Isomerisierung und Ringinversion von Tribenzaspiro[5.5]undecaphanen

For the two possible ring inversions in tribenzaspiro[5.5]undecaphanes—corresponding to the isomerizations79 and97 resp.—no mutual influence is found. Thus the degenerate isomerizations (topomerizations)77 and99 can proceedvia two consecutive (non-concerted) reversals. A ring inversion path similar to that for [2.2]metacyclophane (1) is postulated. The considerable ease of the isomerization of9 as compared to1 can be understood on the basis of thermodynamic arguments.Moreover it is confirmed that the free enthalpy difference G ₃₆₀=3.84 kcal/mol of7 and9 at equilibrium originates almost entirely from the different stabilities of boat and chair shaped benzene rings.These conclusions are drawn from a kinetic study of the thermal isomerization of9 and equilibration experiments in comparison with the corresponding data of1. The activation parameters for the process97 are: G _360isom ^A =26.52 kcal/mole, H _isom ^A =25.35 kcal/mole, S _isom ^A =–3.28 cal/deg·mole (isomerization) and G _360inv ^A =27.03 kcal/mole, H _inv ^A =25.35 kcal/mole, S _inv ^A =–4.67 cal/deg·mol (ring reversal); the corresponding data for the degenerate isomerizations of7 and9—identical with those for the ring reversal in7—were deduced to be G _360inv ^B =30.87 kcal/mole, H _inv ^B =27.50 kcal/mole and S _inv ^B =–9.5 cal/deg·mole.

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Mit 7 Abbildungen

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Herrn Prof.H. Nowotny mit besten Wünschen zum 65. Geburtstag gewidmet.

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7. Mitt.:H. Keller, E. Langer undH. Lehner, Mh. Chem.107, 949 (1976).     

Monolayer vanadia on titania systems from alkoxide precursors. Part II. Activity in primary alcohol oxidation

The activity of V⁵⁺ ion monolayers supported on anatase, rutile and anatase-rutile mixed carrier and of bulk V₂O₅ has been studied in ethanol and n-propanol oxidation. Catalysts exhibited remarkable activity in aldehyde formation. Reaction selectivity was diminished by low temperature combustion.

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V⁵⁺, , -, V₂O₅ -. . .

     

Synthetic studies in the field of chlorobium chlorophyll

By the condensation of -halogenomethyl derivatives of pyrroles with -unsubstituted pyrroles the synthesis of the following unsymmetrical dipyrrolylmethanes has been effected: 5-benzyloxycarbonyl-5-ethoxycarbonyl-3, 3-di(-methoxycarbonylethyl)-4,4-dimethyl-2,2-dipyrrolylmethane (IIIa), 5-benzyloxycarbonyl-5-ethoxycarbonyl-3-(-methoxycarbonylethyl)-4, 4-diniethyl-3-n-propyl-2,2-dipyrrolylmethane(IIIb), 3-acetyl-5-benzyloxycarbonyl-4-ethyl-5-methoxycarbonyl-3, 4-dimethyl-2,2-dipyrrolylmethane (IIIc), and 3-bromo-5-benzyloxycarbonyl-4-ethyl-5-methoxycarbonyl-3, 4-dimethyl-2,2-dipyrrolylmethane (IIId). Hydrogenation of the unsymmetrical dipyrrolylmethanes IIIa, b, c, and d has given the corresponding monocarboxylic acids IVa, b, c, and d. The formylation of the dipyrrolylmethanemonocarboxylic acid IVa has given 5-ethoxycarbonyl-5-formyl-3,3-di(-methoxycarbonylethyl)-4, 4-dimethyl-2,2-dipyrrolylmethane (V).For communication II, see [1].Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 8, pp. 1045–1047, August, 1970.     

Hydroxystilbenes of the inner bark of Pinus sibirica

Summary In addition to pinostilbene and resveratrol, two new stilbene glycosides have been isolated from the phloem ofPinus sibirica R. Mayr, and their structures have been established as 3,4-dihydroxy-5-methoxy-stilbene 4--D-glycopyranoside (pinostilbenoside) and 3,4,5-trihydroxystilbene 4--D-glycopyranoside (resveratroloside).Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 677–682, November–December, 1975.     

