Hydropolymerization of ethylene,initiated by carbon monoxide,on Co-zeolite catalysts at temperatures below 100°C

Conclusions Both the extent of C₂H₄ hydropolymerization, initiated by 0.01% CO, on Co zeolites at a temperature below 100°C, and the initiating effect increase symbatically with increase in the ratio of SiO₂/Al₂O₃ in the zeolite in the investigated limits (from 2 to 10).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 894–896, April, 1974.     

Trifluoromethoxy substituted anilines: metalation as the key step for structural elaboration

Trifluoromethoxy-substituted anilines undergo hydrogen/lithium permutation ("metalation") with optional site selectivity depending on the N-protective group employed. N-tert-Butoxycarbonyl-2- and -4-(trifluoromethoxy)aniline react with tert-butyllithium at the nitrogen-adjacent 6- and 2-position affording, after electrophilic trapping, products 1-6. In contrast, deprotonation of the para isomer occurs at the oxygen-neighboring 3-position, giving rise to the acid 12, when the amino group is carrying two trimethylsilyl groups. sec-Butyllithium attacks 3-trifluoromethoxy-N-mono(trimethylsilyl)aniline at the 2-position, but 3-trifluoromethoxy-N,N-bis(trimethylsilyl)aniline at the 4-position to provide respectively the acids 10 and 11 after carboxylation. The synthesis of two new benzodiazepines illustrates (19 and 22) the preparative potential of the aniline functionalization mediated by organometallic reagents.     

Synthetic analogs of active centers of iron-sulfur proteins: Reactions with phosphates

The interaction of synthetic analogs of active centers of iron-sulfur proteins with phosphates of different structures was studied. It was shown that the process involves ligand exchange and obeys the first-order reaction kinetic equation. The most rapid exchange occurred with the most acidic compound diphenyl phosphate.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2301–2305, October, 1992.     

Reactions of 10-telluroniaanthracene perchlorates with nucleophiles

10-Telluroniaanthracene perchlorates react with nucleophiles (X^–=halide, hydroxide, methoxide) via intermediate free telluroxanthyl radicals. With 9-aryl-10-telluroniaanthracene perchlorates, high yields of 9-aryl-9-X-telluroxanthenes are obtained, but with 10-telluroniaanthracene the principal product is 9,9-bis(telluroxathenyl) as a result of rapid competitive dimerization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 691–695, May, 1989.     

Reactivity differences between molecular and surface silanols in the preparation of homogeneous and heterogeneous olefin metathesis catalysts

The reaction of Mo(N)(CH₂tBu)₃ (1) and SiO_2-(700) generates (SiO)Mo(NH)(CHtBu)(CH₂tBu) (2) when performed in C₆H₆ (material [1/SiO_2-(700)]_C6H6). The grafting occurs presumably by protonation of the nitrido ligand to form an intermediate (SiO)Mo(NH)(CH₂tBu)₃ (3), a pentacoordinated complex, which decomposes into 2 and 2,2-dimethylpropane. While [1/SiO_2-(700)]_C6H6 is highly active in olefin metathesis, [1/SiO_2-(700)]_CH2Cl2 and [1/SiO_2-(700)]_THF are poorly active or inactive catalysts respectively. In contrast, when Mo(N)(CH₂tBu)₃ reacts with a molecular silanol derivative, a soluble model of the surface of SiO_2-(700), it yields a very stable complex, (c-C₅H₉)₇Si₇O₁₂SiO-Mo(NH)(CH₂tBu)₃ (3m), which does not spontaneously generate 2,2-dimethylpropane and an alkylidene complex in contrast to the surface complex. Moreover, 3m does not catalyse olefin metathesis at room temperature as it does not already contain the initiating carbene ligand, and it is necessary to heat up the reaction mixture to 110 °C to obtain low catalytic activity. Nevertheless, the complex 3m generates well-defined metallocarbenes when heated in the presence of PMe₃: (c-C₅H₉)₇Si₇O₁₂SiO-Mo(N)(CHtBu)(P(CH₃)₃)₂ (4m) as a 10:1 mixture of its syn and anti rotamers with the loss of 2 equiv. of 2,2-dimethylpropane.     

Reductive cleavage of axially disymmetric tertiary amines and quaternary ammonium salts by lithium aluminium hydride. Synthesis of new 1,1′-binaphthyl substituted amines

Axially disymmetric tertiary amines or quaternary ammonium salts $\text{A}$ are synthesized by double alkylation of primary or secondary amines with racemic or optically pure 2,2′-bis (bromomethyl)-1,1′-binaphthyl. Their reductive cleavage by lithium aluminium hydride in refluxing THF leads to chiral secondary or tertiary amines $\text{B}$, substituted by a binaphthyl unit, with high yields and absence of racemization.     

Mass-spectrometric behavior of some cyano-substituted 4-(β-chloroethylmercapto)-sym-triazines

Intense [M-Cl]⁺ and [M-CT₂=CCNCl]⁺ ion peaks are characteristic for the mass spectra of 4-(-chloro--cyanoethylmercapto)-sym-triazines. The introduction of monoalkylamino groups into the 2 and 6 positions of the heteroring does not lead to the development of [M-HCl]⁺ ion peaks in the mass spectra or to a change in the characteristic fragmentation pathways.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1268–1270, September, 1982.     

Synthesis of pyrazine alcaloids from Botryllus leachi. Diazines 43

[reaction: see text] Regioselective metalation of pyrazines and cross-coupling reactions provides an easy access to botryllazines A and B and to an isomer of botryllazine A with good yields from chloropyrazine.     

The Gas-Solid Interface the adsorption of nitrogen,argon, neopentane,sulfur dioxide,carbon dioxide and sulfur hexafluoride on rhombic sulfur

Physical adsorption of the title compounds on rhombic sulfur of 0.4 to 0.5 m²/g is reported. The isotherms are of type II for N₂, Ar and C₅H₁₂, of type III for SO₂ and CO₂, and linear for SF₆. There is no hysteresis. The method of Ross & Olivier shows that the surface is relatively heterogenous (γ 17). Isosteric heats of adsorption and c values of the B.E.T. equation are also reported.