Photokatalytische Systeme. XXI. Zum Mechanismus der Photoreduktion von Kaliumchromat in Alkoholen

Photocatalytic Systems. XXI. On the Mechanism of the Photoreduction of Potassium Chromate in Alcohols The photolysis of crown ether complexes of potassium chromate in several alcohols has been investigated by e.s.r.-spectroscopy. Two different relatively long-lived Cr(V) intermediates formed by different reaction pathways have been observed. Radicalic oxidation products of the alcohols (alkoxy and hydroxyalkyl radicals as well as fragmentation products) and of the crown ether have been detected by spin trapping.     

Die Medienabhängigkeit der alkalischen Hydrolyse von Methylmethacrylat-Polymeren

The rate of the alkaline hydrolysis of poly(methylmethacrylate)(PMMA) and copolymers of methylmethacrylate (MMA) and ethyl acrylate increases with increasing dielectric constants of solvents and decreasing capability of solvation of OH^?-ions in aliphatic monofunctional alcohols and aprotic solvents. With respect of the series of alcohols used this dependence yields maximum rates in propanols. The rate of hydrolysis is strongly reduced by higher contents of water. The rate constants of hydrolysis of the ethyl acrylate and MMA units differ by one order of magnitude under the reaction conditions investigated. During hydrolysis suspension copolymers of MMA and ethyl acrylate in ethanol 80°C form homogeneous solutions, highly swollen gels and dispersions under the condition of a low, medium and high content of alkaline hydroxide and water, respectively. The partial hydrolysis offers commercially interesting variants.     

Verwendung von 2-Furaldehyd für die Synthese von selbstlöschenden Polyurethanwerkstoffen

New Utilization Possibility of Furfural for the Synthesis of Self-Extinguishing Polyurethane Resins A new method for the conversion of furfural into heptane-1, 4-diol, 3, 5-dichloroheptane-1, 4-diol as well as 3, 5-dibromoheptane-1, 4-diol is presented, and the possibilities of applying of two last alcohols for the syntheses of self-extinguishing polyurethane resins are discussed. In addition, a method for the preparation of ethyl 3, 5-dichloro-4-keto- and 3, 5-dibromo-4-ketoheptanoate is described.     

Dienoligomerisierung. XV. Palladiumkomplexkatalysierte Telomerisierung von Butadien mit Aminen und Dimerisierung in Gegenwart von Ketoximen

Diene Oligomerization. XV. Palladiumcomplexcatalyzed Telomerization of Butadiene with Amines and Dimerization in the Presence of Ketoximes Butadiene reacts with primary or secondary amines and with the homogeneous catalytic system bis-acetylacetonatopalladium-(II)/triphenylphosphine to form 1-amino-octa-2,7-dienes. The rate and the selectivity of the reaction increase in presence of cocatalysts as triarylphosphates instead of triphenylphosphine and if the reaction proceeds in a protic media — in alcohols, water or lower carboxylic acids. A number of 1-aminoocta-2,7-dienes were prepared. If oximes act as organic nitrogen compounds, only n-octa-1,3,7-triene is selectively formed. Schiff' bases aldolisate under the conditions of the reaction.     

Die katalytische Herstellung von Zuckeralkoholen und deren Verwendung

Catalytic production of sugar alcohols (polyols) and their application . The article surveys the numerous applications of the principal sugar alcohols sorbitol and xylitol and their world production in 1978. Nowadays, the industrial production of sugar alcohols is almost exclusively by catalytic hydrogenation of the corresponding sugars; thus sorbitol is manufactured by hydrogenation of D-glucose, xylitol by hydrogenation of xylose, and mannitol by hydrogenation of invert sugar or fructose. Some 80% of the world production of sugar alcohols are manufactured in batch suspension processes using Raney nickel catalysts. Apart from the Atlas Powder continuous suspension process employing nickel-carrier catalysts, continuous processes have recently been developed which use Raney nickel and prove more economical owing to the lower catalyst costs. Trickling processes with fixed catalyst continue to play a minor role. Available production capacity based on batch suspension processes can be expanded by process optimization and new catalyst developments. A newly developed special Raney nickel catalyst reduces the specific catalyst consumption by about 50%.     

