Hydrodechlorination Reactions of CCl4 Over HZSM-5- and HY-Supported Pt and Pd Catalysts

The hydrodechlorination reactions of CCl₄ have been studied over Pt/HZSM-5, Pt/HY, Pd/HZSM-5 and Pd/HY under hydrogen atmosphere in the 393?C673?K temperature range in a pulse microreactor. The catalysts were prepared by impregnation and were characterised by various physico-chemical means. It has been found that all catalysts were active in the partial to full dechlorination reactions. Typically, over the Pt-containing catalysts methane was the major dechlorinated product, while it was ethane over the Pd-containing catalysts. This latter product predominated over the Pd/HZSM-5 and the quantities of the di- and trichlorinated products were minimal and the monochlorinated one was not formed at all. Phosgene formed was the indication of the partial destruction of the support being more serious for the HY-supported ones.     

Integration of Homogeneous and Heterogeneous Catalytic Processes for a Multi-step Conversion of Biomass: From Sucrose to Levulinic Acid, γ-Valerolactone, 1,4-Pentanediol, 2-Methyl-tetrahydrofuran, and Alkanes

The multi-step conversion of sucrose to various C₅-oxygenates and alkanes was achieved by integrating various homogeneous and heterogeneous catalytic systems. We have confirmed that the dehydration of sucrose to levulinic and formic acids is currently limited to about 30–40% in the presence of H₂SO₄, HCl, or Nafion NR50 in water. Performing the dehydration in the presence of a P(m-C₆H₄SO₃Na)₃ modified ruthenium catalyst under hydrogen resulted in the in situ conversion of levulinic acid to γ-valerolactone (GVL). Levulinic acid can be hydrogenated to GVL quantitatively by using P(m-C₆H₄SO₃Na)₃ modified ruthenium catalyst in water or Ru(acac)₃/PBu₃/NH₄PF₆ catalyst in neat levulinic acid. Formic acid can be used for the transfer hydrogenation of levulinic acid in water in the presence of [(η⁶-C₆Me₆)Ru(bpy)(H₂O)][SO₄] resulting in GVL and 1,4-pentanediol. The hydrogenation of levulinic acid or GVL can be performed to yield 1,4-pentanediol and/or 2-methyl-tetrahydrofuran (2-Me-THF). The hydrogenolysis of 2-Me-THF in the presence of Pt(acac)₂ in CF₃SO₃H resulted in a mixture of alkanes. We have thus demonstrated that the conversion of carbohydrates to various C₅-oxygenates and even to alkanes can be achieved by selecting the proper catalysts and conditions, which could provide a renewable platform for the chemical industry.     

Synthesis and characterization of novel well-defined stars consisting of eight polyisobutylene arms emanating from an octa(dimethylsiloxy)octasilsesquioxane core

The synthesis and characterization of novel stars, octa(polyisobutylenedimethylsiloxy)octasilesquioxane (T₈ ^DPIB), consisting of eight polyisobutylene arms emanating from an octa(dimethylsiloxy)octasilsesquioxane (T₈ ^D) core are described. The synthesis involves: 1) The synthesis of allyl-terminated polyisobutylene (PIB^█01█) prearms, 2) The synthesis of octa(hydrodimethylsiloxy)octasilsesquioxane (T₈ ^DH) precore and 3) Star formation by hydrosilation of PIB^█01█ with T₈ ^DH. Conditions for the precision synthesis and characterization of well-defined octa-arm stars are described. Received: 13 September 1996/Accepted: 14 October 1996     

Alkylation of Benzene with Cyclic Ethers in Superacidic Media

Superacidic trifluoromethanesulfonic acid (triflic acid, TFSA) catalyzes the alkylation of benzene with various cyclic ethers. The characteristic products formed in the reaction of highly reactive oxiranes (methyloxirane, styrene oxide, and cyclohexene oxide) are phenyl-substituted compounds formed as a result of Friedel–Crafts-type mono- and dialkylation. Oxetanes (2-isopropyloxetane) and oxolanes (tetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2,2,5,5-tetramethyltetrahydrofuran), in turn, undergo electrophilic cyclialkylative ring closure (cyclialkylation) to form mainly bicyclic compounds (tetralin, dihydronaphthalene, and naphthalene derivatives). In the majority of cases, alkylated products can be isolated in good to reasonable yields. Reactivity of cyclic ethers, product formation and product distributions are interpreted by taking into account ring strain, acidity of reaction mixtures and stability of carbocationic intermediates.     

