Synthesis of some 5′-O-amino acid derivatives of uridine as potential inhibitors ofUDP-glucuronosyltransferase

Summary In an attempt to develop potential inhibitors ofUDP-glucuronosyltransferase, some 5-O-amino acid derivatives of uridine were synthesized. N-protectedL-amino acids were coupled at the 5-O-position of 2,3-O-isopropylideneuridine by esterification employing the method of symmetrical anhydrides in presence of 4-dimethylaminopyridine, 5-O-(N-benzyloxycarbonyl-O-tert.butyl-L-threonl)-23-O-isopropylideneuridine (1), 5-O-(N-tert.butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylideneuridine and (2), 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (3), and 5-O-(N-tert.butyloxycarbonyl-L-valyl)-2,3-O-isopropylideneuridine (4) were obtained in good yield after column chromatography on silica gel. The treatment of2 withTFA/CH₂Cl₂ (6:1) at room temperature for 30 min led to a selective removal of theBoc group without deblocking of the 2,3-O-isopropylidene group of uridine. Treatment of2 withTFA/H₂O (5:1) at room temperature for 1 h, however, released bothBoc and 2,3-isopropylidene groups. TheZ group of1 was deprotected by catalytic hydrogenolysis over 10% Pd/C/ammonium formate.

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Synthese von 5-O-Aminosäurederivaten des Uridins als potentielle Inhibitoren derUDP-Glukuronosyl-Transferase

Zusammenfassung In einem Versuch, potentielle Inhibitoren derUDP-Glukuronosyl-Transferase zu entwickeln, wurden einige 5-O-Aminosäurederivate des Uridins synthetisiert. N-GeschützteL-Aminosäuren wurden durch Veresterung mit der 5-O-Position des 2,3-isopropylidenuridins gekuppelt (Methode der symmetrischen Anhydride in der Gegenwart von 5-Dimethylaminopyridin). Solcherweise wurden 5-O-(N-Benzyloxycarbonyl-O-tert.butyl-L-threonly)-2,3-O-isopropylidenuridin (1), 5-O-(N-tert.Butyloxycarbonyl-O-benzyl-L-seryl)-2,3-O-isopropylidenuridin (2), 5-O-(N-tert.Butyloxycarbonyl-L-leucyl)-2,3-O-isopropylidenuridin (3) und 5-O-(N-tert.Butyloxycarbonyl-L-valyl)-2,3-O-isopropylidenuridine (4) nach Säulenchromatographie (Kieselgel) in guter Ausbeute hergestellt. Die Behandlung von2 mitTFA/CH₂Cl₂ (6:1) bei Zimmertemperatur (30 min) führte zu einer selektiven Abspaltung derBoc-Gruppe ohne Deblockierung der 2,3-O-Isopropylidengruppe des Uridins. Eine Behandlung von2 mitTFA/H₂O (5:1) bei Zimmertemperatur für 1 Stunde führte hingegen zur Abspaltung sowohl derBoc als auch der 2,3-O-Isopropylidengruppe. DieZ-Gruppe von1 wurde durch katalytische Hydrogenolyse auf 10% Pd/C/Ammoniumformiat abgespalten.

     

Some Specific Features of Conjugate Addition Reactions with Lithium and Magnesium o-Carborane Derivatives

Reactions of lithium and magnesium o-carborane derivatives with ethyl -nitrocinnamate, ethyl -(3-indolyl)--nitroacrylate, and diethyl m-nitrobenzylidenemalonate were studied. Some specific features of these reactions were established, and preparative methods for the synthesis of previously unknown o-carborane derivatives were developed.     

