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Inspired by the easy intercalation of quinoxaline heterocyclic aromatic amines (HAAs) in double-stranded DNA (dsDNA), we synthesized a nucleobase-functionalized molecularly imprinted polymer (MIP) as the recognition unit of an impedimetric chemosensor for the selective determination of a 2-amino-3,7,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (7,8-DiMeIQx) HAA. HAAs are generated in meat and fish processed at high temperatures. They are considered to be potent hazardous carcinogens. The MIP film was prepared by potentiodynamic electropolymerization of a pre-polymerization complex of two adenine- and one thymine-substituted bis(2,2′-bithien-5-yl)methane functional monomer molecules with one 7,8-DiMeIQxtemplate molecule, in the presence of the 2,4,5,2′,4′,5′-hexa(thiophene-2-yl)-3,3′-bithiophene cross-linking monomer, in solution. The as-formed MIP chemosensor allowed for the selective impedimetric determination of 7,8-DiMeIQxin the 47 to 400 μM linear dynamic concentration range with a limit of detection of 15.5 μM. The chemosensor was successfully applied for 7,8-DiMeIQxdetermination in the pork meat extract as a proof of concept.

The gas-phase affinities of different types of anions X–(halogen anions, oxoanions, and hydrogenated anions) toward a model tetralactam-based macrocycle receptor (1), defined in terms of stability of an anion–receptor complex (1+ X–) against its disintegration, were evaluated by dissociation studies using a mass spectrometry-based methodology and supported by theoretical calculations (density functional theory–PBE0). The gas-phase complex with Cl–was found to be tailor-made for the macrocycle 1, while 1+ SA–(SA–= salicylate anion) and 1+ HSO4–were the weakest ones. Other complexes displayed a relatively low-stability dispersion (<1.2 kcal·mol–1). The 1/εrapproach of the electrostatic contribution scaling method was used to predict the stability trends in a dimethyl sulfoxide solvent from the gas-phase binding energy partition using the symmetry-adapted perturbation theory. High deformation energy and differences in solvation energies were suggested to be the main sources of inconsistency in the predicted and experimental stabilities of 1+ F–and 1+ H2PO4–complexes.

Isoprene (C5H8) is the main non-methane hydrocarbon emitted into the global atmosphere. Despite intense research, atmospheric transformations of isoprene leading to secondary organic aerosol (SOA) are still not fully understood, including its multiphase chemical reactions. Herein, we report on the detailed structural characterization of atmospherically relevant isoprene-derived organosulfates (OSs) with a molecular weight (MW) of 212 (C5H8SO7), which are abundantly present in both ambient fine aerosol (PM2.5) and laboratory-generated isoprene SOA. The results obtained from smog chamber-generated isoprene SOA and aqueous-phase laboratory experiments coupled to the S(IV)-autooxidation chemistry of isoprene, 3-methyl-2(5H)-furanone, and 4-methyl-2(5H)-furanone, allowed us for the first time to fully elucidate the isomeric structures of the MW 212 OSs. By applying liquid chromatography interfaced to electrospray ionization high-resolution mass spectrometry, we firmly confirmed six positional isomers of the MW 212 OSs in PM2.5collected from different sites in Europe and the United States. Our results also show that despite the low solubility of isoprene in water, aqueous-phase or multiphase chemistry can play an important role in the formation of OSs from isoprene. Possible formation mechanisms for the MW 212 OSs are also tentatively proposed.

