Novel Copolymers of 4-Fluorostyrene. 1. Alkyl Ring-Substituted 2-Phenyl-1,1-dicyanoethylenes

Novel copolymers of trisubstituted ethylene monomers, alkyl ring-substituted 2-phenyl-1,1-dicyanoethylenes, RC₆H₄CH = C(CN)₂ (where R is 2-methyl, 3-methyl, 4-methyl, 4-ethyl, 4-i-propyl, 4-butyl, 4-i-butyl, and 4-t-butyl) and 4-fluorostyrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r ₁) for the monomers is 4-ethyl (42.6) > 4-butyl (29.4) > 4-t-butyl (26.7) > 4-i-butyl (1.6) > 4-i-propyl (1.29) > 3-methyl (1.26) > 2-methyl (0.8) > 4-methyl (0.4). High T _g of the copolymers, in comparison with that of poly(4-fluorostyrene) indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in 183–500°C range with residue (5–30% wt.), which then decomposed in the 500–800°C range.     

Novel Copolymers of 4-Fluorostyrene. 3. Some Ring-Substituted 2-Phenyl-1,1-dicyanoethylenes

Novel copolymers of trisubstituted ethylene monomers, ring-substituted 2-phenyl-1,1-dicyanoethylenes, RC₆H₄CH=C(CN)₂ (where R is 4-dimethylamino, 4-diethylamino, 3-phenoxy, 3-benzyloxy, 4-benzyloxy, 4-acetoxy, 2-cyano, 3-cyano, and 4-cyano) and 4-fluorostyrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r ₁) for the monomers is 3-benzyloxy (2.9) > 4-cyano (2.7) > 3-phenoxy (1.9) > 4-acetoxy (1.8) > 3-cyano (1.7) > 2-cyano (1.6) > 4-benzyloxy (0.6) > 4-dimethylamino (0.4) = 4-diethylamino (0.4). High T _g of the copolymers, in comparison with that of poly (4-fluorostyrene) indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 290–400°C range with residue, which then decomposition in 400–800°C range.     

Search of manifolds of nonsymmetric Valley-Ridge inflection points on the potential energy surface of HCN

The potential energy surface (PES) of a chemical reaction contains Valley-Ridge inflection points (VRI) if??an often occurring phenomenon??the reaction path branches. In this paper, we introduce a new direct search method to detect these VRI points. It is based on an inductive execution of Gauss?CNewton steps. For the first time, we were able to find not only singular nonsymmetric VRI points, but also whole VRI manifolds on the PES of HCN.     

Synthesis of bis N-heterocyclic carbenes,derivatives and metal complexes

A method for the synthesis and isolation of 1,1′-methylene-bis-(3-aryl-imidazol-2-ylidene) ligands, aryl = 2,6-diisopropyl-phenyl (DiPP), L^DiPP, mesityl (mes), L^mes, is reported, which provides synthetically useful quantities of high purity. Derivatisation of L^DiPP with chalcogenides gave the adducts L^DiPPE₂, E = S, Se, Te. Reaction of L^DiPP with [Pd(tmeda)Me₂], [Pt(μ-SMe₂)Me₂]₂, [Ir(1,5-COD)(μ-Cl)]₂/KPF₆ and [NiBr₂(dme)] gave [Pd(L^DiPP)Me₂] (1), [Pt(L^DiPP)Me₂] (2), [Ir(L^DiPP)(1,5-COD)](PF₆) (3) and [Ni(L^DiPP)Br₂] (4), respectively. The latter was reduced in the presence of CO to [Ni(L^DiPP)(CO)₂] (5). The structures of L^mes, L^DiPPTe₂, and 1–5 are also reported.     

