Amidine als Zwischenprodukte bei Umamidierungsreaktionen. 9. Mitteilung über Umamidierungsreaktionen

Amidines as Intermediates in Transamidation Reactions By loss of water in the presence of p-toluenesulfonic acid/xylole N-aminoalkyllactames form bicyclic amidines. The corresponding N-alkylaminoalkyl-lactames' react to bicyclic amidinium salts or to transamidated products, ring-enlarged by the N-alkylamino residue, respectively (s. Scheme 1). The bicyclic amidines and amidinium salts are partially hydrolyzed by KOH/H₂O to lactames (s. Scheme 2). Which of the two possible isomeric lactames are formed is discussed.     

Multiresidue LC–MS/MS analysis of cephalosporins and quinolones in milk following ultrasound‐assisted matrix solid‐phase dispersive extraction combined with the quick,easy, cheap,effective, rugged,and safe methodology

A sensitive and selective confirmatory method for milk‐residue analysis of ten quinolones and eight cephalosporins by LC‐MS/MS has been developed herein. For the chromatographic separation of target analytes, a Perfectsil ODS‐2 (250 × 4 mm, 5 μm) analytical column was used and gradient elution was applied, using a mobile phase of 0.1% w/w TFA in water and 0.1% w/w TFA in ACN. Ultrasound‐assisted matrix solid‐phase dispersion procedure was applied for the extraction and clean‐up procedure of antimicrobials agents from milk matrix using a mixture of Bond Elut Plexa sorbent and QuEChERS. The method was validated meeting the European Legislation determining selectivity, linearity response, trueness, precision (repeatability and between‐day reproducibility), decision limit, detection capability, and ruggedness following the Youden approach. Recoveries of all antibiotics ranged from 81.7 to 117.9%, while RSD values were lower than 13.7%. Limits of quantification for all examined compounds ranged from 2.4 to 15.0 μg/kg, substantially lower than the maximum residue limits established by the European Union (30–100 μg/kg).     

Environmental Determination of Alkylphenol Polyethoxylate Refractory Residues Using Mass Spectrometric Techniques

Abstract

The use of methane chemical ionisation GC/MS gave satisfactory results when applied to environmental analysis of halogenated octylphenol polyethoxylates residues. In addition the selected ion monitoring GC/MS technique has been successfully applied for simulataneous qualitative and quantitative determination of some refractory metabolites of nonylphenol polyethoxylates in secondary sewage effluent and surface waters.     

Magnetic resonance spectroscopy: a noninvasive diagnosis of gliomatosis cerebri

Gliomatosis cerebri (GC) is characterized by a diffuse infiltration of neoplastic glial cells with preservation of neuronal architecture. It can be very difficult to diagnose during life because the clinical manifestations are protean and tests are often nondiagnostic. The diagnosis of GC needs to be based on radiological, clinical and pathological criteria. We present a patient with GC, which initially presented as acute stroke attack. We discuss the usefulness of noninvasive methods, such a MR spectroscopy, in the diagnosis, grading and management of GC.     

Chemical ionization mass spectra of alkylphenol and linear alcohol polyethoxylates

The chemical ionization mass spectra of some tert-octylphenol ethoxylates and linear alcohol ethoxylates have been determined using methane and ammonia as reactant gases. Proton, [C₂H₅]⁺ and [C₃H₅]⁺ adducts were observed with attachment on the ring as well as on the oxyethylene chain for the tertiary octylphenol ethoxylates. Proton and [NH₄]⁺ addition reactions were also observed. Alkyl ion and olefin displacement reactions were also important fragmentations. Hydride abstraction and proton, [C₂H₅]⁺, [C₃H₅]⁺ and [NH₄]⁺ attachment were the most important reactions occurring for the linear alcohol ethoxylates.     