Nadolol ((2R*,3S*)-5-{[(2R*)-3-(tert-butylamino)-2-hydroxypropyl]oxy}-1,2,3,4 tetrahydronaphthalene-2,3-diol) in substantia was exposed to ionizing radiation generated by a beam of high-energy electrons in an accelerator, in the standard sterilisation dose of 25 kGy and in higher doses of 50 − 400 kGy. The irradiated and non-irradiated (control) samples were analysed by the infrared spectrophotometry, electron paramagnetic resonance, differential scanning calorimetry (DSC) and ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC–MS). The irradiated samples were found to contain free radicals in concentrations much higher than that observed for the other irradiated β-blockers. On the basis of UHPLC–MS results, it was possible to establish structures of 11 compounds of the impurities and/or products of nadolol decomposition. The main product of radiodegradation was concluded to be formed as a result of abstraction of the hydroxyl group and aromatization of the tetrahydronaphthalene ring. The results of DSC measurements confirmed the presence of radiolysis products in the irradiated samples of nadolol. A shift of the endothermic peak corresponding to melting towards lower temperatures (by 4.4 °C at the dose of 400 kGy) was directly proportional to the doses of radiation used, which permits concluding that this method is sensitive and suitable for evaluation of radiodegradation of nadolol in solid phase.

A series of novel, highly phosphorescent cyclometalated iridium(III) complexes of type [(X2C^N)2Ir(Q2bpy)]+PF6–(where X2C^N is 2-phenylpyridine or 2-(2,4-difluorophenyl)pyridine anion and Q2bpy are 4,4′-bifunctionalized 2,2′-bipyridines) is presented. The complexes were fully characterized by means of NMR spectroscopy, high-resolution mass spectrometry (HRMS), cyclic voltammetry, and UV–vis. For several compounds also the crystallographic structures were obtained. The cyclometalates exhibited efficient photoluminescence at 298 K both in solution and in the solid state with good intensity and color purity. The emission wavelength range covered almost the whole visible spectrum and was strongly correlated with the EWG/ERG character of the Q substituent in the ancillary ligand. For further insight into the electronic structure of the complexes, a comprehensive electrochemical support (CV) was introduced, and finally, it was confronted with theoretical background using a density functional theory approach together with time-dependent calculations of the excited states.

The reactions of nitromethane, acetonitrile, and ethyl acetate carbanions with formic acid esters were investigated in the gas phase by mass spectrometry and quantum chemical calculations. It was found that the carbanion of nitromethane practically does not react with formic acid esters and only traces of the Claisen-type addition–elimination reaction product were observed. In the case of the deprotonated acetonitrile, the Claisen-type condensation that yielded the carbanion of cyanoacetaldehyde proceeded almost quantitatively for all the studied formates. Other products, like the Riveros reaction product, were observed in minor amounts. The ethyl acetate carbanion reacts with formates in a much more complex way because it decomposes in a collision cell, yielding the deprotonated ketene anion, which also can react with formic acid esters. Consequently, the Claisen condensation reaction products of both anions were observed as well as the products of other reactions. All the proposed reaction pathways were confirmed by quantum chemical calculations, including the transition-state energies.

Ketoconazole (1-[4-(4-{[(2R,4S)-2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]-methoxy} phenyl)piperazin-1-yl]ethan-1-one) in substantia was irradiated to doses between 25 kGy (standard sterilizing dose) and 800 kGy, using high energy electrons from an electron accelerator. The irradiated and non-irradiated samples were then examined using a variety of spectroscopic (UV, MS, NMR, EPR), chromatographic (TLC, HPLC) and hyphenated (HPLC-MS) methods. With the help of an EPR method the presence of free radicals (1.40 × 1015 spin/g for dose 100 kGy) was detected. The loss of ketoconazole was ca 6, as determined by the HPLC, for the dose of 800 kGy. The radiolytic yield of the process was 4.52 × 10-7 mol/J for the 25 kGy and it decreased to 1.29 × 10-7 mol/J for the 800 kGy dose. On the basis of the HPLC-MS measurements the structures for five main radiolysis products were proposed. It was found that the main radiodegradation processes are: dehalogenation (loss of Cl atom), dehydrogenation of the piperazine ring, Noxidation, hydrolysis and rapture of the C18-O19 bond. Our experiments indicate that ketoconazole is stable in the range of doses between 25-50 kGy and therefore could probably be sterilized using the standard sterilizing dose of 25 kGy.

Unprecedented amido derivativesof the first‐, second‐, and third‐generation Grubbs ruthenium catalysts were prepared, characterized, and tested in ring‐closing metathesis (RCM) of model dienes. In the ruthenium–amide (formally: 2‐ruthenaindole) form, these complexes exhibit nearly no activity in RCM. However, a dramatic increase of activity was observed upon in situ activation with an ethereal solution of HCl (see figure).

