On the dynamic mechanical behavior of nylon 66

Summary The dynamic mechanical properties of nylon 66 films and fibers have been examined, as a function of annealing and drawing, with a Vibron viscoelastometer. It is found that the transition is little affected by annealing treatments, but increase in orientation causes the transition to move to a higher temperature. Experiments, with X-ray diffraction of samples at elevated temperatures, lead to the conclusion that the triclinic to hexagonal phase change does not contribute significantly to the transition. Samples cut parallel and perpendicular to the drawing direction of nylon 66 film, have been used to show that the curves of dynamic tensile modulus versus temperature, for the parallel and perpendicular directions, cross in the neighborhood of the transition. This observation is discussed in relation to the suggestion that the transition is the glass transition in nylon 66.

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Zusammenfassung Die dynamisch-mechanischen Eigenschaften von Filmen und Fasern aus Nylon 66 wurden als Funktion der Temperung und Verstreckung mit einem Virbon-Viskoelastometer untersucht. Die -Umwandlung wird wenig durch die Temperung beeinflußt, aber erhöhte Orientierung läßt siezu höheren Temperaturen verlagern. Messungen der Röntgenstreuung bei erhöhten Temperaturen führen zu dem Schluß, daß der Übergang triklin/hexagonal nicht wesentlich zu der -Umwandlung beiträgt. Proben aus verstrecktem Nylon-66-Film, parallel und senkrecht zur Streckrichtung geschnitten, zeigen, daß die Kurven des dynamischenE-Moduls gegen die Temperatur für beide Orientierungen sich in der Nachbarschaft der -Umwandlung überkreuzen. Diese Beobachtung wird hinsichtlich der Vermutung diskutiert, daß die -Umwandlung den Glasübergang in Nylon 66 darstellt.

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With 5 figures and 2 tables     

A novel synthesis of N-acetyl-α-d-fucosamine 1-phosphate and uridine 5"-diphospho-N-acetyl-α-d-fucosamine

In connection with studies on the biosynthesis of capsular polysaccharides from Staphylococcus aureus, a new synthesis of uridine 5"-(2-acetamido-2,6-dideoxy--d-galactopyranosyl diphosphate) (uridine 5"-diphospho-N-acetyl--d-fucosamine) using 2-azido-3,4-di-O-acetyl-2,6-dideoxy--d-galactopyranosyl nitrate as the key intermediate was carried out. The reaction of this product with cesium dibenzyl phosphate smoothly affords the corresponding -glycosyl dibenzyl phosphate, which undergoes anomerization on treatment with BF₃·Et₂O and 2-bromopyridine to give -glycosyl dibenzyl phosphate in high yield. This product was then transformed into 2-amino-3,4-di-O-acetyl-2,6-dideoxy--d-galactopyranosyl phosphate, subsequently converted into 2-acetamido-2,6-dideoxy--d-galactopyranosyl phosphate and the target nucleoside diphosphate sugar.     

Transformed steroids. 121. Synthesis of the δ-lactone of 3β-acetoxy-16α-hydroxy-6-oxo-24-nor-5α-chol-17(20)-en-23-oic acid

The synthesis of the ¹⁷⁽²⁰⁾-16 analog of natural chiogralactone is described. Attempts to introduce a 6-oxo group directly into the -lactone proved unsuccessful, since the first stage — saponification — took place with the formation of three products: the 3-hydroxy--lactone, the 3-hydroxy-²⁰⁽²²⁾-lactone, and the 15,17(20)-dienoic acid. The synthesis of the desired compound was effected from the ethyl ester of the 5,16-dienoic acid by the scheme 3-acetate3-tosylate6-hydroxy-3,5-cyclosteroid6-oxo-3,5-cyclosteroid6-oxo-5H--lactone. It has been shown that the cyclopropane ring in the 3,5-cyclosteroid -lactone is extremely stable under the conditions of acid treatments.N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 184–187, March–April, 1981.     

