Aziridines. 69. Reactions of N-Acylaziridines with Sodium Metal and Sodium Naphthalenide. Elimination of olefines

Reactions of N-acylaziridines 1a – g (N-benzoyl except 1d ) with sodium or naphthalenide N ^.− in THF provide a variety of products that usually arise via the aziridino ketyls 2 . Homolytic ring opening of 2 generates the amidatoalkyl radicals 3 . Only with a very short reaction time were small amounts of benzil or benzoylnaphthalenes obtained indicating a reversible trapping of 2 by dimerization or coupling with N^.−. Homolysis of 2 produced always the more stable 3 apart from reactions of monomethylaziridines 1c , d where the primary radical i-3c , d is kinetically favoured. The amides R¹CONHCHR⁴CHR²R³ ( 9 , isopropylamides i - 9c , d from 1c , d ) were usually the main products. 9 arise from 3 either by H atom abstraction from THF (probably in sodium metal runs) or by reduction of 3 to carbanions 5 that abstract a proton from THF ( N^.− runs). Addition of 5a (R²⁻⁴ = H) to 1a gives finally the ketone 8a . Self reaction of primary radical 3a is dimerization. Self reaction of tertiary or secondary radicals is disproportionation when an allylamide arises. This isomerizes to an enamide unless it is conjugated. R²R³CCHR⁴ and R¹CONH₂ arise (probably) always. The mechanism, possibly a cyclic process of anion 6 , is not clear.     

Polymer composites containing plasma-treated mica. II. Dielectric properties

The complex relative premittivity K^*(ω) of polymer–mica composites has been studied in the frequency range extending from about 10^?2 to 10⁷ Hz. Microwave plasma treatment in ethylene of the mica flakes leads to significant alterations of K^*(ω) for the matrix polymers used—polyethylene, polystyrene, and a mixture of these two polymers. The origins of the dispersion characteristics were investigated using a series of polyethylene samples containing up to 50 wt-% of untreated mica. Comparing experimental results with theoretical analyses of the Maxwell-Wagner-Debye-like interfacial polarization effect, it is possible to identify two major contributions to K^*(ω): a Debye-like dispersion centered near 10² Hz and a charge-diffusion mechanism which contributes primarily at low frequencies (?10 Hz).     

Humid aging of polyetherimide. I. Water sorption characteristics

The sorption and desorption kinetics of water into polyetherimide (ULTEM 1000) were studied at various temperatures ranging from 20 to 100°C. The water equilibrium concentration increases slightly with temperature from 1.39% (by weight) at 20°C to 1.50% at 100°C. The solubility coefficient, S, calculated from these data, and the water vapor pressure decrease with temperature. The calculated heat of dissolution H_s is close to −43 kJ mol⁻¹, which explains the low effect of temperature on the equilibrium concentration. The diffusion coefficient, D, varies from about 1.10⁻¹² m² · s⁻¹ at 20°C to about 16.10⁻¹² m² · s⁻¹ at 100°C. The apparent activation energy of diffusion, E_D, and the heat of dissolution, H_s, of water in the polymer have opposite values (respectively, +43 and −42 kJ · mol⁻¹). From this observation and a comparison of these data with water diffusion characteristics in other glassy polar polymers, it is hypothesized that the transport rate of water is kinetically controlled by the dissociation of water–polymer complexes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1439–1444, 2000     

13C n.m.r. relaxation study of poly(aspartic acid)

¹³C n.m.r. relaxation parameters (T₁, line widths and NOE factors) and chemical shifts were measured in dependence on pH for several samples of poly(α-l-Asp) differing in molecular mass and polydispersity, and for samples of poly(α,β-d,l-Asp) differing in molecular mass. Poly(α-l-Asp) dissolved at pH 9 and acidified to pH 6-4 can appear in two different forms, A and B. In n.m.r. spectra these forms differ mainly by the width of the bands of side chain carbons which is larger in form A. Conditions for a reproducible generation of either of the two forms were not found although the effect of molecular mass (3–6 × 10⁴), polydispersity, sample concentration (2.0-0.2 mol l^?1), temperature of dissolution (4°C–37°C), concentration of NaCl (0–4 mol l^?1) or rate of acidification (1 pH unit s^?1 week^?1) and rate of mixing were investigated. The dynamics of poly(α,β-d,l-Asp) is almost unaffected by change of pH. The relaxation parameters of poly(α-l-Asp) at pH 9 and 4 differ more in form A than in form B. Analysis of relaxation data for the methine carbon of poly(α-l-Asp) in form A by means of the isotropic model with a log x² distribution of correlation times yields a correlation time of 1 ns at pH 4. This indicates that the dynamics of the backbone is dominated by rapid segmental motions even at pH 4. The dependence of chemical shifts on pH indicates that the chemical shift values are determined mainly by the ionization of the carboxyl group in the side chain rather than by a conformational transition. The evaluated relaxation parameters suggest, when compared with those of polypeptides with known conformational behaviour, that the two forms of poly(α-l-Asp) differ in conformation (α-helix, β-structure).     