Gas‐phase reactions of isomeric nitrophenide ions and p‐halonitrophenide ions with acrylonitrile, methyl acrylate, and ethyl acrylate have been studied using mass spectrometry and computational methods. Depending on the structure of the α,β‐unsaturated compound, formation of adducts to the carbonyl group of the acrylate (for methyl acrylate and ethyl acrylate) and β‐adducts (adducts of p‐halonitrophenide ions to α,β‐unsaturated compounds in β position) was observed. Further transformations of these adducts lead to the products of elimination of an alcohol molecule and the anionic products of intramolecular substitution of a halogen atom, respectively. Copyright © 2012 John Wiley & Sons, Ltd.

Electron ionization (EI) and positive electrospray ionization (ESI) mass spectra of selected diaryl enaminoketones and enaminothiones have been studied. In the EI mass spectra of both classes of compound, molecular ion peaks are accompanied by the peaks corresponding to the [M – H]+ions. The formation of these ions can be rationalized by a cyclization reaction resulting in the formation of the respective isoxazolium and isothiazolium cations. Under positive ESI conditions, in the spectra recorded for the enaminoketones peaks corresponding to the [M + H]+, [M + Na]+and [2M + Na]+ions appeared, while in the spectra recorded for the enaminothiones, peaks corresponding to the [M – H]+ions were dominant. These ions are most likely formed by oxidation of the neutral enaminothione molecules on the surface of the positively charged stainless steel capillary in the ESI ion source (anodic oxidation).

Corroles, ring‐contracted analogs of porphyrins, are an important class of compounds which have attracted the attention of many researchers in the fields of organic, coordination and physical chemistry. In the present work, the stability and the decomposition pathways of a diverse set of meso‐substituted corroles have been studied using mass spectrometry (MS), UV–Vis absorption and preparative methods combined with NMR spectroscopy. Four different ionization methods (electrospray ionization, field desorption, atmospheric pressure photoionization and atmospheric pressure chemical ionization) were utilized to investigate light‐ and oxygen‐induced decomposition in various solvents. It was found that the rate of decomposition in MeCN is significantly higher than in CH2Cl2, hexane, MeOH and ethyl acetate. HR‐MS combined with CID–MS/MS enabled us to identify the products of initial decomposition. Surprisingly, numerous smaller open‐chain compounds were also detected. Large‐scale decomposition of a corrole bearing sterically hindered substituents at positions 5 and 15 allowed us to isolate mg quantities of three decomposition products: isocorrole and isomeric biliverdin‐type species. These are formed as a result of oxygen attack on the meso‐10 position. Copyright © 2010 John Wiley & Sons, Ltd.

Monovinylheptaisobutylsilsesquioxane undergoes efficient crossmetathesis and silylative coupling with styrenes. Allyl derivatives were successfully tested in crossmetathesis in the presence of first generation Grubbs’ catalyst, while heteroatomsubstituted vinyl derivatives vinyl ethers, 9vinylcarbazole efficiently undergo silylative coupling catalysed by ruthenium hydride complexes. Both reactions proceed highly stereoselectively and lead to nearly quantitative formation of Eisomers. Only when vinyl ethers are used does the reaction lead to a mixture of stereoisomers. Atmospheric pressure photoionisation has been successfully used for recording mass spectra of the functionalised silsesquioxanes.

Unimolecular fragmentation patterns of the molecular ions of selected lactams and sultams bearing alkoxymethyl group at the nitrogen atom were studied. The main common fragmentation reaction observed for all compounds studied in this work is the elimination of an aldehyde molecule. This reaction is considered to proceed via two different mechanisms. For lactams, hydrogen rearrangement within an alkoxymethyl group is observed, which leads to the appropriate N‐methyl derivatives. For sultams, transfer of the methyl group to the nitrogen and oxygen atoms, proceeding through an ion–neutral complex, dominates. Another important fragmentation channel characteristic exclusively for lactams is the loss of an alkyl radical. This process takes place within the N‐alkoxymethyl moiety, yielding the appropriate protonated ion of N‐formyllactams. This process is accompanied by relatively high kinetic energy release. Copyright © 2005 John Wiley & Sons, Ltd.

