Mixture Of Diols Research Articles

Long chain n-alkyl diols, hydroxy ketones and sterols in a marine eustigmatophyte, Nannochloropsis gaditana, and in Brachionus plicatilis feeding on the algae

Base-hydrolyzed sterols and long-chain alcohols of a marine eustigmatophyte, Nannochloropsis gaditana have been studied. Sterol composition of N. gaditana is similar to that of other member of this genus, with predominance of cholest-5-en-3β-ol and 24-ethylcholest-5-en-3β-ol. The C29:2 and C30:1 unsaturated aliphatic alcohols were predominant. Saturated and monounsaturated C28 to C36n-alkyl diols occurred as a mixture of positional isomers with ω16 predominating among the C28 alkyl diols, ω18 among C30, C32, C34 and C36 alkyl diols and ω17 for the odd chain alkyl diols. C28–C32 hydroxy ketones were identified for the first time in a marine organism, with a distribution parallelling the alkyl diol mixtures and suggesting a biosynthetic relation between both alcohol classes. N. gaditana was fed to Brachionus plicatilis and the distribution of alkyl diol positional isomers remained the same in the algae and the rotifer fecal pellets. However, digestion resulted in an increase in C30 diols relative to C32 diols and in an enrichment of unsaturated long-chain alcohols relative to alkyl diols.

Mimicry of peptide backbone geometry and heteroatomic side-chain functionality: synthesis of enantiopure indolizidin-2-one amino acids possessing alcohol, acid, and azide functional groups.

Indolizidinone amino acids possessing various heteroatomic side chains at their 5- and 7-positions have been synthesized through modification of hydroxymethyl indolizidinone amino acids 5 and 6. Displacements of the methanesulfonates from alcohols 5 and 6 with sodium azide, as well as oxidation of alcohol 5, have been used to furnish orthogonally protected indolizidin-2-one diamino carboxylates 7 and 8, and indolizidin-2-one amino dicarboxylate 9. Both 5- and 7-hydroxymethylindolizidinone amino acids 5 and 6 were obtained from sequences commencing with the Claisen condensation of alpha-tert-butyl gamma-methyl l-N-(PhF)-L-glutamate to furnish di-tert-butyl 4-carbomethoxy-5-oxo-2,8-di-[N-(PhF)amino]azelate 10 (PhF = 9-(9-phenylfluorenyl)). Subsequent hydride reduction of 10 to an isomeric mixture of diols 12, selective protection of the primary alcohol as tert-butyldimethylsilyl ether 14 and oxidation of the secondary alcohol gave di-tert-butyl 4-tert-butyldimethylsilyloxymethyl-5-oxo-2,8-di-[N-(PhF)amino]azelate 15 as a separable diastereomeric mixture. Linear ketone 15 and alcohol 14 were then converted to the indolizidinone heterocycles by routes featuring reductive aminations, methanesulfonate displacements, and lactam cyclizations. A series of rigid scaffolds designed to mimic the conformations of dipeptides possessing serine, lysine, and glutamate residues has thus been synthesized by this new route for installing heteroatomic side-chain functional groups onto the indolizidin-2-one system.

Synthesis and Surface Properties of Films Based on Solventless Liquid Fluorinated Oligoester

Two kinds of solventless liquid oligoesters, linear and three-armed, were synthesized by direct esterification of a mixture of diacids and diol or triol. The molecular weights of such oligoesters are in the range 800−1000. Linear oligoesters have a single melting point of between −5 and 0 °C while only one glass transition temperature at about −60 °C was found for three-armed oligoesters. The oligoesters were partially end-capped with a perfluoroalkyl group by reacting with perfluoroalkyl acid chloride. A polymeric film was prepared from the homogeneous mixture of normal and fluorinated oligoesters and a liquid polyisocyanate cross-linker and cured at elevated temperatures. As the fluorine content in the films increases from 0 to about 1.4 wt %, the surface tension of the top surface decreases as much as 20 mN/m, indicating that the top surface is mainly occupied by low surface energy fluorine-containing species. The surface enrichment of fluorine-containing species is confirmed by X-ray photoelectron spe...

