Die Elektronenbeugung als Hilfsmittel der Strukturbestimmung organischer Substanzen

Natta, G.; Baccaredda, M.; Rigamonti, R.

doi:10.1007/bf01518084

Cited by 19 publications

(67 citation statements)

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“…An earlier thermodynamic analysis and feasibility studies of BD production was conducted by Bhattacharya et al [22], Natta and Rigamonti [23], and lately, Angelici et al [24]. The data presented in Tab.…”

Section: Thermodynamic Data For the Generally Accepted Route Of Bd Prmentioning

confidence: 97%

“…Ethanol was converted to BD, hydrogen, and water at 400-450°C over a mixture of metal oxides according to a one-step process developed by Sergey Lebedev in the 1930s, which became the foundation of industrial scale production [6][7][8] [23][24][25], whose results showed high performance for silica doped with 2 % tantalum oxide that proved to be the most active among catalysts composed of zirconium, niobium, thorium, uranium, and titanium oxides. These catalysts were also active for the conversion of ethanol and acetaldehyde into butadiene.…”

Section: Catalyst Systems Proposed By Various Authors From the 1930s mentioning

confidence: 99%

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Fundamental Issues of Catalytic Conversion of Bio‐Ethanol into Butadiene

et al. 2014

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This paper reviews issues related to butadiene production via bio-ethanol conversion from the days of Lebedev until today. A catalogue of catalytic systems proposed till date were identified; the inevitable role of various dopants in enhancing catalytic activity, physico-chemical analysis of certain catalytic trends and prospects for the development of the old process by the implementation of process initiators and the use of new generation catalysts with higher performance and better tolerance to coking problems, and the impact of shale gas exploitation on the supply and demand of butadiene were also discussed.

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Section: Thermodynamic Data For the Generally Accepted Route Of Bd Prmentioning

confidence: 97%

Section: Catalyst Systems Proposed By Various Authors From the 1930s mentioning

confidence: 99%

Fundamental Issues of Catalytic Conversion of Bio‐Ethanol into Butadiene

et al. 2014

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“…1-Butanol was the major product detected; this could be obtained by MPV reduction of the carbonyl group in butanal, which was formed in a relatively large amount [18,19,22] by tautomery of the alkenol obtained by the isomerisation of the double bond in crotyl alcohol. The MPV reduction can occur through the reaction with crotyl alcohol itself (which is dehydrogenated to crotonaldehyde), a hypothesis confirmed by a catalytic test performed by co-feeding crotyl alcohol and ethanol (molar ratio = 1:1) ( Table 1).…”

Section: Reactivity Of Proposed Intermediatesmentioning

confidence: 98%

On the Chemistry of Ethanol on Basic Oxides: Revising Mechanisms and Intermediates in the Lebedev and Guerbet reactions

et al. 2014

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A common way to convert ethanol into chemicals is by upgrading it over oxide catalysts with basic features; this method makes it possible to obtain important chemicals such as 1-butanol (Guerbet reaction) and 1,3-butadiene (Lebedev reaction). Despite their long history in chemistry, the details of the close inter-relationship of these reactions have yet to be discussed properly. Our present study focuses on reactivity tests, in situ diffuse reflectance infrared Fourier transform spectroscopy, MS analysis, and theoretical modeling. We used MgO as a reference catalyst with pure basic features to explore ethanol conversion from its very early stages. Based on the obtained results, we formulate a new mechanistic theory able to explain not only our results but also most of the scientific literature on Lebedev and Guerbet chemistry. This provides a rational description of the intermediates shared by the two reaction pathways as well as an innovative perspective on the catalyst requirements to direct the reaction pathway toward 1-butanol or butadiene.

