The palladium electrode in aqueous and nonaqueous titrimetry

Two modifications of the palladium-hydrogen electrode of Schwing and Rogers have been made and tested. A new form of “generation” electrode with a vertical palladium diaphragm and fast constant speed circulation has been devised. This form of electrode responds rapidly and has been used in a variety of acid-base titrations in aqueous and nonaqueous systems.     

Determination of total basicity and available lysine in proteins by nonaqueous titrimetry

A simple method is presented for the determination of the available lysine residues of proteins. The sample is titrated directly with 0.05 or 0.1 M perchloric acid in anhydrous acetic or propionic acid to a potentiometric end-point. The titration is repeated after acylation of the sample. The difference between the two basicity values gives the available lysine content of the proteins. Results are provided for the available lysine contents of bovine serum albumin, human γ-globulin, β-casein, soya bean meals meat meal and milk protein; in most cases, they agree closely with literature data obtained by other methods. The standard error for the procedure is <3.9%.     

The reaction of sulfamic acid derivatives with epoxides

A new method for obtaining N-(b-hydroxyalkyl)sulfamates with 50–95 % yields by the reaction of sulfamic acid derivatives with epoxides is proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1146–1147, June, 1993.     

Rapid analysis of dosage forms of some pharmaceuticals by nonaqueous thermometric titrimetry

The use of the technique of solution thermochemistry is proposed for the rapid assay for quality control and quality assurance of dosage amounts of some ethical formulations of some antimalarial drugs. The active ingredients are chloroquine, hydroxychloroquine, dapsone, proguanil hydrochloride, and pyrimethamine.Assay is done without the separation of the excipients and without isolation or derivatisation of the analytes. The titrations are done in glacial acetic acid and utilise the catalysed hydrolysis of acetic anhydride by perchloric acid to indicate the endpoint of the reactions.The time taken for a typical assay, of a typical dosage amount is about 3–5 minutes. The reproducibility is of the order of 1% for the milligramme amounts of analyte present in the dosage amounts of the drugs.

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Zusammenfassung Es wird die Anwendung eines lösungsthermochemischen Verfahrens zu Schnellbestimmungen bei der Qualitätskontrolle und — sicherung von Wirkstoffeinsatzmengen einiger rezeptpflichtiger Präparate von einigen antimalarischen Arzneimitteln empfohlen. Die aktiven Bestandteile sind Chloroquin, Hydroxychloroquin, Dapson, Proguanilhydrochlorid und Pyrimethamin.Die Bestimmungen werden ohne jegliche Abtrennung der Bindestoffe und ohne Isolierung oder Derivatisierung der zu bestimmenden Substanzen durchgeführt. Die Titrierungen werden in Eisessig durchgeführt und bedienen sich der katalytischen Hydrolyse von Essigsäureanhydrid durch Perchlorsäure als Endpunktindikation der Reaktion.Die Dauer für eine typische Probe bei einer typischen Wirkstoffmenge beträgt etwa 3–5 Minuten. Die Reproduzierbarkeit liegt in der Größenordnung von 1% für Milligrammengen der zu analysierenden Stoffe im Arzneimittel.

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We acknowledge the Nigerian Government for the provision of a grant to one of us (S.I.A.). We acknowledge the following for the gifts of samples of the authentic drugs and the tablets assayed in this work: Imperial Chemical Industries plc; May and Baker plc; Winthrop Laboratories plc; Wellcome Foundation (Medical Division).     

The reaction of sulfamic acid derivatives with epoxides

Reactions of diglycidyl and allylglycidyl ethers with salts of sulfamic acid followed by acidic hydrolysis of the products afforded the corresponding aminoethers. The alcoholysis of sulfamic acids with ethanol was suggested as a method for mild elimination of the sulfo group. For Part 4, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 508–511, March, 1997.     

The reaction of sulfamic acid derivatives with epoxides

The reaction of the salts of sulfamic acid andN-alkylsulfamic acids with glycidol, epichlorohydrin, and epoxy ethers gives the corresponding functionally substituted -hydroxyalkylsulfamates.For communication 1 see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1063–1065, June, 1994.     

