Unknown Isomer Research Articles

PCB AND DDE METHYL SULFONES IN MAMMALS FROM CANADA AND SWEDEN

Levels of PCB methyl sulfones (MeSO2-CBs) and DDE methyl sulfones (MeSO2-DDEs) have been determined in tissues from polar bear (Ursus martimus), beluga whale (Delphinapterus leucas), and false killer whale (Pseudorca crassidens) from the Canadian environment, and grey seal (Halichoerus grypus), otter (Lutra lutra), and wild mink (Mustela vison) from the Swedish environment. Up to 30 MeSO2-CB congeners and three MeSO2-DDE isomers were shown to be present in the analyzed tissues. The concentration of total MeSO2-CBs ranged from 0.1 to 21 μg/g extracted lipids. 3-MeSO2-2,5,2′,4′,5′-penta-CB is the dominating MeSO2-CB congener in all the analyzed samples, but the corresponding 4-MeSO2-CB also is present in high concentrations. A smaller number of MeSO2-CBs, always dominated by the meta-substituted MeSO2-CBs, were present in livers of grey seal, otter, and mink than in adipose tissue or muscle. In all studied mammals the concentrations of MeSO2-CBs were higher in liver than in blubber or muscle. Seven PCB congeners were identified as precursors of the PCB methyl sulfones: 2,4,2′,5′-tetra-CB (CB-49), 2,5,3′,4′-tetra-CB (CB-70), 2,4,5,2′,5′-penta-CB (CB-101), 2,3,4,5,2′,5′-penta-CB (CB-87), 2,3,6,2′,4′,5′-hexa-CB (CB-149), 2,3,4,2′,3′,6′-hexa-CB (CB-132), and 2,3,4,2′,5′-hexa-CB (CB-141). All species except beluga whale contained 3-MeSO2-4,4′-DDE, but at a much lower concentration in mink and otter than in the other mammals. Polar bear and grey seal liver also contained 2-MeSO2-4,4′-DDE. The concentrations of 2- and 3-MeSO2-DDE ranged from 0.01 to 1.3 μg/g extracted lipids. A hitherto unknown MeSO2-DDE isomer was determined in false killer whale blubber by GC-MS, along with 2- and 3-MeSO2-4,4′-DDE and several unknown MeSO2-penta-CBs and MeSO2-hexa-CBs. tris(4-chlorophenyl)methanol was identified in the aryl methyl sulfone fraction of polar bear liver and grey seal blubber samples.

PCB and DDE methyl sulfones in mammals from Canada and Sweden

AbstractLevels of PCB methyl sulfones (MeSO2‐CBs) and DDE methyl sulfones (MeSO2‐DDEs) have been determined in tissues from polar bear (Ursus martimus), beluga whale (Delphinapterus leucas), and false killer whale (Pseudorca crassidens) from the Canadian environment, and grey seal (Halichoerus grypus), otter (Lutra lutra), and wild mink (Mustela vison) from the Swedish environment. Up to 30 MeSO2‐CB congeners and three MeSO2‐DDE isomers were shown to be present in the analyzed tissues. The concentration of total MeSO2‐CBs ranged from 0.1 to 21 μg/g extracted lipids. 3‐MeSO2‐2,5,2′,4′,5′‐penta‐CB is the dominating MeSO2‐CB congener in all the analyzed samples, but the corresponding 4‐MeSO2‐CB also is present in high concentrations. A smaller number of MeSO2‐CBs, always dominated by the meta‐substituted MeSO2‐CBs, were present in livers of grey seal, otter, and mink than in adipose tissue or muscle. In all studied mammals the concentrations of MeSO2‐CBs were higher in liver than in blubber or muscle. Seven PCB congeners were identified as precursors of the PCB methyl sulfones: 2,4,2′,5′‐tetra‐CB (CB‐49), 2,5,3′,4′‐tetra‐CB (CB‐70), 2,4,5,2′,5′‐penta‐CB (CB‐101), 2,3,4,5,2′,5′‐penta‐CB (CB‐87), 2,3,6,2′,4′,5′‐hexa‐CB (CB‐149), 2,3,4,2′,3′,6′‐hexa‐CB (CB‐132), and 2,3,4,2′,5′‐hexa‐CB (CB‐141). All species except beluga whale contained 3‐MeSO2‐4,4′‐DDE, but at a much lower concentration in mink and otter than in the other mammals. Polar bear and grey seal liver also contained 2‐MeSO2‐4,4′‐DDE. The concentrations of 2‐ and 3‐MeSO2‐DDE ranged from 0.01 to 1.3 μg/g extracted lipids. A hitherto unknown MeSO2‐DDE isomer was determined in false killer whale blubber by GC‐MS, along with 2‐ and 3‐MeSO2‐4,4′‐DDE and several unknown MeSO2‐penta‐CBs and MeSO2‐hexa‐CBs. tris(4‐chlorophenyl)methanol was identified in the aryl methyl sulfone fraction of polar bear liver and grey seal blubber samples.

