Systematische untersuchungen über das verhalten von organozinn-verbindungen gegenüber flüssigem schwefeldioxid VI. Zum mechanismus der SO2-einschiebung in die zinn—kohlenstoff-bindung

SO₂-insertion reactions of tetraorganostannanes in liquid sulphur dioxide proceed through an open transition state. Arguments favouring an S_E2 mechanism are presented on the basis of investigations on tetraalkyl-, tetraaryl-, and tetraalkenyl-stannanes, mixed substituted and perfluorinated tetraorganotin compounds as well as organotin halides.     

Systematische untersuchungen über das verhalten von organozinnverbindungen gegenüber flüssigem schwefeldioxid III. SO2-disproportionierung bei einschiebungsreaktionen an tetraalkylstannanen

When liquid SO₂ is allowed to react with the tetraalkyltin compounds (CH₃)₄Sn and (C₂H₅)₄Sn at 60°, disproportionation of sulfur takes place resulting in the formation of the corresponding bis(trialyltin) sulfates, [R₃Sn]₂SO₄, and alkanethiosulfonic acid S-alkyl esters, RSO₂SR (R = CH₃, C₂H₅). The course of the reaction is discussed.     

Systematische untersuchungen über das Verhalten von organozinnverbindungen gegenüber flüssigem schwefeldioxid IV. Reaktionen von alkenylstannanen mit flüssigem SO2

The behaviour of alkenyltin compounds toward liquid SO₂ under different conditions is investigated in this paper. Tetravinyltin gives a monosulfinate at low temperatures and a disulfinate at and above room temperature according to eqns. (1) and (2), respectively. Tetraallyltin always forms the unstable disulfinate which in the course of time decomposes into a polymeric product of composition (C₃H₅)₂Sn · 1.5 SO₂ according to eqn. (3). The trialkenyltin chlorides, R₃SnCl (R = vinyl, allyl) at room temperature take up 1 and 2 moles of SO₂, respectively, forming the corresponding insertion products R₂(RSO₂)SnCl [R = vinyl, eqn. (7)] and R(RSO₂)₂SnCl [R = allyl, eqn. (8)]. Divinyltin dichloride does not react with liquid SO₂ even at a temperature as high as 70°. Alkenyltin sulfinates are also obtained by metathetical reactions between alkenyltin chlorides and sodium sulfinates [eqns. (11) and (12)]. The IR and Raman spectra of the newly prepared compounds are discussed.     

Systematische untersuchungen über das verhalten von organozinn-verbindungen gegenüber flüssigem schwefeldioxid : I. Reaktionen von tetraalkylstannanen mit flüssigem SO2

The SO₂ insertion into teraalkyltin compounds, R₄Sn (R = CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉), was investigated depending on the presence of water, reaction temperature and reaction time. According to eqns. (1)–(5), the reaction products R₃SnO₂SR, R₂Sn(O₂SR)₂, (R₃Sn)₂SO₄, R₂SnSO₄ and R₂SnSO₃ were isolated. Especially; at low temperatures (<0°) the following order of decreasing reactivity of the teraorganostannanes toward SO₂ is established: R = C₂H₅ > CH₃ > n-C₃H₇ > n-C₄H₉ > i-C₃H₇     

Systematische untersuchungen über das verhalten von organozinn-verbindungen gegenüber flüssigem schwefel-dioxid : V. Reaktionen von perfluorierten organozinn-derivaten Mit SO2

To get a clear conception of the mechanism of SO₂ insertion into tin-carbon bonds, reactions of perfluorinated organotin compounds with liquid SO₂ were studied in detail. Of the pure perfluoroorgano derivativs (C₆F₅)₄Sn is completely inert, while (CF₂CF)₄Sn shows a slight reactivity. In mixed tetraorganotin compounds like (C₆H₅)₃SnC₆F₅ and (C₆H₅)₃SnCFCF₂ insertion takes place only into the tinphenyl bond. The case of (CH₃)₃SnC₆F₅ is interesting in so far that the presence of the C₆F₅ group deactivates the whole molecule towards attack by SO₂. Possible reasons for this effect are discussed. We also report on the synthesis of triphenyltin perfluoromethanesulfinate, (C₆H₅)₃SnO₂-SCF₃.     

