Synthese und massenspektrometrische Untersuchungen von Phenyl-pyridyl-ketonen

Various mono-, di- and trichloro derivatives of phenyl-(3-and 4-pyridyl) ketones were synthesized for comparisons with the herbicide 2,5-dichlorophenyl-(4-pyridyl) ketone (A) as well as for MS studies. Derivatives and analogues ofA were also prepared.     

Generation of Phosphide Anions from Phosphorus Red and Phosphine in Strongly Basic Systems to Form Organylphosphines and -Oxides

Abstract

Generation of phosphide anions from phosphorus red or phosphine under the action of strong bases followed by their reactions with organyl halides, electrophilic alkenes and alkynes proves to be the most straightforward and well-controlled route to mono-, di- or triorganylphosphines or phosphine oxides of diverse structure.     

Cyanocalix[4]arenes: synthesis,crystal structures and reactivity studies

Abstract

Herein, we describe an improved method to synthesise mono-, di- and tetra-cyanocalix[4]arene and report their crystal structure determinations. We also report our attempts to further functionalise the cyanocalix[4]arenes into dithiadiazolyl-calix[4]arenes, and propose a hypothesis as to why the cyano group on a calix[4]arene is an extremely challenging group to modify.     

Synthesis and Cationic Photopolymerization of Novel Cycloaliphatic Epoxy Monomers Based on 5,6-Epoxy-1,3-oxepane

Abstract

A novel series of mono-, di-, and trifunctional monomers containing 5,6-epoxy-1,3-dioxepane groups were prepared along with a similar series of epoxycyclohexane monomers. The reactivities of the monomers were compared using both differential scanning photocalorimetry and Fourier transform real-time infrared spectroscopy. The novel monomers containing 5,6-epoxy-1,3-dioxepane groups were highly reactive in photoinitiated cationic polymerization but slightly less reactive than their counterparts based on epoxycyclohexane.     

Schiff bases formed between pyridoxal 5′-phosphate and Amino-β-cyclodextrins: Intramolecular remote ion pair interactions of the phosphate with ammonium moieties

Abstract

Equilibria involved in the Schiff base formations of pyridoxal 5′-phosphate (PLP) and 5′-deoxypyridoxal with mono-, di-, and peraminocyclodextrins have been studied to determine equilibrium binding constants in aqueous media at several pH values. These results, as well as the circular dichroism study, show that remote electrostatic interactions between the negatively charged 5′-phosphate group and a second ammonium group on the cyclodextrins play a significant role in the complexation.     

The Effect of Glyceride Composition on the Mechanical Properties of Alkyd Resin Films

Abstract

The dynamic mechanical properties of dried films prepared from alkyd resins made by the reaction of phthalic anhydride with synthetic mixtures of the mono-, di-, and trilinoleates of glycerol of the same overall composition are reported. The properties of the films dried at room temperature correlate with the microgel content of the resins, which is a function of the monoglyceride content of the original reaction mixture. Films dried at 120°C show smaller differences in mechanical properties.     

Structural Elucidation by Fast Atom Bombardment Mass Spectrometry of Multisulfated Oligosaccharides Isolated from Human Respiratory Mucous Glycoproteins

Abstract

Underivatized mono- and multisulfated oligosaccharides obtained by the alkalineborohydride treatment of human respiratory mucous glycoproteins were analyzed by positive ion fast atom bombardment mass spectrometry (FAB MS). Employing three unique and structurally homologous groups, the FAB mass spectra of a mono- and a disulfated tri- and tetrasaccharide and a mono-, di- and trisulfated branched hexasaccharide were compared. Each produced mass spectra displaying molecular weight-related and structurally significant fragment ions including fragments differing in mass by multiples of 102 amu reflecting the loss of one or more sulfate esters. From these data, combined with monosaccharide composition, the carbohydrate sequence and number and location of sulfate esters can readily be determined. These findings, with other chemical and enzymatic analyses, make FAB MS a valuable tool applicable to the unambiguous structural elucidation of underivatized reduced, linear and branched, mucous glycoprotein oligosaccharides that vary in degree of sulfation.     

Structure-Property Correlations: XV. Properties of Phenol Derivatives

Previously proposed structure-property correlation was used to estimate the properties of methyl- and chlorophenols. The calculated boiling points, octanol-water partition coefficients (logP), energies of the lowest unoccupied molecular orbital (ELUMO), and toxicities [log(1/C _{5 0})] of mono-, di-, tri-, tetra-, and pentachlorophenols, as well as boiling points of mono-, di-, tri-, tetra-, and pentamethylphenols, agree well with the experimental data.     