Addition of cyclopropenylium and tropylium ions to cyclooctatetraene-cobalt and -rhodium cyclopentadienyl complexes

Cyclopropenylium ions [C3R′3]+(R′= Ph or But) react with [Co(η4-cot)(η-C5R5)](R = H or Me, cot = cyclooctatetraene) to give [M{η5-C8H8(C3R′3)}(η-C5R5)]+3(M = Co; R = H, R′= Ph; R = Me, R′= Ph or But); X-ray structural studies on 3(M = Co, R = H, R′= Ph) show an exo-cyclopropene substituent on the cyclooctatrienyl ring. The reaction of [C3Ph3]+ with [Rh(η4-cot)(η-C5Me5)] gives a similar product 3(M = Rh, R = Me, R′= Ph) which rearranges to an unknown isomer 5 whereas [Rh(η4-cot)(η-C5H5)] undergoes electrophilic substitution at the cyclopentadienyl ring to give [Rh(η2,η3-C8H9){η-C5H4(C3Ph3)}]+4. The addition of [C7H7]+ to [Co(η4-cot)(η-C5R5)](R = H or Me) gives [Co{η5-C8H8(C7H7)}(η-C5R5)]+6(R = H or Me) which, in the case of 6(R = Me), rearranges to the 1,2,3,3a-tetrahydropentalenyl complex [Co{η5-C8H8(C7H7)}(η-C5Me5)]+7. Finally, the reactions between [Rh(η4-cot)(η-C5R5)](R = H or Me) and [C7H7]+ give [Rh(η2,η3-C8H9){η-C5H4(C7H7)}]+8 and [Rh{η2,η3-C8H8(C7H7)}(η-C5Me5)]+9 respectively.

Formation of a trans‐1,2,4,5‐Tetraphosphatricyclo‐[3.1.0.02, 4]hexane by [2 + 2] Cyclodimerization of a 3H‐Diphosphirene

Synthesis of a 3H-diphosphirene by reaction of per(trimethylsilyl)-substituted 1,2-diphospha-2-propene with hexachloroethane was the goal. Although it was not possible to isolate this unknown isomer, its formation as an intermediate was demonstrated by further reaction to give the tricyclic dimer 1 with a planar P4 unit.

ChemInform Abstract: Synthesis and 13C NMR of (Trifluoromethyl)hydroxypyrazoles.

Reaction of ethyl 4,4,4-trifluoroacetoacetate with methylhydrazine produced not only the previously reported 5-hydroxy-3-(trifluoromethyl)pyrazole 1 but also its unknown isomer the 3-hydroxy-5-(trifluoromethyl)pyrazole 4. The structure assignements are etablished based on 13 C NMR spectra. Compound 1 was converted to 5-chloro-3-(trifluoromethyl)pyrazolecarboxylic acid 3 in two steps.