The electron ionization‐induced fragmentation patterns of three forensically relevant Schiff bases, originating from the condensation between 2‐, 3‐ and 4‐methoxyamphetamine and the corresponding ketones, were studied. The proposed fragmentation routes and ion structures are supported by high‐resolution data and B/E linked‐scan and mass‐analyzed ion kinetic energy spectra. The rationalization of the ortho effect, which is responsible for the formation of the [M − OCH3] fragment in the case of the imine bearing ortho‐substituted methoxy group, is given. Copyright © 2004 John Wiley & Sons, Ltd.

Unimolecular fragmentation patterns of N‐alkoxymethylated carbostyril and phenanthridinone and their O‐alkoxymethyl isomers were studied. The main fragmentation reaction observed for the studied compounds is the elimination of an aldehyde molecule. The main products of this reaction are the appropriate N‐methyl derivatives, but ions with other structures are also formed. This reaction is supposed to proceed via 1,3‐H shift in the alkoxymethyl group in the case of the N‐alkoxymethyl derivatives and by a multi‐step mechanism for O‐alkoxymethylated compounds. Another important fragmentation common for all studied compounds is the loss of an alkyl radical from N‐ and O‐alkoxymethyl groups, yielding the appropriate stable isomeric cations, which, according to the results of the further fragmentation, undergo fast equilibration reaction via an ion–neutral complex. This process is accompanied by the unusually high kinetic energy release value. Copyright © 2004 John Wiley & Sons, Ltd.

Electron ionization-induced fragmentation patterns of the series of N-(alkoxymethyl)acetanilides and related formanilides and benzanilides have been studied. The main fragmentation reaction observed for all compounds studied is the loss of an alkyl radical from the N-alkoxymethyl group leading to the appropriate protonated N-acylformanilide derivatives. This reaction is accompanied by unusually high kinetic energy release. Other important fragmentations common for majority of the compounds studied are (i) loss of an aldehyde molecule derived from an alkoxyl group yielding an appropriate N-acyl-N-methylaniline, (ii) elimination of a CnH2nO2 fragment derived from N-alkoxymethyl group and carbonyl group oxygen atom and (iii) formation of N-methyleneaniline radical cation. Copyright © 2003 John Wiley & Sons, Ltd.

In the standard electrospray ionization mass spectra of many common, low molecular mass organic compounds dissolved in methanol, peaks corresponding to ions with formula [3M + Met]²⁺ (M = organic molecule, Met = bivalent metal cation) are observed, sometimes with significant abundances. The most common are ions containing Mg²⁺, Ca²⁺ and Fe²⁺. Their presence can be easily rationalized on the basis of typical organic reaction work-up procedures. The formation of [3M + Met]²⁺ ions has been studied using N-FMOC-proline methyl ester as a model organic ligand and Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Fe²⁺, Ni²⁺, Mn²⁺, Co²⁺ and Zn²⁺ chlorides or acetates as the sources of bivalent cation. It was found that all ions studied form [3M + Met]²⁺ complexes with N-FMOC-proline methyl ester, some of them at very low concentrations. Transition metal cations generally show higher complexation activity in comparison with alkaline earth metal cations. They are also more specific in the formation of [3M + Met]²⁺ complexes. In the case of alkaline earth metal cations [2M + Met]²⁺ and [4M + Met]²⁺ complex ions are also observed. It has been found that [3M + Met]²⁺ complex ions undergo specific fragmentation at relatively low energy, yielding fluorenylmethyl cation as a major product. [M + Na]⁺ ions are much more stable and their fragmentation is not as specific. Copyright © 2002 John Wiley & Sons, Ltd.