Reaktion der Azlactone mit Aminoverbindungen, 3. Mitt.: Über die Herstellung der Phenylhydrazide und 4-Nitrophenylhydrazide einiger α,β-disubstituierter Acrylsäuren

Zusammenfassung Ungesättigte Azlactone spalten sich mit Phenylhydrazin bzw. 4-Nitro-phenylhydrazin auf unter Bildung der Phenylhydrazide (1a–1o) bzw. 4-Nitro-phenylhydrazide (2a, 2b) der entsprechenden ,-disubstituierten Acrylsäuren. Zum Unterschied von den durch die Hydrazinolyse entstandenen Hydraziden der ,-disubstituierten Acrylsäuren, die sich leicht zu 3,5-disubstituierten 6-Hydroxy-1,2,4-triazinen^{1, 2} bzw. zu Pyrazolderivaten^{3, 4, 5} cyclisieren lassen, ist es nicht gelungen, unter gleichen Bedingungen die Phenylhydrazide bzw. 4-Nitro-phenylhydrazide zu cyclisieren. Zum Strukturbeweis dienten NMR-Spektren.

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Reaction of azlactones with amino compounds, III: Preparation of the phenylhydrazides and 4-nitrophenylhydrazides of several ,-disubstituted acrylic acids

The reaction of phenylhydrazine and 4-nitrophenylhydrazine with several unsaturated azlactones has resulted in their cleavage to the phenylhydrazides (1a–1o) and 4-nitrophenylhydrazides (2a, 2b), respectively, of the corresponding ,-unsaturated acrylic acids. In contradistinction to the hydrazides of ,-unsaturated acrylic acids, which had previoulsy been obtained by hydrazinolysis of unsaturated azlactones and had easily undergone cyclisation to 3,5-disubstituted 6-hydroxy-1,2,4-triazines^{1, 2} or pyrazole derivatives^3–5, the phenylhydrazides and 4-nitrophenylhydrazides could not be cyclised under comparable conditions. NMR spectroscopy was used to ascertain the structures of the reaction products.

     

Microscopic cross section for ion-molecule reactions with polar molecules

Using Kapitsa's method of separating rapidly varying processes from slower translational motions, a microscopic capture cross section for gas phase ion-molecule reactions is derived (centrifugal barrier approximation), leading to rate coefficients lying between the values of Langevin's theory and those of the locked dipole approximation (LD).

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, , - ( ), , , , LD-.

     

Circular Dichroism Spectra of 5- and 7-Bromo-6-ketosteroids

Circulardichroismspectra of 5- and 7-bromo-6-ketosteroidsof the cholestane and stigmastane serieswere studied. A negative Cotton effect corresponding to the n-* -transition of the ketone was observed in the CD spectra of 5-bromo-6-ketosteroids at 300 nm. The analogous Cotton effect was positive in CD spectra of 7-bromo-6-ketosteroids.     

Steroid compounds of marine sponges. VII. Preparation of derivatives of sokotrasterol and halistanol sulfates and structure-activity interrelationships among these compounds

Five new sulfated derivatives of sokotrasterol and halistanol have been obtained: 24-nor-5-cholane-2,3,6,23-tetraol 2,3,6-tri(sodium sulfate); 24-nor-5-cholane-2,3,6,23-tetraol 2,3,6-tri(sodium sulfate) 23-palmitate; 24,25-dimethyl-5-cholestane-2,3,6-triol 3-(sodium sulfate); 24,25-dimethyl-5-cholestane-2,3,6-triol 6-(sodium sulfate); and 24,25-dimethyl-5-cholestane-2,3,6-triol 2,6-di(sodium sulfate). The inhibiting and membranolytic properties of the polysulfated steroids from sponges and their derivatives have been studied. It has been shown that physiological activity in this series of compounds depends on biphilicity.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 441–445, July–August, 1986.     

Photocatalytic oxidation of isobutene on immobilized in oxide catalysts

Tin oxide species immobilized on silica have been synthesized. These systems are active in the photocatalytic oxidation of isobutene to acetone and their atomic photocatalytic activity is by almost two orders of magnitude higher than for crystalline SnO₂.

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, . , SnO₂.