Uses of Chloromethyldimethylsilyl Ethers as Derivatives for Combined Gas Chromatography-Mass Spectrometry of Steroids

Abstract

Chloromethyldimethylsilyl (CMDMS) ethers are useful derivatives for combined gas chromatography-mass spectrometry. They have characteristically longer retention times than the corresponding trimethylsilyl (TMS) derivatives, and this permits effective fractionation of mono-, di-, and trihydroxy steroids. CMDMS ethers provide mass spectra comparable with those of TMS ethers, but ions containing the CMDMS group are readily recognisable in the former by virtue of the two abundant natural isotopes of chlorine. This facilitates interpretation of spectra and may be expected to aid the location of drug metabolites by selective ion monitoring.     

Quality control of vegetable oil methyl esters used as diesel fuel substitutes: Quantitative determination of mono-, di-, and triglycerides by capillary GC

Vegetable oil methyl esters are increasingly being used as substitutes for petroleum-based diesel fuels. Because the presence of triglycerides and partial glycerides in the fuel as a result of incomplete transesterification of vegetable oils can lead to serious engine problems, continuous quality control of the product is essential. A rapid gas chromatographic method has been developed for the quantitative determination of mono-, di-, and triglycerides in vegetable oil methyl esters. Prior to analysis, mono-, and diglycerides were silylated with N,O-bis(trimethylsilyl)trifluoroacetamide; tridecanoin was used as internal standard. Calibration was performed by analysis of standard solutions containing mono-, di-, and triolein: the calibration plots for mono- and diglycerides showed good linearity, whereas for triglycerides no linearity was observed for triolein concentrations below 0.05 mg/ml. When a non-linear multi level calibration was employed for the quantitation of triglycerides, the method gave excellent quantitative results for mono-, di-, and triglycerides in vegetable oil methyl esters.     

Columnar liquid crystalline benzenetrisamides with pendant 1,3,4-oxadiazole groups

Novel liquid crystal materials based on 1,3,5-benzenetrisamide derivatives with three pendant 2-phenyl-5-(mono-, di-, and/or tri-n-alkoxyphenyl)-1,3,4-oxadiazole arms (Ia–c, IIa–c) were prepared. The mesomorphic properties of these compounds were characterised and studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. The formation of a columnar mesophase was found to be dependent on the number of alkoxy side chains. The compounds Ib and IIb, with a total of six alkoxy chains, and compounds Ic and IIc, with nine alkoxy chains, exhibited an enantiotropic hexagonal columnar (Col_h ) phase with high isotropisation temperatures; however, compounds Ia and IIa with a total of three alkoxy chains formed a crystalline phase. Compounds IIb and c were room temperature liquid crystals.     

Highly Selective Ratiometric Fluorescent Sensor for La(III) Ion Based on a New Schiff's Base

Abstract

A new fluorescent sensor containing (1-[({2-[2-(2-hydroxy-1-naphtyl)-3-(2-{[(E)-1-(2-hydroxy-1-naphtyl)methylidene]amino}ethyl)-1-imidazolidinyl]ethyl}imino)methyl]-2-naphthol) (L) was synthesized for detecting La(III) ratiometrically. Complexation between compound L and La(III) with high selectivity gives rise to a great red shift from 430 to 522 nm in the emission spectra. In acetonitrile, the red shift of fluorescent emission upon lanthanium binding is due to the formation of a 1:1 metal–ligand complex. The fluorescent probe exhibits high selectivity over other common metal ions and mono-, di-, and trivalent cations, which indicates good selectivity for La(III) ions over a large number of interfering cations.     

An effective and regioselective bromination of 1,4,5,8-naphthalenetetracarboxylic dianhydride using tribromoisocyanuric acid

A highly efficient and cost-effective reagent for the bromination of 1,4,5,8-naphthalenetetracarboxylic dianhydride under mild reaction conditions is reported. Bromination of 1,4,5,8-naphthalenetetracarboxylic dianhydride using tribromoisocyanuric acid (TBCA) in concentrated H₂SO₄ is very effective and regioselective. 1,4,5,8-Naphthalenetetracarboxylic dianhydride was brominated smoothly under optimized reaction conditions to give mono-, di- and tetra-brominated products in good to excellent yields using TBCA. As a proof of principle, the potential of this bromination methodology is demonstrated by converting brominated naphthalenetetracarboxylic dianhydrides into N-imide and core functionalized 1,4,5,8-napthalenetetracarboxylic diimides by treating with n-butylamine to yield corresponding mono-, di- and tetra-(n-butylamino)-naphthalene diimides in good yields in one-step reactions.     