Electron ionization-induced fragmentations of 3-cyclopropanospiro and 3-cyclobutanospiro derivatives of selected benzo- and pyridosultams were studied and compared with the thermal decomposition of these compounds. 3-Cyclopropanospirobenzosultams and the corresponding pyridosultams were found to be thermally stable up to 400 °C. At higher temperatures they eliminate an SO2 molecule yielding several dimethylindole derivatives together with other isomeric compounds. Loss of SO2 is also the main fragmentation process of the molecular ions of these compounds with the exception of the 4-NO2 derivative, for which elimination of CH2O is observed. 3-Cyclobutanospirobenzosultams and -pyridosultams eliminate SO2 on heating above 200 °C, yielding the corresponding 2-aryl-1,3-butadienes. Under EI conditions expulsion of SO2 from the molecular ions is also observed. However, elimination of C2H4 is the dominant process except for the 5-OCH3 derivative. Copyright © 2001 John Wiley & Sons, Ltd.

N,N-Dialkyl-o-nitroanilines undergo thermal reaction resulting in the formation of 1,2-dialkylbenzimidazoles—the process known as an example of the tert-amino effect. Similar processes are observed also in electron ionization spectra of these compounds. Elimination of an OH radical from the molecular ions of N,N-dialkyl-o-nitroanilines leads to several isomeric product ions depending on the substituents on the nitrogen atom. Elimination of the second OH radical yields [M-OH-OH]^+• ions, most likely with the structure of the appropriate 1-alkyl-or 1,2-dialkylbenzimidazoles. Mechanisms for these reactions are proposed. © 1998 John Wiley & Sons, Ltd.

Molecular ions of N-alkyl substituted derivatives of o-nitroaniline and some of their fragment ions undergo several fragmentations which are examples of new types of ortho-effects. A fragmentation common to all studied compounds with an unbranched alkyl chain –CH2–(CH2)n–H is the formal loss of H–(CH2)n–COOH (n= 0–3). Other important primary decomposition processes are eliminations of H2O, OH•and HO2•fragments. Reaction mechanisms for these reactions, supported by metastable and collision-induced decomposition spectra of selected model compounds and by deuterium labeling, are proposed. Other fragmentations of the molecular ion of N-alkyl-o-nitroanilines depend on the type of alkyl substituent. For alkyl larger than methyl an important process is the α-cleavage of the C–C bond next to the nitrogen atom yielding the corresponding immonium cation.

Fragmentation patterns upon electron ionization of some 1-alkyl-5-nitro- and 1-alkyl-7-nitro-2,1-benzisothiazoline 2,2-dioxides are described. It is observed that the molecular ions of the 7-nitro isomers undergo rearrangement reactions resulting in the loss of a molecule of the appropriate carbonyl compound and, concurrently, an acyl radical. Mechanisms for these reactions, which can be assumed to be an example of the “ortho-effect”, are proposed.

Fragmentation patterns upon electron ionization of N-(2-nitrophenyl)-methanesulfonamide and selected N-alkyl-N-(2-nitrophenyl)-methanesulfonamides are described. It is observed that the molecular ions of the latter compounds undergo rearrangement reactions resulting in the loss of the molecule of an appropriate carbonyl compound. The molecular ion of N-(2-nitrophenyl)-methanesulfonamide also undergoes rearrangement reaction yielding a benzofurazane radical cation. Proposals for the appropriate “ortho-effect” based reaction mechanisms are given.

Starting from methyl 7-oxo-7-(1-cyclopentene)-heptanoate, a simple synthesis of the methyl esters of 7-oxo- and 7-hydroxy-9,11-dideoxy-PGF1as a model for 7-substituted prostaglandin analogues is described. Ausgehend von Methyl-7-oxo-7-(1-cyclopenten)-heptanoat wird eine einfache Synthese der Methylester von 7-Oxo- und 7-Hydroxy-9,11-dideoxy-PGF1als Modellverbindungen für 7-substituierte Prostaglandinanaloge beschrieben.

A full interpretation of13C NMR spectra of the methyl esters of 7-hydroxy-and 7-oxo-9,11-dideoxy-PGF1 analogues and their synthons is reported.