The use of DSS as an internal standard in PMR studies of nucleic acid interactions

Two commonly used PMR internal reference compounds, 3-(trimethyl silyl) propane sulfonic acid sodium salt (DSS) and 3-(trimethyl silyl) sodium propionate (TSP), have been shown to interact with purine in aqueous solution, causing significant shifts in the resonance position of their reference protons. Tetramethyl ammonium chloride (TMACl) appears to be a more suitable reference compound for such studies.     

Facile one-pot synthesis of polysubstituted quinolines under solvent-free conditions using sulfamic acid as a reusable catalyst

Abstract  

A facile one-pot synthesis of polysubstituted quinoline derivatives has been demonstrated by using sulfamic acid as a reusable catalyst under solvent-free conditions. The synthetic method provides the basis and advantages of a simple experimental procedure and easy recovery and reuse of catalyst, which makes it a highly practical and environmentally benign pathway for the synthesis of polysubstituted quinolines. Interestingly, this one-pot synthesis could produce the products regioselectively in the presence of dis-symmetrical arylamines.     

Reactivity of macroheterocycles with respect to sulfamic acid

It has been established, on the basis of the formation of a 1∶1∶1 inclusion compound of 18,19-benz-1,16-diaza-4,7,10,13-tetraoxoeicosa-17,20-dione with sulfamic acid and water from the interaction of 11–20-membered macrocyclic oxyethyleneamides of phthalic acid with sulfamic acid, that 18–20-membered oxyethylene macrocycles containing six oxygen donor atoms in the macrocycle are effective in the formation of “host-guest” complexes. Physicochemical Institute for the Preservation of the Environment and Mankind, Ministry of Education and Ukraine National Academy of Sciences of Ukraine, Odessa 270100. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1571–1573 November, 1997.     

Reactions of derivatives of sulfamic acid with epoxides

1,3-Diamino-2-propanols were prepared in high yields by reactions of potassium or sodium 3-chloro-2-hydroxypropylsulfamates with amines followed by acid hydrolysis of the 3-amino-2-hydroxypropylsulfamates that formed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2693–2697, November, 1996.     

Volumetric estimation of persulphate using arsenite as a primary standard

The method of estimating the persulphate by direct titration using arsenious acid or sodium arsenite as a primary standard has been described.This method consists in taking a mixture of arsenious acid or sodium arsenite and an excess of potassium iodide in the titration mixture. The mixture is heated to 80°C and solid sodium bicarbonate is added. Persulphate solution is run in from a burette and the liberated iodine is instantaneously consumed by trivalent arsenic. At the end-point an excess drop of persulphate gives a yellow colour due to the liberated iodine remaining unreacted. The results are satisfactory and the error lies within permissible limits.     

The use of vanadium-sulphosalicylic acid complex as a redox indicator

In a previous communication it was reported that vanadium^V gives an intense turquoise-blue colour with sulphosalicylic acid in concentrated sulphuric acid and that the colour reaction is specific and very sensitive for the detection of vanadium^V. During our studies on the nature of the complex, it was found that vanadium^IV gives a negative colour test and that the blue colour developed by the reagent with vanadium^V is discharged on the addition of a reducing agent like iron^II, uranium^IV or hydroquinone. It was also observed that the blue colour is restored by the addition cerium^IV solution. This reversible property of the complex has been further investigated to see if the complex can be used as a redox indicator.     

Acidimetric determination of sodium salts of methyl sulfamic acid

A procedure for the determination of sodium salts of methyl sulfamic acid as tertiary amines by acidimétrie titration in glacial acetic acid was developed. The total error of the procedure did not exceed 1%. The procedure is simple and can be carried out under ordinary laboratory conditions.     

A novel direct and one-pot Mannich synthesis of fluorinated β-aminobutanones with sulfamic acid as a green catalyst

A variety of fluorinated β-aminobutanones could be obtained in good to excellent yields at room temperature through the direct and three-component Mannich reactions of unmodified acetone with aldehydes and fluorinated anilines in one-pot procedure. Among the catalysts screened, sulfamic acid was tested to the best in aspect of outstanding stability, inexpensive cost, ready recovery and excellently catalytic activity. All the new compounds were confirmed by IR, ¹H NMR, ¹³C NMR, ¹⁹F NMR and microanalysis.