Formation of N-butane in the pyrolysis of ethylene [1]

Yields of n-C₄H₁₀ have been measured from the flow pyrolysis of C₂H₄ at 897 (±7) K. From 77 to 720 Torr the order of n-C₄H₁₀ formation was found to be 2.0±0.3 The rate constant for the reaction, was estimated to be 2.4(±0.6)×10^–4l mol^–1s^–1.

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-C₄H₁₀ C₂H₄ 897 (±7) . -C₄H₁₀ 77 720 2.0±0.3. 2C₂H₄C₂H₃+C₂H₅ 2,4 (±0,6)×10^{–4 –1–1}.

     

Thermolysis of complex cyanides,XX. thermal decomposition of Zn[Fe (CN)5NO] · 3H2O and identification of the products of decomposition

The thermal decomposition of Zn[Fe (CN)₅NO] was studied by thermal analysis, IR and Mössbauer spectroscopy. The experimental results showed that the decomposition starts with cyanogen formation, giving a tetracoordinated cyano-nitrosyl intermediate. The NO ligand elimination is followed by a structural rearrangement to Fe[Zn (CN)₄].

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Zusammenfassung Die thermische Zersetzung von Zn[Fe (CN)₅NO] wurde derivatographisch und mittels IR- und Mössbauer-Spektroskopie untersucht. Die Zersetzung beginnt mit Dizyanentwicklung unter Bildung eines tetrakoordinierten Cyano-nitrosyl-Intermediärs. Der Eliminierung des NO-Liganden folgt eine zu Fe[Zn (CN)₄] führende strukturelle Umordnung.

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Zn[Fe(CN)₅NO] , ë . , , - . NO , Fe[Zn(CN)₄].

     

Die Ringinversions-Barriere in [2.2]Metacyclophan

From racemization studies on optically active [2.2]metacyclophanes substituted in position 4, the parameters of activation for the inversion of the tenmembered ring were found to be: G ₄₂₃ =31.5 kcal/mole, H =27.5 kcal/mole and S =–10 Cl/mole.Racemization does not occurvia bond forming or breaking; the value for the inversion barrier is not affected by substituents in position 4 and therefore corresponds to the value of unsubstituted [2.2]metacyclophane, whereas substituents in the bridge exert a distinct influence. These results can easily be explained on the basis of the isoconformational concept.

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Mit 5 Abbildungen

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Herrn Prof. Dr.O. Hoffmann-Ostenhof mit besten Wünschen zum 60. Geburtstag gewidmet.     

Synthesis and Crystal Structures of Copper(I) Complexes with N-Allylhexamethylenetetraminium Chloride Obtained in Different Acidic Media

The crystals of [(CH₂)₆N₄(C₃H₅)]Cu₂Cl₃ (I), [(CH₂)₆N₄(C₃H₅)]Cu₂Cl₃ (II), and [(CH₂)₆N₄(C₃H₅)]CuCl₂ (III) complexes were electrochemically synthesized (ac) from CuCl₂ · 2H₂O and N-allylhexamethylenetetraminium chloride in ethanol solutions at pH 6, 4.5, and 3. Their structures were determined using X-ray diffraction analysis (DARCh diffractometer, MoK radiation, /2 scan mode). Complex Icrystallizes in the monoclinic system: space group A2/a, a = 24.812(6) Å, b = 8.855(3) Å, c = 12.080(2) Å, = 89.21(3)°, and Z = 8. Complex II crystallizes in the triclinic system: space group P , a = 7.618(2) Å, b = 7.048(2) Å, c = 13.150(3) Å, = 97.50(2)°, = 92.70(2)°, = 100.74(2)°, and Z = 2. The crystals of complex III are orthorhombic: space group Pmn2₁, a = 7.478(2) Å, b = 8.827(2) Å, c = 9.662(3) Å, Z = 2. The organic cation in complex I acts as a tridentate ,,-ligand; that in complex II, as a bidentate ,-ligand. In complex III, the organic cation is involved in coordination with the copper(I) atom only through one nitrogen atom.     

