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.     

Chelation of somebisazophenyl-β-diketone derivatives with lanthanide metal ions

Summary The chelation behaviour ofbisazo--diketone compounds with La, Ce, Nd, Sm, Gd, Er, and Lu ions was investigated. Composition and stability constants of the chelates have been determined by conductometric and potentiometric techniques. Electronic absorption, IR, and¹H NMR spectra as well as molar conductance and elemental and thermal analyses were used to characterize the complexes.

---

Komplexierung einiger Lanthaniden mitBisazophenyl--diketon-Derivaten

Zusammenfassung Das Komplexierungsverhalten einigerBisazophenyl--diketone mit La, Ce, Nd, Sm, Gd, Er und Lu wurde untersucht. Zusammensetzung und Stabilitätskonstanten der Chelate wurden mit konduktometrischen und potentiometrischen Methoden bestimmt. Zur Charakterisierung der Komplexe wurden UV/Vis-, IR- und¹H-NMR-Spektroskopie sowie molare Leitfähigkeit, Elementaranalyse und thermische Analyse herangezogen.

     

Determination of solid state basicity of rare earth oxides by thermal analysis of their carbonates

Relative basicities of the rare earth oxides (M₂O₃) were determined from the measurement by TG - DTA of decomposition temperatures of the carbonates of Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb. From the comparison of this data with that published by Head and Holley, a sequence of basicity has been proposed for the entire range of rare earth oxides. This sequence in decreasing basicities is: La > Pr ~ Nd > Sm > Gd ~ Eu > Tb ~ Ho ~ Er > Dy Tm Yb Lu > Ce. Basicity of rare earth oxides, therefore, does not decrease progressively with an increase in atomic number.

---

Zusammenfassung Die relative Basizität der Seltenerdenoxide (M₂O₃) wurde mittels der durch TG-DTA-Untersuchungen festgestellten Zersetzungstemperaturen der Karbonate folgender Metalle bestimmt: Ce, Pr, Sm,Eu, Gd, Tb, Dy, Ho, Er und Yb. Aufgrund eines Vergleiches der hier ermittelten Daten mit denen von Head und Holley wird für die Basizität der Seltenerdenoxide folgende Reihenfolge aufgestellt: La > Pr Nd > Sm > Gd Eu > Tb Ho Er > Dy Tm Yb Lu > Ce. Wie ersichtlich nimmt die Basizität der Seltenerdenoxide mit ansteigender Ordnungszahl nicht progressiv ab.

---

---

This research forms part of a larger nationally coordinated program on natural gas conversion conducted in collaboration with the Divisions of Materials Science & Technology and Fuel Technology, and with BHP Melbourne Research Laboratories.

---

The author is grateful to Dr E. Patsalides of Sydney University for his generous donation of eight rare-earth oxides. The author wishes to thank the colleagues for their contribution to this work: Mr K. Riley and Mr W. Godbeer (chemical analysis), Dr P. F. Nelson and Mr R. Quezada (FTIR analysis), Mr A. Home (XRD analysis), Mr S. P. Chatfield (thermal analysis) and the project leader, Mr R. J. Tyler for his constant encouragement and valuable suggestions.     

Spectrophotometric study of Nd,Sm, and Ho complexation in chloride solutions at 100–250°C

Complex formation in Ln chloride solutions is studied by spectrophotometric method. Electronic absorption spectra of Nd³⁺, Sm³⁺, and Ho³⁺ ions are measured in the range of supersensitive transitions in solution with Cl^– ion concentration from 0 to 5 mol/l in 100–250°C temperature interval under saturated vapor pressure. The Nd and Sm spectra represent integrated curves that mainly consist of Ln³⁺ and LnCl²⁺ absorption bands (with stability constant ₁), while the Ho spectra consist of Ho³⁺ and HoCl ₂ ⁺ absorption bands (with ₂). The stability constants ₁ and ₂ calculated for each wave number by linear regression method acquire steady values and have the meaning of the best unbiased linear estimates. Thermodynamic values of log₁ for Nd, Sm, and Ho monochlorides lie in a narrow interval at constant temperature. In the case of Nd and Sm, the temperature curves of log₁ and log₂ have smaller slopes as compared to that of Ho, which is explained by the effect of a covalent component in their spectra that adds to the ionic nature of the bonds in monochloride complexes. The ₂ values increase in the order Nd相似文献   