Oberflächenstrukturierung polymerer fasern durch UV-laserbestrahlung. 6. Zur vermeidung von vergilbungen bei der laserbehandlung von polymeren

It is shown in this paper, that during laser treatment of polymeric materials the occurrence of discolouring layers of laser crack deposits onto the substrate can be avoided without preventing the formation of a laser-induced microstructuring of the surface. Using water, alcohols, ethers or aqueous surfactant solutions as impregnating media during laser treatment a high degree of whiteness of fabrics can be maintained.     

Die Vernetzung von Perfluoralkenen aus dem strahlenchemischen Abbau von Polytetrafluorethylen zu höhermolekularen Carbonylverbindungen

The investigations were based on mixtures of perfluoroalkenes produced by electron-beam irradiation of PTFE wastes. Results concerning perfluorohept-1 -en showed that the terminal perfluoroalkenes react preferably with dinucleophilic reactants to form non-saturated ether and amid structures. Reactions of perfluoroalkene mixtures with nucleophilic reactants (dioles, diamines) lead to crosslinking. Primary addition products of terminal perfluoroalkenes hydrolyze with amines or phenols/alcohols to carbonyl compounds and form allylic structures. Internal perfluoroalkenes of the mixture and allylic products, respectively, add the nucleophilic compound and rearrange partially into stable vinylic products. Mixed ether-ester structures and non-saturated polyamides, respectively, are formed. The dinucleophilic reactant determines essential properties of the fluorine compound. Thermally and chemically induced substitution leads to highly crosslinked structures opening new areas for fluorocarbons.     

Process of adsorption-desorption for a series of chemically similar solvents trough ethylene vinyl acetate polymer. Modelling and experiment

The process of absorption and desorption of some alcohols through polymers materials are studied here in order to evaluate the capacity for absorption for these liquids, and to determine the effect of vinyl acetate incorporated in the polymer. The polymer exhibits low capacity and high diffusivity depending on two parameters: size of sorbed penetrant, and vinyl acetate percent. A mathematical model, based on a numerical method with finite differences, is built in order to describe the process. The model can lead to the kinetic of transfer of alcohols, in good agreement with experiments for either absorption or desorption of alcohols. The profiles of concentration as well as the kinetics are evaluated.     

Synthetic detergents from animal fats. IV. Sodium 9,10-dichlorooctadecyl sulfates

Summary Sodium 9,10-dichlorooctadecyl sulfates were prepared by the addition of chlorine to oleyl and to elaidyl alcohols, and sulfation of the dichlorooctadecanols with chlorosulfonic acid. The sodium 9,10-dichlorooctadecyl sulfates are readily soluble in water at 25°C and resemble sodium oleyl sulfate in detergent and surface-active properties. Tallow alcohols can be chlorinated by the addition of chlorine and sulfated with one of the usual sulfating agents to produce an adequately soluble detergent and surface-active agent. I, II, and III in this series are references (5), (4), and (7), respectively. Presented at the meeting of the American Oil Chemists' Society in Minneapolis, October 1954. A laboratory of the Eastern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Untersuchungen zum Nachweis von Emulgatoren in Lebensmitteln, 6. Mitteilung

Investigations on Detection of Emulsifiers in Foodstuffs Properties and the possibility of detection of emulsifiers based on o-phosphoric acid esters of fatty alcohols and their ethoxy derivatives for the cosmetic preparations, are investigated and a simple procedure for their specific detection is given.     