Land application of poultry litter and water quality in Oklahoma,U.S.A.

With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m² plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha^–1, which amounts to contributions of approximately 410 kg N and 140 kg P ha^–1 yr^–1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L^–1) and tilled treatments (16.7 and 6.1 mg L^–1). However, values for the half-area application (5.6 and 2.0 mg L^–1) were similar to the control (5.7 and 1.3 mg L^–1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L^–1 (no till). In all cases, < 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha^–1) compared to the control (3501 kg ha^–1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.     

Novel block ionomers. III. Mechanical and rheological properties

Select rheological (dynamic viscoelastic) and mechanical properties of novel block cationomers and anionomers and their blends have been investigated. The block ionomers were linear di‐ and triblocks, and symmetric three‐arm stars comprising hydrophobic polyisobutylene (PIB) blocks attached to ionized poly(methacrylic acid) (PMAA^?X⁺, where X⁺ = Na⁺, Zn²⁺) and poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA⁺I^?) blocks. The specific structures investigated were the well‐defined diblocks PIB‐b‐PMAA^? and PIB‐b‐PDMAEMA⁺ and their blends, the triblocks PMAA^?‐b‐PIB‐b‐PMAA^? and PDMAEMA⁺‐b‐PIB‐b‐PDMAEMA⁺ and their blends, and the three‐arm star anionomer Φ(PIB‐b‐PMAA^?)₃. For comparison, the properties of the precursor PIBs and unionized blocks have also been studied. Hydrogen bonding between the carboxyl groups of the PMAA blocks in PIB‐b‐PMAA diblocks leads to inverse micelles. Neutralization of the PMAA by Zn(AcO)₂ and quaternization of the PDMAEMA segments by CH₃I in the triblock copolymers and star copolymers yielded ionic domains, which self‐assemble and produce physical networks held together by coulumbic interaction. The physical/chemical characteristics of the domains control the viscoelastic behavior and mechanical properties of these block ionomers. The mechanical properties of the various block ionomers were significantly enhanced relative to the precursors, and they were thermally stable below the transition temperature. Further, the thermomechanical properties of these novel materials were satisfactory even above 200°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1516–1525, 2003     

Studies concerning the growth of cadmium dendrites. I. Morphology in alkaline media

The morphology of cadmium dendrites formed during potentiostatic electrodeposition onto nickel and cadmium substrates from cadmate solutions in alkaline supporting electrolyte has been investigated. The morphology is potential dependent for deposition under convective diffusion conditions to a nickel substrate. For 1.05×10^?4 mol dm^?3 Cd(OH) ₄ ^2? /30% KOH solutions, 2D- fern dendrites are observed at an overpotential of ?150mV, needle dendrites at ?200 mV, and large ‘filled-in’ fern dendrites at ?300 mV. Similar results were found at the higher concentration, 2.4×10^?4 mol dm^?3 Cd(OH) ₄ ^2? /50% KOH, but the time taken to grow an equivalent morphology and length were reduced in proportion. Crystalline aggregate dendrites were observed on a cadmium substrate in 1.05×10^?4 mol dm^?3 Cd(OH) ₄ ^2? /30% KOH, becoming more crystalline and well defined with increase in overpotential. A significant induction time of the order 8 h was observed for all deposition onto stationary nickel and cadmium wires. Under the well-defined diffusion conditions at a rotating nickel disc electrode only one morphology, namely small ferns, was observed over a wide range of overpotentials. The current-time behaviour is presented, and the current is shown to have a (time)² dependence, indicative of progressive nucleation of dendrites. The induction time, indicated approximately by the current minima, had decreased significantly.     

