From benzene

If the byproduct reaction is reversible and inerts are present, then changing the concentration of inerts if there is a change in the number of moles should be considered, as discussed above. Whether or not there is a change in the number of moles, recycling byproducts can suppress their formation if the bj iroduct-forming reaction is reversible. An example is in the production of ethylbenzene from benzene and ethylene ... 

Bromobenzene,Cf,HfSr. B.p. 155°C. Prepared from benzene by direct bromination in the presence of a carrier (Ij, Fe, AICI3) or by... 

For adsorption on Spheron 6 from benzene-cyclohexane solutions, the plot of N N2/noAN2 versus N2 (cyclohexane being component 2) has a slope of 2.3 and an intercept of 0.4. (a) Calculate K. (b) Taking the area per molecule to be 40 A, calculate the specific surface area of the spheron 6. (c) Plot the isotherm of composition change. Note Assume that is in millimoles per gram. 

TR-CRS has been used to study many molecules from benzene [115. 116. 117 and 118] to betacarotene [119]. 

Figure Bl.6.10 Energy-loss spectrum of 3.5 eV electrons specularly reflected from benzene absorbed on the rheniiun(l 11) surface [H]. Excitation of C-H vibrational modes appears at 100, 140 and 372 meV. Only modes with a changing electric dipole perpendicular to the surface are allowed for excitation in specular reflection. The great intensity of the out-of-plane C-H bending mode at 100 meV confimis that the plane of the molecule is parallel to the metal surface. Transitions at 43, 68 and 176 meV are associated with Rli-C and C-C vibrations.

To obtain the free acid, dissolve the potassium salt in 50 ml. of cold water, filter the solution if a small undissolved residue remains, and then boil the clear solution gently whilst dilute sulphuric acid is added until the separation of the acid is complete. Cool the solution and filter off the pale orange-coloured crystals of the benzilic acid wash the crystals on the filter with some hot distilled water, drain well, and then dry in a desiccator. Yield of crude acid, 4 g. Recrystallise from benzene (about 50 ml.) to which a small quantity of animal charcoal has been added, filtering the boiling solution through a preheated funnel fitted w ith a fluted filter-paper, as the benzilic acid readily crystallises as the solution cools alternatively, recrystallise from much hot water. The benzilic acid is obtained as colourless crystals, m.p. 150°. 

Fit securely to the lower end of the condenser (as a receiver) a Buchner flask, the side-tube carrying a piece of rubber tubing which falls well below the level of the bench. Steam-distil the ethereal mixture for about 30 minutes discard the distillate, which contains the ether, possibly a trace of unchanged ethyl benzoate, and also any biphenyl, CeHs CgHs, which has been formed. The residue in the flask contains the triphenyl carbinol, which solidifies when the liquid is cooled. Filter this residual product at the pump, wash the triphenyl-carbinol thoroughly with water, drain, and then dry by pressing between several layers of thick drying-paper. Yield of crude dry product, 8 g. The triphenyl-carbinol can be recrystallised from methylated spirit (yield, 6 g.), or, if quite dry, from benzene, and so obtained as colourless crystals, m.p. 162. ... 

Steam-distil the ethereal solution and discard the distillate. The residue in the flask is triphenyl-carbinol and solidifies on cooling. Filter at the pump, wash with water, drain and dry. Yield of crude product 0 6 g. Recrystallise when dry from benzene to obtain colourless crystals m.p. 162°. 

To about ro ml. of the ester add about 0 5 g. of 3,5-dim trobenzoic acid and 0 25 ml. of cone. H3SO4. Heat the mixture gently under reflux for 5 minutes. Add very carefully about 10 ml. of water, make alkaline with NaOH and filter at the pump. Recrystallise the solid 3,5-dinitrobenzoate from benzene and take the m.p. (M.ps., pp. 536-530.)... 

Formation of a Quinoxaline. Heat together for 5 minutes under reflux 0 2 g. of phenanthraquinone dissolved in i ml. of glacial acetic acid and 0-2 g. of O -phenylene diamine also dissolved in i ml, of glacial acetic acid. The yellow substituted quinoxaline (p. 305) separates rapidly. Cool, filter and recrystallise from benzene m.p. 225 . 