Synthesis and study of L-arabinopyranosides of 5- and 6-nitroindoles

Condensation of 5- or 6-nitroindoline with L-arabinose gave 1--L-arabinopyranosyl-5 (or 6)-nitroindolines, which, after acetylation, dehydrogenation, and removal of the protective groups, are converted to 1--L-arabinopyranosyl-5(or 6)-nitroindoles and then to the corresponding amino derivatives. 1--L-Arabinopyranosyl-6-nitro-3-bromo-(iodo)indoles were obtained. The selective 2-O- and 3-O-deacetylation of 1-(2, 3, 4-tri-O-acetyl)--L-arabinopyranosyl-6-nitroindole was accomplished.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 224–229, February, 1979.     

Enthalpy of formation of triphenylphosphine sulfide

The first measurements of the enthalpies of combustion, sublimation, and fusion of an organo-phosphorus sulfide, triphenylphosphine sulfide, are reported: _c H _m ^o (C₁₈H₁₅PS, cr)=–(10752.58 ±2.90), _sub H _m ^o (C₁₈H₁₅PS, 403 K)=(136.80±6.09), and _fus H _m ^o (C₁₈H₁₅PS, T_m=435.92 K) =(30.53±0.21) kJ·mol^–1. Correction of the phase change enthalpies toT=298.15K and p^o =0.1 MPa results in the standard phase change enthalpy values of _sub H _m ^o (298.15 K)=(142.8 ±6.8) and _fus H _m ^o (298.15 K)=(19.28±0.21) kj·mol^–1. Accordingly, the enthalpies of formation of solid, liquid, and gaseous triphenylphosphine sulfide are derived: _f H _m ^o (C₁₈H₁₅PS, cr) =(63.20±2.56), _fH _m ^o (C₁₈H₁₅PS, l)=(82.48±2.57), and _fH _m ^o (C₁₈H₁₅PS, g)=(206.0±7.3) kJ·mol^–1. From these ancillary data, the P=S double-bond enthalpy is 394 kJ-mol^–1 and in good agreement with earlier reaction calorimetry results. These phosphorus sulfide values are compared with those for the arsenic sulfides. Plausibility arguments are given for our results.     

Densities and Partial Molar Volumes of Some Amino Acids and Diglycine in Aqueous n-Propanol Solutions at 25°C

Apparent molar volumes, V , of glycine, DL--alanine, DL--amino-n-butyric acid, L-valine, L-leucine, and diglycine in water and in 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 m _B [molality of n-propanol in water (mol-kg^–1)] aqueous solutions of n-propanol have been obtained from densities of their solutions at 25 °C measured by using a precise vibrating-tube digital densimeter. The calculated partial molar volumes of amino acids and diglycine at infinite dilution, V _2,m ^o , have been used to obtain the corresponding transfer volumes, _tr V _2,m ^o , from water to different n-propanol–water mixtures. _tr V _2,m ^o values are positive for glycine, DL-- alanine, and diglycine (except at lower concentration 1.0 m _B ), negative for L-valine, and both positive and negative for the remaining amino acids over the concentration range studied. The side-chain contributions and hydration numbers have been calculated from V _2,m ^o data. Interaction coefficients have also been obtained from the McMillan–Mayer approach and the data have been interpreted in terms of various interactions.     

The supramolecular structures and reactivities of some complexes of chiral crown ethers with borane ammonia

