Bleaching of kraft cellulose by the ClO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O<Subscript>2</Subscript> scheme

The influence of conditions of a two-stage treatment of deciduous and coniferous kraft cellulose (by the ClO₂-H₂O₂ scheme) on the degree of its delignification and bleaching was studied. The optimum ratio of reagents in each stage of the treatment was elucidated.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 10, 2004, pp. 1735–1738.Original Russian Text Copyright © 2004 by Shcherbakova, Demin.     

Determination of 90 Sr in milk by solvent extraction of 90Y (author's transl)

In order to replace the conventional method using violent fuming nitric acid, a new method for the determination of 90 Sr in milk has been developed by using the solvent extraction with bis (2-ethylhexyl) phosphoric acid (HDEHP). The daughter nuclide 90Y in a radiochemical equilibrium with its parent 90Sr was extracted with 2:1 HDEHP-toluene from the acid solution (1M HCL) of milk ash sample prepared by dry-ashing. After stripping with 8M HCL, 90Y, together with stable yttrium added as carrier, was precipated as oxalate to prepare beta-counting source. The radiochemical purity was confirmed by decay curve. The decontamination of strontium was checked by applying non-dispersive fluorescence X-ray analysis using 133Ba as irradiating source. Bone samples of cow were also analyzed by the same method and the results were compared with those obtained by other methods. The duplicate crosschecking analyses of finely ground bone samples were carried out to examine the effectiveness of this method. This simple new method was found to be very effective for the routine analysis of 90Sr in these samples.     

Ethynyl carbonium ions. 1. Reaction of 2.6-diaryl-4-phenylethynylpyrulium perchlorates with oxygen-containing nucleophiles

When 2,6-diaryl-4-phenylethynylpyrylium perchlorates are refluxed in water, methanol, or ethanol, they are converted to monomethinecyanines, the formation of which is explained by hydration of the phenylethynyl group and subsequent [2+2]-cycloaddition of the resulting 2,6-diaryl-4-benzoylmethylenepyrans to the starting pyrylium salt. The corresponding pyridine derivatives were obtained by the action of ammonia and aniline on the monomethinecyanines. The IR and PMR spectra of the compounds and the results of x-ray diffraction analysis of 2,6-diphenyl-4-[1-(2,6-diphenyl-4-pyranylidene)-2-phenyl-3-benzoylallyl]pyridine are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 885–890, July, 1988.     

Mössbauer study of carbide phases in catalysts for ammonia synthesis

Samples of a catalyst CA-1 for ammonia synthesis were studied. After reduction the samples were treated with CO₂ or with a mixture of 1% O₂+2.4% H₂O+CO₂ at temperatures between 600 and 783 K. Mössbauer spectroscopy data indicate that above 600 K carbide phases and magnetite are formed. A probable mechanism for carbide formation is suggested.     

Thermodynamics of micellar solubilization of various water-insoluble dyes

Summary A linear relation between the free energy of micellar solubilization,G _s ⁰ , and surfactant alkyl chain length is shown. This relation is found to be valid for various water-insoluble dyes in different homologous series of surfactants. It is further shown that the change inG _s ⁰ per added CH₂ group is constant in these various systems, within the experimental accuracy.

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Zusammenfassung Es wurde gezeigt, daß zwischen der freien Energie der mizellaren SolubilisierungG _s ⁰ und der Alkylkettenlänge des Tensids eine lineare Beziehung besteht. Diese Beziehung gilt für verschiedene wasserunlösliche Farbstoffe mit verschiedenen homologen Reihen von Tensiden. Es wird weiterhin gezeigt, daß die Änderung vonG _s ⁰ pro CH₂-Gruppe in diesen verschiedenen Systemen innerhalb der experimentellen Fehlergrenze konstant ist.

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With 1 figure and 1 table     

A new intramolecular cyclisation reaction—I : Novel synthesis of benzo(k,1)thioxanthene-3,4-dicarboxylic anhydride and derived dyestuffs

A new direct synthesis of benzo(k,1)thioxanthene-3,4-dicarboxylic anhydride from 4-nitro-naphthalene-1,8-dicarboxylic anhydride and 2-aminobenzenethiol is reported; 4-(2-aminophenylthio) naphthalene-1,8-dicarboxylic anhydride and 4-phenylthionaphthalene-1,8-dicarboxylic anhydride are also formed. Similar reaction in presence of amyl nitrite or sodium nitrite results in formation of larger amounts of 4-phenylthionaphthalene-1,8-dicarboxylic anhydride, together with other products arising from the oxidation of 2-aminobenzenethiol; one such product is the new heterocycle 9,10-dithiaphenanthrene. 4-(2-Aminophenylthio)-naphthalene-1,8-dicarboxylic anhydride is rapidly converted by amyl nitrite or sodium nitrite in dimethylformamide into benzo(k,1)thioxanthene-3,4-dicarboxylic anhydride, constituting a novel one-stage intramolecular cyclisation reaction of greater convenience than the conventional two stage Pschorr cyclisation.     

Hetero analogs of alloxazines. 2. Structure and tautomerism of 6,8-dimethyl-7,9-dioxo-5h-6,7,8,9-tetrahydropyrimido[4,5-b][4′,5′-e][1,4]thiazines

It is demonstrated by ¹³C NMR spectroscopy that the dipyrimidothiazines that are formed in the reaction of 1,3-dimethyl-5-nitro-6-chlorouracil with 4-R-5-amino-6-mercaptopyrimidines are dipyrimido[4,5-b][4,5-e] [1,4]thiazines. The tautomeric transformations of these compounds were studied.For communication 1, see [1]Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1426–1432, October, 1992.     

Determination of cadmium by atomic-fluorescence and atomic-absorption spectrophotometry

The adaptation of a conventional atomic-absorption/flameemission spectrophotometer to the measurement of atomic-fluorescence in an air-acetylene flame is described. The determination of cadmium on the same instrument by both atomic-fluorescence and absorption shows that, even with a rather simple and inefficient means of exciting and measuring fluorescence, results can be obtained which indicate that the fluorescence technique is considerably more sensitive than atomic-absorbance and is equally free from inter-element interference.     

Non self-consistent field theory

Roothaan's SCF method [2] is reformulated so that two non-SCP methods are developed to solve the eigenequation. The results from these methods can be used as starting eigenfunctions for Roothaan's SCF method.

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Zusammenfassung Die self-consistent field Methode von Roothaan [2] wird neu formuliert: dabei werden zwei Nicht-SCF Methoden zur Lösung der Eigenwertgleichung entwickelt. Deren Resultate können als Anfangsfunktionen bei Rechnungen mit der SCF-Methode von Roothaan benutzt werden.

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Résumé La méthode SCF de Roothaan [2] est reformulée en développant deux méthodes non-SCF pour la solution de l'équation aux valeurs propres. Les résultats de ces deux méthodes peuvent être utilisées comme fonctions de départ pour la méthode SCF de Roothaan.

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The title Theoretical Chemistry has been transferred to the Division of Physical Chemistry.