Studies on Pollutants. VIII. Trace Analysis of Vanadium with N-p-Methoxyphenyl-2-furohydroxamic Acid

Abstract

A highly sensitive, selective, and rapid method for the spectrophotometric determination of trace amounts of vanadium(V) is described. Vanadium(V) is extracted from 4–8 M hydrochloric acid solutions as its violet complex with N-p-methoxyphenyl-2-furohydroxamic acid (MFHA) in chloroform. The extract shows maximum absorbance at 545 run (E = 7.3 × 10³ L.mole^?1 cm^?1) and obeys Beer's law over the range 0–12 ppm of vanadium; Sandell's sensitivity being 0.007 μg/cm². The method has been applied for the analysis of vanadium in pond water, rock phosphates, and steels.     

Radikalreaktionen von N-Heterocyclen. I. Synthese und Struktur eines N,N-verknüpften Bipyrazols

Radical Reactions of N-Heterocyclic Compounds. I. Synthesis and Structure of an N,N-Linked Bipyrazole 5(3)-Amino-3(5)-(phenylamino)-pyrazole-4-carboxylic acid ethyl ester ( 1 ), which is a very good antioxidant, reacts under mild reaction conditions with dibenzoyl peroxide or with tert.-butoxy radicals under formation of a bipyrazole 4 . Evidence of the structure of 4 is given by ¹H-n.m.r., ¹³C-n.m.r., i.r. and u.v. spectroscopic measurements, respectively and especially by ¹⁵N-n.m.r. measurements of ¹⁵N labelled compounds 1 and 4 . The bispyrazole 4 reacts with Pb(IV)-acetate, the product isolated was the 5-amino-e-anilino-1-(1-anilino-2-cyano-2-ethoxycarbonylethenyl-azo)-pyrazole-4-carboxylic acid ethyl ester (7). The formation of this substance is a chemical proof of the structure of 4 .     

Two-dimensional n.m.r. studies of polybutadiene adducts with dihalocarbenes

A variety of two-dimensional (2D) n.m.r. experiments were performed on the adducts of 1,4-polybutadienes (PBD) with difluorocarbene (:CF₂) and fluorochlorocarbene (:CFC1) to assign stereochemical microstructure, carbon types, and syn and anti isomers. A 2D homonuclear ¹⁹F J-correlated (COSY) spectrum of the trans-PBD:CF₂ adducts at complete conversion showed that the geminal fluorines were equivalent in the isotactic and syndiotactic stereochemical triads (AA' singlets), but nonequivalent in the heterotactic triad (AB quartet). The 2D homonuclear ¹⁹F J-resolved experiment confirmed this finding and gave a geminal coupling constant of 160 Hz. Pentad stereosequence fine structure was observed in the 2D spectra but not in the 1D spectra. Editing of carbon types proved difficult by the distortionless enhancement by polarization transfer (d.e.p.t.) pulse sequence (Doddrell, D. M., Pegg, D. T. & Bendall, M. R., J. Magn. Reson., 1982, 48 , 323) for PBD:CFC1 adducts, owing in part to different magnitudes of the ¹J₁₃ scalar coupling constant. A 2D heteronuclear ¹³C-¹H J-resolved experiment was superior and also provided the coupling constants, which ranged from 130 Hz (acyclic methylenes) to 167 Hz (cyclopropyl methines). The identity of syn and anti structures in cis-PBD:CFC1 adducts was rigorously established by a 2D heterocorrelated ¹⁹F-¹H nuclear Overhauser experiment (NOESY). It is noteworthy that the more hindered structure with chlorine syn to the alkyl groups is preferred by 1·65:1. Analysis of a model compound obtained from cis-5-decene gave ³J couplings of 20 and ≤ 3 Hz for the syn and anti compounds, respectively. These couplings were obscured in the 1D polymer spectrum by stereosequence broadening, but their values could be extracted by 2D ¹⁹F-¹H J-resolved spectroscopy.     

Radical polymerization in disperse systems,by J. Bartoň, I. Capek. Ellis Horwood Ltd,Chichester/VEDA,Bratislava, 1994. pp. 352, price £68. ISBN 0-13-752353-X

Radical copolymerization of zinc acrylate (ZnA₂) with acrylonitrile (AN), initiated by As₂S₃–styrene complex(I), in dimethyl Sulphoxide (DMSO) at 90 ± 0.1°C for 1.0h under inert atmosphere, yields non-alternating copolymers. The kinetic expression is R_p ∝ [I]^0.33 [ZnA₂]^0.25 [AN]^0.44, i.e. the system follows non-ideal kinetics, which is due to primary radical termination as well as degradative chain transfer reactions. The values for activation energy (E) and k²_p/k_t are 128kJ mol⁻¹ and 8.57 × 10⁻⁷ litre mol⁻¹ s⁻¹, respectively. Thermal stability, solubility in different solvents, and IR and NMR spectra have been evaluated.     