     

Triterpene glycosides ofCauliphyllum robustum. The structures of caulosides B and C

Summary Two triterpene glycosides — caulosides b and c — have been isolated from a methanolic extract of the leaves ofCaulophyllum robustum maxim. Cauloside b has been identified as hederagenin 3--L-rhamnopyranosyl-(12)--L-arabinopyranoside, while cauloside c has the structure of hederagenin 3-0--L-arabinopyranosyl(13)--L-pyranosyl-(12)--L-arabinopyranoside.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center of the Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 174–176, March–April, 1979.     

LLX separation of carrier-free,94,95,97,103Ru,93,94,95,96,99mTc and95,96Nb produced in alpha-particle activated molybdenum by TOA

A radiochemical charged particle activation procedure for the simultaneous production of carrier-free radioisotopes of more than one element in a single target and their subsequent separation through LLX has been demonstrated. The carrier free isotopes,^95,96Nb,^{93,94,95,96,99m}Tc and^94,95,97,103Ru formed through Mo(,pxn), Mo(,pxn) and Mo(,xn) nuclear reactions with 40 MeV -particle as detected by nondestructive -ray spectroscopy, have been effectively separated through LLX using TOA as an anionic extractant. Separation of the bulk matrix of molybdenum from the carrier free products has been monitored radiometrically using isotopic^93,99mMo formed through the Mo(,xn) reaction, as radioindicators for the target element. Purity of the separated carrier free radionuclide has been verified by -ray spectrometry.     

Formation of 3,4-dihydro-α-carbolines from 2-aminoindole

In the condensation of 2-aminoindole with ,-unsaturated oxo compounds, in contrast to ordinary aromatic amines and a number of heterocyclic amines, the direction of cyclization is reversed. The general scheme of the reaction includes the reaction of the position of 2-aminoindole with the activated double bond of the oxo compound via a mechanism of the Michael type and condensation of the carbonyl group of the unsaturated carboline structure, which subsequently undergoes aromatization. The intermediate 3,4-dihydro--carbolines were produced and isolated; this made it possible in a number of cases to establish the structures of the final -carbolines. The structures of the 3,4-dihydro compounds were confirmed by the set of spectral characteristics. Data from the UV, IR, PMR, and mass spectra are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 945–951, pp. 945–951, July, 1977.     

Transformed steroids. 181. Synthesis of 16α,17α-cyclohexano-19-norprogesterone

Oxidative functionalization of the 19-angular methyl group of pregna-D₆-pentarane with its subsequent removal gave 16,17-cyclohexano-19-norprogesterone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1636–1638, July, 1990.     

Crystal and molecular structures of the alkaloid verdine

An x-ray structural analysis has been made with the object of reliably determining the structure of the alkaloid verdine. The position of the hydroxy group, not determined by other methods has been found and it has been established that the alkaloid verdine has the structure and configuration of 1,3,6-trihydroxy-5-jervanin-12-en-11-one.Institute of the Chemistry of Plant Substances, Academy of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 753–758, November–December, 1984.     

Inclusion Behavior of α-Cyclodextrin with 2-Methylnaphthalene in Aqueous Solutions

By means of absorption and fluorescence spectroscopy, 2-methylnaphthalene (2MN) was found to be incorporated into the cavity of -cyclodextrin (-CD) to form a 1 : 1 inclusion complex. The 1 : 1 inclusion complex further associated with another -CD molecule, resulting in the formation of a 2 : 1 -CD-2MN inclusion complex. The equilibrium constants for the formation of the 1 : 1 and 2 : 1 inclusion complexes were estimated to be 44.6 and 376 mol-1 dm3, respectively, on the basis of a simulation of the observed 2MN fluorescence intensities. The induced circular dichroism spectra suggested that 2MN, buried within the -CD inclusion complexes, resided in a different orientation relative to the CD symmetry axis, as compared to 2MN within a -CD inclusion complex.     

Rearrangement ofα -trifluoromethyl-β-dialkylamino-β-fluoroacrylic acid N.N-dialkylamides

Conclusions When heated in the presence of a catalytic amount of BF₃ etherate,-trifluoromethyl--diethylamino--fluoroacrylic acid N, N-dimethylamide is reversibly isomerized to-trifluoromethyl--dimethylamino--fluoroacrylic acid N, N-diethylamide. The methyl esters of-trifluoromethyl--diethylammo--fluoroacrylic acid and-trifluoromethyl--phenoxy--fluoroacrylic acid N,N-dimethylamide are not isomerized under the same conditions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No.1, pp.137–141, January, 1976.     