Whereas 1 1 crystalline complexes have been isolated between borane ammonia and methyl 4,6-O-benzylidene-2,3-dideoxy--d-galactopyranosido [2,3-b]-1,4,7,10,13,16-hexaoxacyclo-octadecane (1), methyl 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido [2,3-b] (methyl 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido [2,3-k]-1,4,7,10,13,16-hexaoxacyclo-octadecane (3), and (1R,2R,7R,24R)-3,5,8,11,14,17,20,23,26,28-decaoxatricyclo-[21.4.0.0^2,7]octacosane (4), the hosts, methyl, 4,6-O-benzylidene-2,3-dideoxy--d-mannopyranosido[2,3-b] 1,4,7,10,13,16-hexaoxacyclo-octadecane (2) and 1,4 1,4 3,6 3,6-tetra-anhydro-2,2 5,5-bis-O-oxydiethylenedi-d-mannitol (5) have yielded 2 1 (guest:host) crystalline complexes with borane ammonia as guest. X-ray analyses of the supramolecular structures of BH₃NH₃ ·1, (BH₃NH₃)₂ ·2, BH₃NH₃ ·3, BH₃NH₃ ·4, and (BH₃NH₃)₂ ·5 have been carried out and BH₃NH₃ ·1, BH₃NH₃ ·2, and (BH₃NH₃)₂ ·5 have been shown to reduce acetophenone with enantiomeric excesses of 5, 13, and 10% respectively. Supplementary Data relating to this article (atomic coordinates of the hydrogen atoms and thermal parameters) are deposited with the British Library as Supplementary Publication No. SUP 82017 (74 pages).Dedicated to Professor H. M. Powell.     

The crystal structures of α, ω-diaminoalkanecadmium(II) tetracyanonickelate(II)-Aromatic molecule inclusion compounds. V. Toluidine clathrates of the hosts built of the diamines, 1,4-diaminobutane, 1.5-diaminonentane,and 1,8-diaminooctane

The crystal structures have been analyzed for the threeo-toluidine clathrates,catena-[catena--(1,4-diaminobutane)cadmium(II) tetra--cyanonickelate(II)]-o-toluidine(2/3),4-o,catena-[catena--(1,5-diaminopentane)cadmium(II) tetra--cyanonickelate(II)]-o-toluidine(3/4),5-o, andcatena-[catena--(1,8-diaminooctane)cadium(II) tetra--cyanonickelate(II)]-o-toluidine(1/1),8-o, for am-toluidine onecatena-[catena--(1,5-diaminopentane)cadmium(II) tetra--cyano-nickelate(II)]-m-toluidine(1/1),5-m, and for ap-toluidine onecatena-[catena--(1,8-diaminooctane)cadium(II) tetra--cyanonickelate(II)]-p-toluidine(1/1),8-p. 4-o crystallizes in the triclinic space groupP,a/Å = 9.806(3),b/Å = 14.388(3),c/Å = 7.725(2), /° = 89.71(2), /° = 89.96(2), /° = 98.12(2),V/ų = 1078.8(5),Z = 2, 3750 reflections,R = 0.056;5-o: tetragonalP4lmmm, (a = b)/Å = 7.485(7),c/Å = 10.06(3),V/ų = 563(2),Z = 1, 573 reflections,R = 0.19;8-o: monoclinicP2/m,a/Å = 11.513(4),b/Å = 7.626(1),c/Å = 7.101(1), /° = 109.63(3),V/ų = 587.2(2),Z = 1, 1682 reflections,R = 0.058;5-m: orthorhombicPbam,a/Å = 12.254(6),b/Å = 20.62(1),c/Å = 7.804(1),V/ų = 1972(1),Z = 4, 2240 reflections,R = 0.059; and8-p: triclinic,P,a/Å = 11.52(1),b/Å = 7.632(3),c/Å = 7.039(4), /° = 88.93(4), /° = 109.71(5), /° = 82.81(9),V/ų = 576.9(6),Z = 1, 2598 reflections,R = 0.042. Their structures are substantially similar to the already-known structure ofcatena-[catena--(1,6-diaminohexane)cadmium(II) tetra--cyanonickelate(II)]-o-toluidine(1/1): the guest toluidine molecules are accommodated in the cavities formed betweencatena-[cadmium(II) tetra--cyanonickelate(II)] layers bridged by the ambidentate ,-diaminoalkane ligands at the cadmium(II) atoms. The carbon chain length of the ,-diaminoalkane influences the number of cavities per formula unit and the deformation of the metal complex layers.     

