Synthesis of polymers by using divalent metal salts of mono(hydroxyethyl) phthalate: Metal-containing polyurethanes

As difunctional compounds containing an ionic bond in the molecule, divalent metal salts (I) of mono(hydroxyethyl) phthalate were prepared in high purity and high yield. Mg and Ca were selected as divalent metal. Metal-containing polyurethanes containing ionic links in the main chain were synthesized by the polyaddition reaction of I or, I–glycols with diisocyanates. The polyurethane obtained were glassy materials or white powders, depending on the species of diisocyanates and glycols. Close agreement between observed and calculated values of metal content of the polyurethanes were obtained. The viscosities (in dimethyl-formamide) of the polyurethanes decreased markedly with increasing of metal content. Moreover, the decomposition temperatures were lowered by introduction of metals into the polyurethanes. However, the decomposition rates of metal-containing polyurethanes were lower than those of polyurethanes not containing metal.     

Synthesis of polymers by using divalent metal salts of mono(hydroxyethyl) phthalate: Metal-containing polyurethane-ureas

A series of metal-containing polyurethane-ureas containing ionic links in the main chain was synthesized by the polyaddition reaction of hexamethylene diisocyanate with mixtures of metal salts of mono(hydroxyethyl) phthalate and bisureas containing two hydroxyl groups which were obtained from monoethanolamine and diisocyanates. The polyurethane-ureas obtained were generally yellowish powders or solids. Close agreement between observed and calculated values of metal content of the metal-containing polyurethane-ureas was obtained. The viscosities (in dimethylformamide) of polyurethane-ureas decreased markedly with increase of metal content. Moreover, the decomposition temperatures were lowered a little by introducing metals into the polyurethane-ureas. Dimethylformamide, m-cresol, and dimethyl sulfoxide were comparatively good solvents for the metal-containing polyurethane-ureas; however, the polymers were insoluble in all other solvents.     

Optically active poly(hydroxyurethane)s derived from cyclic carbonate and L-lysine derivatives

The polyaddition of L -lysine hydrochloride and bifunctional five-membered cyclic carbonate 1 was carried out in DMAc in the presence of 1 equiv of DBU or 2 equiv of sodium hydride for 24 h to afford optically active polyurethane 2 bearing hydroxy and carboxyl group. The polyaddition of L -lysinol and 1 was also carried out in NMP to afford higher molecular weight of optically active polyurethane 3 bearing hydroxy group in quantitative yield. These polyurethanes reacted with cupric acetate, sodium tetrahydroborate, and titanium tetraisopropoxide to afford the corresponding crosslinked gels immediately. © 1996 John Wiley & Sons, Inc.     

Optically active tricarbonyl(cyclohexadienyl)iron(1+) salts: Synthetic equivalents to spatially directed organic cations

Optically active tricarbonyl (cyclohexdienyl)iron(1+) salts I, II and III are examples of olefin complexes with moleoular asymmetry due to coordination uith a transition metal. Their reactions serve to direct the eventual specific formation of a new chiral centre of known absolute configuration. The absolute configuration of the 2-methoxy-5-methyl salt I is defined its application to the asymmetric synthesis of λ-disubstituted cyclohexenones is described.     

Optically active Phosphine oxides : Synthesis and absolute configuration of (menthoxycarbonylmethyl) phenylvinyl phosphine oxide

The enantiomeric(-)(menthoxycarbonlymethyl)phenylvinylphosphine oxide 1b has been prepared and its absolute configuration rigorously established via chemical correlation. One-step decarbalkoxylation of (-)-ethyl(methoxycarbonylmethyl)phenyphosphine oxide 6 was effected with LiCl-H₂O-DMSO and shown to proceed without concomitant racemization at phosphorus.     

Determination of potassium and sodium in mixtures of their salts by means of cation exchangers

Methods for the determination of two substances in aqueous solutions (or water-soluble mixtures) are described. A sample of the solution is dried and the residue accurately weighed. Another sample of the same volume is passed through a cation exchanger (when cations are to be determined), saturated with one of the ions in the solution. After washing with distilled water the combined effluent and wash-water are dried and the residue carefully weighed. From these weighings the composition of the solution is determined by simple calculations, the maximum relative error being < 2.0%. The method may be used for the determination of anions, if an anion exchanger is used instead of the cation exchanger.A variation of the method consists in passing the solution through a cation exchanger in the hydrogen form. The number of equivalents is determined by standard alkali titration and from this and the weight before the ion-exchange passage the composition of the solution can be determined. In this case, however, the maximum relative error is larger. This method is directly applicable to the determination of anions.     

