Zur Synthese sulfonierter Derivate von 4-Fluoranilin

Syntheses of Sulfonated Derivatives of 4-Fluoroaniline Synthesis of 2-amino-5-fluorobenzenesulfonic acid ( 2 ) was achieved by baking the hydrogen sulfate of 4-fluoroaniline ( 1 ). Sulfonation of p-fluoroacetanilide ( 4 ) with oleum followed by hydrolysis gave 5-amino-2-fluorobenzenesulfonic acid ( 3 ). The same reaction with 1 yielded 3 in an impure state. The structures of 2 and 3 were confirmed by converting the diazonium chlorides derived from 5-fluoro-2-nitroaniline ( 5 ) and from 2-fluofo-5-nitroaniline ( 8 ) to 5-fluoro-2-nitrobenzene-sulfonyl chloride ( 6 ) and 2-fluoro-5-nitrobenzenesulfonyl chloride ( 9 ), respectively, followed by hydrolysis of 6 to 5-fluoro-2-nitrobenzenesulfonic acid ( 7 ), and of 9 to 2-fluoro-5-nitrobenzenesulfonic acid ( 10 ), and by final reduction. Compound 10 was also obtained by sulfonation of 1-fluoro-4-nitrobenzene ( 11 ) with oleum.     

Fragmentation of synthetic cannabinoids with an isopropyl group or a tert‐butyl group ionized by electron impact and electrospray

This study described a fragmentation pattern of 21 synthetic cannabinoids with an isopropyl group or a tert‐butyl group by electron impact ionization quadrupole mass spectrometry and electrospray ionization time‐of‐flight mass spectrometry in the positive mode. The compounds were categorized into four types according to substituted group such as a terminal amide and ester. The characteristic fragment ion in each group was obtained. The main common fragment ions for the two ionizations were formed by C–N cleavage of the amide group adjacent to the N‐hetero rings. Additionally, the fragment ions indicated the difference in the basic structure as well as substituted group, which are useful for estimating the chemical structures of unknown compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

2-fluoro-3-nitroaniline and 2-fluoro-1,3-phenylenediamine

2-Fluoro-3-nitroaniline (I), erroneously reported in the literature, has been synthesized by partial reduction of 2-fluoro-1,3-dinitrobenzene (II). Total reduction of (II) gives 2-fluoro-1,3-phenylenediamine (V). The NMR parameters of 1-fluoro-2,4-dinitrobenzene (IV), 2-fluoro-5-nitroaniline (III) and compounds (I), (II) and (V) are reported.     

Mechanism of formation of doubly charged fragments from bis-benzyltetrahydroisoquinolines under electron impact

Some bis-benzyltetrahydroisoquinolines [α,α′-di-N,N-(1-benzyl-1,2,3,4-tetrahydroisoquinoline)-p-xylene and various substituted analogues] give rise to very abundant doubly charged fragment ions under electron impact, corresponding to the loss of the two benzyl groups. Substituent effects, ionization and appearance energy measurements and metastable transitions show that these doubly charged ions are formed (at least in part) from singly charged precursors by a heterolytic cleavage (charge separation).     

Studies in organic mass spectrometry. 12–Electron impact ionization mass spectra of some 3-nitropyrroles

The positive-ion electron impact ionization mass spectra of eight substituted 3-nitropyrroles were examined. The major fragment ions arise by ortho interactions between the 3-nitro group and the 2-methyl or 2-aryl group.     

Negative-mode MALDI mass spectrometry for the analysis of pigments using tetrathiafulvalene as a matrix

Negative-mode matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) analysis of industrial pigments was performed using tetrathiafulvalene (TTF), an electron donating compound, as a matrix. Comparing with other matrices such as tetracyanoquinodimethane (TCNQ), dithranol, 2-hydroxy-6-nitroaniline (HNA), and harmine hydrochloride, the most abundant analyte ions were produced by the TTF as radical or deprotonated anions. In addition, fragment ions in the negative mode of operation are also found to be much less abundant than those in the positive mode of operation.     

Mass spectra of ferrocenophanes. Cyclic peroxide derivatives

The electron impact mass spectra of two 6-membered cyclic peroxides of ferrocenophane depend sensitively on the temperature of the sample heater of the direct inlet system. It is confirmed that their spectra contain some fragment ion peaks arising from thermal decomposition or rearrangement products, but that the ion at m/e (M–28) is due to elimination of ethylene from the molecular ions of the peroxides by a retro Diels-Alder type reaction.     