Poly(urea-urethane) polymers with multi-functional properties

Polyurea-urethanes with multifunctional properties were synthesized by reacting 4,4′-diphenylmethane disocyanate (MDI) with a two diol mixture of polytetramethylene glycol (PTMG (1000, 2000) and biocidal quaternary ammonium monomer ((N-benzyl-N-dodecyl-N-bis2-hydroxyethyl) ammonium chloride (BDAC)), and extended with N-(2-hydroxyethyl) ethylene diamine (HEDA) to form PU polymers. The PU polymer was then grafted with a disperse dye via a coupling agent of epichlorohydrin to form a dye grafted polyurethane with biocidal and covalent bond dyeing properties. In consideration of the mechanical properties, it is found that both the modulus and the strength of the dye grafted PU polymer films are lower than those of pure PU polymers due to the bulkiness of their dye molecules. For thermal properties, the dye grafted PU polymers exhibit higher Tgh than those without dye molecules. However,neither the Tgs nor the Tms vary in the presence of BDAC or dye molecules, but they are changed with various chain lengths of the soft segment. For dyeing properties, the effective dyeing efficiency of dye grafted PU is over 85%. Moreover, the dye grafted PU polymers exhibit lower dye migration (Mp%) than those of simple mixtures of PU and dyestuff, and they show a higher grade of color fastness when exposed to light. In the shake method of antibacterial testing, the modified PU polymers exhibit a long lasting biocidal activity.

Dielectric relaxation study of diol mixtures

The dielectric relaxation of binary and ternary diol mixtures was studied. Diols of different chain lengths namely ethane-1,2-diol, propane-1,3-diol, butane-1,4-diol and pentane-1,5-diol were used. The relaxation spectra were analyzed in a single Cole–Davidson term. The effective dielectric relaxation time is shown to depend exponentially on the number density of dipoles or molecules. An empirical equation is suggested.

Synthesis of the namenamicin A–C disaccharide: towards the total synthesis of namenamicin

Progress towards the total synthesis of namenamicin (1), the only enediyne antitumor antibiotic of marine origin, is reported. Two methods were investigated for the stereoselective introduction of the highly unusual quaternary C-4 center of the A-ring. Spirocyclic [3,3]-sigmatropic rearrangements of the thiocarbonates 6 and 10 gave products 7 and 11, from processes involving approach of the sulfur atom solely to the α-faces of the substrates. The desired stereochemistry of the quaternary center was ultimately obtained by way of an intramolecular Michael addition of a xanthate anion derived from the α,β-unsaturated methyl ester 18. Further functional group manipulations provided an olefin 25 which underwent dihydroxylation to give a mixture of diastereomeric diols 26, allowing access to both potential diastereomers of the natural product. The A ring intermediate 29 was found to be a viable substrate of glycosidation with a glycosyl fluoride of the C ring aminosugar 30, providing the protected A–C disaccharide subunit of 1.

New deeply coloured and fluorescent polymers with 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole units in the main chain

New deeply coloured and fluorescent copolyesters and -urethanes with 1,4-dioxo-3,6-diphenyl-pyrrolo[3,4-c]pyrrole (DPP) units in the main chain were prepared. The chromophoric units are incorporated in the backbone via their N-alkylated lactam groups. The DPP-containing monomer 1,4-dioxo-2,5-bis(6-hydroxyhexyl)-3,6-diphenylpyrrolo[3,4-c]pyrrol (2) was obtained by N-alkylation of 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (1) with 6-chlorohexanol. Copolyesters were prepared by (a) solution polycondensation of mixtures of 2 and 1,12-dodecanediol with terephthaloyl chloride and (b) melt polycondensation of the diol mixture with dimethyl terephthalate using tetrabutoxytitanium as catalyst. Copolyurethanes were prepared by polyaddition of mixtures of 2 and 1,12-dodecanediol with hexamethylene diisocyanate. The copolyesters are readily soluble in common organic solvents, while the copolyurethanes are only soluble in rather exotic solvents such as p-cresol. Polymer solutions are yellow to orange with optical absorption maximum at 470 nm and fluorescence maximum at 520 nm, the Stokes-shift being about 50 nm. All copolymers are partially crystalline, the crystallinity decreasing with increasing DPP content. Possible origins for the influence of the DPP content on the crystallinity of the polymers are discussed. The thermal stability of the copolyesters is independent of the DPP content, the decomposition temperature being about 646 K. The limit of thermal stability of the copolyurethanes is about 600 K and increases slightly with DPP content.