Green synthesis and characterization of phosphorus flame retardant crosslinking agents for epoxy resins

The flame‐retardant efficacy of phosphorus‐containing reactive amine hardeners for epoxy resins is well‐known; however their synthesis often applies hazardous, objectionable reagents. The aim of this work is to develop an effective synthesis method for the preparation of P‐containing amines, which can act as flame‐retardant crosslinking agent in epoxy resins. The syntheses and testing of an aliphatic and two aromatic amines are described: curing properties, glass transition temperature, thermal stability, and flame‐retardant performance of the amines are studied. On the basis of these results, the scaling‐up and the optimization of the synthesis of the phosphorus‐containing aliphatic amine hardener in ReactIR? in situ FTIR apparatus is discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40105.     

Taming logic

In this paper, we introduce a general technology, calledtaming, for finding well-behaved versions of well-investigated logics. Further, we state completeness, decidability, definability and interpolation results for a multimodal logic, calledarrow logic, with additional operators such as thedifference operator, andgraded modalities. Finally, we give a completeness proof for a strong version of arrow logic.Thanks to ILLC for financial and CCSOM for technical support.Supported by Hungarian National Foundation for Scientific Research grant Nos. F17452 and T16448.Supported by Hungarian National Foundation for Scientific Research grant No. T16448.     

Attraction of male turnip mothsAgrotis segetum (Lepidoptera: Noctuidae) to sex pheromone components and their mixtures at 11 sites in Europe,Asia, and Africa

Selected combinations of (Z)-5-decenyl, (Z)-7-dodecenyl, and (Z)-9-tetradecenyl acetates, the pheromone components of the turnip mothAgrotis Segetum were tested for field attractancy at six, two, and three sites in Europe, Asia, and Africa, respectively. At all of the sites in Eurasia and in northern Africa the ternary mixture of the acetates captured most males, while at the sites south of the Sahara in Africa, (Z)-5-decenyl acetate alone was responsible for attraction. Differences in male attraction among the populations studied confirm the existence of significant population variation in the pheromone ofA. segetum. Interpretation of the present results together with earlier studies suggests that this variation is more or less continuous in Eurasia and north Africa, while a clearly distinct pheromone type is present in the areas south of the Sahara desert.     

Effect of radon measurement methods on dose estimation

Different radon measurement methods were applied in the old and new buildings of the Turkish bath of Eger, Hungary, in order to elaborate a radon measurement protocol. Besides, measurements were also made concerning the radon and thoron short-lived decay products, gamma dose from external sources and water radon. The most accurate results for dose estimation were provided by the application of personal radon meters. Estimated annual effective doses from radon and its short-lived decay products in the old and new buildings, using 0.2 and 0.1 measured equilibrium factors, were 0.83 and 0.17 mSv, respectively. The effective dose from thoron short-lived decay products was only 5 % of these values. The respective external gamma radiation effective doses were 0.19 and 0.12 mSv y(-1). Effective dose from the consumption of tap water containing radon was 0.05 mSv y(-1), while in the case of spring water, it was 0.14 mSv y(-1).     

TiO2-based photocatalytic degradation of 2-chlorophenol adsorbed on hydrophobic clay

The combination of adsorption and heterogeneous photocatalysis has been investigated as a promising technology for the removal of organic water pollutants. A laboratory study of the removal and decomposition of 2-chlorophenol (2-CP) as a toxic organic pollutant was carried out under various conditions with an organophilized clay mineral (hexadecylpyridinium chloride-modified montmorillonite; HDPM) as adsorbent and Degussa P25 TiO2 as photocatalyst. Three different oxidation processes leading to the degradation of 2-CP were compared: direct photolysis, heterogeneous photocatalysis in a TiO2 suspension, and the decomposition of substrate adsorbed on HDPM in the presence of TiO2. Both the degradation of 2-CP and the formation of intermediates were analyzed by HPLC, the total organic carbon content and the total organic and inorganic chloride contents were measured to monitor the mineralization process, and X-ray diffraction and thermoanalytical measurements were made to characterize the hydrophobic clay adsorbent. The heterogeneous photocatalytic degradation of dissolved (2-CP/UV/TiO2) and desorbed 2-CP (2-CP/HDPM/UV/TiO2) appeared to be equally efficient, whereas direct photolysis of 2-CP was far less efficient in the oxidative destruction. HDPM proved to be a suitable adsorbent, capable of adsorbing toxic organics from water. It was demonstrated that the adsorbent (at relatively high concentration) did not decrease the rate of mineralization of 2-CP. The results confirmed that the adsorbent retains its structure and composition during the mineralization process, and thus it can be reused without regeneration. The combination of adsorption and heterogeneous photocatalysis studied may be an efficient and economical means of accumulating, removing, and oxidizing organic water contaminants, and its application is in accordance with the growing environmental demands.