Complexation of the Non-steroidal Anti-inflammatory Drug Loxoprofen with Modified and Unmodified β-Cyclodextrins

The inclusion complex of the anti-inflammatory drug, loxoprofen, with -cyclodextrin-(CD), sulfated -CD, and glycerol ether -CD was studied by UV-VIS absorption and ¹H-NMR spectroscopy in solution. The inclusion complex of loxoprofen with -CDs was prepared by freeze-drying, and then characterized in the solid state by thermal analysis, X-ray diffraction, FT-IR and FT-Raman spectroscopy, and scanning electron microscopy (SEM). Furthermore, a physical mixture of loxoprofen/-CD (1/1, mol-%) in the solid state was also characterized. The solubility of the loxoprofen increased on addition of -CDs. The solubility enhancement of the loxoprofen with -CDs is in the following order: glycerol ether -CD > sulfated -CD > -CD.     

Ab initio Study of β-lactam antibiotics

Ab initio SCF-MO-LCAO calculations have been performed with a 7s3p/3s GTO basis set for the CH₃O--lactam + OH^– reaction which is related to the mode of action of -lactam antibiotics. The comparison of the present results with the previous ones for -lactam + OH^– and 3-cephem + OH^– shows that the CH₃O substitution has a negligible effect on the amidic bond breaking of -lactam, so that this group probably influences other steps of the antibiotic reactivity of cephaloporins.     

The effects of cyclodextrin inclusion of the ferrocenemonocarboxylate anion on the kinetics of its oxidation by bis(pyridine-2,6-dicarboxylato)cobaltate(III) in aqueous solution

The effects of -, -, dm-(heptakis(2,6-di-O-methyl)--) and -cyclodextrins (CD) on the kinetics of the electron-transfer reaction of the ferrocenemonocarboxylate anion (FCA^–) with bis(pyridine-2,6-dicarboxylato)cobaltate(III) have been investigated in aqueous solution (0.20 M Na₂HPO₄, pH 9.2) at 25.0°C. Substantial decreases in the rate constants for the electron-transfer reactions were observed upon cyclodextrin inclusion of the reductant, due to an increase in the FCA^0/– reduction potential and to the insulation of the reductant from oxidant. The inclusion stability constants for {FCA·CD}^– were evaluated from the¹H NMR and kinetic data, and the order of the stability constants was found to be -CDdm-CD-CD>-CD.     

NMR Spectral Assignment of Per-substituted Key-Intermediates of β-Cyclodextrin and Implications in the Structures of the Derivatives

The compounds, 6-per-O-(t-butyldimethylsilyl)--cyclodextrin(1), 2,3-per-O-benzyl-6-per-O-(t-butyldimethylsilyl)--cyclodextrin(2), 2,3-per-O-benzyl--cyclodextrin (3),2,3,6-per-O-benzyl--cyclodextrin (4),2,3,6-per-O-benzoyl--cyclodextrin (5), are used as keyintermediates in the synthesis of selectively substituted -CD derivatives. Simple and assignable ¹H and ¹³C NMR spectra (chemical shifts and coupling constants) were obtained for compounds1–4 indicating C₇ symmetry, ⁴C₁ glucose conformation and major arrangement of H6, H6' atoms at the primary side. The derivative 5, however, gave very broad peaksat room temperature. The peaks could partially be assigned at 270 K, but the broadening was still present at 220 K. This implies that there exist several conformers of similar energyand C₁ symmetry that continuously interchange, since there is not a single type of stabilizing interaction thatpredominates. We attributed this phenomenon to the presence of the carbonyl group, which probablydisfavors - stacking and induces random arrangements of the aromatic rings.     