Oxazaborolidine-catalysed reduction of alk-2-ene-1,4-diones. A convenient access to chiral 1,4-diols

An efficient method for the preparation of C 2-symmetric, chiral alk-2-ene-1,4-diols ( 4) has been achieved, based on the borane-mediated reduction of symmetric alk-2-ene-1,4-diones ( 2) in the presence of oxazaborolidine (R)- 1 . In general, the presence of the double bond in 2 has been beneficial (compared with the related saturated 1,4-diketones 3) not only as far as the stereoselectivity in the reduction step is concerned, but also because it allowed us to remove meso- 4 by chomatography and/or to improve the stereochemical purity of several resulting mixtures of diols 4 by Sharpless' epoxidation. Enantioenriched compounds 4 have been readily reduced to saturated diols with negligible loss of optical purity.

Alternating polyesteramides based on 1,4-butylene terephthalamide: 3. Alternating polyesteramides based on mixtures of linear diols (4NTm,p)

Strictly alternating polyesteramides consisting of 1,4-butylene terephthalamide diester and mixtures of aliphatic diols have been synthesised in the melt in the presence of a titanium catalyst. To increase the molecular weight a solid state post condensation was applied. The composition was determined with 1H NMR. The thermal properties were analysed with differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). With the mixture of diols the structural regularity of the diester part in polymers was disturbed. Although this disturbance caused the polymers to be fast crystallising ( ΔT < 32°), highly crystalline polymers. It was found that the melting temperature decreased linearly with increasing length of the diols in the mixture. The melting temperatures with the mixtures of diols were lower than with a single diol. The reason for this is probably thinner lamella. Mechanical tests on the melt processed polyesteramides showed high glass transition temperatures and a high modulus above the glass transition temperature. These polyesteramides have a T g T m ratio of 0.70–0.72. This high ratio is probably due to the relatively low melting temperatures. The water absorption, is close to the values for polyesters (1.3–1.7 wt%). Disturbing the alternating structure of the polyesteramide by esteramide interchange reactions resulted in a loss of the thermal and mechanical properties.

Total synthesis of (±)-9-deoxygoniopypyrone. Application of the iodocyclofunctionalization reaction of bold α-allenic alcohol derivatives

The synthesis of ( ±)-9-deoxygoniopypyrone (1) from the α-allenic alcohol 5 is described. Iodocyclofunctionaliztion of the N-tosyl carbamate derivative of 5 using I2and Ag2CO3provided, in a highly diastereoselective and regioselective fashion, the vinyl iodo syn-vicinal diol 4. Two routes were explored in order to introduce the third stereogenic centre in the molecule. Reductive deiodination of the vinyl iodide and diastereoselective epoxidation of the derived acetonide14 using mCPBA provided a mixture of epoxides 15 and 16 (2:1) in which the desired threo diastereomer predominated. Alternatively, dihydroxylation of acetonide 14 (OsO4, NMO) yielded a mixture of diols 21 and 22 (2:3) which were separated after monosilylation (TBDMSCl) of the primary alcohol. The major silyl ether erythro diastereomer 24 was converted to the desired epoxide 15 by mesylation (MsCl, Et3N) and epoxide formation (TBAF) with inversion of stereochemistry. The minor threo diastereomer 23 was also converted to the desired epoxide 15 (TBAF; ArSO2Cl; NaOMe). Epoxide opening was effected with lithium acetylide and the resulting alkyne 27 was carbonylated (MeLi, ClCO2Me) to afford the α , β-acetylenic ester 28. Semi hydrogenation over Lindlar's catalyst followed by protecting- group removal under acidic conditions provided ( ±)-8-epigoniodiol 30. Finally, conversion of 30 to ( ±)-9-deoxygoniopypyrone 1 was effected under basic conditions (DBU).Key words: ( ±)-9-deoxygoniopypyrone, α-allenic alcohol, iodocyclofunctionalization, syn-diol.

Electrosyntheses from aromatic aldehydes in a flow cell. Part II. The cross-coupling of benzaldehydes to unsymmetrical diols.

It is demonstrated that the reduction of mixtures of two benzaldehydes in acidic water-methanol in a membrane flow cell with a lead cathode can lead to a mixture of diols including the unsymmetrical diol, e.g. 4-F-C6H4-CH(OH)-CH(OH)-C6H5. In the conditions employed, the ratio of the three diol products follows the statistical distribution expected for the coupling of two different radical intermediates produced in the same ratio as the concentrations of their precursors. The yield and current efficiency for the diols are excellent when the pH and potential are selected so that a le- reduction of both benzaldehydes occurs. The yield of unsymmetrical dimer based on one reactant can be increased substantially by using the other carbonyl compound as a sacrificial reagent.