Optically active coordination compounds---XLVIII. Synthesis, resolution and interconversions of isomers of tris-salicylatocobaltate(III)

Stable aqueous solutions of the green ion [Co(sa1)₃]³⁻ (sa1 = dianion, C₆H₄( )(CO ), of salicylic acid, 2-hydroxybenzoic acid) are obtained from [Co(NH₃)₅ C1]C1₂ and an excess of salicylic acid. Several salts, [C][Co(sa1)₃] have been characterized, where C = [Co(NH₃)₆]³⁺ and [M(en)₃]³⁺ (M = Co or Rh, EN = 1,2-diamino-ethane). By using (+)-[Rh(en)₃]³⁺, optical resolution via less soluble diastereoisomeric salts has been achieved, and isomerization and racemization have been studied. Resolved tris-malonatocobaltate(III) has been used as a model. A novel thermochromism (77-293 K) in solid Δ(+)-[Rhen₃]Λ[Co(sa1)₃ is described.     

Tetracyanomanganate(II) and its salts of divalent first-row transition metal ions

The first known paramagnetic, tetrahedral cyanide complex, [Mn(II)(CN)(4)](2)(-), is formed by the photoinduced decomposition of [Mn(IV)(CN)(6)](2)(-) in nonaqueous solutions or by thermal decomposition in the solid state. In acetonitrile or dichloromethane, photoexcitation into the ligand-to-metal charge transfer band (lambda(max) = 25 700 cm(-1), epsilon = 3700 cm(-1) M(-1)) causes the homolytic cleavage of cyanide radicals and reduction of Mn(IV). Free cyanide in dichloromethane leads to the isolation of polycyanide oligomers such as [C(12)N(12)](2)(-) and [C(4)N(4)](-), which was crystallographically characterized as the PPN(+) salt C(40)H(30)N(5)P(2): monoclinic space group = I2/a, a = 18.6314(2) A, b = 9.1926(1) A, c = 20.8006(1), beta =106.176(2) degrees, Z = 4]. In the solid state Mn(IV)-CN bond homolysis is thermally activated above 122 degrees C, according to differential scanning calorimetry measurements, leading to the reductive elimination of cyanogen. The [Mn(II)(CN)(4)](2-) ion has a dynamic solution behavior, as evidenced by its concentration-dependent electronic and electron paramagnetic spectra, that can be attributed to aggregation of the coordinatively and electronically unsaturated (four-coordinate, 13-electron) metal center. Due to dynamics and lability of [Mn(II)(CN)(4)](2-) in solution, its reaction with divalent first-row transition metal cations leads to the formation of lattice compounds with both tetrahedral and square planar local coordination geometries of the metal ions and multiple structural and cyano-linkage isomers. alpha-Mn(II)[Mn(II)(CN)(4)] has an interpenetrating sphalerite- or diamond-like network structure with a unit cell parameter of a = 6.123 A (P43m space group) while a beta-phase of this material has a noninterpenetrating disordered lattice containing tetrahedral [Mn(II)(CN)(4)](2-). Linkage isomerization or cyanide abstraction during formation results in alpha-Mn(II)[Co(II)(CN)(4)] and Mn(II)[Ni(II)(CN)(4)] lattice compounds, both containing square planar tetracyanometalate centers. alpha-Mn(II)[Co(II)(CN)(4)] is irreversibly transformed to its beta-phase in the solid state by heating to 135 degrees C, which causes a geometric isomerization of [Co(II)(CN)(4)](2)(-) from square planar (nu(CN) = 2114 cm(-1), S = (1)/(2)) to tetrahedral (nu(CN) = 2158 cm(-1), S = (3)/(2)) as evidenced by infrared and magnetic susceptibility measurements. Mn(II)[Ni(II)(CN)(4)] is the only phase formed with Ni(II) due to the high thermodynamic stability of square planar [Ni(II)(CN)(4)](2)(-).     

Synthesis of thymidine 5′-(β-l-mannopyranosyl) and (4,6-dideoxy-l-lyxo-hexopyranosyl) pyrophosphates

Conclusions We have prepared thymidine 5-(-L-mannopyranosyl pyrophosphate), thymidine 5-(4,6-dideoxy--L-lyxohexopyranosyl pyrophosphate), and thymidine 5-(4,6-dideoxy--L-lyxo-hexopyranosyl pyrophosphate), all analogs of thymidine 5-(-L-rhamnopyranosyl pyrophosphate), which is involved in the biosynthesis of the O-specific chains ofSalmonella lipopolysaccharides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2588–2591, November, 1976.     