Zur Kenntnis der Chemie der Metallcarbonyle und der Cyanokomplexe in flüssigem Ammoniak. XXXI. Über die Reaktionen von kationischen η5-Cyclopentadienylmolybdäncarbonyl-Komplexen mit flüssigem Ammoniak

The Chemistry of Metal Carbonyls and Cyano Complexes in Liquid Ammonia. XXXI. On the Reactions of Cationic η⁵-Cyclopentadienyl-molybdenumcarbonyl Complexes with Liquid Ammonia Depending on the reaction conditions, the cationic complexes [η⁵-C₅H₅Mo(CO)₃L]⁺ (L = NH₃, PPh₃, CO) react with liquid ammonia according to: The characteristics and reactivities of the new carbomoyl derivatives are described.     

Reaktionen von Kohlensuboxid. Teil I. Die Reaktionen von H-Atomen mit C3O2

Ohne Zusammenfassung     

Reaktionen von Kohlensuboxid Teil II. Die Reaktion von OH-Radikalen mit C3O2 und mit Keten

Ohne Zusammenfassung     

Reaktionen von Glutaminsäuredimethylester im Massenspektrometer. 21. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

The mass spectral fragmentation of dimethyl glutamate ( 1 ) and its deuterated derivatives 1a , 1b and 1c has been investigated. By loss of a methoxycarbonyl group from the molecular ion an ion of m/e 116 is generated. The latter splits off methanol (m*), the resulting fragment of m/e 84 giving raise to the base peak of the spectrum. Only part of the hydrogen transferred to the leaving group originates from thc amino group, as was suggested earlier [2] [3]. Basing on experiments with deuterated compounds we propose an additional mechanism for the reaction, i.e. hydrogen transfer from C(3) to methoxyl. The fragment generated by both processes is most likely to be a pyrrolinonium ion. Thermal side reactions in the mass spectrometer (formation of pyroglutamic acid ester) followed by fragmentation may lead to the same ion. – The mechanisms discussed are supported by the mass spectral fragmentation of N-acetyl-glutamic acid diesters 3 , 3a , 3b and 3d and of the N, N-dimethyl derivatives 4 and 4a . – The fragmentation reactions investigated are similar to some of 1,3-trimethylenediamine derivatives [7]. This means that there are parallels in the mass spectral fragmentation of difunctional compounds irrespective of the nature of the functional groups.     

Photoinduzierte Reaktionen von 3-Phenyl-2H-azirinen mit Carbonsäureestern 40. Mitteilung über Photoreaktionen

Irradiation (280–350 nm light) of a benzene solution of 3-phenyl-2H-azirines 1a – e in the presence of carboxylate esters, whose carbonyl groups are activated by electron withdrawing groups situated in the acyl or alkyl moiety, produces 5-alkoxy-3-oxazolines (Tab. 1 and 4, Scheme 2) isolated in 18–82% yield. These heterocycles undoubtedly originate by regiospecific addition of the ester carbonyl group to the azirine-derived benzonitrile-methylide ‘dipole’ (Scheme 1). The 5-(2,′ 2′, 2′-trifluoroethoxy)-3-oxazolines, derived from 2′, 2′, 2′-trifluoroethyl carboxylic esters, on treatment with methanolic hydrogen chloride at low concentration, are smoothly transformed into the corresponding 5-methoxy-3-oxazolines (e.g. 16 → 17 , Tab. 5). Utilizing this process, various hitherto relatively unknown 9. 5-alkoxy-3-oxazolines become accessible. The constitution of the adducts is based essentially on spectral data. The structure of trans-5-methoxy-2,4-diphenyl-5-trifluoromethyl-3-oxazoline (trans- 14 ), the addition product of methyl trifluoroacetate and the benzonitrile-benzylide from 2,3-diphenyl-2H-azirine ( 1d ), was determined by X-ray crystallography (Section 5). Benzonitrile-isopropylide ( 22 ), resulting from the photochemical transformation of 2,2-dimethyl-3-phenyl-2H-azirine ( 1a ), also reacts with S-methyl thiobenzoate to give 2,2-dimethyl-5-methylthio-4,5-diphenyl-3-oxazoline ( 26 ). Ethyl cyanoacetate protonates predominantly the dipolar species derived from 1a at the nitrile C-atom and yields after work-up ethyl α-cyano-cinnamate ( 29 ) and ethyl isopropylidene-cyanoacetate ( 30 ) (Scheme 4). The relative rate of addition (k_rel) of benzonitrile-isopropylide ( 22 ) to methyl α-haloacetates and dimethyl oxalate was determined by competition experiments (Section 6). Log k_rel correlated satisfactorily (r = 0.97) with the pK_a of the acide derived from the ester reactant: log k_rel = ? 1.72 pK_a + 2.58 or with Taft's substituent constants σ*: log k_rel = 2.06 σ* ? 4.11 [k_rel(methyl dichloroacetate) = 1; Section 7.1]. On the basis of the results obtained, the mode of reaction of the so-called benzonitrile-methylide ‘dipole’ is discussed and a model for the transition state of addition of ester-carbonyl groups is proposed that accounts for the observed regiospecifity and steroselectivity.     