Phthalocyaninartige Bor-Komplexe

Zusammenfassung Aus Halogenboranen und Organohalogenboranen (RBX ₂R=C₆H₅, Cl, Br;X=F, Cl, Br) sowie aus Organoboranen oder Thioboranen entstehen mit Phthalodinitril Triisoindolo-[1,2,3-cd1,2,3-gh1,2,3-kl][2,3a,5,6a,8,9a,9b]-hexaazaboraphenalene von denen die B–Cl- und B–F-Verbindungen näher charakterisiert werden.Dekaboran(14), Diboran(6) oder Boranaddukte von Stickstoffbasen liefern hingegen mit Phthalodinitril metallfreies Phthalocyanin.

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Triisoindolo[1,2,3-cd1,2,3-gh1,2,3-kl][2,3a,5,6a,8,9a,9b]-hexa-azaboraphenalene

Triisoindolo[1,2,3-cd1,2,3-gh1,2,3-kl][2,3a,5,6a,8, 9a,9b]-hexaazaboraphenalenes are obtained from the reactions of haloboranes and organohaloboranes (RBX ₂R=C₆H₅, Cl, Br;X=F, Cl, Br) as well as from organoboranes or thioboranes with phthalodinitrile. The B–Cl and B–F compound have been characterized by analyses, i.r.-, u.v.- and mass-spectrometry.Diborane(6), dekaborane(14) and amine-boranes, however, upon reaction with phthalodinitrile lead to high yields of metal free phthalocyanine.

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Herrn Prof. Dr.M. Pailer zum 60. Geburtstag gewidmet.     

Calculation of two-center zero-field splitting integrals

Two-center zero-field splitting (ZFS) integrals have been calculated by numerical integration of Coulomb repulsion integrals which are evaluated over basic charge distributions as defined by Roothaan in terms of Slater atomic orbitals. The method is applied to the calculation of the ZFS integrals for -, - and - electron interactions on C, N and N⁺ centers. Numerical results are given.

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Zusammenfassung Zweizentren ZFS-Integrale sind mittels numerischer Integration von Coulombintegralen berechnet worden, und zwar die -, -- und --Integrale an C-, N- und N⁺-Zentren. Die numerischen Resultate werden mitgeteilt.

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Résumé Les intégrales bi-centriques de séparation à champ nul (ZFS) ont été calculées par intégration numérique des intégrales de répulsion coulombiennes évaluées pour les distributions de charge fondamentales définies par Roothan en termes d'orbitales atomiques de Slater. La méthode est appliquée au calcul des intégrales ZFS pour les interactions -, - et - sur les centres C, N et N⁺. Résultats numériques.

     

Certification of fat-soluble vitamins,carotenoids, and cholesterol in human serum: Standard reference material 968b

In Standard Reference Material 968b, fat-soluble vitamins and cholesterol in human serum, certified values are provided for cholesterol, retinol, retinyl palmitate, -tocopherol, trans--carotene, total -carotene (trans plus cis isomers), total -carotene, and lutein. Non-certified values are also reported for -tocopherol (includes -tocopherol), -tocopherol, zeaxanthin, -cryptoxanthin, trans-lycopene, trans-lycopene, trans--carotene, total lycopene, 9-cis-carotene, 13- plus 15-cis--carotene, and 15-cis--carotene. Both certified and non-certified values are based on the agreement among results from three different liquid chromatographic analytical procedures developed at NIST and from an interlaboratory comparison exercise among institutions that participate in a NIST-managed Micronutrients Measurement Quality Assurance Program. Cholesterol is certified in this material using the NIST isotope dilution/mass spectrometric definitive method.     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphan/Azodicarbonsäurediethylester, 4. Mitt.: Transformationen an Mannose und Galaktose