On the existence of two distinguishable isomers of CS3: carbon trisulfide and carbon disulfide S-sulfide

Collision experiments, using tandem mass spectrometry methodologies, provide evidence that carbon trisulfide, CS{sub 3}, is a viable molecule in the gas phase, as are its radical cation and anion, respectively. An experimental distinction, whether the species possess D{sub 3h} or C{sub 2v} symmetry (2 versus 3) could not be achieved, though ab initio MO calculations favor the latter form. Labeling studies point to the existence of a second, hitherto unknown isomer which is assigned as carbon disulfide S-sulfide (6). This isomer forms a cation radical 6{sup {sm bullet}+} whose dissociation pattern is also distinct from that of 2{sup {sm bullet}+} (3{sup {sm bullet}+}). The experimental findings are supported by ab initio MO calculations.

Synthesis and 13C NMR of (trifluoromethyl)hydroxypyrazoles

AbstractReaction of ethyl 4,4,4‐trifluoroacetoacetate with methylhydrazine produced not only the previously reported 5‐hydroxy‐3‐(trifluoromethyl)pyrazole 1 but also its unknown isomer the 3‐hydroxy‐5‐(trifluoromethyl)pyrazole 4. The structure assignments are established based on 13C nmr spectra. Compound 1 was converted to 5‐chloro‐3‐(trifluoromethyl)pyrazolecarboxylic acid 3 in two steps.

Stereochemistry of nitrogen heterocycles. 68. Stereochemistry of 2,5-dimethyl-4-piperidone, 2,5-dimethyl-4-piperidol, and their N-benzoyl derivatives

The isomers of 1-benzoyl-2,5-dimethyl-4-piperidone were obtained and equilibrated (89.8% cis ⇄ 10.2% trans isomer, preferred conformations 2a, 5e, and 2a, 5a). The position of the equilibrium between the isomers of 2,5-dimethyl-4-piperidone was determined by two independent methods (89.5% trans ⇄ 10.5% cis isomer). The differences in the free energies of the isomers, the conformational energy of the Β-CH3 group, and the energy of syn-axial 1,3-interaction between the CH and the unshared electron pair were calculated; the decrease in the conformational energy of the Β-methyl group in the series of piperidine (1.6), 4-piperidone (1.47), and N-acyl-4-piperidone (1.28 kcal/mole) was explained by the successive weakening of the repulsive interaction between the Β-CH3 group and the n-pair of the nitrogen as a result of the flattening of the ring and of the conjugation between the free electron pair of the nitrogen and the π electrons of the acyl carbonyl group. The last previously unknown fourth isomer of 2,5-dimethyl-4-piperidol, which exists in the 2e,4a,5a conformation, was obtained by the reduction of cis-1-benzoyl-2,5-dimethyl-4-piperidone followed by debenzoylation. In contrast to the secondary amine, its N-benzoyl- and N-benzyl-substituted derivatives exist in the alternative 2a,4e,5e conformation. The configurations and conformations of the isomers were determined by means of the IR and NMR spectra.

Structures of the tetrahydrogenated menaquinones fromActinomadura angiospora, Faenia rectivirgula, andSaccharothrix australiensis

The structures of the tetrahydrogenated menaquinones fromActinomadura angiospora, Faenia rectivirgula, andSaccharothrix australiensis were determined by mass spectrometry and proton nuclear magnetic resonance spectrometry. The positions of saturation of the tetrahydrogenated menaquinones fromFaenia rectivirgula andSaccharothrix australiensis were units II plus III (counting from the ring system), whereas that ofActinomadura angiospora had units III and VIII hydrogenated. The tetrahydrogenated menaquinones fromFaenia rectivirgula andSaccharothrix australiensis are similar to those characterized from other Gram-positive taxa to date, whereas that fromActinomadura angiospora represents a hitherto unknown isomer.

Fast time-resolved IR spectroscopy. The photolysis of trans-[.eta.-C5Me5Fe(CO)2]2, the detection of cis-[.eta.-C5Me5Fe(CO)2]2, and the activation energy for cis to trans isomerization

Fast (..mu..s) time-resolved IR spectroscopy is used to follow the UV flash photolysis of trans-(Cp*Fe(CO)/sub 2/)/sub 2/(Cp* = etaC/sub 5/Me/sub 5/) in cyclohexane solution at room temperature. The primary photoproducts observed on this time scale are Cp*Fe(CO)/sub 2/ (major product) and Cp*Fe(..mu..-CO)/sub 3/FeCp* (minor product). The Cp*Fe(CO)/sub 2/ radicals dimerize to reform both the cis and trans isomers of (Cp*Fe(CO)/sub 2/)/sub 2/. The previously unknown cis isomer decays into the thermodynamically more stable trans isomer by a first-order process with activation energy 68 +/- 5 kJ mol/sup -1/.