Reaktionen von Bleitetraacetat mit alicyclischen Alkoholen,III. Cyclopropyl- und Cyclobutylcarbinole. 18. Mitteilung über Reaktionen mit Bleitetraacetat

When treated with lead tetraacetate, cyclopropylcarbinol and cyclopropylmethylcarbinol do not give β-fragmentation products resulting from the intermediate formation of cyclopropyl radicals; however, cyclopropylmethylcarbinol affords a small amount of a fragmentation product which arises from C_α? C_β bond cleavage involving removal of a methyl radical. In contrast, cyclobutylcarbinol undergoes β-fragmentation in 18% yield with formation of both the unrearranged cyclobutyl acetate and the rearranged cyclopropylmethyl acetate. These results suggest the following order of increasing radical stability: cyclopropyl < methyl < cyclobutyl, whereas the isolation of the isomeric fragmentation acetates in the lead tetraacetate reaction of cyclobutylcarbinol represents further evidence that in the β-fragmentation process the initially produced carbon radical fragment is in major part oxidized to the corresponding carbonium ion before final product formation.     

Elektrochemische Untersuchungen über das enantiomerenselektive Verhalten von chiralen Ionophoren in flüssigen Membranen

Electrochemical Investigations of the Enantiomer Selectivity of Chiral Ionophores in Liquid Membranes The enantiomer selectivity of a series of chiral neutral ionophores was investigated by electrochemical methods using ionophore-solvent-polymer membranes and chiral ammonium salts as substrates. The potentiometrically determined enantiomer selectivities are in good agreement with the results of electrodialytic transport studies.     

Die Cyclocopolymerisation von Diallyl-Verbindungen und SO2. 5. Mitt. Copolymerisation einiger 4-substituierter 1,6-Heptadien-Derivate mit SO2

Ohne Zusammenfassung     

Darstellung und eigenschaften von und reaktionen mit metallhaltigen heterocyclen XXII. Synthese, eigenschaften und kristallstruktur des sechsgliedrigen heterocyclus [(h-C5H5)NiSP(CH3)2]2 und dessen verhalten gegenüber alkinen

The heterocycle [(h⁵-C₅H₅)NiSP(CH₃)₂]₂ is obtained by treatment of (h⁵-C₅H₅)₂Ni with (CH₃)₂HPS in toluene and crystallizes monoclinic in the space group P2₁/c with Z = 2. The highly reactive three-membered ring (h⁵-C₅H₅)$\text{NiSP}$(CH₃)₂ which is a dissociation product of [(h⁵-C₅H₅)NiSP(CH₃)₂]₂, can be trapped with bis(methoxycarbonyl)acetylene to give the PS containing nickelacyclopentadiene (h⁵-C₅H₅)$\text{NiSP(CH}{}_3\text{)}{}_2\text{CRC}$R (R  CO₂CH₃).     