Reaction of methyl -D-galactopyranoside (1) with two equivalents oft-butyldimethylchlorosilane yields methyl 2,6-bis-O-(tBDMSi)--D-galactopyranoside (1 b), methyl 3,6-bis-O-(tBDMSi)--D-galactopyranoside (1 c) and methyl 4,6-bis-O-(tBDMSi)--D-galactopyranoside (1 d). Likewise methyl -D-mannopyranoside (6) affords methyl 2,6-bis-O-(tBDMSi)--D-mannopyranoside (6 d) and methyl 3,6-bis-O-(tBDMSi)--D-mannopyranoside (6 b), which can be isomerised withTPP/DEAD to methyl 4,6-bis-O-(tBDMSi)--D-mannopyranoside (6 f). Methyl 6-O-(tBDMSi)--D-galactopyranoside (1 a) and methyl 6-O-(tBDMSi)--D-mannopyranoside (6 a) can be prepared from1 or6 with one equivalent oft-butyldimethylchlorosilane.Without an external nucleophile the sugar derivatives1 a and1 b react withTPP/DEAD to form the 3,4-carbonato--D-galactopyranosides1 h and1 i and the 3,4-carbonato-2-O-ethoxycarbonyl--D-galactoside (1 j). In contrast to the formation of the compound1 i by means ofTPP/DEAD the reaction of1 a withTPP and Di-t-butyl-azodicarboxylate (DTBAD) yields the 2,3-anhydro--D-taloside (4 b) and only a small amount of1 i. The epoxide4 b can be cleaved withp-nitrobenzoylchloride/pyridine to the 3-chloro-3-deoxy-2,6-di-O-p-nitrobenzoyl--D-idoside (5). Reaction of1 c and1 d withTPP/DEAD yields the 2,3-anhydro--D-gulopyranoside (2), which can be transformed with NaN₃/NH₄Cl to the 2-azido-2-deoxy--D-idopyranoside (3).Likewise6 a and6 d can be converted to the 3,4-anhydro--D-talosides (7 a and7 b). Reaction of7 b or6 d withTPP/DEAD/NH₃ leads to 3,4-anhydro-2-azido-2-deoxy--D-galactopyranoside (8) and 3-azido-3-deoxy--D-altropyranoside (10), resp.The epoxide7 b is opened with NaN₃/NH₄Cl to the 4-azido-4-deoxymannosides (11 a and11 c) and the 3-azido-3-deoxy--D-idopyranoside (12), while the epoxide8 affords the 2,4-di-azido-2,4-dideoxy--D-glucopyranoside (9).Structures were elucidated by¹H-NMR-analysis of the corresponding acetates.

H. H. Brandstetter undE. Zbiral, Helv., im Druck.     

Zur Mannich-Reaktion von Dihydro-6-methyl-2(1H)-pyrimidinonen

Zusammenfassung Dihydro-4,4,6-trimethyl-2(1H)-pyrimidinone reagieren mit Formaldehyd und sekundären bzw. primären Aminen zu 6-Dialkylaminoäthylidentetrahydro-2(1H)-pyrimidinonen bzw. Hexahydro-2(1H)-pyrido[4,3-d]Pyrimidinonen. Mit Succindialdehyd bzw. Glutardialdehyd und primären Aminen entstehen 5,7-Äthanohexahydro-2(1H)-pyrido[4,3-d]pyrimidinone bzw. Tetrahydro-6,8-propano-6H-pyrimido[1,6-c]pyrimidin-1(2H)-one. Die 6-Dialkylaminoäthylidentetrahydro-2(1H)-pyrimidinone geben mit Phenolen Tetrahydrospiro([1]benzopyran-2,4(1H)-pyrimidin)-2(3H)-one, mit cycl. -Dicarbonylverbindungen Hexahydrospiro([1]benzopyran-2,4(1H)-pyrimidin)-2,5(3H, 6H)-dione bzw. Tetrahydrospiro(2H,5H-pyrano[3,2-c][1]benzopyran-2,4(1H)-pyrimidin)-2(3H),5-dione bzw. mit Malonestern -(Tetrahydro-4,4-dimethyl-2-oxo-6-pyrimidyl)-äthylmalonester.Zusammenfassung Dihydro-4.4.6-trimethyl-2(1H)-pyrimidinones react with formaldehyde and sec. and prim. amines resp. to 6-dialkylaminoethylidentetrahydro-2(1H)-pyrimidinones and hexahydro-2(1H)-pyrido[4.3-d]pyrimidinones, resp. succindialdehyde and glutaraldehyde with primary amines give 5.7-ethanohexahydro-2(1H)-pyrido[4.3-d]pyrimidinones and tetrahydro6.8-propano-6H-pyrimido[1.6-c]pyrimidin-1(2H)-ones, resp. 6-Dialkylaminoethylidentetrahydro-2(1H)-pyrimidinones react with phenols to tetrahydrospiro([1]benzopyran-2.4(1H)-pyrimidin)-2(3H)-ones, with cyclic -dicarbonyl compounds to hexahydrospiro([1]benzopyran-2.4 (1H)-pyrimidin)-2,5 (3H), 6H)-diones and tetrahydrospiro(2H,5H-pyrano[3.2-c][1]benzopyran-2.4(1H)-pyrimidin)-2(3H),5-diones, resp., with malonates -(tetrahydro-4.4-dimethyl-2-oxopyrimidyl-6)-ethylmalonates.

