Solute Benzophenone

In acidic buffered solutions benzophenone-3,3 4,4 -tetracar-boxylic acid is reduced in two steps at the dropping mercury electrode. This corresponds to two quasidiffusion waves [59], of which the first represents reduction of the carbonyl group (n = 2) and the second corresponds to the benzene nuclei (n = 4). Both waves... 

Figure Bl.16.16. TREPR spectrum of TEMPO radicals in 1,2-epoxypropane solution with benzophenone, 1 ps after 308 inn laser flash. Reprinted from [45],...

Dissolve 1 g. of powdered benzophenone in 6-7 ml. of cold isopropanol with shaking, add 1 drop of glacial acetic acid, and then confine the solution either in a glass receiver having a ground-glass stopper, or in a tube which is sealed... 

In the following preparation to illustrate the Meen.vein-Pormdorf-Verley reduc tion, a solution of benzophenone in isopropanol is rapidly reduced in the presence of aluminium isopropoxide to benzhydrol (CaHs)2CO (C Hj)jCH OH. It is clear that the aluminium isopropoxide must take some essential part in this reaction, for benzophenone when dissolved even in cold isopropanol with a trace of acetic acid is reduced to tetraphenylethyleneglycol (p. 150). 

To a few drops of formalin solution add a few drops of dinitro-phenylhydrazine reagent A (p. 263) a yellow precipitate is produced in the cold. Acetaldehyde and acetone give orange-coloured precipitates. Dissolve water-insoluble compounds e.g-y benzaldehyde, salicylalde-hyde, acetophenone and benzophenone) in a small volume of methanol before adding reagent B. With benzophenone the precipitate forms slowly. 

Iodoform reaction. To 0 5 ml. of acetone add 3 ml. of 10% KI solution and 10 ml. of freshly prepared sodium hypochlorite solution and mix well. A pale yellow precipitate of iodofonn is rapidly formed without heating. Acetophenone similarly gives iodoform, but the mixture must be shaken vigorously on account of the limited solubility of acetophenone in water. Benzophenone does not give iodoform. 

Bisulphite addition compound. Shake 1 ml. of acetone with 0 5 ml. of a saturated solution of NaHS03. A white precipitate is formed, the mixture becoming warm and then, on cooling, almost solid. Acetophenone and benzophenone, having the >CO group directly joined to tlie benzene ring, do not respond to the test (p- 257). 

Bfflizophenone condenses with hydroxylamine hydrochloride in the presence of excess of sodium hydroxide solution to 3deld benzophenone oxime, m.p. 142° ... 

Method 2. Into a 500 ml. round-bottomed flask place 120 ml. of dry A.R. benzene, and 35 g. (29 ml.) of redistilled benzoyl chloride. Weigh out 30 g. of finely-powdered, anhydrous aluminium chloride into a dry corked test-tube, and add the solid, with frequent shaking, during 10 minutes to the contents of the flask. Fit a reflux condenser to the flask, and heat on a water bath for 3 hours or until hydrogen chloride is no longer evolved. Pour the contents of the flask wliile still warm into a mixture of 200 g. of crushed ice and 100 ml. of concentrated hydrochloric acid. Separate the upper benzene layer (filter first, if necessary), wash it with 50 ml. of 5 per cent, sodium hydroxide solution, then with water, and dry with anhydrous magnesium sulphate. Isolate the benzophenone as in Method 1. The yield is 30 g. 

In an alternative method of preparation, benzophenone is used. Prepare the Grignard reagent from 13 -5 g. of magnesium turnings as above, cool in cold water, and add a solution of 91 g. of benzophenone (Section IV,139) in 200 ml. of dry benzene at such a rate that the mixture refluxes gently. Reflux the mixture for 60 minutes, and isolate the triphenylcarbinol in the manner described above. The yield is of the same order. 

The selective intermolecular addition of two different ketones or aldehydes can sometimes be achieved without protection of the enol, because different carbonyl compounds behave differently. For example, attempts to condense acetaldehyde with benzophenone fail. Only self-condensation of acetaldehyde is observed, because the carbonyl group of benzophenone is not sufficiently electrophilic. With acetone instead of benzophenone only fi-hydroxyketones are formed in good yield, if the aldehyde is slowly added to the basic ketone solution. Aldols are not produced. This result can be generalized in the following way aldehydes have more reactive carbonyl groups than ketones, but enolates from ketones have a more nucleophilic carbon atom than enolates from aldehydes (G. Wittig, 1968). 

The reaction was conveniently carried out in DME in the presence of benzophenone, and the yields were in the range 20-30%. In ethanol solution, 1,3,5-trimethylpyrazole (177 R = R = R = Me, R = H) yielded (183) and (184) (69T3287). In contrast with the previously observed sensitized photorearrangements (67HCA2244, 67CC488), this last reaction was not sensitized by acetophenone or benzophenone. 