Vibrational spectra and normal coordinate analysis of CF 3 compounds : Part XLVI. Synthesis, vibrational spectra, normal coordinate analysis and electron diffraction investigation of the cis isomer of hexafluoroazomethane

The hitherto unknown cis isomer of hexafluoroazomethane has been prepared by the reaction of CICN with AgF 2 under mild conditions. It isomerizes rapidly to the trans isomer when exposed to daylight, but is stable in the dark. The compound has been characterized by NMR and UV spectra. Infrared and Raman spectra have been recorded and assigned with the assistance of a normal coordinate analysis. The molecular structure of cis-CF 3NNCF 3 has been determined by gas phase electron diffraction, and a planar CNNC skeleton, d(NN) 1.229(8) Å, d(CN) 1.494(5) Å, and ∠NNC 122.1(8)° has been established. Compared with the trans isomer, the higher sterc strain due to F⋯F repulsions is released by a ∮.03 Å d(CN) lengthening and a 9° widening of the NNC angle.

NMR-electrolysis combined method (NMREL). Basic principles and some applications

Electrolysis conducted directly in a sample tube of an NMR spectrometer (NMREL) has been applied to various kinetic and analytical problems and to the study of the mechanisms of electroorganic reactions. The kinetics of anion-radical decay was studied for benzoquinone, ubiquinone Q 0, p-nitrotoluene, 4-nitroorthoxylene, and p-toluenenitrile; and kinetics of electron transfer was studied for the symmetric system: M −· T + M ⇌ M + M −·. Three NMREL techniques were tested to find the rate constants in the series of the compounds. Asymmetric electron transfer M −· + N ⇌ M + N −· was studied for endoergic reactions leading to both stable N −· and unstable N −· and the electron transfer and N −·-decay rate constants were estimated. An analytical treatment has been proposed based on NMR signal broadening due to electron exchange, brought about by an electrochemical reaction. The potentialities of this treatment were demonstrated by the analysis of a 3-nitroorthoxylene + xylene mixture: the presence of xylene was detected accurately even for 20-fold excess of the other component. For electroreduction of vitamin A in DMF- d 6, NMREL has found an earlier unknown axerophtene isomer along with the usual product.

Reductive cleavage of the 9,10-bond in 11-oxygenated steroids: a new method for the partial synthesis of the vitamin D skeleton

11-Oxygenated steroids with a ring A dienone system are reduced in non-protic media with cleavage of the 9,10-bond, and the resulting 9,10-secosteriods (2) or (5) were converted into 9,10-secocholesta-1,3,5(10)-triene-3-ol (12), an unknown isomer of cholecalciferol (vitamin D3).

Alpha-decay properties ofFr205,206,207,208: Identification ofFrm206

Alpha-particle and $\ensuremath{\gamma}$-ray spectral measurements were made for $^{205\ensuremath{-}208}\mathrm{Fr}$. A new $\ensuremath{\alpha}$ emitter (${T}_{\frac{1}{2}}=0.7\ifmmode\pm\else\textpm\fi{}0.1$ sec and ${E}_{\ensuremath{\alpha}}=6.930\ifmmode\pm\else\textpm\fi{}0.005$ MeV) was observed and identified with the decay of a previously unknown isomer in $^{206}\mathrm{Fr}$. From the $\ensuremath{\alpha}$ particle and $\ensuremath{\gamma}$ ray intensities, $\ensuremath{\alpha}$ decay branching ratios were deduced for $^{205\ensuremath{-}208}\mathrm{Fr}$ utilizing available information concerning the nuclides' (electron capture + positron) decay properties. Reduced widths were calculated and compared with those of neighboring nuclei.RADIOACTIVITY $^{205,206,207,208}\mathrm{Fr}$, measured ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}$, ${E}_{\ensuremath{\alpha}}$, ${I}_{\ensuremath{\alpha}}$; deduced $\ensuremath{\alpha}$-branching ratios; identified $^{206}\mathrm{Fr}^{m}$. Mass separation.