Synthesis of polyesters by using divalent metal salts of monohydroxyethyl phthalate: Metal-containing polyesters from such metal salts,anhydride, and epoxide

Synthesis of metal-containing polyesters by reactions of the divalent metal salts of monohydroxyethyl phthalate with phthalic anhydride and epoxide were investigated. It was found that the metal carboxylate groups of these metal salts catalyze the above reactions. These reactions were further studied in model reactions with the use of the Ca salt of monoethyl phthalate. Products obtained were linear metal-containing polyesters containing ionic links in the main chain; they were yellow or slightly yellow glassy materials; yields were generally high. Molecular weights obtained by the end-group analyses were generally low; with increase in content of the metal salts in the feed the molecular weight of the polyesters decreased. Inherent viscosities (in DMF at 30°C) of the metal-containing polyesters were low, ranging from 0.033 to 0.052. Elemental analyses are generally in good agreement with the calculated values. Thermogravimetric analyses of the polyesters were also discussed.     

Synthesis of polymers by use of divalent metal salts of monohydroxyethyl phthalate: Metal-containing isocyanurate-type crosslinked polyurethanes

Divalent metal salts (I) of monohydroxyethyl phthalate have catalytic activity for polymerization of isocyanate groups. The synthesis of novel metal-containing isocyanurate-type crosslinked polyurethanes were investigated by the crosslinking reaction of I in DMF with diisocyanates or urethane prepolymers, that is, diisocyanate adducts of polyethylene glycol. 2,4-Toluene diisocyanate and diphenylmethane diisocyanate were used as diisocyanates, and DMF was the solvent. The crosslinking reactions were followed by determining the gelation time. Gelation time decreased with increasing temperature. The Ca salt was more effective than the Mg salt in the crosslinking reaction. The yields of resulting metal-containing three-dimensional polymers decreased with increasing metal content in the feed. The Ca salt was more easily introduced into the network polymers than the Mg salt was. Decomposition temperatures decreased on introducing metals into the network polymers. Some physical properties of the metal-containing network polymers are also discussed.     

Synthesis and structures of non-cyclic and cyclic mono- and bisphosphonium salts derived from 1,8-bis(diphenylphosphino)naphthalene

A monoalkylated 1,8-bis(diphenylphosphino)naphthalene (dppn) was prepared by treating diphosphine with 1,8-bis(bromomethyl)naphthalene. Unprecedented cyclizations of monophosphonium salts in polar solvents, such as DMF or acetonitrile were elucidated. The mechanistic pathway of the cyclization reaction was postulated and X-ray crystal structure analyses of the resulting 2,2-diphenyl-2,3-dihydro-1H-2-phosphoniaphenalene bromide was performed. 1,8-Bis(diphenylphosphino)naphthalene and α,α′-dibromo-o-xylene afforded—despite unfavorable steric strain—the first dialkylation product of 1,8-bis(phosphino)naphthalene, namely corresponding cyclic bisphosphonium salt. The use of acetonitrile as the solvent was the key for this synthesis. The bromide anions were exchanged in metathesis reaction with hexafluorophosphate anions and the new compound was fully characterized including single crystal X-ray diffraction. The large distance between phosphorus atoms of 3.974 ? clearly demonstrate a strong proximity effect in this hindered bisphosphonium salt.     

Synthesis of pyrylium salts and pyridine bases by the bisacylation of cyclic tertiary alcohols

The catalytic acylation of 1-methyl- and 1-ethylcyclopentan-1-ols, 1-methyl- and 1-ethylcyclohexan-1-ols, 1-methylcycloheptan-1-ol, and 1-methyl- and 1-ethyl-1-tetralols with carboxylic acid anhydrides in the presence of 70% HClO₄ has been studied. A method for the synthesis of substituted 3,4-cycloalkeno-3,4-dihydro(3,42, 1)naphthopyrylium salts and the corresponding pyridine bases has been developed.     