Commercial benzene may contain thiophene C H S, b.p. 84°, which cannot be separated by distillation or by fractional crystallisation. The presence of thiophene may be detected by shaking 3 ml. of benzene with a solution of 10 mg. of isatin in 10 ml. of concentrated sulphuric acid and allowing the mixture to stand for a short time a bluish-green colouration is produced if thiophene is present. The thiophene may be removed from benzene by any of the following methods —... 

Commercial 2 4-dichlorophenoxyacetic acid may be recrystallised from benzene m.p. 139-140°. Reflux 10 g. of the acid with 15 ml. of thionyl chloride on a steam bath for 1 hour, distil off the excess of thionyl chloride at atmospheric pressure and the residue under reduced pressure 2 4-dichlorophenoxyacetyl chloride (8 g.) passes over at 155-157°/22-23 mm. It occasionally crystallises (m.p. 44-5-45-5°), but usually tends to remain as a supercooled liquid. 

Dissolve 0-2 g. of fructose in 10 ml. of water, add 0-6 g. of cw-methyl-phenylhydrazine and sufficient rectified spirit to give a clear solution. Since the fructose may not be quite pure, warm the mixture slightly, allow to stand, preferably overnight, so that any insoluble hydrazones may separate if present, remove them by filtration. Add 4 ml. of 50 per cent, acetic acid to the filtrate it will become yellow in colour. Heat the solution on a water bath for 5-10 minutes, and allow to stand in the dark until crystalUsation is complete it may be necessary to scratch the walls of the vessel to induce crystalUsation. Filter the crystals and wash with water, followed by a little ether. RecrystaUise the orange-coloured methylphenylosazone from benzene m.p. 152°. 

Pimelic acid. Heat a mixture of 18 g. of pentamethylene dicyanide and 250 g. of 50 per cent, sulphuric acid by weight in a 750 ml. round-bottomed flask under reflux for 9 hours. INIost of the pimehc acid separates from the cold reaction mixture. Filter oflF the crystaUine acid upon a sintered glass funnel. Saturate the filtrate with ammonium sulphate and extract it with three 50 ml. portions of ether. Dissolve the residue on the filter (which is shghtly discoloured, but is fairly pure pimehc acid) in the combined ethereal extracts, dry with anhydrous sodium or magnesium sulphate, and remove the ether by distiUation. Recrystallise the residual sohd acid from benzene containing 5 per cent, of ether. The yield of pure pimehc acid, m.p, 105-106°, is 22 g. 

An alternative method of separation consists in treating the dry residue several times with a warm mixture of benzene and ether. The residual solid (about 20 g.) is moderately pure succinic acid, m.p. 183-184°. Upon evaporating the benzene - ether extract, and recrystallising the residue from chloroform or from benzene, about 70 g. of glutaric acid, m.p. 95-96°, are obtained. 

The ketones are readily prepared, for example, acetophenone from benzene, acetyl chloride (or acetic anhydride) and aluminium chloride by the Friedel and Crafts reaction ethyl benzyl ketones by passing a mixture of phenylacetic acid and propionic acid over thoria at 450° and n-propyl- p-phenylethylketone by circulating a mixture of hydrocinnamic acid and n-butyric acid over thoria (for further details, see under Aromatic Ketones, Sections IV,136, IV,137 and IV,141). 

The iodobenzene is conveniently distilled under reduced pressure and the fraction b.p. 77- 80°/20 mm. or 63-64°/8 mm. collected. The product has a higher degree of purity than that obtained directly from benzene (Section IV,21). 