Aspekte bei der Hydrierung von Fetten und Fettsäuren

Aspects of Hydrogenation of Fats and Fatty Acids Hydrogenation of fat products is of great significance, both for human and animal nutrition as well as for technical purposes. In the area of nutrition, adequate food for the increasing world population is unthinkable without utilization of all fat resources, that can be made available as food fats only after catalytic hydrogenation. In the area of technical use, a similar development is observed owing to shortage of mineral oils. Thus, fatty alcohols derived from vegetable oils and waxes can already compete in price with fully synthetic fatty alcohols derived from mineral oils. In the past 70 years of hydrogenation of fats till the present time, catalysts based on nickel have been most commonly used. In addition, small proportions of catalysts based on copper and noble metals have also been used. Homogenous catalysts have been used very recently. The present communication deals primarily with the hydrogenation of neutral fats and fatty acids using nickel catalysts. The aspects of selectivity and isomerization in the partial hydrogenation of neutral fats are discussed. In the hydrogenation of fatty acids and their derivatives, emphasis is laid on other factors, such as activity, poisoning and acid resistance of the catalyst. These factors are discussed.     

Alcohol Synthesis via Fischer–Tropsch Synthesis over Activated Carbon Supported Alkaline Earth Modified Cobalt Catalyst

Although numerous efforts have been made in direct syngas conversion to higher alcohols via Fischer–Tropsch synthesis, the higher alcohols distribution remains a challenge. Here, we introduce alkaline earth metal oxide as promoter into activated carbon supported cobalt catalyst to tune distribution of higher alcohols. With the addition of Mg, the distribution of C_2-5 alcohols increase from 41.2 to 75.8% accompanying with distribution of C_6-18 alcohols decrease from 52.8 to 14.0%. Ba-promoted Co based catalyst (CoBa/AC) presents similar alcohols distribution to un-promoted catalyst, while the alcohol selectivity over CoBa/AC is higher than Co/AC. For promoted catalysts, the distribution of C_6-18 alcohols increased in the order of Mg?<?Ca?<?Sr?<?Ba. The characterization results exhibit that the promoter addition facilitates the cobalt carbide formation, which leads to enhancement of selectivity to higher alcohols. The available active cobalt sites of promoted Co based catalysts increase in the same above order of Mg?<?Ca?<?Sr?<?Ba.

Graphic Abstract

     

Solvent nature effect in preparation of perovskites by flame pyrolysis: 2. Alcohols and alcohols + propionic acid mixtures

The effect of either pure alcohols or alcohols + propionic acid mixtures as solvents for the preparation by flame pyrolysis of a standard LaCoO₃ catalyst, to be employed for the catalytic flameless combustion of methane, has been investigated. All the catalysts proved very active for the mentioned reaction. Low-MW pure alcohols showed however less suitable than alcohols-propionic acid mixtures, leading to lower perovskite phase purity, less particle size homogeneity and lower specific surface area. The high volatility of the solvent seems to be the major cause, together with the improper behaviour of nitrates (forced by solubility reasons) as perovskite metals precursors. However, the addition of propionic acid to the alcohols allowed to use the acetates as precursors and hence to obtain high perovskitic phase purity, high SSA and uniform particle size. Moreover, the increase of combustion enthalpy of the solvent, through the addition of higher-MW alcohols, leading to progressively higher flame temperature, strongly improved the thermal resistance of the catalyst, without lowering catalytic performance.     

The flavor problem of soybean oil. IV. Structure of compounds counteracting the effect of prooxidant metals

Summary A study has been made of the effectiveness of various polycarboxylic acids and polyhydric alcohols in improving the stability of soybean oil. Certain observations have been made regarding the structural groups required and the possible mechanism of reaction. Since salts and esters of organic acids are inactive, free carboxyl groups are required. Among the four carbon atom dicarboxylic acids activity increases with the number of hydroxyl groups. Within the polyalcohols activity increases with the increase in number of hydroxyl groups. Steric immobility and loss of hydroxyl groups by dehydration reduces activity. Evidence is presented which attributes to citric acid and certain polyhydric alcohols the role of metal scavenger. For example, it has been demonstrated that the addition of citric acid and sorbitol to soybean oil containing prooxidant metallic salts effectively increases the oxidative and flavor stability of the oil. By using a sample of treated soybean oil with no detectable tocopherols, in order to eliminate synergistic effects of citric acid, it has been shown that the prooxidant effect of iron stearate is counteracted by the presence of citric acid. The demonstration that polyhydric alcohols increase the flavor and oxidative stability is compatible with their known metal complexing properties. Evidence is presented which indicates a relationship between flavor stability and oxidative stability. Presented at the 39th Annual Meeting of the American Oil Chemists' Society, May 4–6, 1948, in New Orleans, Louisiana. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

