Studies on the analytical chemistry of iodonium compounds. Part III

Summary A procedure is described for the determination of the diphenyliodonium cation in the range 1.0 to 4.0 mg, by extraction from solution buffered at p_H 9.5 into chloroform as the diethyldithiocarbamate followed by conversion into the copper(II) complex. Absorbance measurements are made on the chloroform solution of the copper(II) diethyldithio-carbamate at 435 nm, and a linear relation exists between absorbance and cation content within the range specified. The optimum conditions for the extraction are discussed.

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Zusammenfassung Ein Verfahren zur Bestimmung von Diphenyliodoniumkationen in der Größenordnung von 1,0 bis 4,0 mg wurde beschrieben. Es beruht auf deren Extraktion aus gepufferter Lösung (p_H=9,5) mit Chloroform als Diäthyldithiocarbamat und dessen Überführung in einen Kupfer(II)-komplex. Die Absorption des Kupfer(II)-diäthyldithiocarbamats in Chloroformlösung wurde bei 435 nm gemessen. Sie steht in linearem Verhältnis zur Kationenkonzentration. Die optimalen Bedingungen für die Extraktion werden erörtert.

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Résumé On décrit un procédé pour le dosage du cation diphényliodonium dans le domaine de 1,0 à 4,0 mg, en l'extrayant d'une solution tamponnée à p_H 9,5 par le chloroforme, à l'état de diethyldithiocarbamate puis en le transformant en complexe du cuivre-II. On effectue les mesures de densité optique sur la solution dans le chloroforme du diéthyldithiocarbamate de cuivre-II à 435 nm; il existe une relation linéaire entre la densité optique et la teneur en cation dans le domaine spécifié. On discute les conditions optimales pour effectuer l'extraction.

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Part II. Mikrochim. Acta [Wien]1966, 539.     

Studies on the analytical chemistry of iodonium compounds. Part VIII

Summary Procedures are described for the titration of 10–200 mg of diphenyliodonium cation with sodium tetraphenylborate, and a turbidimetric procedure for 10–200g of the cation.

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Zusammenfassung Die maßanalytische Bestimmung von 10 bis 200 mg Diphenyljodoniumkation wurde beschrieben; ebenso eine nephelometrische Methode für 10 bis 200g.

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Part VII: Mikrochim. Acta [Wien]1970, 1125.     

Studies on the analytical chemistry of iodonium compounds. Part. VII

Summary A procedure is described for the determination of 0.2–3.5 mg of the diphenyliodonium cation by extraction of its hexathiocyanatoferrate(III) Complex from slightly acidic solution into 1,2-dichloroethane. Absorbance measurements are made directly on the organic extract at 485 nm. Beer's law is not obeyed and a calibration curve must be used.

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Zusammenfassung Ein Verfahren für die Bestimmung von 0,2 bis 3,5 mg Diphenyljodoniumkation durch Extraktion seines Hexathiocyanatoferrat(III)-komplexes aus sehwach saurer Lösung mit 1,2-Dichloräthan wurde beschrieben. Die Absorption des organischen Extraktes wurde unmittelbar bei 485 nm gemessen. Das Beersche Gesetz ist nicht anwendbar, weshalb man eine Eichkurve verwenden muß.

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Part VI: Mikrochim. Acta [Wien]1967, 564. The work reported in this paper forms part of a thesis submitted byAnthony J. Bowd to the Faculty of Science of the University of London in partial fulfilment of the requirements for the degree of Doctor of Philosophy.     

Studies on the analytical chemistry of iodonium compounds

Summary A procedure is described for the determination of the diphenyliodonium cation by weighing as the molybdophosphate. The range of the method is 10–200 mg of cation. The effects of interfering substances and the conditions of precipitation are discussed and a coefficient of variation of 0.11% has been obtained.

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Zusammenfassung Ein Verfahren zur gravimetrischen Bestimmung von Diphenyljodonium-Kation als Molybdänphosphat wurde beschrieben. Es ermöglicht die Bestimmung von 10 bis 200 mg Kation. Die Wirkung störender Substanzen und die Fällungsbedingungen wurden erörtert. Ein Variationskoeffizient von 0,11% wurde festgestellt.

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Résumé On décrit un procédé de dosage du cation diphényliodonium par pesée à l'état de phosphomolybdate. La méthode couvre le domaine de 10–200 mg de cation. On discute les effets des substances qui interfèrent et les conditions de précipitation et l'on obtient un coefficient de variation de0,11%.

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Part III: Mikrochim. Acta [Wien] 1966, 1051.     

127I NQR spectra in several iodonium compounds

Interionic coordination interactions and their relationship to the behaviour of NQR spectral parameters, e²Qq_zz, η and ϑν/ϑE_z have been studied for several unsubstituted iodonium salts. The quadrupole coupling constants, e²Qq_zz, ha found to be linearly related to the asymmetry parameter, η.     

Contributions to the chemistry of silicon-sulfur compounds. Part 59

The contribution of vacant orbitals of the silicon atom to the electronic structure of silanethiols and their corresponding deprotonated species have been studied by means of ab initio and EHT MO methods. The results have been compared with those of the corresponding carbon compounds to clarify the peculiar properties of the silanethiols. The deprotonation process does strengthen the Si-S bond, but this effect is not considered to be due to the SSi dative bonding as suggested by Salinger and West.Dedicated to Professor Hans Georg von Schnering on the occasion of his sixtieth birthday. For Part 58 see ref. [1].     