Hydrolysis of p-tolunitrile to p-toluic acid. Boil a mixture of 5 g. of p-tolunitrile, 80 ml. of 10 per cent, aqueous sodium hydroxide solution and 15 ml. of alcohol under a reflux condenser. (The alcohol is added to prevent the nitrile, which volatUises in the steam, from crystalhsing in the condenser it also increases the speed of hydrolysis. The alcohol may be omitted in the hydrolysis of nitriles which are hquid at the ordinary temperature, e.g., benzo-nitrUe.) The solution becomes clear after heating for about 1 hour, but continue the boiling for a total period of 1 - 5 hours to ensure complete hydrolysis. Detach the condenser and boil the solution for a few minutes in the open flask to remove dissolved ammonia and incidentally some of the alcohol CAUTION /). Cool, and add concentrated hydrochloric acid until precipitation of the p-toluic acid is complete. When cold, filter off the p-toluic acid with suction and wash with a little cold water. Recrystallise from a mixture of equal volumes of water and alcohol (methylated spirit) or from benzene. The yield of p-toluic acid, m.p. 178°, is 5-5 g. 

Naphthyl methyl ether (nerolin). Use 36 0 g. of p-naphthol, 10-5 g. of sodium hydroxide in 150 ml. of water, and add 31 -5 g. (23 -5 ml.) of dimethyl sulphate whilst the mixture is cooled in ice. Warm for 1 hour at 70-80°, and allow to cool. Filter oflF the naphthyl methyl ether at the pump, wash with 10 per cent, sodium hydroxide solution, then liberally with water, and drain thoroughly. Recrystallise from benzene or methylated spirit. The yield is 33 g., m.p. 72°. 

Benzophenone is more conveniently prepared from benzene and excess of carbon tetrachloride ... 

Hydrolysis of benzyl cyanide to phenylacetamide. In a 1500 ml. three-necked flask, provided with a thermometer, reflux condenser and efficient mechanical stirrer, place 100 g. (98 ml.) of benzyl]cyanide and 400 ml. of concentrated hydrochloric acid. Immerse the flask in a water bath at 40°. and stir the mixture vigorously the benzyl cyanide passes into solution within 20-40 minutes and the temperature of the reaction mixture rises to about 50°, Continue the stirring for an additional 20-30 minutes after the mixture is homogeneous. Replace the warm water in the bath by tap water at 15°, replace the thermometer by a dropping funnel charged with 400 ml. of cold distilled water, and add the latter with stirring crystals commence to separate after about 50-75 ml. have been introduced. When all the water has been run in, cool the mixture externally with ice water for 30 minutes (1), and collect the crude phenylacetamide by filtration at the pump. Remove traces of phenylacetic acid by stirring the wet sohd for about 30 minutes with two 50 ml. portions of cold water dry the crystals at 50-80°. The yield of phenylacetamide, m.p. 154-155°, is 95 g. RecrystaUisation from benzene or rectified spirit raises the m.p. to 156°. 

Decane-1 10-dicarboxylic acid from sebacic acid. Convert sebacic acid into the acid chloride by treatment with phosphorus penta-chloride (2 mols) and purify by distillation b.p. 146-143°/2 mm. the yield is almost quantitative. Dissolve the resulting sebacoyl chloride in anhydrous ether and add the solution slowly to an ethereal solution of excess of diazomethane (prepared from 50 g. of nitrosomethylurea) allow the mixture to stand overnight. Remove the ether and excess of diazomethane under reduced pressure the residual crystalline 1 8-bis-diazoacetyloctane weighs 19 -3 g. and melts at 91° after crystaUisation from benzene. 

Azlactone of a-benzoylaminocinnamic acid. Place a mi.xture of 27 g. (26 ml.) of redistilled benzaldehyde, 45 g. of Mppuric acid (Section IV,54), 77 g. (71-5) ml. of acetic anhydride and 20-5 g. of anhydrous sodium acetate in a 500 ml. conical flask and heat on an electric hot plate with constant shaking. As soon as the mixture has liquefied completely, transfer the flask to a water bath and heat for 2 hours. Then add 100 ml. of alcohol slowly to the contents of the flask, allow the mixture to stand overnight, filter the crystalline product with suction, wash with two 25 ml. portions of ice-cold alcohol and then wash with two 25 ml. portions of boiling water dry at 100°. The yield of almost pure azlactone, m.p. 165-166°, is 40 g. Recrystallisation from benzene raises the m.p. to 167-168°. 

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