Benzene on silica

Types TV and V They are considered to reflect capillary condensation phenomena, i.e., possibility of condensation of gases in minute pores of the adsorbent at pressures even below the saturation pressures of p0 of the gas and may show hysteresis effect. An example of type IV is furnished by adsorption of benzene on silica gel at 50 C and that of type V by adsorption of water vapour on activated charcoal at 100 C. 

Plot the isosteric heat of adsorption vs the amount adsorbed from the following data of Shen and Smith for benzene on silica gel. Using a constant value of 34.8 X 10 cm" for the surface area occupied by one benzene molecule, convert the coordinate showing the amount adsorbed to fraction of the surface --------covered- -t0tal-sur-faee-area-=-832-m /g)7--------------------------------------... 

What is the value of log for elution of w-nitroanisole by benzene from 16% HjO-SiOa (narrow pore) From Table 6-1 we have log = —0.93 and a = 0.60. The value of e for benzene on silica is 0.25 (Table... 

Calorimetric studies of microporosity were made by Cancela et al., who measured the heat liberated during the adsorption of benzene on silica. They verified that the energy of adsorption is highest in micropores and measured the area still open to adsorption of nitrogen at various stages of adsorption of benzene (174). 

Wessely and co-workers [90] have applied TLC on a preparative scale instead of fractional distillation in order to isolate the hydro-quinone acetate formed during treatment of hromo phenols with lead tetraacetate. They worked with benzene on silica gel G layers and visualised by spraying with diazotised sulphanilic acid or a I % solution of p-dimethylaminobenzaldehyde (Rgt. No. 72). 

Figure 3.3.42 Typical shapes of adsorption isotherms pA- partial pressure of adsorbate A, p - vapor pressure of liquid A, 0a = coverage relative to monolayer capacity type I Langmuir adsorption, for example, benzene on silica gel, NH3 on charcoal, or H2S on molecular sieve (Figure 3.3.40) type II multilayer BET type of adsorption, for example, water on AI2O3, N2 on silica type III multilayer adsorption, for example, bromine on silica, type IV and V multilayer adsorption and capillary condensation in pores, for example, water on silica or benzene on Fe203 (IV) and water on charcoal (V).

Bromo-3-iodo-l-(4-methylphenylsulfonyl)indole (0.476 g, 1.00 mmol), methyl acrylate (0.108 g, 1.25 mmol), EtjN (0.127 g, 1.25 mmol) and Pd(OAc)2 (11 mg, 0.050 mmol) were mixed in a tube, purged with argon and the tube was sealed and heated to 100°C for 1 h. After cooling, it was opened and mixed with CH2CI2 (50 ml). The solution was washed with water and dried (Na SOJ. The residue was purified by chromatography on silica using 1 3 benzene-hexane for elution. The yield was 0.350 g (81%). 

Thioindigo [522-75-8] M 296.2, m >280 . Adsorbed on silica gel from CCl4/ benzene (3 1), eluted with benzene, crystd from CHCI3 and dried at 60-65°. [Wyman and Erode J Am Chem Soc 73 1487 1951.] This paper also gives details of purification of other thioindigo dyes. 

With 2537 k-Light. 1 g (140) in 140 ml anhydrous dioxane is irradiated for 20 hr at room temperature with a Hanau NK 6/20 low-pressure mercury lamp placed in a central water-cooled quartz finger. 0.19 g of (141) crystallize from the crude reaction mixture as described above. Chromatography of the residual material on silica gel with benzene-ethyl acetate (4 1) gives 0.29 g of B-nortestosterone acetate [(142) 28.5 %] and starting material (140). 

B. Methyl indole-4-carboxylate (30). A mixture of 7.0 g (28 mmol) of methyl trans-2-[ -(dimethylamino)vinyl]-3-nitrobenzoate(29) in 140 mL of dry benzene which contained 1.4 g of 10% Pd/C was shaken in a Parr apparatus under Hj (50 psi) for 1.5 h. The catalyst was removed by filtration, and the benzene solution was washed with 30 mL of 5% aq. HCl, brine and dried over MgS04. After removal of the solvent under reduced pressure, the residue was purified via chromatography on silica gel to furnish 6.9 g (82%) of methyl indole-4-carboxylate (30). 

Benzhydryl 3Sodium hydride, 24 mg (4B mg of a 50% suspension of NaH in mineral oil, which has been washed with hexane to remove the oil), is added. When hydrogen evolution has ceased, 126 mg dimethyl sulfate is added. The solution is stirred for one hour at room temperature,diluted with 100 ml benzene and washed six times with water the last wash is made to pH B, if necessary, by adding sodium bicarbonate. The solution is dried over MgS04, filtered and evaporated, leaving benzhydryl 3eluting with 25 1 chloroform-ethyl acetate. 

To which a solution of manganese sulfate (15 g), 3.1 g of chromium trioxide, 72 ml of water and 3.5 ml of sulfuric acid was added. After stirring for 3.5 hours at 3°C, extracted with diethyl ether. The organic layer was washed with water, dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using ethyl acetate-benzene (1 1) as eluent to give 2.35 g of the title compound. 

The allcylation of a number of aromatic compounds through the use of a chloroa-luminate(III) ionic liquid on a solid support has been investigated by Holderich and co-workers [87, 88]. Here the allcylation of aromatic compounds such as benzene, toluene, naphthalene, and phenol with dodecene was performed using the ionic liquid [BMIM]C1/A1C13 supported on silica, alumina, and zirconia. With benzene, monoalkylated dodecylbenzenes were obtained (Scheme 5.1-56). 

CH2C12 (500 mL). The CH2C]2 phase was separated and washed withH2Q, dried (Na2S04)and evaporated under reduced pressure, The residue was dissolved in benzene (200 mL), absorbed on silica gel (10 g) (0.05 0.2 mm) and the silica gel was then washed with portions of benzene (100 mL). The benzene washings were combined and evaporated to give the product, which was dissolved in hexane, and the solution cooled to 0 C, whereupon the pure dibenz[ft,/]azcpinc crystallized. 

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