New Polymer Syntheses. 89. Thermosetting Cholesteric Oligoesters Having Propargyl Endgroups

Three series of cholesteric oligoesters containing propargyl endgroups were prepared by polycondensations of three different dicarboxylic acid dichlorides with mixtures of diols and monofunctional propargyl derivatives in pyridine. These three series are based on terephthaloylchloride, naphthalene-2,6-dicarbonylchloride, and biphenyl-4,4′-dicarbonylchloride. tert-Butylhydroquinone, phenylhydroquinone, and isosorbide were the diols, and propargyl alcohol, 4-propargylthiophenol, and 6-propargyloxynaphthaloyl chloride served as chain stoppers. All isolated oligoesters were thermotropic, but only a few of them were capable of forming a Grandjean texture upon shearing of the cholesteric melt. The thermal crosslinking of the propargyl endgroups was monitored by an exothermic process in the DSC measurements. The lowest cure temperatures (200–240°C) were observed for the 6-propargyloxy-2-naphthoic acid endgroups. Thermal crosslinking in the cholesteric phase was observed for four samples.

Novel reaction of aminopyridines with glyoxal and formaldehyde; synthesis of 4,8-di (N-aminopyridyl) 2,6-dioxa 4,8-diazabicyclo[3.3.0]octane, 6,8-di(N-aminopyridyl) 2,4-dioxa 6,8-diazabicyclo[3.3.0]octane and X-ray structural study of related 1,3-di(N-aminopyridyl) 4,5-dihydroxy imidazolidine

Condensation of 2-aminopyridine with glyoxal proceeds with high selectivity to a mixture of meso and dl diol 7 to be easily transformed into the corresponding bicyclooctane 2a and 3a with formaldehyde and acetonitrile as solvent. In water, however, the reaction selectively produces imidazolidine 4a. Based on NMR analysis, the major diastereomers were assigned as syn derivatives. X-ray crystal structure of 4a shows a planar configuration for imidazolidine ring, in line with two anomeric effects, first a strong n N → σ C-O ∗ interaction and second a weak n O → σ C-N ∗ one. A network of hydrogen bonding between pyridyl nitrogens and hydroxy hydrogens forms a pattern of twelve atom in a chair-like conformation.

Dielectric properties of some ternary mixtures of normal alcohols and aliphatic diols with heptane

The static permittivity has been investigated for the ternary mixtures of 1,6-hexanediol/n-dodecanol/heptane, 1,2-ethanediol/n-dodecanol/heptane, and 1,6-hexanediol/n-hexanol/heptane. In addition, the static properties of pure n-hexanol and binary solutions of n-hexanol, cyclohexanol and n-heptanol in n-heptane have been studied together with the binary mixture hexanediol/hexanol. The results are discussed. Broadband dielectric relaxation spectra (at 20 to 40 °C) are reported for the three ternary systems. The concentration of the polar substances ranges from alcohol mole fraction x = 0.1 to 1. The dependence of relaxation parameters on concentration and temperature of the ternary mixtures is discussed.

Synthesis of diastereomeric mixtures of 5'-C-hydroxymethylthymidine and introduction of a novel class of C-hydroxymethyl functionalised oligodeoxynucleotides.

Novel 5'-C-hydroxymethyl substituted derivatives of thymidine have been prepared by dihydroxylation of the 5'C-methylene nucleoside 1. Osmium tetraoxide catalysed dihydroxylation of 1 afforded a 3:2 epimeric mixture of diols 2, whereas asymmetric dihydroxylation using AD-mix-alpha and AD-mix-beta resulted in mixtures 3 and 4 of the two epimeric diols, both enriched with the same diastereomer. Nucleosides 2 were transformed into phosphoramidites 8 which were used for solid phase synthesis of oligodeoxynucleotides (ODNs) containing 5'-C-(hydroxymethyl) functionalised thymidine monomers. This novel class of C-hydroxymethyl modified ODN-analogues exhibited promising affinity towards both complementary DNA and RNA as well as resistance towards 3'-exonucleolytic degradation.

