Solvatation preferentielle dans les systemes ternaires polyvinylpyrrolidone/solvant halogene/solvant donneur de proton—III: Confrontation des resultats obtenus par diffusion de la lumiere et par spectroscopie infra-rouge

We have compared the experimental results of study of the preferential solvation of polyvinylpyrrolidone in halogenated solvent/proton-donor solvent mixtures, obtained by light scattering and i.r. spectroscopy and described in the two preceding papers. The preferential adsorption of the proton-donor solvent is explained by the formation of a hydrogen-bond complex of polymer with proton-donor solvent, on which other proton-donor molecules are bound by induced autoassociation. This complexing occurs even in mixtures where the “inert” solvent (1,2-dichloroethane) is preferentially adsorbed; this is experimental proof of a differing solvation of the chains in their close neighbourhood and within short range of them.     

NMR.-Investigation of the Formaldehyde Addition and Oligomerisation Equilibria in the System Formaldehyde/Water/Acetic Acid/Hydrochloric Acid

An NMR. investigation of the state of formaldehyde in acidic solutions has been carried out. Solutions of DCl/D₂O/CD₃COOD containing two sources of formaldehyde, i.e. paraformaldehyde (I) and trioxane (II), were used for this purpose. In systems I and II the effect of various D₂O/CD₃COOD ratios, at a constant DCl concentration, was studied, while for II the effect of changing DCl concentration was also investigated. The results show that in aqueous solution, formaldehyde exists primarily as the monomeric and linear oligomeric forms of methylene glycol. Reducing the amount of D₂O (at constant DCl concentration), while increasing the CD₃COOD content, results in an increase in the polymeric species and in trioxane. In addition, substitution of water by acetic acid results in systems that are catalytically more active than aqueous solutions of the same hydrochloric acid concentration. Along with the usual polymer-monomer equilibria which exist in such solutions, side reactions of methylene glycol with the hydrochloric acid present also occur to a small extent, e.g. acetylation, substitution of OH by Cl and the Cannizzaro reaction. It is suggested that these findings will result in a better understanding of the formaldehyde crosslinking reactions in cotton cellulose.     

Al(Cap)3 as initiator in the anionic polymerization of ε-caprolactam at high temperature

Mechanism for polymerization of ε-caprolactam in the presence of both sodium and aluminum caprolactamate was investigated at 171°C. The role of Al(Cap)₃ as an initiator was revealed. The apparent rate constant of propagation reaction decreased with the increase in the concentration of Al(Cap)₃, as the two different metal salts interact even at 171°C. The activation energy of the overall polymerization reaction with this catalyst system was estimated to be 41.18 kcal/mole.     

Azines and azoles. 64. Mass spectra and tautomerism of 2-aryl-4,6-dioxo-1,3-thiazines

Mass spectra of 2-aryl-4,6-dioxo-1,3-thiazines were studied and the general fragmentation paths of these compounds determined. Based on mass spectra of compounds with fixed structures, 2-aryl-5,5-dialkyl-4,6-dioxo-1,3-thiazines, 4-alkoxy- and 4-acyloxy-2-aryl-6-oxo-1,3-thiazines, the decomposition paths of the dicarbonyl and hydroxycarbonyl forms were determined. It was concluded on the basis of the obtained data that 2-aryl-4,6-dioxo-1,3-thiazines exist in the gas phase predominantly in the hydroxycarbonyl form.For Communication 63, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1409–1412, October, 1987.     

TOPICAL UROCANIC ACID ENHANCES UV-INDUCED TUMOUR YIELD AND MALIGNANCY IN THE HAIRLESS MOUSE

Epidermal urocanic acid has been postulated to be the mediator of the specific state of immunosuppression induced by UV irradiation, by which UV-initiated tumour cells are able to evade normal recognition and can survive to grow progressively into malignant tumours. These experiments demonstrate that topical application of UV-irradiated urocanic acid systemically suppresses the contact type hypersensitivity response to oxazolone in hairless mice. In addition, topically applied urocanic acid markedly increases the overt tumour yield and the degree of malignancy in hairless mice exposed chronically to daily minimally erythemal doses of simulated solar UV light. Topical urocanic acid also increases the number of latent UV-initiated tumours, detectable by croton oil promotion. Therefore UV photoproducts of urocanic acid can both systemically suppress contact hypersensitivity in the epidermis, and also enhance early survival of UV-initiated tumour cells resulting in augmentation of UV photocarcinogenesis.     