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Mannich reaction with dihydro-6-methyl-2(1H)-pyrimidinones

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Herrn Prof. Dr.F. Kuffner zum 65. Geburtstag gewidmet.     

Synthesis and physico-chemical and biological studies on ruthenium (III) complexes with Schiff bases derived from aminocarboxylic acids

Summary Ruthenium(III) complexes of types [Ru(L)₃], [Ru(L)Cl(H₂O)₂], [Ru(L)Cl₂]_n, [Ru(L)Cl(H₂O)]_n(LH =Schiff bases derived from anthranilic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; LH₂=Schiff bases derived from anthranilic acid and salicylaldehyde oro-hydroxyacetophenone; LH=Schiff bases derived fromp-aminobenzoic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; LH₂=Schiff bases derived fromp-aminobenzoic acid and salicylaldehyde oro-hydroxyacetophenone) have been synthesized and characterized on the basis of elemental analyses, conductance, magnetic moment and spectral (electronic, i.r. and¹H n.m.r.) data. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory and various parameters have been evaluated. On the basis of the electronic spectra, an octahedral geometry has been established for all these complexes except [Ru(L)Cl₂]_n. The complexes [Ru(L)Cl₂]_n are pentacoordinate and a trigonal-bipyramidal environment, D_3h, is suggested for the ruthenium(III) ion. The thermal behaviour of these complexes has also been studied by t.g., d.t.g and d.s.c techniques. Heats of reaction for the decomposition steps were calculated from the d.s.c. curves. The antifungal and antiviral activities of the complexes with Schiff bases derived from anthranilic acid were also investigated.     

Coumarin glycosides ofHaplophyllum performatum. structures of haploperosides C,D, and E

New coumarin glycosides — haploperosides C, D, and E — have been isolated from the epigeal part of theHaplophyllum performatum (MB) Kar et Kir. On the basis of chemical transformations and spectral characteristics, haploperoside D has the structure of 6-methoxy-7-[0--L-rhamnopyranosyl-(1 2)--D-glucopyranosyloxy]-2H-benzopyran-2-one, and haploperoside C that of 6-methoxy-7-[0--L-rhamnopyranosyl-(1 6)-(2-0-acetyl--D-glucopyranosyloxy)]-2H-benzopyran-2-one. The structure of haploperoside E has been established as 7-[0--L-rhamnopyranosyl-(1 2)-0--L-rhamnopyranosyl-(1 6)--D-glucopyranosyloxy]-2H-benzopyran-2-one. The structures of haploperosides A and B have been refined. An assignment has been made of the carbon signals in the¹³C NMR spectra of haploperosides A, D, C, and E.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 27–35, January–February, 1985.     