Effects of NCO/OH Molar Ratio on the Concentration of Allophanate Linkages in Linear Polyurethane Formation

The reaction of bis (4-isocyanatophenyl) methane (MDI) with a diol mixture of α, ω - dihydroxypoly (ethylene adipate) (E, Mn=2000) and ethylene glycol (EG) (molar ratio=1 2) were studied to determine the effects of the NCO/OH molar ratio of polyurethane formation in N, N-dimethylformamide (DMF) on the concentrations of allophanate linkages and viscosity retention of an essentially linear polyurethane solution used industrially for coatings. Even slight increase in NCO/OH molar ratio increased the concentration of allophanate linkages in polyurethanes. Viscosity retention of polyurethane solution following a stability test decreased with increase in the concentrations of allophanate linkages in polyurethanes. Polyurethanes containing less than 5 × 10-3 mmol· g-1 allophanate linkages were shown to exhibit more than 90 % viscosity retention after a stability test at 70°C for 30 h which was required to the polyu rethane solution used for coatings.

Synthesis and properties of homo and copolycyanurates

Three homopolycyanurates were synthesized by stirred interfacial polycondensation of 2-morpholino-4,6-dichloro-s-triazine with each of three aromatic diols viz. bisphenol-A (BPA), bisphenol-C (BPC) and bisphenol-S (BPS). Three copolycyanurates were synthesized using each of the following mixtures of diols: (BPA + PBC), (BPC + BPS) and (BPA + BPS). Polymer yields were in the range 65–83%; products were characterized by density, viscosity measurements, i.r. spectra, solubility tests and thermogravimetric analysis. The polymers had reduced viscosities in the range 0.45–0.84 dl/g in chloroform at 30°. All the polymers were amorphous and soluble in chlorinated solvents. Homopolycyanurate derived from BPC and copolycyanurate derived from BPA and BPC showed greater thermal stability than the others.

Miscible blends of polycarbonate with polyurethane elastomers

AbstractPolyurethane elastomers based on aliphatic polycarbonate diols and/or polypropylene glycols form miscible blends with polycarbonate, thus potentially improving its resistance to microcrack initiation and growth. Up to 20 wt.‐% of synthesized polyurethane elastomers were dissolved in polycarbonate via solution casting or melt mixing. Some phase separation was detected in films cast from solutions with 10 to 20 wt.‐% of polyurethane elastomers; such blends usually turned into single‐phase systems by subsequent thermal annealing. Among the tested polyurethane elastomers, the products based on toulene diisocyanate and mixtures of polycarbonate diols with polypropylene glycols were found to be effective modifiers for polycarbonate; therefore, they were also used in the blends prepared by melt mixing and processed by injection moulding.

Ｎ，Ｎ−ジメチルホルムアミド溶媒中でのポリウレタン合成におけるアリファナート結合生成反応抑制剤の影響

I n order to retard formation of allophanate linkages in the reaction of phenyl isocyanate with N-phenylurethane in N, N-dimethylformamide (DMF) in the presence of various inhibitors, phosphoric acid was selcted as most effective inhibitor. The reaction of bis(4-isocyanatophenyl)methane (BIM) with a diol mixture of poly(ethylene adipate) (Mn=2000) and ethylene glycol (molar ratio=1: 2; NCO/OH molar ratio=1.00) in DMF was studied to clarify the effects of addition of phosphoric acid on the concentration of allophanate linkages in resulting polyurethanes. Increase in the content of phosphoric acid results in decrease in the concentration of allophanate linkages. The addition of phosphoric acid more than 60 ppm was found to retard formation of allophanate linkages below 3 x 10-3 mmol The viscosity retention after stability test decreased with increasing the concentration of allophanate linkages in the polyurethanes.

ポリウレタン合成における反応温度のアロファナート結合含量に対する影響

In the reaction of bis(4-isocyanatophenyl)methane (BIM) with a diol mixture of poly(ethylene adipate) (Mn=2000) and ethylene glycol (molar ratio=1: 2; NCO/OH molar ratio=1.00)in bulk and in N, N-dimethylformamide (DMF), the effects of reaction temperature on the concentration of allophanate linkages in resulting polyurethanes were studied. When the reaction temperature of polyurethane formation in bulk was higher than 120 °C, increase in the reaction temperature results in decrease in the concentration of allophanate linkages. This phenomenon was explained by that the degradation of allophanate linkages was predominantly proceeded rather than their formation when the reaction temperature is higher. On the other hand, when the reaction temperature of polyurethane formation in DMF was higher than 100 °C, the polyurethane with high molecular weight was not formed because the reaction of BIM with DMF results in the deviation of NCO/OH molar ratio from 1.00. Therefore increase in the reaction temperature of polyurethane formation in DMF was inapplicable to decrease in the concentration of allophanate linkages.