The hydrolysis and fluoride complexation behavior of Fe(III) at 25°C and 0.68 molal ionic strength

Fe(III) hydrolysis and fluoride complexation behavior was examined in 0.68 molal sodium perchlorate at 25°C. Our assessment of the complexation of Fe(III) by fluoride ions produced the following results: log_F1 = 5.15₅, log_F2 = 9.10₇, log_F3 = 11.96, log_F4 = 13.7₅, where log_Fn = 5.15₅=[FeF _n ^(3-n)+ ][Fe³⁺]^–1[F^–]^–n. The stepwise fluoride complexation constants,FK _n+1, obtained in our work (where log_F K _n+1 =log_Fn) indicate that K _n+1/K _n =0.072±0.01. Formation constants for equilibria, Fe³⁺+nH₂OFe(OH) _n ^(3–n)+ +nH⁺, expressed in the form _n ^* [Fe(OH) _n ^(3-n)+ ][H⁺]ⁿ ,[Fe ³⁺]^-1, were estimated as ₁ ^* = –2.754, and ₂ ^* –7. Our study indicates that the results of previous hydrolysis investigations include very large overestimates of Fe(OH) ₂ ⁺ formation constants.     

Sterol glycosides from the Far Eastern holothurianCucumaria japonica

Sterol -D-xylopyranosides and arabinopyranosides in a ratio of 9:1 have been isolated from a lipid extract of the musculocutaneous sac of the Far Eastern holothurianC. japonica. The main components of both glycosidic fractions were identified as derivatives of cholesta-7,22-diene-3-ol, cholest-22-en-3-ol, 5-cholestan-3-ol, 24-ethylcholesta-7,22-dien-3-ol, and 24-methylene-, 24-methyl-, and 24-ethyl-cholest-22-en-3-ols.Institute of Immunology, Ministry of Health of the USSR, Moscow. M. M. Shemyakin Institute of Biorganic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 54, pp. 615–620, September–October, 1984.     

Bis-β-diketones as lonophores for Mg2+ in solvent polymeric membranes

Lipophilic bis--diketones have been prepared by covalently linking two-diketone subunits. Potentiometric studies on liquid membrane electrode cell assemblies showed no improvement of the ion selectivities induced by the bridged systems in comparison to unbridged-diketones. The dissociation constants of the enol functions in the bis--diketones indicate that under the conditions of the EMF measurement probably only one-diketone unit is deprotonated in the liquid membrane phase. The complexation of these-diketones with Mg²⁺ and Ca²⁺ was studied by¹³C NMR-monitored titrations in a homogeneous organic phase.On leave from the Chemistry Department, University of Warsaw, Warsaw, Poland     

The Coordination Number of Lu(III) in a Mixed System of Methanol and Water

The stability constants (_1(F)) of the monofluoro complex of Lu(III) and those (_1(Cl)) of the monochloride solvent-shared ion-pair of Lu(III) have been determined in mixed solvents of methanol and water at 0.10 and 1.00 mol·dm^–3 ionic strengths, respectively. The variation in ln_1(F) with an increase in the mole fraction of methanol (X _s) in the mixed solvent system showed an acute-angled convex inflection point at X _s 0.12, an acute-angled concave inflection point at X _s 0.22, and another acute-angled convex inflection point at X _s 0.27. It was concluded that the first and the second convex inflection points denoted the CN of Lu³⁺ from CN = 8 to a mixture of CN = 8 and 7 and from CN = 8 and 7 to a mixture containing CN = 6, respectively. The concave point is the starting point of a change in the CN of Lu(III) in LuF²⁺ from CN = 8 to a mixture of CN = 8 and 7. The values of two inflection points of the CN around Lu³⁺ are consistent with the inflection points of the variation in the values of ln_1(Cl) versus the dielectric constant of the mixed solvent.     

