Benzene into molecular sieves

Benzene adsorption into molecular sieves was extensively studied via IR spectroscopy by several workers. Karge et al. [791 ] used the prominent band at 1478 cm" to identify benzene adsorbed in zeoUtes. De Mallmann and Barthomeuf [792,793] apphed FTIR spectroscopy of benzene adsorbed on various faujasite-type zeohtes (Na-X,Rb-X,Cs,Na-XNa-Y,Rb-Y,dealuminatedY) to determine the sites of adsorption and showed that the site preference depended on the balance between cation acidity and oxygen basicity. For a quantitative evaluation of the... 

As mentioned earlier, benzene adsorption into molecular sieves, especially into faujasite-type zeolites, was extensively studied via IR spectroscopy by Barthomeijf and colleagues [792,793]. IR investigations of adsorption of benzene and especially simple benzene derivatives (toluene, ethylbenzene, xylenes) on zeolites were largely related to problems of diffusion (cf. Sect. 5.6.4) and catalytic reactions such as alkylation and isomerization (see Sect. 5.6.3). 

Preparation of Reactants. Reagent-grade, thiophene free benzene was stored over 4A molecular sieves and sodium ribbon in a helium atmosphere. Styrene was distilled to remove dissolved oxygen and moisture and stored under a helium atmosphere. Prior to use, styrene was injected into a copious quantity of methanol to determine if any polymerization had occurred. If there was... 

The material boiling above 470°F is separated into oils, resins, and n-pentane insoluble residue. The residue is separated into asphaltenes and benzene insolubles by extraction with benzene while the oils are separated into aromatics and saturates. The saturates can be further separated into n-paraffins and non-n-paraffins with 5 A molecular sieves... 

To a stirred suspension of 3 g of methyl 2-endo-hydroxy-l-exo-hydroxymethyl-3a, 8b-cis-2,3,3a,8b-tetra hydro-1 H-5-cyclopenta[ bjbenzofuran-carboxylate in 30 ml of anhydrous tetrahydrofuran was added 1.5 ml of a solution which is obtained by dissolving 10 ml of 1,1-diethoxyethane and 200 mg of p-toluenesulfonic acid monohydrate into 10 ml of tetrahydrofuran followed by drying over molecular sieves, and the mixture was stirred for 14 hours at 60°C and then cooled. To the reaction mixture was added 100 mg of sodium hydrogen carbonate, and the mixture was stirred for 10 min at room temperature. Then, water was added to the reaction mixture and the mixture was extracted three times with ethyl acetate. The combined organic layers were washed with water and aqueous saturated solution of sodium chloride, was dried, and was concentrated to give 3.5 g of the crude crystals. The crude crystals were recrystallized from benzene-hexane to yield 2 g of the title compound (m.p. 162-163°C). 

By using potassium as a carbon gasification catalyst, it is possible to obtain activated carbons of large adsorption capacity (large micropore volume), but with micropores of small dimensions. Nevertheless, these materials could not be converted into carbon molecular sieves by carbon deposition from benzene pyrolysis. Success was achieved with chars which were activated only to a limited extent [16]. 

Secondary amines can be converted into the corresponding imines, in a highly efficient single step, upon treatment with 2 equiv. of t-BuOOH in benzene in the presence of RuCl2(PPh3)3 catalyst at room temperature [134]. This is the first catalytic oxidative transformation of secondary amines to imines, which are hardly accessible by conventional methods. A 4A molecular sieve is needed to prevent the hydrolysis of product imines in some cases. The oxidations of tetrahydroisoquinoline 61 and allylamine 63 gave the corresponding cyclic imine 62 and azadiene 64 in 98% and 80% yields, respectively (Eqs. 3.75 and 3.76). 

Alkoxy-a,/S-unsaturated aldehydes 201 could be converted into the corresponding polyenals 202 in the presence of DBU and molecular sieves 3A or 4A in benzene, tetrahydrofuran, acetonitrile, or dichloromethane at... 

Manganates and permanganates are rarely used to convert alcohols into aldehydes because permanganate oxidizes aldehydes to acids. However, when adsorbed on molecular sieves, potassium permanganate in benzene at 70 C oxidizes benzyl alcohol and dnnamyl alcohol to the aldehydes in 80 and 94% yields, respectively. Saturated aliphatic alcohols give very... 

All solvents and monomers were purified and stored under nitrogen atmosphere. The r-butyl chloride (r-BuCl, Eastman) was distilled from calcium hydride under nitrogen atmosphere prior to use. Diethylaluminum chloride (Et2 A1C1, Texas Alkyls Co.) was purified by vacuum distillation (bp °C/mm Hg 110/25). Ethyl chloride (EtCl, Linde Division, Union Carbide Co.) was purified by passing through a column packed with Molecular Sieves and barium oxide. The m-3-hexene (Chemical Samples Company) was distilled under nitrogen prior to use. The polybutadiene, Diene 35, from the Firestone Tire and Rubber Company and high 1,2-polybutadiene were purified by reprecipitations from benzene into excess acetone. 

The best approach to improving separations is to work toward reactions that achieve 100% yields at 100% conversions. Frequently, this will require more selective catalysts. The previous chapter contained an example moving in this direction. Toluene was disproportionated to benzene and xylenes using a silica-modified zeolite catalyst.23 After removal of benzene and unchanged toluene by distillation, the xylene remaining was a 99% para-isomer. It was clean enough to put directly into the process of oxidation to terephthalic acid. This avoided the usual separation of xylenes by crystallization or by a molecular sieve. There are times when an equilibrium can be shifted by removal of a product or by-product continuously to give 100% conversion. The familiar esterification with azeotropic removal of water or removal of water with a molecular sieve is an example. 

Benzoic Acid Titration Method In this method (4) powered alumina samples were first activated in stream of N2 gas at 200°C. About 0.5g of the sample is weighed and taken into sample vial closed with a septum. Acid indicator (1 wt.% dissolved in benzene dried over molecular sieve 4A) is added to this sample and kept for 24 hrs. by constantly shaking the vial... 

Materials. The reagents Mo(CO)e, W(CO)6, iodine, tetrapropyl-ammonium bromide, tetrabutylammonium iodide, propionic acid, benzoic acid, pivalic acid, and 1,2-dibromoethane were obtained from commercial sources and used without purification. The solvents chlorobenzene, 1,2-dichloroethane, o-dichlorobenzene, toluene, decahydronaph-thalene (decalin), and cyclohexane were purged 10-30 min with a stream of dry nitrogen prior to use. Acetonitrile was dried over molecular sieves (4A) and also purged with nitrogen prior to use. Benzene used in the preparation of MoW(02CC( 113)3)41 was carefully dried and stored over calcium hydride, then vacuum distilled into the reaction vessel when needed. 

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