Vinyloge Acylverbindungen. XXI. 1H-NMR-spektroskopische Untersuchungen an 3-Chlor-propen-iminiumsalzen

Vinylogous Acyl Compounds. XXI. ¹H-N.M.R. Spectroscopic Investigations on 3-Chloropropen-iminium Salts The ¹H-n.m.r. data of a series of 3-aryl-3-chloropropeniminium salts 5 are reported. From the vicinal coupling constants ³J(H¹, ²H) as well as from NOE difference spectra follows that salts of type 5 have throughout E(1,2)Z(2,3) configuration.     

Compositional study of crude oils using fourier transform n.m.r. Characterisation

The Fourier transform (FT) ¹H- and ¹³C-nuclear magnetic resonance (n.m.r.) spectra of three crude oils have been recorded at room temperature on a Jeol pulsed FT-n.m.r. spectrometer. The branchiness index has been calculated from ¹H-n.m.r. spectra and the percentage of aromatic carbons (% CA) from the ¹³C-spectra. The results are discussed and the usefulness of n.m.r. techniques in such studies considered.     

Characterization of pressure-sensitive adhesives. II. Water vapor permeation studies

The permeability of water vapor in a composite film [a Mylar (trademark of DuPont, Inc.) film coated with a pressure sensitive adhesive on both sides] and a Mylar film (type D) have been determined at 23°C. The water vapor permeability in the pressure sensitive adhesive, Flexbond 150 (a trademark of Air Products and Chemicals), and the Mylar film have been found to be 3.23 × 10^?7 and 2.30 × 10^?8 cm³ (STP) cm · cm^?2 · s^?1 · (cm Hg)^?1, respectively, at 23°C.     

Anodic substitutions in emulsions under phase transfer catalysis conditions. I. Cyanation of dimethoxybenzenes

An emulsion electrolysis technique in the two-phase system water-dichloromethane containing NaCN and a phase transfer agent (PTA) has been examined with 1,2- and 1,3-dimethoxybenzenes as a function of various parameters (nature of Q⁺, X^–, anodic potential, cyanide ion concentration in the organic phase, preparative current potential curves). The anodic cyanation results indicate that the anode wetting phenomena, the extraction of cyanide ion and the competitive oxidation of X^– are the determining factors. It is shown that the best criterion for a successful anodic cyanation is to operate under conditions of maximum coverage of the anode by the organic layer. Among all the PTA studied (cetyltrimethylammonium bromide,nBu4N⁺HSO ₄ ^– ,nBuP⁺₃Br^–, benzethonium chloride and A 336), A 336, a very hydrophobic PTA, affords the best chemical (81%) and current (77%) yields with 1,2,-dimethoxybenzene.     

Understanding polymer morphology. Arthur E. Woodward. Carl Hanser Verlag,Munich, 1995. pp. ix + 130, price DM38.00. ISBN 3-446-17431-1

An investigation was undertaken regarding the adsorption of heavy metal ions (CrO^2?₄ or Pb²⁺) and phenol from solution with a highly crosslinked amphoteric starch containing the phosphate anionic group and the tertiary amine cationic group. The adsorption process was found to be dependent on initial pH and concentration for both metal ions, and to be concentration-independent for the phenol organic substance. The adsorption follows the Langmuir adsorption isotherm for CrO^2?₄, and the Freundlich adsorption isotherm for Pb²⁺. The adsorption mechanism confirms that the Na⁺ of the sodium phosphate group and the Cl^? of the tertiary amine group are used to exchange Pb²⁺ and CrO^2?₄ ions, respectively, and the tertiary amine group is used to adsorb phenol.     