The Ionic Strength Dependence of Rare Earth and Yttrium Fluoride Complexation at 25°C

Formation constants for the complexation of yttrium and rare earth elements(YREE) by fluoride ions have been measured at 25°C. The ionic strength ()dependence of YREE formation constants in perchlorate solution for ionicstrengths between 0 and 6 molar can be expressed aslog_F1 (M, ) =log_F1 ^o (M) –3.066 ^0.5/(1 + 1.769 ^0.5)+ 0.1645 where log_F1 ^o(M) represents MF²⁺formation constants at zero ionic strength.The log_F1 ^o(M) results obtained inthis work are: Y(4.46), La(3.62), Ce(3.86),Pr(3.84), Nd(3.82), Sm(4.15), Eu(4.27), Gd(4.24), Tb(4.37), Dy(4.39), Ho(4.28),Er(4.27), Tm(4.29), Yb(4.39), and Lu(4.25). The relative magnitudes of YREEformation constants are independent of ionic strength. The pattern oflog_F1(M,),formation constants obtained in this work [relative magnitudes oflog_F1 ^o (M)],exhibits a shallow minimum between Dy and Yb. In contrast to the smoothpattern of stability constants expected if fluoride were to interact with bare ions(with monotonically decreasing crystal radii between La and Lu), theinteractionof F^– with YREEs, which have extensive hydration spheres[M(H₂O)_8–9 ³⁺] resultsin a relatively complex pattern of lanthanide stability constants. The fluoridecomplexation behavior of yttrium differs distinctly from the behavior of any rareearth. Although the crystal radius of Y3;pl is approximately equalto that of Ho³⁺,differences in the covalence/ionicity of Y³⁺ relative to therare earths leads to aYF²⁺ stability constant that exceeds that of any rare earthelement (REE).     

Improvement of Solubility and Dissolution of 19-Norprogesterone via Inclusion Complexation

In an effort to modify the solubility and dissolution rate of the contraceptive steroid, 19-norprogesterone in order to improve its bioavailability, the cyclodextrin complexation approach was chosen. In solution, the complex formation with -cyclodextrin (-CD), hydroxyethyl -cyclodextrin (HE--CD) and hydroxypropyl -cyclodextrin (HP--CD) was confirmed by using solubility, UV, IR and ¹H-NMR spectrophotometric techniques. The phase solubility diagrams were categorized as A_L-type. The complexing affinity of the CDs investigated were ranked as follows: -CD > HP--CD > HE--CD. The complexation thermodynamic parameters were obtained from the temperature dependence of the dissociation constants. In the solid state, differential scanning calorimetery (DSC) and optical microscopy methods were utilized to characterize the complexes. Dissolution studies showed that such molecularly encapsulated forms offered a marked improvement in the dissolution rate compared to the parent drug.     

Effect of 2-Hydroxypropyl-β-cyclodextrin on Release Rate of Metoprolol from Ternary Metoprolol/2-hydroxypropyl-β-cyclodextrin/Ethylcellulose Tablets

The effect of 2-hydroxypropyl--cyclodextrin (HP--CyD) on the release of a water-soluble ₁-selective adrenoreceptor antagonist, metoprolol (Met), from ternary Met/HP--CyD/ethylcellulose (EC) tablets was investigated. The release rate of Met from the ternary tablets was dependent on amounts of HP--CyD in the tablets, i.e., the rate decreased when small amounts of HP--CyD were added, while large amounts of HP--CyD accelerated the rate. The slowest rate was observed for the tablet consisted of a 30/10/60 weight ratio of Met/HP--CyD/EC. The analyses of the release rates by the Korsmeyer equation and their temperature dependence suggested that Met is released from the EC matrix containing HP--CyD according to the diffusion-controlled mechanism. The water penetration studies and the micro- and macroscopic observations suggested that the retarding effect of HP--CyD is attributable to a viscous gel formation in small pores on the surface of the tablets, where HP--CyD gels may work as a barrier for the water penetration into the tablets and the release of the drug from the tablets. The in-vitro release property of the ternary tablets was reflected in the in-vivo absorption profile in dogs. The results indicated that a combination of HP--CyD and EC is useful for the release control of water-soluble drugs such as Met.     

