in the presence of a large excess of bromide ion.     

Mercurous Dimethylglyoximato Nitrate,Hg2(Dmg)2(NO3)2

Colourless needles of mercurous dimethylglyoximato nitrate, Hg₂(Dmg)₂(NO₃)₂, grow from a diluted nitric acid solution of mercurous nitrate and dimethylglyoxime. The crystal structure (triclinic, P1¯, a = 728.50(13), b = 1066.8(2), c = 1167.9(2) pm, α = 93.78(2)°, β = 94.16(2)°, γ = 98.61(2)°, R_all = 0, 0726) contains the cations [Hg₂(Dmg)₂]²⁺ and “non‐coordinating” (NO₃)^— anions. In the cation, two neutral dimethylglyoxime molecules coordinate bidentately with Hg—N distances in the narrow range of 236 to 239 pm to the mercurous ion, Hg₂²⁺, which exhibits a Hg—Hg bond distance of 252.23(8) pm).     

Potentiometrische Bestimmung von einwertigem Quecksilber mit Jod(I)-chlorid

Zusammenfassung Ein Verfahren zur potentiometrischen Titration von Quecksilber(I) nitrat bzw. Quecksilber(I)-perchlorat mit 0,1 n Jodmonochloridlösung wurde ausgearbeitet. Zur Indikation diente eine blanke Platinelektrode, als Bezugselektrode eine gesÄtt. Kalomelelektrode. Der mittlere Fehler der Bestimmung betrug 0,7%, wenn 170 mg Quecksilber vorgelegt waren.Ferner wurde ein Verfahren zur Bestimmung von Quecksilber(I)-chlorid entwickelt. Hierfür wird 0,1 n Jodmonochloridlösung im überschu\ zugegeben und nach einer Schütteldauer von 30 min das unverbrauchte Jodmonochlorid mit 0,1 n Hydrazinsulfatlösung zurücktitriert. Die Bestimmungsfehler sind dabei in der Regel nicht grö\er als 0,6%.

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Summary A method has been developed for the potentiometric titration of mercurous nitrate or mercurous perohlorate with 0.1 N iodine monochloride solution. A platinum electrode is employed for indication, a saturated calomel electrode for reference. With 170mg of mercury the average error is 0.7%. Furthermore, a procedure has been worked out for the determination of mercurous chloride, comprising addition of 0.1 N iodine monochloride solution in excess, shaking for 30min, and back-titration of unreacted iodine monochloride with 0.1 N hydrazine sulphate solution. Errors usually do not exceed 0.6%.

     

Electrochemical nucleation: Part III. The electrodeposition of mercury on vitreous carbon

The electrochemical nucleation of mercury on vitreous carbon from solutions of mercurous nitrate in aqueous KNO₃ has beenstudied as a function of overpotential and mercurous ion concentration. The nucleation is predominantly progressive and the singlepotential step experiment leads to nuclear number densities and to steady state nucleation rate constants. The double potentialstep experiment is complicated by the progressive nature of the nucleation and largely invalidated by the resultant dispersion ofnuclear sizes. The interpretation of the transients from potentiostatic-galvanostatic and related pulse trains are also complicatedby the similar features and it is suggested that equilibrium steady state and non-steady properties of nucleating systems arebest studied at very small electrodes at which a single nucleus is formed.     

Über mikrochemische Reaktionen des Merkuro-Ions

Zusammenfassung Es wurde festgestellt, daß Merkuro- und Merkuri-Salze sich gegenüber Kalium-Kobalt-Rhodanid und Kalium-Zink-Rhodanid gleichartig verhalten. Die Empfindlichkeit der hierbei auftretenden Kristallfällungen wurde bestimmt.Als unterscheidendes Reagens zwischen Merkuro- und Merkuri-Salzen erwies sich Pikrolonsäure, die lediglich mit Merkuro-Salzen reagiert und den Nachweis von 0,01 Merkuro-Ion gestattet.