NMR Study of Non-freezing Water in Protein-Modified Carbon Adsorbents

Temperature dependences of ¹H NMR spin–spin relaxation were studied for the non-freezing water at the surface of carbon matrices modified with proteins (human serum albumin (HSA) and mouse immunoglobulin (MIG)) in the presence of water-soluble carbodiimide. The entropy, S , and enthalpy, H , values characterizing molecular mobility in non-freezing water were estimated. The compensation effect was observed for all modified samples, which is well approximated by the linear dependence of the type H = T ₀S + H ₀. The compensation temperature T ₀ = 231 ± 33 corresponds to such a state of non-freezing water, when the effect of modifying additives on the isobaric potential of molecular mobility activation in the non-freezing water, G , is minimal. The G has approximately constant value equal to H ₀ = 24.2 ± 0.5 kJ/mol. Modification of the base carbon matrix with MIG protein results in higher structurization of the non-freezing water, whereas HSA reduces this structurization. The observed effects are explained in terms of the hydration of modifying agents and also by the peculiarities of their location on the surface of carbon adsorbent.     

Relative rate coefficients of⊙OH-radical interactions in nonaqueous medium

For measuring relative rate coefficients of OH-radical reactions in organic media a competitive method has been used. As reference, 2-propanol was applied. For ethylbenzene and 1-phenylethanol the rate coefficients of H-abstraction relative to that of 2-propanol are 1.4 and 2.9, respectively.

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OH. 2-. H 1-, 2-, 1,4 2,9, .

     

A differential scanning calorimetric study of phase transitions in Na2SO4

The results of a differential scanning calorimetric study of the transitions involving the various polymorphs of Na₂SO₄ are described. They are discussed in the light of their crystal structures and also in conjunction with more recently published data regarding these transitions.

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Zusammenfassung Die Ergebnisse einer mit Differentialabtastkalorimetrie durchgeführten Untersuchung der Übergänge verschiedener Polymorphe von Na₂SO₄ werden beschrieben. Sie werden im Hinblick ihrer Kristallstrukturen und im Zusammenhang mit verschiedenen unlängst veröffentlichten Daten bezüglich dieser Übergänge diskutiert.

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Résumé On décrit les résultats de l'étude, effectuée par analyse calorimétrique différentielle, des transitions mettant en jeu les diverses formes polymorphes de Na₂SO₄. Les résultats sont discutés en tenant compte des données récemment publiées sur ces transitions.

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. , .

     

Relative reactivities of phosphites in reactions with hydrotrioxides

Studies of the interaction of hydrotrioxides ROOOH of ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1,1-dimetoxyethane, 1,1-diethoxyethane, benzaldehyde and tetrahydrofuran with trimethyl triisopropyl, tributyl, triallyl, triphenyl and tri-o-chresyl phosphites (RO)₃P have revealed that in mild conditions ROOOH rapidly and selectively oxidizes (RO)₃P to the corresponding phosphates. The reaction stoichiometry has been established. Aromatic phosphites are shown to be of inferior reactivity to ROOOH as compared with aliphatic phosphites.

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, 1-, 2-, 1-, 2-, 1,1-, 1,1-, -, -, -, -, -, -, -- (RO)₃P. ROOOH (RO)₃P . . , ROOOH .

     

Combination and disproportionation of methyl and 2-propyl radicals with 1,1,2-trimethylallyl radicals

The combinations and disproportionations of the CH₃ and 2-propyl (iP) radicals with the 1,1,2-trimethylallyl (TMA) radical have been studied in the gas phase in the temperature interval of 389–451 K and 490–540 K, respectively. For the ratios of the terminal (t) and non-terminal (n) combinations of the CH₃ and iP radicals with the TMA radical, values of 1.9±0.1 and 2.84±±0.10 were obtained, respectively. The ratios of the tt and tn and nn to tn combinations of the TMA radical were 1.59 and 0.46, respectively. The disproportionation-combination rations were (CH₃ , TMA)=0.022±±0.012 and (iP, TMA)=0.026±0.011.

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CH ₃ 2- (iP) 1,1,2- (TMA) : 389–451 K 490–540 K. (t) (n) TMA 1,9±0,1 2,84±0,10, . tt tn nn tn TMA 1,59 0,46, . (CH ₃ , TMA)=0,022±0,012 (iP, TMA)=0,026±0,011.

     

Kinetics and Mechanism of Monomolecular Heterolysis of Commercial Organohalogen Compounds: XXXV.1 Solvation Effects on the Activation Parameters of Heterolysis of 1-Bromo-1-methylcyclopentane and 1-Bromo-1-methylcyclohexane. Correlation Analysis of Solvation Effects

Kinetics of heterolysis of 1-bromo-1-methylcyclopentane and -cyclohexane in protic and aprotic solvents were studied. Correlation analysis of the effect of solvent parameters on G , H , and S was performed.     

