No description available.

Long-chain alkylbenzenes are industrially synthesized precursors to commercial surfactants such as laundry detergent. The process of benzene alkylation currently utilizes homogeneous acidic catalysts (HF, AlCl3, etc.), which cause a multitude of problems such as production of toxic waste, hazards to workers, and corrosion of expensive industrial equipment. These problems can be avoided by the use of heterogeneous highly acidic catalysts. Solid catalysts do not corrode equipment and are relatively simple to remove from the post-reaction mixture. Phosphotungstic acid (PTA) supported on silica gel could be a possible catalyst due to its high acidity with an estimated pKa ≈ -13. However, it is soluble in many solvents and can be leached from silica gel during the process. The objective of this research is to obtain a superacidic stable heterogeneous catalyst containing covalently immobilized PTA, and evaluate its activity and stability in the alkylation of benzene by long-chain alkenes. The catalyst PTA/SiO2 was prepared via the sol-gel method by co-condensation of PTA with tetraethoxysilane in acidic media. Surfactant Pluronic P123 was used as a template to form porous structure. Then the catalyst was granulated to prevent caking of the powder during reaction. For granulation, the powder PTA/SiO2 was mixed with aluminum oxide (an inert adhesive agent) and pressured at 7 t to make tablets. The tablets were converted to granules of 1-2 mm diameter and calcined at 400 °C to remove moisture. FT-IR spectra confirmed the presence of PTA in the obtained material. Analysis by atomic absorption spectroscopy showed PTA contents of 0.027 mmol/g. The catalyst was mesoporous with BET surface area of 168 m2/g and mean particle size of 856 nm. The reaction of alkylation of benzene by octene-1 and decene-1 was carried out in a fixed bed flow reactor at 200-250 °C where mixtures of benzene and an alkene flowed through the catalyst with constant rate. Products were collected and analyzed on a GC chromatograph. The catalyst demonstrated good catalytic activity at temperatures above 200 °C. In all experiments mixtures of isomeric alkylbenzenes were obtained with 2-phenylalkanes as main products. Decreasing of flow rate and ratio alkene:benzene favored conversion of alkenes. Characterization of the catalyst after the reaction showed little changes in porosity and particle size. No leaching of PTA was observed. However, carbon deposits were found on the catalyst that requires regeneration before next use in catalysis.

The purpose of this investigation was to study the known methods of forming acetals and find one or several that could be used in further investigation. In connection with the reactions, the use of various catalysts was pertinent. Some of the catalysts used were hydrogen chloride, calcium chloride, ferric chloride, aromatic sulfonic acids, and other. There was no data available comparing the sulfonic acids with the inorganic salts and mineral acids. For that reason one of the subsidiary problems of this investigation was such a comparison. In order to investigate stability, several acetals were subjected to conditions intended to produce ring acetylation. These conditions are the same imposed by a Friedel Crafts reaction or a Fries rearrangement.

Linear alkylbenzenes (LAB) are semi-products in the manufacture of linear alkylbenzene sulfonate surfactants that are active ingredients of various detergents. The use of traditional soluble acids (e.g. hydrofluoric acid or aluminum chloride) as catalysts for production of LAB results in the formation of large amounts of acidic toxic wastes. In this work, an efficient heterogeneous catalyst containing immobilized phosphotungstic acid (PTA) was synthesized and tested in the alkylation of benzene by higher alkenes. Sol–gel synthesis of silica gel from tetraethyl orthosilicate and PTA, as precursors, produced a mesoporous material containing covalently embedded PTA clusters. Obtained superacidic catalyst demonstrated high catalytic activity in liquid-phase alkylation of benzene by higher alkenes. Conversion of alkenes to corresponding phenylalkanes on this catalyst was significantly higher than on pure PTA. Covalent embedding of catalytically active HPA clusters prevented their leaching from the catalyst surface, which enabled its excellent catalytic properties.

学位プログラム名: 京都大学大学院思修館 / 京都大学 / 新制・課程博士 / 博士(総合学術) / 甲第23345号 / 総総博第18号 / 新制||総総||3(附属図書館) / 京都大学大学院総合生存学館総合生存学専攻 / (主査)教授 山敷 庸亮, 教授 杉山 弘, 教授 積山 薫 / 学位規則第4条第1項該当 / Doctor of Philosophy / Kyoto University / DGAM

No description available.

No description available.

Meta-diisopropylbenzene is reacted with propylene over the acid form of the molecular sieves SAPO-5, mordenite, offretite, beta, hexagonal and cubic faujasite (hex and FAU), L, SAPO-37, and an amorphous silica-alumina at temperatures around 463 K in a flow-type fixed-bed reactor. A small amount of cracking is observed. The main reactions of meta-diisopropylbenzene are isomerization and alkylation. This alkylation is proposed as a new test reaction to characterize the effective size of the voids in larger pore (12 T-atom rings or above) molecular sieves by measuring the amount ratio of formed 1,3,5- to 1,2,4-triisopropylbenzene. In most cases, this ratio increases with the increasing effective void size of the molecular sieves in the order: SAPO-5 < mordenite < offretite < beta < hex ≈ FAU < L < SAPO-37 < amorphous silica-alumina. Since samples with the FAU topology show lower selectivities to 1,3,5-triisopropylbenzene than the mesoporous, amorphous silica-alumina, pore curvature has an influence on alkylation selectivity even for voids of 13 A size. / Ph. D.

The alkylation of various compositions of propane with ethylene at atmospheric pressure in the presence of various concentrations of ortho-phosphoric acids and mixtures of ortho-phosphoric acid and hydrochloric and sulfuric acids as catalyst was investigated. Physical conditions studied were (1) temperature ranging from 40 to 200°C., (2) length of run from six to eight hours, and (5) vapor feed rate from 100 to 200 eubie centimeters per minute. From the results obtained from this research, it is evident that pipe still vapors composed of ethylene and propane cannot be alkylated at atmospheric pressure and relatively low temperatures with the use of 85-100 per cent ortho-phosphoric acid as a catalyst. No mechanism of reaction has been proven. / M.S.

Utilizing primary amines as alkyl coupling partners has garnered attention in recent years due to their widespread availability, facile preparation and purification, and presence in a variety of common building blocks. The reemergence of Katritzky salts has enabled deaminative alkylation and arylation of alpha primary and alpha secondary amines. The Rovis group has developed deaminative conditions for alpha tertiary amines utilizing redox-active imines to generate tertiary carbon-centered radicals. Herein, we couple this tertiary alkyl radical to haloarenes to generate benzylic quaternary centers, a common motif in pharmaceuticals and natural products. We then applied this methodology in the realm of isotopic exchange to generate 15N-primary amines from their naturally occurring 14N-analogues. By activating alpha primary and alpha secondary amines to Katritzky pyridinium salts and alpha tertiary amines to redox-active imines, we can engage primary alkyl amines in a late-stage isotopic exchange with complete and selective isotopic labeling.