Influence of heat treatment conditions on the porosity changes of sulfonated styrene/divinylbenzene copolymers

Sulfonic cation exchangers with two ion exchange group concentrations (0.5 and 2.4 mmol/g, samples A and B, respectively) were obtained by sulfonation of a porous styrene (S) and divinylbenzene (DVB) copolymer with chlorosulfonic acid. Strong thermal decomposition of the sulfonated copolymer A, accompanied by significant changes in its porous structure, starts at ca. 400°C. The char has no sulfonic groups. After heat treatment at 400°C in steam, a sorbent was obtained (yield 65%) that shows higher phenol sorption than the untreated sample when related to the bed volume. The chlorosulfonic derivatives of the initial copolymer were less thermally resistant than the sulfonic ones obtained by hydrolysis. Pyrolysis of the cation exchanger B, in its H+ and Ca²⁺ forms, was carried out at 900°C (yield of both chars close to 30%). By subsequent steam activation at 800°C to a 50% burn-off of the char, sorbents with well-developed, but distinctly different, porous structures were obtained. The activated char from the sulfonated copolymer in its hydrogen form was highly microporous and indicated an effective surface area of 1180 m²/g. However, because of a low contribution of mesopores, its ability to adsorb phenol from the liquid phase was not very high. The activated char from the calcium-doped copolymer, indicating a smaller surface area (580 m²/g) but characterized by a well-developed mesoporosity, was a better sorbent for phenol. © 1994 John Wiley & Sons, Inc.     

Intra- versus intermolecular hydrogen bonds in salicylamide derivatives

The crystal structures, solid-state infrared patterns, and thermal properties of two polymorphs of 4-nitrosalicylanilide are presented. In both polymorphs, intramolecular hydrogen bonds are found between the phenol oxygen and the amide proton, and intermolecular hydrogen bonds are found between the amide carbonyl oxygen and the phenol proton. These hydrogen bond patterns are compared to those found in other known salicylamide derivatives and an analysis is given of the factors contributing to preferences for intra- or intermolecular hydrogen bonds in these structures. Crystal data: polymorph, orthorhombic,Pbca,a=11.003(4),b=27.959(7),c=7.622(5) Å,Z=4,V=2345(3) ų, andR=0.038 (1351 reflections); polymorph, monoclinic,P2₁/a,a=28.36(1),b=11.64(1),c=7.293(8) Å,=90.68(6)°,Z=8,V=2408 ų, andR=0.043 (2425 reflections).     

The stereochemistry of quaternary N-methyl sparteinium cations, their derivatives, stereoisomers and analogues : Part II. Molecular and crystal structure, and IR spectra of methiodide and methperchlorate of 2-oxosparteine

The crystal and molecular structures of two quarternary salts of 2-oxosparteine (II), the methiodide (IICH⁺₃ • I⁻) and the methperchlorate (IICH⁺₃ • ClO⁻₄) have been determined on the basis of X-ray and IR data. The studies were performed by analogy to previously investigated quaternary salts of sparteine (I), the methiodide (ICH⁺₃ • I⁻) and the methperchlorate (ICH⁺₃ • ClO⁻₄). As expected, the configurations and conformations of cationic parts within the two pairs of quaternary salts are identical, except for the structure of their A/B fragments, which in ICH⁺₃ cations have the character of tertiary amines, but in IICH⁺₃ that of lactams.

On the basis of accumulated X-ray and IR data the similarities and differences in the modes of interaction of perchlorate and iodide anions with quaternary cations, and especially with their N⁺---CH₃ groups are discussed. In this discussion are also included the methiodide and methperchlorate of -isosparteine: IIICH⁺₃ • X⁻ (X⁻ = I⁻ or ClO⁻₄) where N⁺---CH₃ groups are cisoidally oriented to the basic nitrogen atoms. The most interesting observations are as follows: (i) When N⁺---CH₃ groups are easily accessible for direct quasi hydrogen bonding interactions with counter anions and when other positive charged groups, for instance lactam groups, are absent in quaternary cations, perchlorate anions interact more strongly than the iodide anions and in consequence introduce conformational changes into the ring with N⁺---CH₃ group as well as into further rings. (ii) Perchlorate and iodide anions interact with N⁺---CH₃ groups similarly and very weakly if at all, when the N⁺---CH₃ groups are for steric reasons inaccessible to counter anions or when in quaternary cations there are additional groups which attract the counter anions electrostatically. The last mechanism operates in both quaternary salts of 2-oxosparteine and this is the reason why their monocrystals are isosteric and IR spectra almost identical. (iii) The sterically hindered N⁺---CD₃ groups in both IIICD⁺₃ • X⁻ salts give rise in their IR spectra to two doubles of sharp, well resolved bands which indicate the presence of two different rotamers stabilized by two modes of weak intramolecular hydrogen bonds with basic N atoms. (iv) In IIICH⁺₃ • X⁻ and IIICD⁺₃ • X⁻ salts the perchlorate and iodide anions do not interact at all with the rotating and vibrating N⁺---CH₃ (N⁺---CD₃) group but the structures of these salts are not isosteric since the perchlorate anions interact more strongly than iodide anions with the A/B fragment of the IIICH⁺₃ cations. This is visible from the shapes and intensities of the so-called “trans” band in the IR spectra of both salts.     

Thermal copolymerization of acrylonitrile with methacrylate units arranged in matrix

Copolymerization of acrylonitrile with methacrylates on a matrix has been examined (using methacrylate of p-cresol-formaldehyde resin). It has been found that the copolymerization proceeds at 70° without an initiator. The reactivity ratios depend on the length of the matrix used. The method of calculating Q and e according to the Alfrey-Price scheme has been discussed for the system under investigation.     

