Reactions of C4?C6 alkanes on platinum and platium-gold films

Results are reported on the reactions of n-butane, n-pentane and n-hexane on Pt and Pt/Au alloy films. The results are compared with those obtained for Pt–Au alloys on a SiO₂ carrier. It is concluded that alloying can change the selectivity of the catalyst. No indication has been found for the possible role of oxygen in the high selectivity of Pt in non-destructive reactions.

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-, - - Pt . , Pt–Au SiO₂. , . - Pt .

     

Interaction of phosphomolybdovanadium heteropolyacids with hydrazine hydrate studied by a calorimetric method

The heats of interaction of VO ₂ ⁺ and of heteropolyacids H_3+nPMo_12−nV_nO₄₀ (n=1,2,3,6) with N₂H₄ have been measured.

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Измерены теплоты взаимодействия VO ₂ ⁺ и гетерополикислот H_3+nPMo_12−nV_nO₄₀ (n=1,2,3,6) с N₂H₄.

     

A chemical study ofPlectranthus glaucocalyx Maxim.

Summary A previously unknown crystalline substance C₂₀H₂₈O₄, calledplectrin, has been isolated from the leaves ofPlectranthus glaucocalyx Maxim., family Labiatae.Khimiya Prirodnykh Soedinenii, Vol. 1, No. 6, pp. 427–428, 1965     

A study of the reactions of the chemical modification of chymotrypsin. I

Summary The reaction of chymotrypsin with a number of modified analogs of the specific inhibitor of chymotrypsin L-1-tosylamido-2-phenylethyl chloromethyl ketone has been studied; the compounds investigated were D-1-tosylamido-2-phenethyl chloromethyl ketone, phenethyl chloromethyl ketone (PECK), and benzylethyl chloromethyl ketone (BCMK).It has been shown that D-TAPK does not possess inhibiting activity. The inhibiting capacity of PECK is considerably reduced. A simultaneous decrease in the length of the carbon chain and the elimination of the tosylamino group (BCMK) practically destroys the inhibiting action of the reagent.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 2, pp. 116–120, 1968     

Free-radical addition reactions initiated by metal oxides, VI

CuO catalyzed additions of ethyl cyanoacetate, initiated thermally and by di-tert-butyl peroxide, to 1-decene and ethyl 10-undecylenoate were investigated. The CuO catalyzed reaction proceeds already at 80°C at a high rate, produces 11 adducts in high yields and represents the first example of catalysis in radical addition reactions of non-halogenated compounds.

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1- 10-, CuO, -.-. , CuO, 80°C, 11 . .

     

Influence of solvent on platinum catalyst formation

The adsorption properties of Pt-black reduced in various solvents (water, sulfuric acid, ethanol, alkali, heptane) have been studied. The nature of solvent is shown to influence the catalyst surface formation, the heat of hydrogen adsorption and the ratio of its forms.

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Pt-, : , , , , . , , .

     

The effect of preparation conditions on the activity and stability of copreciptitated Ni/Al2O3 catalysts for the methanation of carbon monoxide

The activities and stabilities of coprecipitated Ni/Al₂O₃ methanation catalysts depend markedly on their preparation and pretreatment. The results are discussed in relation to the structure of the precipitate and to changes which occur during calcination and reduction.

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Ni/Al₂O₃ . , .

     

The structure of karatavic acid

Conclusions Karatavic acid has been isolated from the resin of the roots ofFerula karatavica Rgl. et Schmalh; this is an ether of umbelliferone and a hydroxy acid C₁₅H₂₄O₃ probably having the humulane type of hydrocarbon skeleton. Two possible structural formulas—(I) and (II)—have been proposed for karatavic acid.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 5, pp. 283–287, 1968     

Spectrographic estimation of Ga, In and Tl in semiconductor grade selenium

Summary An emission spectrographic method for the estimation of Ga, In and Tl in semiconductor grade selenium at less than a ppm concentration has been developed. The impurities were separated from 1 g of selenium by volatilizing it from its solution in nitric acid and sulphuric acid. The residue containing the impurities was dissolved in small amounts of 6 M HCl and was loaded along with the washings on 10 mg mixture containing graphite (90%) and sodium chloride carrier (10%) in the electrode crater. The spectra were excited in a d.c. arc carrying 13 A current. The detection limits lie in the range of 0.0025–0.005 ppm. The precision of the method ranges from 7–12% for these elements. The recoveries of impurities from selenium were confirmed using radioactive tracers.

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Spektrographische Bestimmung von Gallium, Indium und Thallium in Halbleiterselen

Zusammenfassung Eine 1 g-Probe wird in Salpeter- und Schwefelsäure gelöst und die Verunreinigungen durch Verflüchtigung des Selens isoliert. Sie werden in 6 M HCl gelöst und zusammen mit einem Graphit/NaCl-Gemisch (91) in die Elektrode eingebracht. Zur Anregung dient ein Gleichstrombogen (13 A). Die Nachweisgrenzen liegen im Bereich von 0.0025–0.005 ppm, der Variationskoeffizient bei 7–12%. Die Wiedergewinnung der Verunreinigungen wurde mit Hilfe von Radioindicatoren geprüft.