Prediction of the non-Newtonian viscosity and shear stability of polymer solutions

The structure-property relationships derived here permit the prediction of both the zero-shear viscosity ₀, as well as the shear rate dependent viscosity . Using this molecular modeling it is now possible to predict over the whole concentration range, independently of the molecular weight, polymer concentration and imposed shear rate. However, the widely accepted concept: dilute — concentrated, is insufficient. Moreover it is necessary to take five distinct states of solution into account if the viscous behavior of polymeric liquids is to be described satisfactorily. For non-homogeneous, semi-dilute (moderately concentrated) solutions the slope in the linear region of the flow curve (= must be standardized against the overlap parameterc · []. As with the ₀-M-c-relationship, a-M -c- relationship can now be formulated for the complete range of concentration and molecular weight. Furthermore, it is possible to predict the onset of shear induced degradation of polymeric liquids subjected to a laminar velocity field on the basis of molecular modeling. These theoretically obtained results lead to the previously made ad hoc conclusion (Kulicke, Porter [32]) that, experimentally, it is not possible to detect the second Newtonian region.Roman and Italian symbols a exponent of the Mark-Houwink relationship - b exponent of the third term of the ₀-M -c relationship - c concentration /g · cm^–3 - E number of entanglements per molecule - F(r) connector tension - f function - G _i ^A shear modulus; A indicates that it /Pa has been evaluated by a transient shear flow experiment; i is the shear rate to whichG ^A refers to - G storage modulus /Pa - G _p plateau modulus /Pa - H() relaxation spectrum /Pa - h shift factor (₀/_r) - K _H Huggins constant - K _b third constant of the ₀-M -c relationship - K constant of the Mark-Houwink relationship - M molecular weight /g · mol^–1 - M _e molecular weight between two /g · mol^–1 entanglement couplings - N number of segments per molecule - n slope in the power-law region of the flow curve - p p-th mode of the relaxation time spectrum - R gas constant /8.314 J·K^–1·mol^–1 - r direction vector - T temperature /K Greek symbols ß reduced shear rate - shear rate /s^–1 - shear viscosity /Pa·s - _s solvent viscosity /Pa·s - _sp specific viscosity - ₀ zero-shear viscosity /Pa·s - apparent viscosity at shear rate - reduced viscosity - viscosity of polymeric liquid in /Pa·s the second Newtonian region - [] intrinsic viscosity/cm³·g^–1 - screening length/m - /g·cm ^–3 density - relaxation time/s - ₀ experimentally derived relaxation time/s - angular frequency of oscillation Indices conc concentrated - corr slope corrected - cr critical - deg degradation - e entanglement - exp experimental - mod moderately concentrated/semi-dilute - n number average - p polymer - R Rouse - rep reptation - s solvent - sp specific - theo theoretical - weight average - relaxation time - o experimental or steady state - * critical - ** transition moderately conc. — conc. - + transition dilute — moderately cone. Paper presented at the 2nd bilateral U.S.-West German Polymer Symposium, Yountville, the 7th–11th September 1987.     

On theC v toC p conversion for solid linear macromolecules

TheC _v toC _p conversion for solid linear macromolecules via the Nernst-Lindemann equationC _p -C _v =A ₀,C _p ² T/T_m is discussed on hand of data for 10 crystals and seven glasses. An average value ofA ₀=(5.11±2.41) · 10^–3 mol K J^–1 was calculated if the mole is assumed to refer to heavy atoms only. ThisA ₀ is numerically equal to the original Nernst—Lindemann constant.