Über eine neue automatische Apparatur zur Zentigramm-Bestimmung von Kohlenstoff und Wasserstoff in organischen Substanzen

Zusammenfassung Das vom Verfasser undE. Sucharda schon 1928 angewandte Prinzip, die durch das Verhalten der Substanz beim Erhitzen bewirkten Druckschwankungen im Verbrennungsrohre zum Zwecke der automatischen Regulierung der Vergasungsgeschwindigkeit der Substanz bei der Elementaranalyse auszunutzen, wurde bei der Konstruktion einer neuen, elektrisch betriebenen, automatischen Apparatur angewandt. Hierbei wird das mit der Substanz gefüllte Mikroschiffchen mittels eines elektrischen Hochfrequenzgenerators erhitzt. Der Stromzufluß zu dem Hochfrequenzgenerator wird durch die erwähnten Druckschwankungen einoder ausgeschaltet. Die Verbrennung verläuft dann bei praktisch konstantem Druck im Verbrennungsrohre, also auch bei konstantem Sauerstoffüberschuß. Die neue Apparatur wird an Hand beigefügter Abbildungen beschrieben. Als Absorptionsmittel für Stickstoffoxyde werden 1 bis 2 g Bleidioxyd in einem 12 cm langen Porzellanschiffchen bei 190° angewandt. Die Absorption des Wassers erfolgt durch wasserfreies Kobaltchlorid, die der Kohlensäure ausschließlich durch Ascarit. Die Sauerstoffgeschwindigkeit im Verbrennungsrohre beträgt 8 ml pro Minute. Bei Substanzen, die mehr als 10% N enthalten, wird zwischen den Kohlensäureabsorptionsapparat und den Wasserabsorptionsapparat ein mit Mangandioxyd gefüllter Apparat eingeschaltet.

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Summary The principle used by the author andE. Sucharda as early as 1928, which employs the variations in pressure in the combustion tube resulting from the behavior of the substance when heated, for automatically regulating the rate of gasifying the substance was applied in the construction of a new electrically operated automatic apparatus. The micro boat charged with the sample is heated by means of a high frequency generator. The flow of current to the high frequency generator is switched on and off by the variations in pressure mentioned above. The combustion then proceeds at practically constant pressure in the combustion tube, and even when there is a constant excess of oxygen. The new apparatus is described in the accompanying figures. The nitrogen oxides are absorbed in 1 to 2 grams of lead dioxide contained in a porcelain boat (12 cm long) at 190°. The absorption of the water is by means of anhydrous cobalt chloride, while the carbon dioxide is taken up in ascarite. The speed of the oxygen in the combustion tube is 8 ml per minute. In the case of samples that contain more than 10% nitrogen, an apparatus filled with manganese dioxide is placed between the carbon dioxide absorber and the apparatus for taking up the water.

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Résumé Le principe de l'utilisation des variations de pression qui se produisent dans un tube à combustion en analyse élémentaire, lors du chauffage de la substance, a été utilisé dès 1928 par l'auteur etE. Sucharda pour la régulation automatique de la gazéification de cette substance. Il a été appliqué à la construction d'un nouvel appareil automatique commandé électriquement. La micronacelle qui contient la substance est chauffée électriquement à l'aide d'un générateur de courant de haute fréquence. Les variations de pression pendant la combustion provoquent l'ouverture ou la fermeture du circuit d'alimentation de ce générateur. Il en résulte que la combustion est effectuée à pression pratiquement constante ainsi qu'à excès d'oxygène constant. Ce nouvel appareil est décrit sur les figures de la publication.On utilise 1 à 2 grammes de bioxyde de plomb disposés dans une nacelle de porcelaine de 12 cm de longueur, portée à 190° pour absorber les oxydes de l'azote. L'eau est absorbée par du chlorure de cobalt anhydre et l'anhydride carbonique exclusivement par de l'ascarite. Le débit du courant d'oxygène dans le tube de combustion est de 8 ml par minute. Pour les substances contenant plus de 10% d'azote, on intercale un absorbeur à bioxyde de manganèse entre l'absorbeur à anhydride carbonique et l'absorbeur à eau.

     

Etude de la chloration du polychlorure de vinyle en fonction de sa tacticite

Polyvinyl chloride samples of various tacticity have been prepared and photochlorinated in CCl₄ for 4 hr. The chlorination degree correlates directly with the degree of syndiotacticity. Initial PVC with syndiotacticity about 56 per cent, which can be regarded as alternate sequences of syndiotactic and isotactic diads, is quickly chlorinated. The mechanism of chlorine attack on the macromolecula is directly connected with the stereoregularity.     

Complexes of carbonyl compounds with RnAIX3n compounds : IV. The evidence for the formation of cyclic complexes chloroaluminium compounds

Reasonably stable 1 : 2 complexes are formed by carbonyl compounds with chloroaluminium compounds, usually in equilibrium with a 1: 1 complex, however with trimethylaluminium only a 1 : 1 complex is formed. In the case of complexes with an excess of MeAlCl₂, a disproportionation reaction occurs. Possible structures are discussed in light of PMR and IR spectroscopy, dipole moments and molecular weight determination. The previously proposed cyclic six-membered ring is the most reliable structure for the 1 : 2 complex.     

Investigations of aromatic polyesters with polynaphthalene systems in the main chain—VI: NMR studies of the structure of the aromatic copolyesters

Nuclear magnetic resonance spectra of several kinds of terephthalic copolyesters of 4,4′dihydroxydinaphthyl 1,1′ and 2,2 bis(4-hydroxyphenyl) propane were recorded. Proton signals of the terephthalic acid unit corresponding to heterolinkages and homolinkages could be observed in the range from 8.23 to 8.53 ppm. The average sequence lengths and the degrees of randomness in the copolyesters were calculated from the intensities of these signals.