Metallkomplexe mit anionischen Liganden von Elementen der 4. Hauptgruppe. VII. Über das Substitutionsverhalten von Carbonylnitrosyl-und Nitrosyltrifluorphosphin-Übergangsmetallkomplexen gegenüber Trichlorstannid-Ionen

Metal Complexes with Anionic Ligands of Elements of the Main Group IV. VII(¹) Substitution Reactions of Carbonylnitrosyl and Nitrosyltrifluorophosphine Transition Metal Complexes with Trichlorostannid L-substitution by [SnCl₃]^? occurs if the nitrosyl complexes Co(NO)L₃ and Fe(NO)₂L₂ (L = CO or PF₃) are reacted with [N(C₂H₅)₄][SnCl₃] thermically in tetrahydrofuran as well as photochemically induced in methylenechloride. The complexes Co(NO)L₃ yield the mono-substitution products [N(C₂H₅)₄][Co(NO)L₂SnCl₃], with the iron compounds Fe(NO)₂L₂ only the disubstituted derivative [N(C₂H₅)₄]₂[Fe(NO)₂(SnCl₃)₂] can be isolated. On the other hand CO substitution at (π-C₅H₅)Mo(NO)(CO)₂ by UV irradiation did not suceed both with [SnCl₃]^? and with PF₃. From the IR-spectroscopic data a leastly with PCl₃ comparable π-acceptor ability is derived for the trichlorostannido ligand.     

Das Reaktionsverhalten von Cp2NbCl2 gegenüber WF6—Struktur von [Cp2NbCl2]4[WF6]2[WCl6]

The oxidation of Cp₂NbCl₂ with pure WF₆ in SO₂ solution yielded the cationic metallocene species [Cp₂NbCl₂]⁺[WF₆]⁻ essentially in quantitative yield. The same reaction carried out in the presence of either equimolar amounts or a two-fold excess of HCN led to the preparation of the new niobocenium salt [Cp₂NbCl₂]₄⁺[WF₆]²⁻ which was studied by single crystal X-ray diffraction. This compound represents the first example of a structurally characterized metallocene-WF₆⁻ complex, and crystallizes in the tetragonal system: space group, P4₁2₁2(No. 92), a = 11.083(8) Å, c = 48.285 (9) Å; Z = 8; R = 0.0759, R_W = 0.0841. ab]Die Oxidation von Cp₂NbCl₂ mit reinem WF₆ führt in SO₂-Lösung zur Synthese von [Cp₂NbCl₂ ]⁺[WF₆]⁻ in nahezu quantitativer Ausbeute. Die analoge Reaktion führt unter Anwesenheit der äquimolaren Menge oder eines zweifachen Überschusses an HCN zur Ausbildung des Niobocenium-Komplexsalzes [Cp₂NbCl₂]₄⁺ [WF₆]₂⁻[WCl₆]²⁻, von dem eine Röntgenstrukturanalyse angefertigt wurde. Diese Verbindung repräsentiert den ersten structurell charakterisierten Vertreter eines Metallocen-WF₆⁻-Komplexes und kristallisiert im tetragonalen System: Raumgruppe P4₁2₁2 (Nr. 92), a = 11.083(8) Å, c = 48.285(9) Å; Z = 8; R = 0.0759, R_W = 0.0841. kw]Niobium; X-ray diffraction; Oxidation; Metallocenes     

Thermische Reaktionen im Massenspektrometer Modellreaktionen zur Untersuchung thermischer Umalkylierungen. 11. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

During the introduction of an organic compound into the mass spectrometer thermal reactions can take place before the ionisation process, thus changing the structure of the compound. On the basis of known experimental results the following reactions, which are independent of electron bombardment are discussed: decarboxylation, dehydration, loss of alcohols, decarbonylation, decomposition of carboxylic esters, retro aldol reaction and similar processes, retro DIELS -ALDER reaction, isomerisation, disproportionation, hydrogenolysis-dehydrogenolysis, transalkylation, dimerisation, and pyrolysis of quaternary nitrogen containing compounds. Finally, the results of novel model reactions concerning thermal transalkylation are discussed.     

Reaktionen von N4+-Clusterionen mit O2 und CH4

Ohne Zusammenfassung     

Über Chalkogenocarbonate. XL. Untersuchungen über Dithiocarbamidsäure SC(SH)(NH2) 4. Reaktionen von Dithiocarbamaten mit Oxalylchlorid

2-Thioxo-1,3-thiazolidine-4,5-dione and some derivatives of this compound have been prepared by interaction of dithiocarbamic acid and N-substituted dithiocarbamates with oxalychloride (formula see ?Inhaltsübersicht”?). The chemical and physical properties of this new class of compounds are described.