Percutaneous absorption of ketoprofen from acrylic gel patches containing d-limonene and ethanol as absorption enhancers.

The percutaneous absorption of ketoprofen (KPF) from gel patches containing d-limonene and ethanol was investigated in rats. Plasma levels of KPF varied with the kind of polymers which constitute the gel patch, and the highest level was observed when the copolymer of ethylacrylate (EA) and diethyleneglycolmethacrylate (DEGMA) was used as a vehicle. The amount of KPF permeating through the rat skin from the gel patch was well correlated with that of ethanol. Permeations were enhanced with increase in the amount of d-limonene distributed from the vehicle to the skin tissue. The amount of d-limonene accumulated in the skin varied greatly with the kind of polymers; the highest accumulation was observed with the EA-DEGMA copolymer, and decreased with increasing affinity of d-limonene to the polymers. The reason EA-DEGMA copolymer showed the highest percutaneous absorption of KPF from gel patches containing d-limonene may be the hydrophilic nature of this polymer which showed the lowest affinity to d-limonene.     

Reaction of styrene with sulfur and triiron dodecacarbonyl and the molecular structure of the complex Fe2(CO)6(SCH2S)

Reaction of excess styrene with Fe₃(CO)₁₂ and sulfur (60°C, 15 h, Ar, S/Fe₃(CO)₁₂ 0.6 g-atom/mole) gave Fe₂(CO)₆S₂, Fe₃(CO)₉S₂, Fe₂(CO)₆(S₂CO), Fe₂(CO)₆S₂(PhCHCH₂), PhCHCH₂S₄, and a novel binuclear complex Fe₂(CO)₆(S₂CH₂S), whose structure was analyzed by x-ray crystallography. The crystals are monoclinic, a=7.764(3), b=13.205(4), c=6.628(6) Å, =98.97(3)°. V=671.2(7) ų, Z=2, space group P2₁/m. The bond lengths are Fe-Fe 2.520(2), Fe-S 2.236(2), S-S 2.078(4), C-S 1.825(12), Fe-CO 1.784(8), and CO 1.148(9) Å.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 930–934, April, 1991.     

Matrixreaktion von GaF mit o-atomen: ir-spektrum von OGaF

It is possible to synthesize OGaF in an argon matrix by co-condensation of GaF with O atoms. The stretching vibrations of this compound are found at 943 and 690 cm⁻¹ (¹⁶O⁶⁹GaF). An exact calculation of the force field is possible with the aid of the observed ¹⁶O/¹⁸O and ⁶⁹Ga/⁷¹Ga shifts. The following force constants are found: f(GaO) = 6.32; f(GaF) = 4.69; f(GaO/GaF) = −0.1 [10²Nm⁻¹]     

1,2,4-Triazine and triazole derivatives from α-keto acids and thiosemicarbazides

Thiosemicarbazides of 2-hydroxyphenylglyoxylic acid, which, depending on the conditions, undergo cyclization to interconvertible 5-(2-hydroxyphenyl)-6-oxo-1,2,4-triazine-3-thiones or (2-hydroxy-benzoyl)-²-1,2,4-triazoline-5-thiones, are formed by the action of thiosemicarbazide and its homologs on coumarindione. The thiosemicarbazones of 2-hydroxyphenylglyoxlyic and other 2-substituted phenylglyoxylic acids undergo cyclization to 6-(2-hydroxyphenyl)-5-oxo-1,2,4-triazine-3-thiones.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp, 116–121, January, 1977.