Synthesis and conformational behaviour of ditosyldiaza[2.2]orthometacyclophanes

Summary The N,N-ditosyl-diaza[2.2]orthometacyclophanes5a, b were synthesized from N,N-ditosyl-metaphenylenediamine by reaction with (Z)-1,4-dichlorobutene and 1,2-bis-bromomethylbenzene, respectively. Low temperature NMR studies showed that the compound5b exists as a 1:1 mixture of chair and boat form of the strained (E,Z)-diazanonadiene ring. At room temperature all corresponding resonances are averaged on the NMR time scale (including all four ethylene bridge protons). Going to lower temperatures, in a first step the methylene bridge inversion is frozen (giving twoexo H and twoendo H, G ca. 52kJmol^–1). In a second step the chair and boat form can be observed separately (G ca. 43.5 kJ mol^–1 for the chair/boat flip). The assignments were confirmed by 2D NMR experiments.Dedicated to Prof. Dr. E. L. Eliel on the occasion of his 70th anniversary     

Kinetic characteristics of the ring-chain tautomeric equilibria of 2,3,3-trimethyl-1-aryl-2-hydroxy-5-pyrrolidones

The kinetics of the ring—chain tautomeric equilibria of a number of p-substituted 2,3,3-trimethyl-1-aryl-2-hydroxy-5-pyrrolidones in 50% aqueous pyridine were studied by dynamic PMR spectroscopy, and the effect of substituents on the kinetic parameters of this process was determined. The free energies of activation (G) decrease regularly on passing from electron-donor to electron-acceptor substituents. A good correlation between G and the ⁺ and substituent constants is observed. On the basis of the data obtained, it was concluded that the ratedetermining step in the process is detachment of a proton under the influence of the base to give the corresponding anion.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 758–763, June, 1978.     

Diacetylenic Derivatives of Fe2(CO)6(μ-EE′): Spectroscopic Investigations of Fe2(CO)6{μ-EC(H) = C(C≡ CMe)E′} (E = E′, E ≠ E′; E, E′ = S, Se, Te)

The diacetylenic adducts, Fe₂(CO)₆{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe₂(CO)₆(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (¹H, ¹³C, ⁷⁷Se, and ^l25Te) spectroscopy. Trends in the chemical shifts of ⁷⁷Se and ¹²⁵Te NMR spectra of Fe₂(CO)₆{-EC(H) = C(C CMe)E} with a variation of EE are discussed.     

Phenolate complexes of iron(III) in dimethylsulphoxide solution

Summary The formation of complexes between Fe³⁺ and 2,4-dinitrophenol, 4-nitrophenol and 4-methylphenol is studied in dimethylsulphoxide solution. The reaction proceeds almost to completion and the occurrence, in solution, of complexes with higher stoichiometry than 11 is reported for the first time. The following stability constants are determined (25 °C, 0.1 M KClO₄): Fe^III-2,4-dinitrophenolate ₁=1.8×10³, ₂=4.4×10⁵; Fe^III-4-nitrophenolate ₁=1.10×10⁷, ₂=2.5×10¹² ₃=3.9×10¹⁶; Fe^III-4-methylphenolate =1.7×10¹².The binding of a phenolate ligand to iron(III) strongly decreases its affinity for other phenolate ligands. The superior -donor, 4-methylphenolate (OC₆H₄Me)^–, only forms a 11 complex, Fe(OC₆H₄Me)²⁺. The e.s.r. spectrum of this species clearly prove it is a true iron(III) complex and does not contain iron(II), in opposition to recent claims. However, the complex Fe(OC₆H₄Me)²⁺ easily undergoes a ligand-to-metal electron transference. Addition of an excess of 1,10 phenanthroline yields the iron(II) complex [Fe(o-phen)₃]²⁺ instantaneously.     

Catalytic oxidation of cycloalkane heteroanalogs as a way to polyfunctional compounds

Liquid phase oxidation of cycloalkane diheteroanalogs catalyzed by compounds of Cu²⁺, Ni²⁺, Co²⁺, Cr³⁺, Fe³⁺ has been studied. It has been established that these catalysts can be applied to intensify, oxidize and increase the selectivity of this process.

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: Cu², Ni²⁺, Co²⁺, Cr³⁺, Fe³⁺. .