Synthesis of beta-hydroxy-beta-(fluoronitrophenyl)alanines: vital components in the assembly of biologically active cyclic peptides

[formula: see text] Numerous biologically active cyclic peptides, such as the antibiotic vancomycin, contain amino acid residues connected through side-chain biaryl or aryl-alkyl ether linkages. Nucleophilic aromatic substitution reactions have recently been shown to provide a general method for the formation of such ether linkages, and consequently the synthesis of functionalized fluoronitro-substituted aromatic amino acids is of great interest. Herein, a method for the stereospecific synthesis of 3-fluoro-4-nitro- and 4-fluoro-3-nitro-threo-beta-hydroxyphenylalanine is described.     

Synthesis of heterocycles by means of pyridinium halides (review)

Cyclization processes that take place in the presence of pyridinium halides and lead to the formation of oxygen-containing and sulfur-containing heterocycles, as well as to benzoxazoles and benzothiazoles, are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 579–594, May, 1977.     

聚乙二醇(PEG)桥连的新型双N-杂环卡宾-膦的合成及其在水相Suzuki反应中的应用

通过乙酸1-(2-二苯膦基二茂铁基)乙基酯与PEG-400衍生的双咪唑化合物反应,制得新型PEG桥连的双咪唑盐-膦配体,其结构经1HNMR,<31>PNMR和MS鉴定.初步催化研究表明,该PEG桥连的双咪唑盐一膦可作为支持配体在有机和水相中高产率地实现Pd催化的溴代芳烃和苯硼酸的Suzuki偶联反应.     

Preparation and characterization of monovalent cation selective sulfonated poly(ether ether ketone) and poly(ether sulfone) composite membranes

Highly charged cation permeable composite membranes were prepared by blending of sulfonated poly(ether sulfone) (SPES) with sulfonated poly(ether ether ketone) (SPEEK) in 0 to 90% weight ratio, to adjust the hydrophobic properties and ion selective nature. Extent of sulfonation was confirmed by 1H NMR and ion exchange capacity and degree of sulfonation depending on blending composition. These membranes were characterized as a function of weight fraction of SPEEK by recording ion-exchange capacity, water uptake, thermogravimetric analysis, membrane conductivity and membrane potential in equilibration with different electrolytic solutions. Membrane permselectivity and solute flux were estimated using these data on the basis of non-equilibrium thermodynamic principles and for observing the selectivity of different membranes for mono- or bivalent counter-ions. It was observed that relative selectivity for monovalent in comparison to bivalent counter-ions were increased with the decrease in SPEEK content in the composite membrane matrix. The range of SPEEK content in the blend from 60 to 80% appears the most suitable for the selective separation of monovalent ions from bivalent ions. Furthermore, highly charged nature and stabilities of these membranes extend their applications for the electro-assisted separations of similarly charged ions as well as other electro-membrane processes.     

Ion pairing in fast-exchange host-guest systems: concentration dependence of apparent association constants for complexes of neutral hosts and divalent guest salts with monovalent counterions

An equilibrium treatment of complexation of neutral hosts with dicationic guests having univalent counterions includes two possible modes: (1) dissociation of the ion pair prior to interaction of the free dication with the host to produce a complex that is not ion paired and (2) direct complexation of the ion pair to produce an ion paired complex. This treatment is easily modified for complexation of neutral guests by dianionic hosts, or divalent hosts by neutral guests. The treatment was tested by a study of fast-exchange host-guest systems based on paraquats or viologens (G(2+)2X(-)) and crown ethers (H). The bis(hexafluorophosphate) salts of viologens are predominantly ion paired in acetone; the value of the dissociation constant of paraquat bis(hexafluorophosphate) was determined to be 4.64 (+/- 1.86) x 10(-4) M(2). The complex based on dibenzo-24-crown-8 and paraquat bis(hexafluorophosphate) is not ion paired in solution, resulting in concentration dependence of the apparent association constant K(a,exp), (= [complex]/[H][G(2+)2X(-)]) which is well fit by the treatment, according to mode (1), yielding K(ap) = 106 (+/-42) M(-1). However, the four complexes of two different bis(m-phenylene)-32-crown-10 derivatives and bis(p-phenylene)-34-crown-10 with paraquat derivatives are all ion paired in solution and therefore K(a,exp) is not concentration dependent for these systems, mode (2). X-ray crystal structures support these solution-based assessments in that there is clearly ion pairing of the cationic guest with its PF(6)(-) counterions in the solid states of the latter four examples in which access of the counterions to the guests is granted by the relatively large cavities of the hosts and dispositions of the guest species within them.