On-Line Thermospray-LC-MS von nichtionischen Tensiden

On-line Thermospray-LC-MS of Nonionic Surfactants Nonionic surfactants are often homologues with different degrees of ethoxylation. In addition, many products contain mixtures of nonionic surfactants, which differ in their chemical nature (e.g. polyglycol ethers of fatty alcohols and nonylphenol, sorbitan esters, fatty acid alkanolamides). For the analysis of such complex mixtures efficient separation methods are necessary: Thin layer chromatography is frequently applied to determine the type of surfactant. However, problems arise in quantitative evaluation and in determination of the hydrocarbon chain-distribution. The applicability of gaschromatography is limited by the requirements of volatility and thermal stability. Liquid chromatography should be an appropriate method for quantification, provided chromatographic resolution is sufficient. However, the identification is difficult if a refractive index detector is used because in such complex mixtures overlapping peaks are to be expected. For these reasons a universal and specific detector is required. In this contribution it is shown that the mass spectrometer may be linked to a liquid chromatograph by means of a modern Thermospray-Interface. This technique may be favourably applied to the analysis of nonionic surfactants.     

Folgeprodukte halogenierter Aldehyde. X. Die Synthese von O-Polyhalogenalkyl-dichlorphosphaten und O,O-Dialkyl-O-polyhalogenalkyl-phosphaten

Derivatives of Halogenated Aldehydes. X. The Synthesis of O-Polyhalogenoalkyl Phosphorodichloridates and O,O-Dialkyl-O-polyhalogenoalkyl Phosphates The phosphorodichloridates 2a – e are prepared by reaction of halogenated aldehydes or of glyoxylic acid n-butyl ester with phosphorus pentachloride or PCl₃Br₄ and subsequent treatment with sulfur dioxide. The compounds 2a – e give the phosphates 3a – i by reaction with alcohols.     

小分子醇对聚乳酸热稳定性的影响

使用转矩流变仪并结合数学模型方法,研究了小分子醇对聚乳酸(PLA)热稳定性的影响,计算了体系的黏度、流动活化能和降解速率常数。结果表明:醇会促进PLA的降解,添加量越大,对PLA热稳定性的影响越大;在相同添加量下,碳链短的醇比碳链长的醇更能促进PLA的降解,单官能度的醇比双官能度的醇更能促进PLA的降解;相对于羧酸,醇对PLA热稳定性的影响较小。     

Verwendung von N-chlor-nylon 66 zur oxydation von alkoholen

N-Chlor-Nylon 66, obtained through a treatment of Nylon 66 with tert-butylhypochlorite, can be used for oxidation of alcohols. The influence of the reaction medium and the content of chlorine on the yield has been investigated. The formed ketones, aldehydes and esters have been determined by gaschromatrography. Oxidation reactions proceed under mild conditions (e. g. 35°C) and often give higher yields than the analogous reactions with low-molecular N-halogen-amides.     

Die chromatographische Analyse der Gemische von aliphatischen Dicarbonsäuren und Lactonen

The Chromatographic Analysis of Mixtures of Aliphatic Dicarboxylic Acids and Lactones The separation and identification of 37 aliphatic dicarboxylic acids and lactones have been carried out by means of paper chromatography in three solvent systems and by thinlayer chromatography in one solvent system. On the basis of results obtained and relationships derived, it is possible to identify, without any isolation, the individual dicarboxylic acids and lactones in an unknown mixture of compounds with relative ease. Especially, it is very well possible to separate the cis- from trans-isomer of unsaturated acids and the hydroxy acids. This method has been tested in the analysis of mixtures resulting from γ-irradiated addition of alcohols to maleic acid; the method can be used for the analysis of natural materials.