Development and validation of two LC-MS/MS methods for the detection and quantification of amphetamines, designer amphetamines, benzoylecgonine, benzodiazepines, opiates, and opioids in urine using turbulent flow chromatography

In the context of driving ability diagnostics in Germany, administrative cutoffs for various drugs and pharmaceuticals in urine have been established. Two liquid chromatography–tandem mass spectrometry methods for simultaneous detection and quantification of amphetamines, designer amphetamines, benzoylecgonine, benzodiazepines, opiates, and opioids in urine were developed and validated. A 500-μL aliquot of urine was diluted and fortified with an internal standard solution. After enzymatic cleavage, online extraction was performed by an ion-exchange/reversed-phase turbulent flow column. Separation was achieved by using a reversed-phase column and gradient elution. For detection, a Thermo Fisher TSQ Quantum Ultra Accurate Mass tandem mass spectrometer with positive electrospray ionization was used, and the analytes were measured in multiple-reaction monitoring mode detecting two transitions per precursor ion. The total run time for both methods was about 15 min. Validation was performed according to the guidelines of the Society of Toxicological and Forensic Chemistry. The results of matrix effect determination were between 78 % and 116 %. The limits of detection and quantification for all drugs, except zopiclone, were less than10?ng/mL and less than 25 ng/mL, respectively. Calibration curves ranged from 25 to 200 ng/mL for amphetamines, designer amphetamines, and benzoylecgonine, from 25 to 250 ng/mL for benzodiazepines, from 12.5 to 100 ng/mL for morphine, codeine, and dihydrocodeine, and from 5 to 50 ng/mL for buprenorphine and norbuprenorphine. Intraday and interday precision values were lower than 15 %, and bias values within?±?15 % were achieved. Turbulent flow chromatography needs no laborious sample preparation, so the workup is less time-consuming compared with gas chromatography–mass spectrometry methods. The methods are suitable for quantification of multiple analytes at the cutoff concentrations required for driving ability diagnostics in Germany.     

Synthesis of New N‐(5‐Oxo‐2,5‐dihydro)pyrrol‐3‐yl Glycines and N‐(5‐Oxo‐2,5‐dihydro)pyrrol‐3‐yl Glycines Esters

Following our efforts towards the synthesis of new potential inhibitors of Xanthine Dehydrogenase (XDH), we describe here a general method for the preparation of N-(5-oxo-2,5-dihydro)pyrrol-3-yl glycines and N-(5-oxo-2,5-dihydro)pyrrol-3-yl glycine esters from glycine ethyl ester hydrochloride and various 4-hydroxy-5-oxo-2,5-dihydro-1H-pyrrole-3-carboxylic acid esters and carbonitriles.     

The Effect of Lipid Composition on the Permeability of Fluorescent Markers from Photosensitized Membranes

There is evidence indicating that the cellular locus of PDT action by amphiphilic sensitizers are the cellular membranes. The photosensitization process causes oxidative damage to membrane components that can result in the cell's death. However, it was not yet established whether lipid oxidation can cause free passage of molecules through the membrane and, as a result, be the primary cause of the cell's death. In this work, we studied the effect of liposomes' lipid composition on the kinetics of the leakage of three fluorescent dyes, calcein, carboxyfluorescein and DTAF, which were trapped in the intraliposomal aqueous phase, after photosensitization with the photosensitizer deuteroporphyrin. We found that as the degree of fatty acid unsaturation increased, the photosensitized passage of these molecules through the lipid bilayer increased. We also found that the rate of leakage of these molecules was affected by their size and bulkiness as well as by their net electric charge. In liposomes that are composed of a lipid mixture similar to that of natural membranes, the observed passage of molecules through the membrane is slow. Thus, the photodynamic damage to lipids does not appear to be severe enough to be an immediate, primary cause of cell death in biological photosensitization.     

Transfer Hydrogenation of Ketones with 2‐Propanol and Raney® Nickel

Raney nickel in refluxing 2‐propanol containing a trace of HCl is an effective catalytic system for the reduction of ketones to secondary alcohols.     

Mild conversion of propargylic alcohols to α,β-unsaturated enones in ionic liquids (ILs); a new ‘metal free’ life for the Rupe rearrangement

A mild and selective transition metal free protocol for the conversion of propargylic alcohols to cyclic and acyclic α,β-unsaturated enones via the Rupe rearrangement is reported. The method utilizes the Brønsted acidic ionic liquid [BMIM-SO₃H][OTf] as catalyst and [BMIM][PF₆] as solvent and offers the potential for recycling and reuse of the IL solvent. The feasibility to synthesize bicyclic fused cyclopentenone derivatives via a Rupe → Aldol → Nazarov sequence utilizing this protocol has also been demonstrated.