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Summary It has been found that mercurous and mercuric salts react in a similar way with potassium cobalt thiocyanate and potassium zinc thiocyanate. The sensitivity of the resulting crystalline precipitates has been determined.Picrolonic acid proved to be a reagent by which mercurous salts can be distinguished from mercuric salts: picrolonic acid reacts only with mercurous salts and allows to detect 0,01 of mercurous ion.

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Résumé L'auteur trouva, que les combinaisons mercuriques et mercureuses ont les mêmes réactions sur le sulfocyanure potassique de cobalt et sur le sulfocyanure potassique de zinc. La sensibilité des précipitations de cristaux, qui accompagnent ces réactions, fut déterminée.L'auteur trouva, qu'on peut distinguer les combinaisons mercuriques des combinaisons mercureuses à l'aide de l'acide picrolonique, qui réagit seulement sur les sels mercureux, en permettant de déceler jusqu'à 0,01 de ionènes mercureux.

     

Assay of Sulfur in Organic Liquids Using a Mercury Displacement Method

Abstract

A method for the assay of sulfur in organic liquids is presented. The method utilizes an oxidative combustion process coupled with a piezoelectric crystal detector. The sulfur dioxide evolved upon combustion of the organic liquid is bubbled through a mercurous nitrate solution. The mercury vapor produced is detected by a piezoelectric crystal due to the formation of a mercury amalgam.     

A novel coating technology of KNO3 to reduce the hygroscopicity of pyrotechnics

Journal of Thermal Analysis and Calorimetry - Strong hygroscopicity will pose a huge challenge to the safety of pyrotechnic agents. In this paper, surface modification of potassium nitrate was...     

A thermogravimetric study of acidic and basic solutes in two molten alkali metal nitrate eutectics

The reaction of ten oxyanions and oxides, acting as Lux—Flood acids have been studied in both lithium nitrate—potassium nitrate and sodium nitrate—potassium nitrate eutectics and the stoichiometries of the reactions established. A series of acids arranged in order of decreasing strength has been drawn up, which is very similar for both eutetic solvents.Five Lux—Flood bases have also been studied in these two solvents. Sodium carbonate proved to be very stable to 500°C. Sodium peroxide revealed significant differences in stability and solubility in the two solvents, while lithium, sodium and potassium hydroxides showed differences in the two melts and also considerable differences between each other, suggesting that little cation exchange takes place in these solutions.     

Preparation and comprehensive characterization of [Hg6(alanine)4(NO3)4].H2O

A new mercury-alanine complex has been isolated from reaction mixtures of mercurous nitrate dihydrate and alanine (L and D enantiomers). The solid-state structure contains mercury(I) and mercury(II) associated by alanine ligands in a polymeric array. The disproportionation of mercury(I) to mercury(II) and mercury(0) was facilitated by alanine and is evidenced by the appearance of mercury(0) in reactions of mercury(I) with the 20 common amino acids. This complex is the first mercury(I)-amino acid complex characterized in the solid state. The compounds have been comprehensively characterized using X-ray crystallography, solid-state and solution-state nuclear magnetic resonance spectroscopy, vibrational spectroscopies, and electrospray ionization mass spectrometry.     

Bestimmung anorganischer Verunreinigungen in Natriumsulfonaten

Zusammenfassung Es wird eine Methode zur Bestimmung von Sulfat und Chlorid in Sulfonaten beschrieben: Sulfat wird mit Bleinitrat gefällt und überschüssiges Blei mit Hexacyanoferrat(II)-lösung zurücktitriert, Chlorid wird direkt mit Quecksilber(I)-nitratlösung titriert.

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Summary A method is described for the determination of sulphate and chloride in sulphonates: sulphate is precipitated by lead nitrate and excess of lead is back titrated by ferrocyanide solution, chloride is titrated directly by mercurous nitrate solution.