Contributions to the chemistry of silicon-sulfur compounds. Part 58

The deviation from tetrahedral configuration at the silicon atom has been studied by modified EHT calculations. The geometry and energy of spiranes M(S₂C₂H₄)₂, M=C, Si were optimized with bond lengths constrained at experimental values starting from experimental or assumed geometry. Additionally Si(SR)₄, R=H, CH₃ as model compounds, have been studied with EHT. Full geometry optimizations with MM2 were also carried out for spiranes M(E₂C₂R₄)₂ and M(E₂C₂H₂)₂, M=C, Si, Ge, E = O, S, Se and R=H, CH₃. The performed MM2 calculations gave no evidence for significant deviation from the ideal spiro configuration. The EHT calculations, on the other hand, show that D₂ conformers of Si(S₂C₂H₄)₂ and Si(SR)₄ are the most stable in somewhat distorted conformation because of the operation of an anomeric effect. The anomeric interactions in S₄ conformers do not cause those spiro angle deviations. The energy differences between D₂ and S₄ conformers are small. The existence of S₄ conformers has been predicted in vapor phase by comparison of the observed and calculated splittings of lone pair ionization potentials.Presented as a poster at 10th IUPAC Conference on Physical Organic Chemistry 5–10 August 1990, Haifa, Israel. For Part 57, see ref. [1].     

Studies on the synthesis of heterocyclic compounds. Part I. The pschorr reaction in the pyrazole series

Preparation and structural evidence of N-methyl-(1,3-R,R'-pyrazol-5-yl)-o-nitrobenzamides (VIIIa, b) are discussed. Diazotisation of related o-aminobenzamides XIa,b followed by the Pschorr reaction afforded a very complex mixture from which pyrazolo[3,4-c]isoquinolin-5-ones XIIa.b in 7–10% yields together with N-methyl-(1,3-R,R'-pyrazol-5-yl)-o-hydroxybenzamides (XIIIa) in 15–20% yields were isolated.     

Studies on the chemistry of pharmacologically active heterocycles. Part I. Acid hydrolysis of hydrazino-1,2,4-triazine derivatives

The acid hydrolysis of 3-hydrazino-5,6-disubstituted-1,2,4-triazine, 3,5-dihydrazino-6-substituted-1,2,4-triazine, and 2-hydrazinopyrimidine derivatives was studied. It was found that the reaction proceeded through the formation of 3-keto and 3,5-diketo derivatives of the related 2,3-dihydro, 2,3,4,5-tetrahydro-1,2,4-triazines, and 2-keto derivatives of 1,2-dihydropyrimidines. It was concluded from these reactions that in 1,2,4-triazine derivatives the C-5 carbon is more reactive than the C-3 carbon toward nucleophiles. The reaction mechanism is discussed.     

Studies on the syntheses of heterocyclic compounds. Part DCXLIV . Catalytic reduction of homoproaporphine related compounds

Hydrogenation of the homoproaporphine (IV) over platinum oxide gave a mixture of the cyclohexanols VIIa and VIIb. In contrast, reduction of IV on palladium provided the cyclo-hexanone VI, which was also obtained from VIIb by oxidation. Treatment of the cyclohexanols VIIa and VIIb under hydrogen on platinum oxide afforded the same mixture of VIIa and VIIb.     

Studies of fluorine-containing bismaleimide resins. Part I: Synthesis and characteristics of model compounds

A series of fluorine-containing bismaleimide (FBMI) monomers are synthesized by a 2-step reaction for using as the applications of low-k materials. The synthesized FBMI monomers are characterized by the ¹H, ¹³C, ¹⁹F nuclear magnetic resonance (NMR) spectroscopy and element analysis. These FBMI monomers react with free radical initiator or self-cure to prepare FBMI-polymers. All the self-curing FBMI resins have the glass transition temperatures T _g in the range of 130–141°C and show the 5% weight loss temperatures T _5% of 280–322°C in nitrogen atmosphere. The higher heat resistance of self-curing FBMI resin relative to FBMI-homopolymer is due to its higher cross-linking density. The FBMI resins exhibit improved dielectric properties as compared with commercial bismaleimide (BMI) resins with the dielectric constants ? lower than 2.44 which is related to the low polarizability of the C-F bond and the large free volume of CF₃ groups in the polymers. Besides, the flame retardancy of all these FBMI resins could be enhanced via the introduction of Br-atom.     

Applications of electron spin resonance in the analytical chemistry of transition metal ions: Part I. Factors affecting the signal amplitude

An evaluation of the effect of modulation amplitude (M) and microwave power (P) on the peak-to-peak amplitude (A) of the first derivative e.s.r. signal of each of Mn²⁺, VO²⁺ and Cu²⁺ is described. It is shown that A is not directly proportional to M over all values of M and therefore for optimal precision of measurement, M should be kept constant. A varies with P^k, where k is a constant for a particular metal ion-solvent system. Limits of detection and concentration ranges of analytical utility are also reported.     

Organic chemistry of superoxide. I. Oxidations of aromatic compounds.

Potassium superoxide is a selective oxidant for aromatic compounds with the order of susceptibility of substituent groups being -SH>-NH₂-OH. Only o- and p- disubstituted amines and phenols are oxidized but monosubstituted thiols react.     

Studies on the syntheses of heterocyclic compounds. Part CCLXXIII. Synthesis of C-nordihydrocorynantheol and its related compounds

Mannich reaction of tryptamine with 3,3,4-triethoxycarbonylhexaldehyde (IV) gave the cyclized product (VIII), whose hydrolysis, followed by decarboxylation, afforded the acid (IX). After esterification of IX, reduction of ester (X) with lithium aluminum hydride gave the C-nordihydrocorynantheol (II). The syntheses of IV and XV were also described. Furthermore, the Mannich reaction of L-N-benzyl-1-methyltryptophan methyl ester (XV) with IV was also examined. This reaction gave the ester (XVII), which was hydrolyzed and decarboxylated to give the acid (XVIII). Esterification of XVIII, followed by catalytic hydrogenation, gave the lactam (III).