Zur Synthese sulfonierter Derivate von 2-Fluoranilin

Syntheses of Sulfonated Derivatives of 2-Fluoroaniline Synthesis of 4-amino-3-fluorobenzenesulfonic acid ( 3 ) was achieved in two ways: reaction of 2-fluoroaniline ( 1 ) with amidosulfonic acid and by first conventionally converting 4-nitro-3-fluoroaniline ( 8 ) to 4-nitro-3-fluorobenzenesulfonyl chloride ( 9 ) followed subsequently by hydrolysis to 3-fluoro-4-nitrobenzenesulfonic acid ( 10 ) and reduction. Hydrogenolysis of 3 gave sulfanilic acid ( 7 ). Both, sulfonation of fluorobenzene ( 6 ) to 4-fluorobenzenesulfonic acid ( 11 ) followed by nitration and sulfonation of 1-fluoro-2-nitrobenzene ( 12 ) led to 4-fluoro-3-nitrobenzenesulfonic acid ( 13 ). Reduction of 13 gave the isomeric 3-amino-4-fluorobenzenesulfonic acid ( 4 ), which was also obtained both by sulfonation of 1 and by sulfonation of o-fluoroacetanilide ( 14 ) followed by hydrolysis. Selective hydrogenolyses of 2-amino-5-bromo-3-fluorobenzenesulfonic acid ( 15 ), prepared by reaction of 4-bromo-2-fluoroaniline ( 16 ) with amidosulfonic acid, and of 4-amino-2-bromo-5-fluorobenzenesulfonic acid ( 20 ), obtained by sulfonation of 5-bromo-2-fluoroaniline ( 19 ) yielded the isomers 2-amino-3-fluorobenzenesulfonic acid ( 5 ) and 3 , respectively. The fourth isomer, 3-amino-2-fluorobenzenesulfonic acid ( 2 ), was synthesized by sulfur dioxide treatment of the diazonium chloride derived from 2-fluoro-3-nitroaniline ( 21 ) to 2-fluoro-3-nitrobenzenesulfonyl chloride ( 22 ), followed by hydrolysis to 2-fluoro-3-nitrobenzenesulfonic acid ( 23 ) and final Béchamp-reduction.     

Effect of substituent group interaction in the fragmentation of some pyrrolidin-3-ones

The decomposition after electron impact of some N-alkyl and N-aryl pyrrolidin-3-ones has been examined and fragmentation mechanisms influenced by the substituents on the nitrogen have been observed. Accurate mass measurement, deuterium labelling, kinetic energy release measurements and metastable (DADI) ion abundances, permit the elucidation of the probable mechanism of formation of the most intense fragment ions. The available experimental evidence indicates the occurrence of rearrangement processes leading to important product ions in the mass spectra of the N-aryl derivatives. This type of fragmentation has been interpreted as the result of the combined action of two groups on the nitrogen atom of the heterocyclic nucleus.     

Metastable fragment ions from carbinolamine ethers

The secondary decomposition of fragment ions produced by electron impact of carbinolamine ethers was studied by mass analysed ion kinetic energy spectrometry. A new case was observed of ions of the same structure leading to the same fragments through different mechanisms competing in the metastable time frame and accompanied by a different partitioning of the excess energy (internal vs translational). The role of a fractional positive charge localized at saturated centres in the reactivity of these gaseous organic ions is discussed.     

The mass spectra and ionization potentials of the neutral fragments produced during the electron bombardment of aromatic compounds

A mass spectrometer equipped with a dual ionization chamber ion source has been used to characterize directly the neutral species produced in the dissociative ionization of gases by electron impact. Neutral fragment mass spectra have been obtained for the electron ionization and fragmentation of benzene, toluene, o-xylene, m-xylene, p-xylene, mesitylene and isotopically labeled toluene. The neutral fragment mass spectra correlate well with the structures of the molecules. The abundant species in the neutral fragment mass spectra also correlate reasonably well with the abundant complementary positive ions of the normal mass spectra. Ionization potentials have been determined for the abundant neutral species produced. Where comparisons with values reported elsewhere are possible, the agreement is usually within ±0.2 eV or less.     

Ortho effect in the fragmentation of 2-acetoxychalcones under electron impact

2-Acetoxychalcones decompose under electron impact conditions by loss of an acetoxy fragment to form flavylium ions. The effect is restricted to the ortho position and is reduced after hydrogenation of the chalcone double bond. The intense flavylium ion originates—as shown by specific labelling with ¹⁸O—from two different fragmentation lines: (a) direct loss of an acetoxy radical by cleavage of the phenolic Ar? O bond and (b) sequential elimination of ketene and a hydroxy radical.     