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“…More recently it has been observed in this laboratory that hydrogen peroxide solutions on cooling do not always solidify completely a t temperatures below their corresponding eutectic, a result not easily reconciled with occurrence of solid solutions in the system (5). I t is now obviouswhy these solutions can be supercooled with respect to the addition compound, H2O2.2Hz0; the limited stability of this hydrate is confirmed both by its low symmetry (16) and the flatness of its freezing point curve (Fig. 2) F r o m t h e present s t u d y a n d a similar o n e m a d e o n the s y s t e m hydrazinewater (14) i t m u s t be concluded that the p o o r results o b t a i n e d in a t t e m p t i n g t o freeze o u t t h e ice o r the p u r e c o m p o u n d a r e d u e entirely to the difficulty of removing the mother liquor from t h e crystals.…”

Section: 5021mentioning

confidence: 97%

“…On the other hand, these arguments were opposed by the following ones: the lattice constant of hydrogen peroxide is the same in frozen solutions (82 and 90%) as in the pure compound according to a n X-ray investigation (16). More recently it has been observed in this laboratory that hydrogen peroxide solutions on cooling do not always solidify completely a t temperatures below their corresponding eutectic, a result not easily reconciled with occurrence of solid solutions in the system (5).…”

Section: 5021mentioning

confidence: 99%

Hydrogen Peroxide and Its Analogues: Ii. Phase Equilibrium in the System Hydrogen Peroxide – Water

Foley¹,

Giguère²

1951

Can. J. Chem.

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A precision freezing point apparatus with platinum resistance thern~on~eter was used to investigate the system hydrogen peroxide -water over the whole concentration range. The freezing point of the purest sarnple of hydrogen peroxide obtained by repeated fractional crystallizations of a large quantity of 99.6% pure solrrtion was found to be -0.461°C.; that of the dihydrate was -52.1OoC. T h e two eutectlcs occur a t concentrations of 45.2% and d1.2yO Hz02 and a t temperatures of -52.4" and -5G.5"C. respectively. Contrary to what has been reported previously, water and hydrogen peroxide do not form solid solutions together. This was proved conclusively by applying the technique of radioactive tracers to the 'wet residr~e' method of Schreinemakers.The purpose of this investigation was threefold. First, to redetermine the freezing point of pure hydrogen peroxide, with greater accuracy than heretofore (3). Second, to scttle the question of solid solutions in the systenl hydrogen peroxide -water (6). Third, to use freezing point measurements for evaluating the degree of purity of very concent~atcd hydrogen peroxide. Indeed, the usual chemical nlethods of analysis are of little use for that purpose since the remaining traces of water cannot be determined directly (4). Other physical metl~ocls investigated so far are either not sensitive enough or subject to errors due to spontaneous decomposition. These three objectives arc closely interconnected; for instance, the existence of solid solutions would render determinations of freezing point rather problematic. At the same time it could rule out the possibility of using this method for accurate analysis. Experimental Methods and Results Freezing PointsAn apparatus similar to that originated by Mair (12) and perfected subsequently by Rossini and his collaborators (7,13,20) a t the National Bureau of Standards was constructed for this purpose. T h e double-walled, silvered freezing tube had an internal diameter of 3 cm. and the rate of heat transfer was controlled by adjusting the pressure inside the annular space. The cold head was provided by a large Dewar flask filled with dry ice and acetone. The problem of stirring the sample presented some experimental difficulties sincc most materials catalyze the clecornposition of hydrogen peroxide. Stirrers made of glass rods were too fragile. Aluminum or highly polished stainless steel has been recommended a s suitable for this purpose (18); the latter was selected because of its greater strength. T h e stirrer was in the form of a double helix fashioned iliunz~script receiued October 4, 1950.

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Die Elektronenbeugung als Hilfsmittel der Strukturbestimmung organischer Substanzen

Cited by 19 publications

References 0 publications

Fundamental Issues of Catalytic Conversion of Bio‐Ethanol into Butadiene

Fundamental Issues of Catalytic Conversion of Bio‐Ethanol into Butadiene

On the Chemistry of Ethanol on Basic Oxides: Revising Mechanisms and Intermediates in the Lebedev and Guerbet reactions

Hydrogen Peroxide and Its Analogues: Ii. Phase Equilibrium in the System Hydrogen Peroxide – Water

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