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Zusammenfassung An Hand von sich auf 10 Kristalle und 7 Gläser beziehenden Daten wird die Umrechnung vonC _v -inC _p -Werte für feste lineare Makromoleküle mittels der Nernst-Lindemann-GleichungC _p -C _v =A ₀ C _p ² T/T _m diskutiert. Ein Durchschnittswert vonA ₀=(5.11±2.41) · 10^–3 mol K J^–1 wurde unter der Annahme berechnet, daß sich das Mol nur auf schwere Atome bezieht. DieserA ₀-Wert ist numerisch gleich der ursprünglichen Nerns-Lindemann-Konstanten.

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10 , - C _v C _p , —C _p –C _v = _{0 p} ² / . , , ₀ (5.11±2.41) · 10^–3 · ^–1. ₀ — .

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Support by the National Science Foundation, Polymers Program (Grant No. DMR 83-17097) is gratefully acknowledged.     

Steroid saponins and sapogenins ofAllium IX. The structure of aginoside

Summary From a methanolic extract of the skins of the bulbs ofAllium giganteum Rgl, a new steroid glycoside has been isolated — aginoside, which is (25R)-5-spirostan-2, 3, 6-triol 3-0-{[0--D-xylopyranosyl-(13)-]-[0--D-glucopyranosyl-(12)]-0--D-glucopyranosyl-(14)-0--D-galactopyranoside}.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 480–486, July–August, 1976.     

σ-π separation: Excited H2 as a model system

The low-lying states of H₂ consist of one core () and one valence () electron and afford a direct evaluation of intershell - interaction. After resolution of the electronic energy into only, only, and - parts, it is shown that an electronic change in this model system is due solely to a change in the electrons. Simple Hückel theory is examined. If the molecular core is represented properly, regardless of the wave function the calculated and parameters are in reasonable agreement with the empirical parameters. This agreement appears to be due to a fortuitous cancellation of energy contributions.

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Zusammenfassung Die niedrig liegenden -Zustände des H₂ bestehen aus einem Rumpfelektron und einem Valenzelektron und ermöglichen eine direkte Auswertung der --Wechselwirkung zwischen zwei Schalen. Nach der Zerlegung der elektronischen Energie in -,- und --Anteile wird gezeigt, daß eine elektronische Veränderung in diesem Modellsystem nur auf eine Veränderung des -Elektronenanteils zurückgeht. Die einfache Hückeltheorie wird untersucht. Wenn der Molekülrumpf geeignet dargestellt wird, so sind, unabhängig von der -Wellenfunktion, die berechneten Parameter und in guter Übereinstimmung mit den empirischen Parametern. Diese Übereinstimmung scheint auf eine starke Auslöschung von Energieanteilen zurückzugehen.

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Résumé Les états inférieurs de H₂ consistent en un électron de coeur () et un électron de valence () et fournissent une évaluation directe de l'interaction entre couches -. Après expression de l'énergie électronique en parties , et -, on montre qu'une modification électronique de ce système modèle est due seulement à une modification des électrons . La théorie de Hückel simple est examinée. Si le coeur moléculaire est convenablement représenté, quelle que soit la fonction d'onde , les paramètres at calculés sont en accord raisonnable avec les paramètres empiriques. Cet accord apparaît comme le résultat d'une compensation fortuite de contributions énergétiques.

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Work performed in part under the auspices of the U.S. Atomic Energy Commission.

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Work aided by the U.S. Public Health Service via grant GM 08068.     

Zur Kenntnis der cis-trans-Asymmetrie, 7. Mitt.

Zusammenfassung Es wird über die Umsetzungen voncis- undtrans--Phenylzimtsäurechlorid mit 1,3-Diamino-2-phenyl-propan berichtet. Aus 2-Phenyl-3-(trans--phenylcinnamoylamino)-propylamin konnten nach der Aufspaltung in Antipoden mitcis--Phenylzimtsäurechlorid optisch aktive 1-cis,3-trans-Bis-(-phenylcinnamoylamino)-2-phenyl-propane (cis,trans-III) erhalten werden.6. Mitt., Mh. Chem.92, 1197 (1961). 5. Mitt., Naturwiss.48, 500 (1961).