Mechanism of adsorption,electroreduction and hydrogenation of compounds with ethylenic bonds on platinum and rhodium: Part II. Comparison of the electroreduction and catalytic hydrogenation processes

The catalytic liquid-phase hydrogenation of maleic acid on platinum and rhodium has been investigated. It is shown that the rate-determining step of this process as well as of the electroreduction process of maleic acid is the interaction of the chemisorbed particle of maleic acid with the adsorbed hydrogen which is formed at the preceding rapid stage of either the dissociative adsorption of molecular hydrogen, or the electrochemical stage of hydrogen ion discharge. The rate of the process with the same degree of surface coverage with hydrogen and chemisorbed particles of maleic acid does not depend on whether the process is carried out catalytically or electrochemically, on whether maleic acid and hydrogen were preliminarily adsorbed on the surface of the electrode-catalyst or not. With due regard for the mutual influence of chemisorbed particles participating in the rate-determining stage, the main kinetic equations for the electroreduction and catalytic hydrogenation processes have been derived. The difference in the rates of electroreduction of maleic acid on platinum and rhodium, with the same degree of electrode surface coverage with reactants, is shown to be the result of differences in the adsorption heats (or bonding strength with the surface) of hydrogen and maleic acid on these two metals. Experimental procedures are described in Part I [1].     

Total synthesis of 13- and 14-azaequilenines via heterocycloaddition

Benzo-[f]-quinolines and benzo-[f]-isoquinolines were prepared via heterocycloaddition of N-butyloxycarbonylmethylenetoluene sulfonamide to a vinyl dihydronaphthalene. Structural assignments were based on PMR and mass spectral analysis. 13- and 14-aza-equilenines have been obtained via standard procedures starting from the respective adducts.     

Neopentylallylsodium

Neopentylallylsodium (NpANa) has been prepared by the reaction of neopentylallyllithium with an equivalent amount of sodium 2,2-dimethyl-1-butoxide in hydrocarbon solvent. NpANa is stable in diethyl ether and THF solvents for extended periods of time, and proton NMR and UV data are reported for NpANa in THF at various temperatures. A more substantial degree of ionic delocalization is indicated for NpANa as compared to NpALi and apparently is greater for the trans isomer of NpANa. UV absorption maxima for NpANa and NpALi are explained in terms of cis/trans ratios rather than in terms of ion pairing.     

Phase relationships and some magnetic properties of spinels in the systems M1−xNixCr2S4 where M = Mn,Fe, Co

Phase relationships between spinel and defect NiAs structures in the systems M_1?xNi_xCr₂S₄ (where M = Mn, Fe, Co) were investigated. It was found that the spinel structure is stable between x = 0 and x = 0.3 when M = Mn or Fe. When M = Co the spinel is formed in the region x = 0 to x ～ 0.4. The apparent stabilization of the defect NiAs phase by Ni²⁺ may be related to the strong sixfold site preference of Ni²⁺. Curie temperatures of all three ferrimagnetic systems increases with increasing Ni²⁺ substitution. This is probably due to higher NiS covalency.     

The preparation of bis- and tris-(trimethylsilyl)acetic acid

Contrary to an earlier report, lithiation of tris(trimethylsilyl)methane followed by carbonation does not yield the acid (Me₃Si)₃CCO₂H, (I), if an alkali extraction step is included in the work up; the product is actually the acid (Me₃Si)₂CHCO₂H, (II). The acid (I) can be obtained if the alkali extraction is omitted. Separate experiments have confirmed that (I) is rapidly converted into (II) by aqueous or methanolic base.     

Reaction of di- and trisubstituted ethynylsilanemagnesium halides with dimethylethynylfluorosilane

Conclusions The reaction of magnesium bromide derivatives of di- and triethynylsilanes with dimethylethynylfluorosilane gave 1,2-disubstituted silylacetylenes containing ethynyl and vinyl groups at the silicon atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2614–2616, November, 1984.     

Synthesis of azetidin-3-ones. Structure of N-tosyl-2-ethylazetidin-3-one

A one-step synthesis of azetidin-3-ones by intramolecular cyclization of 1-diazo-3-arenesulfamoylalkan-2-ones was developed. The yield of cyclic product increases to 70% in the presence of an alkyl or benzyl substituent in the hydrocarbon chain of the diazoketone. The structure of N-tosyl-2-ethylazetidin-3-one was studied by x-ray diffraction analysis and it was shown that the four-membered ring has 15 inflection.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 468–473, April, 1987.     

Relative viscosity and the solvation number in solutions

It has been shown that part of the free volume of a solvent attaching to the solvation shell must be excluded from the total free volume in the Bachinskii equation. This determines the increase of viscosities of solutions with positive solvation. An equation has been obtained for the inverse relative viscosity of solutions ₀/ = 1-zN₂/(1-N₂), where no and are the dynamic viscosities respectively of the solvent and the solution; z is the solvation number, N₂ is the mole fraction of dissolved material. A method is proposed for determining the solvation number (hydration) from solution viscosity data. Solvation numbers obtained by this method are in good agreement with values of z obtained from the literature and determined by other methods.Translated from Teoreticheskaya i Experimental'naya Khimiya, Vol. 21, No. 5, pp. 627–631, September–October, 1985.The author wish to express their gratitude to professors Yu. Ya. Fialkov and M. A. kvadrigin for fruitful discussions of the result of the current work.     

Organotellurium derivatives of dicarboxylic acids

The freshly prepared sodium salts of ortho-phthalic acid and tetrabromo ortho-phthalic acid react with diaryltellurium dichlorides in chloroform to afford new dimeric organotellurium carboxylates, R₂Te(C₈X₄O₄)₂ (X = H, Br). The new compounds contain fourteen membered rings and the detailed structure is discussed particularly in the light of the ¹H NMR spectrum of (p-EtOC₆H₄)₂Te(C₈H₄O₄)₂ which shows inequivalence of p-ethoxy groups. The sebacate derivatives of tellurium(IV) are oligomeric and iso- and terephthalic acids failed to give well defined products.     

An efficient synthesis of [1,1]ferrocenophane via 1,1′-bis(6-fulvenyl)ferrocene

[1,1]Ferrocenophane can be prepared by reduction of 1,1′-bis(6-fulvenyl)ferrocene with complex borohydrides to give the dianion of 1,1′-bis(cyclopentadienylmethyl)ferrocene. Reaction of this dianion with ferrous chloride produces the ferrocenophane in good yield.