4,4′-Dipyridyl complexes of rare-earth thiocyanates

4,4-Dipyridyl complexes of rare-earth thiocyanates of the formulaLn(4-dipy)₂(NCS)₃·5H₂O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 4-dipy = 4,4-dipyridyl) have been synthesized. The IR spectra of these compounds and other physical properties are discussed. The thermal decomposition of some compounds (in the order Gd ÷ Lu) has been investigated.

---

4,4-Dipyridylkomplexe von Seltenerdmetallthiocyanaten

Zusammenfassung Es wurden 4,4-Dipyridylkomplexe des TypesLn(4-dipy)₂(NCS)₃·5H₂O mitLn = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu und Y dargestellt. Die IR-Spektren und andere physikalische Eigenschaften werden diskutiert und die thermische Zersetzung von einigen Verbindungen (in der Reihe Gd ÷ Lu) untersucht.

     

Fraktionierte Kristallisation von Ammonium- und Magnesiumdoppelnitraten der Ceriterden; Bestimmung der Trennfaktoren und Vergleich der Trennwirkung

Summary The Separation Factors for Pr/La, Nd/Pr, and Sm/Nd, characterizing the crystallization of ammonium and magnesium double nitrates under practical conditions, were determined analytically and are discussed. They confirm that La and Pr can be separated better by fractional crystallization of ammonium double nitrates, whereas in the presence of Sm the magnesium double nitrates are preferable.

     

Effect of the Formation of Inclusion Complexes With β-Cyclodextrin on the Photoisomerization and Fluorescence Properties of Aromatic Norbornadiene Derivatives

The valence photoisomerization of four aromatic norbornadiene (NBD)derivatives has been studied in ethanol and in 0.01 M -cyclodextrin(-CD) water–ethanol (v/v, 99/1) solution (WECD). Observedfirst-order rate constants are found to be of the same order of magnitude inethanol and WECD, ranging between 0.1 and 0.28 s^-1, accordingto the compound. These photoisomerization kinetic properties are attributedto the formation of inclusion complexes between NBDs and -CD. Thestoichiometry is 1 : 1, and association constants ranging between 310 and390 M^-1 have been determined fluorimetrically, usingBenesi–Hildebrand plots and a nonlinear regression method. Thestructure of the inclusion complexes is discussed on the basis of AMIsemiempirical dimension calculations and photophysical properties.     

Polymorphism of (+)N-tosyl-L-glutamic acid

It has been shown that polymorphism is the reason for the occurrence of (+)N-tosyl-L-glutamic acid 1 with various melting points. 1 occurs in two crystalline forms: and . Form -1 (prisms) having a melting point of 145–147°C is chemically pure and stable. Form -1, however, is unstable and is formed as a result of the stabilizing effect of an organic solvent not introduced into the structure of the crystal. At about 125°C the forms is transformed to the form. The melting point of the form depends on the amount and type of solvent contained in the crystal, which, during measurement cannot leave the system.     

Triterpene glycosides of Hedera taurica. IV. Structure of hederosides A1, A2, D1, and D2 from the berries of Crimean ivy

New triterpene glycosides have been isolated from the berries of Crimean ivyHedera taurica Carr. (family Araliaceae) — hederoside A₁ (methyl ester of 3-O--D-glucopyranosylhederagenin) and hederoside D₁ 3-O-[O--D-glucopyranosyl]-(12)--D-glucopyranosyl]hederagenin and also the known glycosides 3-O--D-glucopyranosyloleanolic acid and 3-O-[O--D-glucopyranosyl-(12)--L-arabinopyranosyl]hederagenin. The structures of these compounds were established on the basis of the results of chemical methods and¹H and¹³C NMR spectroscopy.M. V. Frunze Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 228–230, March–April, 1990.