Electron impact study of C6H5+ fragment ion obtained from three molecules

C₆H₅ ⁺ fragment ion produced from toluene,n-propylbenzene and acetophenone have been studied using an electron impact technique. The ionization efficiency data have been treated by the inverse convolution first differential technique. First and higher appearance energies for ions produced from the three precursors are reported. The heats of formation for the ions obtained at threshold from the three molecules are calculated     

Further correlations between fragment ion intensity and critical energy. Unimolecular covalent bond fragmentation

A correlation of fragment ion intensity with critical energy found in the collisional activation spectra of [C₄Ph]⁺˙ ions produced by electron impact can also be found in the unimolecular mass-analysed ion kinetic energy spectra of these ions. The P(E) functions of the unimolecular and collisionally activated ions should differ not only in width but also in structure and therefore, the hypothesis that P(E) functions do not have an important effect on these correlations is tested successfully.     

Mass spectral fragmentation patterns of heterocycles. IV . Tetracyclic phenothiazines. IX. Electron impact promoted mass spectral fragmentation of pyrrolo[3,2,1-kl]phenothiazine

The mass spectral fragmentation patterns of pyrrolo[3, 2, 1-kl]phenothiazine ( 1 ) and its 1, 10-dideuterioderi-vative [2] are reported. The site of deuterium substitution in 2 was established by examination of its ¹³C nuclear magnetic resonance spectrum. The heteroaromatic stability of 1 to electron impact is exemplified by the occurrence of the molecular ion as the base peak and the formation of a reasonably intense M²⁺ ion. An intense M-1 ion is also observed. The more abundant fragment ions appear to result from sulfur ionization. Fragment ions arising from ionization of the nitrogen constitute only a small fraction of the total ion current. Proposed fragmentation pathways of 1 are supported by the detection of appropriate metastable ions, exact mass measurements, and electron impact spectrum of 2 .     

Mechanistic study of the decomposition reactions of azobenzene

The electron impact-induced fragmentation of azobenzenes and its d₁, d₂, d₅, d₁₀, and ¹⁵N analogues was studied by mass Spectrometry and ion kinetic energy spectroscopy. The main fragment ions found in the mass spectrum of azobenzene are due to two parallel stepwise processes from the molecular ion: the expulsion of N₂ and two hydrogen radicals producing an ion at m/z 152 having possibly a biphenylene radical cation structure and loss of C₆H₅? and N₂. Except in the elimination of two hydrogen atoms from [M ? N₂]^+· ions, hydrogen scrambling between the phenyl rings does not feature in azobenzene upon electron impact.     

Mass spectrometry of some 10β-Fluoro-1,4-estradien-3-oxo steroids

The mass spectrometric behavior of some 10β-fluoro-1,4-estradiene-3-oxo steroids under two different ionization conditions (electron inpact and fast atom bombardment) was studied with the aid of mass-analyzed ion kinetic energy spectroscopy. The influence of fluorine in the fragmentation pattern was investigated by comparison with the behavior of 10-methyl analogs. In particular, the presence of fluorine at position 10 seems to reflect the weakening of C(9)? C(10) bond. Further, when an acyloxy moiety is present at position 17, the primary ring cleavages typical of steroids become disfavored and fragment ions related to the acyloxy substituents are detected.     

A study of some imidazo[l,5-a]benzodiazepin-6-ones by electron impact mass spectrometry. characterization by tandem mass spectrometry of a distonic fragment ion

The mass spectra of several imidazo[l,5-a]benzodiazepin-6-one derivatives of neuropharmacological significance were determined in order to establish their decomposition paths under electron impact. A novel distonic fragment ion was observed and it was possible to demonstrate by consideration of metastable ions and by tandem mass spectrometry that it undergoes isomerization to the corresponding classical structure.     

The electron impact induced fragmentation of 1,3-diphenyl-2-pyrazoline

The electron impact induced fragmentation of 1,3-diphenyl-2-pyrazoline was studied by nitrogen-15, carbon-13 and deuterium labelling, substitution in the para position of one of the phenyl rings by fluoro and methoxy groups, and ion kinetic energy spectroscopy, as well as accurate mass measurements. In the fragmentation pathway observed all the ions in the mass spectrum of 1,3-diphenyl-2-pyrazoline (except m/e 103) originate from the molecular ion, which in all compounds is the base peak. The formation of prominent fragment ions is discussed.     

The energetics of resonant dissociative electron attachment to molecules of five-membered heterocyclic compounds

The thermochemistry of resonant dissociative electron attachment processes for furan, thiophene, selenophene, and pyrrole molecules has been studied. The structures of the dissociation products originating from negative molecular ions at energies ranging from 2 to 6 eV have been established using the measured appearance energies of fragment ions and the known thermodynamic functions of radical and molecular dissociation products. Heats of formation and electron affinities for some radicals and molecules have been assessed by calculations and estimated experimentally. It has been concluded that the majority of the fragment ions are formedvia rearrangement processes in molecular or fragment ions.