Polarization and back em.f. in electrodialysis

Polarization and limiting current in electrodialysis (ED) are mass transfer phenomena usually described in terms of greatly rising electrical resistance of the depleted film. A simple and universally applicable technique has been developed to examine these. In actual operating conditions, direct measurement of the back electromotive force in a spirally wound electrodialysis (SPED) module suggests that the increase in ohmic resistance is minimal; the main mechanism is a large fall in the net e.m.f. From experimental results it is possible to evaluate membrane surface concentrations and hydrodynamic boundary layer thickness directly.List of symbols C concentration (m) - C concentrate/diluate concentration ratio - C ^* surface concentration, (m) - D diffusion coefficient (m² s^–1) - E _b back e.m.f in a cell pair, (V) - F Faraday constant (C mol^–1) - I _lim limiting current density (A m^–2) - n change in charge number in electrode reaction - R gas constant (J K^–1 mol^–1) - t elapsed depolarization time (s) - t elapsed polarization time in Equation 12 (s) - T _s,T _m solution, membrane transport number - T absolute temperature (K) - V applied voltage across module (V) - w quantity of diffusing species (mol m^–2) - x distance from membrane surface (m) - activity coefficient - thickness of the boundary layer (m) - relaxation time (s)     

Anodic substitution in emulsions under phase transfer catalysis conditions. II. Acetoxylation of dimethoxybenzenes

The anodic acetoxylation of 1,2-dimethoxybenzene in H₂O-CH₂Cl₂ emulsions with different phase transfer agents (nBu₄N⁺HSO ₄ ⁻ ,nBuP⁺ φ ₃Br⁻, Aliquat 336, Hyamine 1622 and CTAB) has been investigated. The conversion rates and the electrochemical efficiencies are mainly governed by two parameters: (a) the anode wetting by an organic layer which varies with the nature of the catalyst as shown by the preparative polarization curves; (b) the competitive oxidation of the counter-ions present in the organic phase (CH₂C1₂). The latter point is very important in the case of bromide salts. On the basis of these observations, the use ofnBu{4}N⁺HSO ₄ ⁻ appears to be the best compromise for the case of anodic acetoxylation of aromatic substrates in the media studied.     

Extraction of Europium(III) into W/O Microemulsion Containing Aerosol OT and a Bulky Diamide. I. Cooperative Effect

Abstract

The extraction of Eu(III) from aqueous HNO₃ solution into a water‐in‐oil (W/O) microemulsion occurring in hexane was studied. Aerosol OT (AOT^?) was used as an anionic surfactant, and a bulky diamide (DA), N,N ^′‐dioctyl‐N,N ^′‐dimethyl‐2‐(3^′‐oxapentadecyl)propane‐1,3‐diamide, was employed as an electrically neutral extractant. The combination of AOT^? and the DA shows a very strong cooperative effect on the metal extraction. The microemulsion containing AOT^? alone in hexane, equilibrated with the acidic solution, is unstable. However, in the presence of the electrically neutral extractant acting as a “masking” ligand to H⁺, the microemulsion in the hexane phase is dramatically stabilized, which enhances the distribution of Eu(III) to the organic phase. The distribution of the metal in the micellar extraction system is also greatly affected by the concentration of an electrolyte, such as HNO₃ or NaNO₃, playing two important roles, i.e., the formation of the microemulsion, “promoting” the metal extraction, and the ion‐exchange of the metal ion for the cation yielded from the electrolyte, contrarily, “suppressing” the metal extraction.     

Antiinflammatory polymer-bound steroids for topical applications. I. Synthesis and characterization

Covalent binding of hydrocortisone and dexamethasone to hydrophylic biocompatible macromolecular carriers through hydrolizable carbonate linkage was investigated according to two complementary strategies. (a) Radical copolymerization of hydrocortisone-²¹C-vinylcarbonate with N-vinylpyrrolidone (NVP,60°C), or N-[tris(hydroxymethyl)methyl]acrylamide (THMMA, 50°C) in dimethylacetamide solution: In spite of a nearly zero reactivity ratio for the steroid monomer which behaves as a degradative transfer agent—C_T ～ 5.7 × 10^?2 and 6.8 × 10^?3 for NVP and THMMA, respectively–this process may afford fairly high molecular weight polymers (M?_w ? 10⁴–10⁵) with high enough hydrocortisone content (0.03–0.10 mole.fraction). (b) Condensation of the hydrocortisone or dexamethasone-²¹C-chloroformates onto poly(oxyethylene glycol) (M?_n = 6220) or hydroxypropylcellulose (HPC, M?_w = 1.35 × 10⁵) in tetrahydrofuran solution (30°C): This straightforward process is of low efficiency (yields >50%), and only HPC derivatives show good chemical homogeneity.