N-methylation of etioporphyrin I and octaalkyl-5-azaporphyrins : X-ray structure of trans-Na,Nb-dimethyletioporphyrin I triiodide

Improved procedures are reported for the preparation of mono-, di- and tri-N-methyl-etioporphyrin I. Demethylation of N_a, N_b, N_c-trimethyletioporphyrin I under acidic, basic or thermal conditions gives N_a, N_b-dimethyl etioporphyrin I. N-Methylation of octaalkyl-5-azaporphyrins leads, in general, to mixtures of the isomeric mono-, di- and tri-N-alkylated 5-azaporphyrins. An X-ray crystal structure of N_a,N_b-dimethyl etioporphyrin I triiodide confirms the trans arrangement of the N-Me groups. The two N-methylated pyrrole rings are twisted 27° to each other.     

Thermal decomposition of 4,4′-isopropylidene bis-2,6-dibromophenol (tetrabromobisphenol-A)

The thermal decomposition of tetrabromobisphenol-A (TBBPA) was found to proceed via an autocatalytic free-radical process. The major products of the decomposition are HBr; mono-, di- and tribromobisphenol-A; phenol; mono-, di-, and tribromophenol; and eventually, char. It was generally found that o- and p-halophenols are thermally unstable. In contrast, the m-bromophenol, 3,5-dibromo-2,4,6-trimethylphenol (dibromomesitol) was found to be quite stable. In addition, o- and p-halo-substituted phenols were found to react with LiI at 250°C to produce I₂, while m-halophenols did not. These results are explained by the formation from o- and p-halo-substituted phenols of a reactive halocyclohexadienone.     

Rapid HPLC Methods for the Separation and Quantitation of a Mono-, Di-, and Tri-Saccharides Mixture and Applications

Abstract

A simple, rapid method has been developed for the separation and quantitation of mono-, di-, and tri-saccharides. The method utilizes a 30cmx 3.9mm i.d. Microbondapak NH₂ column, refractive index detection and water-acetonitrile elution. Two chromatographic systems are described. The isocratic mode was necessary to develop a procedure. 20 Carbohydrate's retention times were evaluated. To optimize the separation of nine water-soluble sugars, a gradient mode flow-programming was used. Separation was achieved within 28 minutes. The low detection limit (4 micrograms) of the above chromatographic procedure and its different possibilities could be of great interest to the analyst. The method has been successfully applied to quantify the major carbohydrates found in two types of commercial honey.     

Beiträge zur Chemie von Phosphorverbindungen mit Adamantanstruktur. X. Zur Solvolyse von Phosphor(III/V)-oxiden

Contributions to the Chemistry of Phosphorus Compounds with Adamantane Structure. X. Solvolysis of Phosphorus(III/V) Oxides The phosphorus(III/V) oxides of adamantan-like structure have been prepared by oxydation of phosphorus or of phosphorus trioxide with oxygen and characterized by analysis in water solution and by ³¹P n.m.r. spectroscopy. Paper chromatographic and n.m.r. studies show that the alcoholysis of the phosphorus(III/V) oxides leads to tri-, di-, and monoesters of phosphorous acid and also to mono-, di-, and cyclotriphosphoric acid, in dependence on their P^III and P^V contents. Nucleophilic attack by the alcohol takes place not statistically but in principle on the P^III atoms of the phosphorus(III/V) oxide molecule and their primary degradation products. In analogy to the alcoholysis the hydrolysis of the phosphorus(III/V) oxides yields phosphorous acid, mono-, di-, and cyclotriphosphoric acid. The mechanism of degradation is discussed.     

Crystal Structures of Mono-, Di-, and Tri(p-tert-butyl)-thiacalix[4]arenes: Dimeric Self-inclusion Behavior

X-Ray crystal structures of the mono-, di-, and tri(p-tert-butyl)-substituted thiacalix[4]arenes (TC4As; 1, 2, and 3, respectively) have beendetermined. TC4As 1–3 adopt a cone conformation and form dimeric self-inclusion units in such a manner that phenol moieties are inserted into the cavity of each molecule. In all the crystal structures of 1–3, lateralface-to-face interactions exist between the phenol rings that do not bear a tert-butyl substituent, and seemingly, this molecular assembly stabilizes the formation of self-inclusion. TC4As 1 and 2 adopt a cone conformation with C₂ symmetry, leading to the formation of rim-to-rim intermolecular hydrogenbonds so as to link the dimeric units up and down. On the other hand, 3 adopts a regular cone conformation with C₄ symmetry to form cyclic hydrogen bonds withinthe rim part of TC4A.     

The normal coordinate analysis of hydrogen bonded adducts of chloroacetic acids with dimethyl sulphoxide

The modified valence force field and the potential energy distribution were calculated for adducts of mono-, di-, and trichloroacetic acids with dimethyl sulphoxide. The calculated force constants gave a good fit to the experimental frequencies of normal adducts and their OD and CD₃ analogues. The hydrogen bond strength increases from mono- to trichloroacetic acid and this is reflected in the decrease of the K_O-H force constant and increase of k_O?h.