Decomposition of N‐benzyl‐o‐nitroaniline during pyrolysis and upon electron ionization has been studied. Pyrolysis of N‐benzyl‐o‐nitroaniline starts above 450 °C and yields 2‐phenylbenzimidazole and 1‐phenyl‐1,3‐dihydrobenzimidazol‐2‐one as the main products. Upon electron ionization N‐benzyl‐o‐nitroaniline undergoes several fragmentations, the most important being eliminations of H2O, OH·and HO2·. All of these processes are the examples of different ortho‐effects. Elimination of H2O leads mainly to the formation of 1‐phenyl‐1,3‐dihydrobenzimidazol‐2‐one, similar to the pyrolytic decomposition. Reaction mechanisms for the main fragmentation processes are discussed. © 1998 John Wiley & Sons, Ltd.

Carbanions stabilized with sulfur containing substituents are versatile intermedi-ates in organic synthesis. The great value and importance of such carbanions is connected with specific properties of the sulfur atom which is capable to exist in a variety of valent states and to form many functional groups. These various sulfur-containing groups exert different carbanion stabilizing effects and can also serve as leaving groups in nucleophilic substitution or elimination reactions. Taking into account numerous types of sulfur containing functional groups and a variety of reactions they can promote, it is well understandable that reactions of sulfur-containing carbanions have been thoroughly studied and widely exploited in organic synthesis. The reactions of such carbanions with aliphatic electrophilic partners: alkylating agents, carbonyl compounds and Michael acceptors consist a major section of this field and were subject of numerous studies as well as many monographs.1 Contrary to that, not very much was known about reactions of such carbanions with electrophilic aromatic compounds. Actually, there are only few reports on nitroarylation of sulfur-containing carbanions via replacement of halogen orfho- or para- to the nitro group in halonitrocornpounds.2 There are also some reports on the alkylation of nitroarenes and heterocyclic compounds in the reaction with sulfonium3 and sulfoxonium4 ylides, dimethylsulfoxide carbanion,5 and dialkyl or alkyl aryl sulfones carbanions.6

Decomposition of N-benzyl-o-nitroaniline during pyrolysis and upon electron ionization has been studied. Pyrolysis of N-benzyl-o-nitroaniline starts above 450 °C and yields 2-phenylbenzimidazole and 1-phenyl-1,3-dihydrobenzimidazol-2-one as the main products. Upon electron ionization N-benzyl-o-nitroaniline undergoes several fragmentations, the most important being eliminations of H2O, OH^· and HO2^·. All of these processes are the examples of different ortho-effects. Elimination of H2O leads mainly to the formation of 1-phenyl-1,3-dihydrobenzimidazol-2-one, similar to the pyrolytic decomposition. Reaction mechanisms for the main fragmentation processes are discussed. © 1998 John Wiley & Sons, Ltd.

2-Substituted cis-2-cyclopentene-1,4-diol derivatives are used as starting materials for prostaglandin synthesis1. Two papers concerning the synthesis of these compounds have been published so far 1,2. In this paper we would like to present an alternative method for synthesis of 2-substituted cis-2-cyclopen-tene-1,4-diols from easily available cis-2-cyclopentene-1, 4-diol diacetate 13.

No Abstract.

Ground fruit bodies of Cantharellus cibarius(chanterelle) were extracted with dichloromethane and subjected to CC followed by preparative HPLC, which led to the isolation of glycerol 1,2- and 1,3-dilinoleates and glycerol tridehydrocrepenynate. Extraction of C. cibariusfruit bodies with ethanol or methanol afforded fatty acid ethyl or methyl esters as a result of esterification/transesterification reactions. Insecticidal activity of the isolated glycerides and esters was much lower than that of the crude extracts and chromatographic fractions suggesting a synergistic effect of some of the compounds present in the mixture.

The synthesis of unsymmetrical alkyl acetals via addition of primary alcohols to allyl ethers mediated by various ruthenium complexes is described.

The successful isomerization of N‐allylazole uses KOH/18‐crown‐6 [cf.

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