Reaction of Haloacrylic Acids with Phosphorus Nucleophiles

-Chloroacrylic acid reacts with triphenylphosphine to give (E)-(2-carboxyvinyl)triphenylphosphonium chloride. The same reaction with -halomethacrylic acids yields, depending on the temperature, either (2-carboxypropenyl)triphenylphosphonium halides or their isomeric (2-carboxyallyl)triphenylphosphonium halides. The possibility of unusual isomerization of the first compounds to the latter is shown. Synthesis of 1,2-(diphenylphosphinoyl)ethane from -chloroacrylic acid is carried out.     

Energy shift of vanadium Kα X-rays accompanying EC decay in51Cr-labeled compounds

The VK X-rays induced by the electron capture decay of⁵¹Cr-labeled compounds and the fluorescent X-rays of the vanadium compounds have been measured with a Bragg spectrometer. The evident chemical shifts of the K₁ and K₂ lines were observed for the oxidation state both by electron capture and photoionization. The differences of the K peak energy (K₁ and K₂ peaks) with the modes of the excitation were also obtained. The K peaks of⁵¹Cr shift to lower energy by ca. 0.5 eV than those of vanadium at the same oxidation state. This is because the probability of the electron shake up (and shake off) during the electron capture decay is extremely small, as compared to photoionization.     

Geometry of α-cyclodextrin inclusion complex with m-nitrophenol deduced from quantum chemical analysis of carbon-13 chemical shifts

The host-guest orientation and the position of the guest m-nitrophenol (MNP) in the -cyclodextrin (-CD)-MNP inclusion-complexation induced carbon-13 NMR chemical shifts of MNP with those predicted by quantum chemical calculation. In the calculation, the non-polar environmental effect produced by the -CD cavity on the carbon-13 shifts of included guest molecule has been formulated by the so-called NMR solvent effect theory. Here, carbon-13 shift displacements are assumed to be induced by transference of the guest from polar aqueous phase with higher dielectric constant to the non-polar -CD cavity with lower dielectric constant. Among a variety of host-guest orientation investigated, only the geometry in which the nitrophenyl group is located in the -CD cavity and the hydroxyl groups is exposed to the aqueous phase can reproduce qualitatively the observed carbon-13 shift displacements of MNP. This geometry is consistent with that in the solid state determined by the X-ray method.     

Improved synthesis of 6-deoxy-1,2-O-isopropylidene-β-L-talofuranose and 6-deoxy-1,2-O-isopropylidene-β-L-idofuranose

Summary The key step in the preparation of 6-deoxy-1,2-O-isopropylidene--L-talofuranose (7) and 6-deoxy-1,2-O-isopropylidene--L-idofuranose (13) is the selective exchange of the 6-O-mesyl rest of 3-O-acetyl-5,6-O-dimesyl-1,2-O-isopropylidene--D-allofuranose (4) and 3-O-acetyl-5,6-O-dimesyl-1,2-O-isopropylidene--D-glucofuranose (10) by acetate group (potassium acetate/18-crown-6).

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Ein neuartiger und präparativ nützlicher Zugang zu 6-Desoxy-1,2-O-isopropyliden--L-talofuranose und 6-Desoxy-1,2-O-isopropyliden--L-idofuranose

Zusammenfassung Schlüsselschritt bei der Herstellung von 6-Desoxy-1,2-O-isopropyliden--L-talofuranose (7) und 6-Desoxy-1,2-O-isopropyliden--L-idofuranose (13) ist der selektive Austausch der primären Mesyl-Gruppe in 3-O-Acetyl-5,6-O-dimesyl-1,2-O-isopropyliden--D-allofuranose (4) und 3-O-Acetyl-5,6-O-dimesyl-1,2-O-isopropyliden--D-glucofuranose (10) durch den Acetat-Rest in Gegenwart von Kaliumacetat/Kronen-Ether.