Umamidierungsreaktionen an cyclischen Amino-amid-Systemen. 3. Mitteilung über Umamidierungsreaktionen

Transamidation Reactions with Cyclic Amino-amides Lactames which are substituted at the nitrogen atom by a 3-aminopropyl residue are transformed under base catalysis to cyclic amino-amides enlarged by 4 ring atoms. The formed ring must be at minimum 12-membered. Scheme 2 illustrates this result: the 8-membered 7 is transamidated in 96% yield to the 12-membered ring 8 (in the presence of potassium 3-aminopropylamid in 1, 3-propanediamine), the 9-membered 10 to the 13-membered ring 11 (97%) and the 11-membered 14 to the 15-membered ring 15 . Furthermore, the 13-membered ring 27 (Scheme 5) is transformed to the 17-membered 28 . In the case of the 15-membered lactame 15 it is demonstrated that 14 is not formed back under the conditions of the transamidation. Large ring lactames which are substituted at the nitrogen atom by a 3-(alkylamino) propyl group lead under base catalysis to an equilibrium mixture, e.g. the 17-membered 26 is in equilibrium with the 21-membered 29 . This result is similar to the behavior of the corresponding open-chain amino-amides [2]. Because of transannular interactions, the 11-membered ring 2 is not stable: transamidation of the 7-membered 1 (Scheme 1) doesn't give the expected 2 , but its water elimination product 3 in small yield. The N-tosyl derivative of 2 , namely 20 , is synthesized by an independent route (Scheme 3). Detosylation of 20 yields the 7-membered 1 instead of 2 . Concerning the mechanism of this interesting reaction see Scheme 4.     

S-P wave interference in K+K− photoproduction near K+K− threshold

A mass-dependent asymmetry was observed in the decay angular distribution of a photoproduced K⁺K^? system near the K⁺K^? threshold. The corresponding moments 〈Y₁⁰〉 have been evaluated. Interpreting the asymmetry as an S-P wave interface due to the states S₉₉₃¹(0⁺) and ø₁₀₁₉(1^?) one can compute the moments 〈Y₁⁰〉 through an amplitude analysis. The theoretical calculation reproduces the experimental results well, if one assumes a real S-wave amplitude for the S₉₉₃¹. The data cannot be explained by a non-resonant real S-wave. Other possibilities have been discussed. An estimate of the photoproduction cross section of the $\text{S}{}^1\text{→}\text{K}{}^{\mathrm{+}}\text{K}{}^{\mathrm{?}}$ can be given on the basis of the above hypothesis.     

Elastic and inelastic φ photoproduction

The differential cross section of the reaction (γp → pφ) has been measured in the t range 0 ? t ? 0.4 GeV² and for photon energies from 3.0 to 6.7 GeV. In particular for the small t region the measurement accuracy was better than 10%. We obtained for the slope parameter B in an exponential parametrization of the differential cross section dσ/dt = Ae^?Bt values of $\text{B ? 6 ± 0.5}\text{GeV}{}^{\mathrm{?2}}$ which are significantly larger than the slopes obtained by most other experiments at higher t values. This indicates a t dependence of B particularly in the small t region.An energy dependence of the optical point (dσ/dt)_t=0, observed in our measurements, has been explained as a kinematic effect due to the VDM relation. A fit of our measurements is in excellent agreement with all other published values of (dσ/dt)_t=0(γp → φp), this implies that σ_tot(φp) must be essentially energy independent in this energy range.Spin density matrix elements of the φ have been evaluated and an analysis of the helicity amplitudes has been carried out. This analysis confirmed s-channel helicity conservation. Moments of spherical harmonics of the $\text{K}\text{K}$ angular decay distribution have been computed for 10 MeV $\text{K}\text{K}$ mass-bins from threshold to 1.3 GeV. The mass dependence of the normalized moments is generally smooth. Contributing amplitudes have essentially only even moments. The moment 〈Y₂⁰〉/〈Y₀⁰〉 changes sign above the φ mass.Differential cross sections for the inelastic φ production γp → φX have been evaluated for the first time both with respect to t?t_min and M_K. The integrated inelastic cross sections are comparable in size with the elastic ones. The slopes of the differential cross sections dσ/dt appear to become flatter with increasing M_X.