Synthesis of the ladybug alkaloids (±)-propyleine and (±)-isopropyleine. Modification of the published structure of propyleine

The total syntheses of the ladybug alkaloids (±)-propyleine and (±)-isopropyleine are described. Evidence that the alkaloid propyleine is actually a rapidly interconverting mixture of propyleine and a previously unknown isomer isopropyleine is presented.

Structures and spectra of the isomers HNCO, HOCN, HONC, and HCNO from ab initio quantum mechanical calculations

Ab initio calculations are reported on the equilibrium geometries, dipole moments, rotational constants, and force constants of the isomers HOCN, HNCO, HCNO, and HONC. The most accurate calculations on the unknown isomer HOCN lead to a predicted geometry of R OH = 0.96 ± 0.005 A ̊ , R OC = 1.302 ± 0.007 A ̊ , R CN = 1.153 ± 0.007 A ̊ , 〈HOC = 109 ± 1°, 〈OCN = 177 ± 1° in a planar trans conformation. This structure has rotational constants B = 10.64 ± 0.12 GHz and C = 10.47 ± 0.12 GHz, accurate enough to encourage a radio search for this species in dense interstellar clouds as well as experiments designed for terrestrial identification. In much less accurate calculations, not extensive enough to provide error bars, an approximate structure for the other unknown isomer, HONC, is R HO = 1.05 A ̊ , R ON = 1.14 A ̊ , R NC = 1.26 A ̊ , 〈HON = 109°, 〈ONC = 172.5°, in a planar trans conformation. The calculated structures of HNCO and HCNO are in good agreement with experiment. The nonlinearity of the heavy-atom axis is firmly established for HOCN, HNCO, and HONC. In all of the molecules the angle of the hydrogen-bending motion is strongly coupled to the angle formed by the heavy atoms. These hydrogen-bending motions are discussed in detail, especially the potential for inversion in HNCO and the quasi-linear potential in HCNO.

Pigments of the Porifera: Demospongiae. I. Carotenoids of Axinella verrucosa

Studies were made of some carotenoids extracted from Axinella verrucosa (O. schmidt) (Porifera: Demospongiae), a species which occurs in the Gulf of Naples. α-carotene, renieratene, isorenieratene, and an unknown isomer of renieratene have been isolated.

Hashish : Synthesis of (+)-Δ 4-tetrahydrocannabinol

Alkylation of olivetol with p-menth-4-en-3,8-diol ( 3) afforded Δ 4-tetrahydrocannabinol, an unknown isomer of the hashish active constituent Δ 1-THC, together with the “abnormal” isomer. The attack of olivetol onto the positions 3 and 5 and resp. 3 and 8 of ( 3) yielded derivatives of 2,6-methano-2H,1-benzoxocin-7-ol and new 2,3,4,4a-tetrahydroxanthenes.

Total synthesis of (±)-marmin and related coumarin monoterpenes

(±)-Marmin ( 1a) and its cis isomer ( 1b) have been synthesized from 7-neranyloxycoumarin ( 10a) and 7-neryloxycoumarin ( 10b), respectively, by way of the corresponding terminal epoxides 2a and 2a. The geometrically and positionally specific route confirms the structure and, in particular, the irons double bond geometry of natural (+)-marmin and epoxide (+)- 2a. The latter, upon reaction with stannic chloride in benzene gives rise to the naturally occurring cyclic monoterpene coumarin types 3 and 6 as well as the previously unknown double-bond isomer 13.

The Aroma of Hops III. The Occurrence of Diterpenes in Hop Oil

AbstractTwo diterpene hydrocarbons have been isolated from hop oil. One is camphorene, the other is a hitherto unknown camphorene isomer. These terpene hydrocarbons, now called para and meta camphorene were not signalled before in hop oil.