Commercially available anhydrous diethyl ether is distilled under nitrogen from a solution of the sodium benzophenone radical anion generated by treating a solution of 10 g of benzophenone and 1 L of ether with 10 g of sodium ribbon until a dark blue or purple color persists. 

To the wa-propyl alcohol filtrate is added another i5o-g. portion of benzophenone and the solution is exposed to sunlight as in the first reduction. The benzopinacol which separates is filtered and dried. The yield in the second and subsequent runs is 142-143 g. (94-95 per cent of the calculated amount). This procedure can be repeated with the same filtrate until six or seven portions (900-1050 g.) of benzophenone have been reduced. 

Diphenylmethane has been prepared with aluminum chloride as a catalyst from methylene chloride and benzene, from chloroform and benzene as a by-product in the preparation of triphenylmethane, and from benzyl chloride and benzene. It has been prepared by the reduction of benzophenone with hydriodic acid and phosphorus, or with sodium and alcohol. It has also been made by heating a solution of benzyl chloride in benzene with zinc dust, or with zinc chloride. The above method is only a slight modification of the original method of Hirst and Cohen. ... 

The intermediate diphenylhydroxymethyl radical has been detected after generation by flash photolysis. Photolysis of benzophenone in benzene solution containing potential hydrogen donors results in the formation of two intermediates that are detectable, and their rates of decay have been measured. One intermediate is the PhjCOH radical. It disappears by combination with another radical in a second-order process. A much shorter-lived species disappears with first-order kinetics in the presence of excess amounts of various hydrogen donors. The pseudo-first-order rate constants vary with the structure of the donor with 2,2-diphenylethanol, for example, k = 2 x 10 s . The rate is much less with poorer hydrogen-atom donors. The rapidly reacting intermediate is the triplet excited state of benzophenone. 

Chloro-1 -methyl-6-phenyl4H-s-triazolo-[4,3-a] [1,4] -benzodiazepine A stirred suspension of 5-chloro-2-[3-(bromomethyl)-5-methyl4H-1,2,4-triazol4-yl] -benzophenone (391 mg, 0.001 mol) in tetrahydrofuran (15 ml) was cooled in an ice-bat hand treated with a saturated solution of ammonia in methanol (12.5 ml). The resulting solution was allowed to warm to ambient temperature and stand for 24 hours. It was then concentrated in vacuo. The residue was suspended in water, treated with a little sodium bicarbonate and extracted with methylene chloride. The extract was washed with brine, dried with anhydrous potassium carbonate and concentrated. The residue was crystallized from methylene chloride-ethyl acetate to give... 

A) 1-(2-Amino-5-chlorophenyll-1-(2-fluorophenyll-2-a2a-but-1-en-4-ol A mixture of 40 g of 2-methylimidazole hydrochloride and of 90 g of 2-amino-5-chloro-2 -fluoro-benzophenone in 240 ml of ethanolamine is heated at 135 for 2 hours. After cooling, the reaction mixture is poured into an aqueous sodium bicarbonate solution. The mixture is extracted with ether, the organic phase is washed repeatedly with water and is dried over sodium sulfate, and the solvent is evaporated to dryness. The residual oil is chromatographed on a silica column, elution being carried out with a 50/50 mixture of cyclohexane and ethyl acetate. 

A slight excess of mineral acid, such as sulfuric or hydrochloric acid is added to acidify the mixture which is then chilled and the solid which separates is filtered off. It is then treated with an aqueous solution of dilute sodium hydroxide to dissolve the hydantoin from the solid unreacted benzophenone. After filtration, the alkaline extract is then acidified to cause the separation of solid pure diphenylhydantoin which is filtered off and dried. It melts at 293° to 296°C. 

Preparation of 2-Cyc/opropy/methy/amino-5-Ch/orobenzophenone To a solution of 315 g (1.09 mols) of 2-cyclopropylmethylamino-5-chloroDenzhydrol in 4 liters of benzene is added 453.6 g (5.22 mols) of manganese dioxide, freshly prepared according to the method of Attenburrow et al, J.C.S. 1952, 1104. The mixture is then refluxed for VA hours, filtered, and the filtrate evaporated under vacuum. The reddish residue is recrystallized from 510 ml of 90% acetone-10% water, giving 181 g of pure 2-cyclopropylmethylamino-5-chloro-benzophenone, MP 79° to 80°C (58% yield). Upon concentration of the mother liquor a second crop of 2-cyclopropylmethylamino-5-chlorobenzophenone weighing 34.1 g and melting at 76.5°-78°C are obtained. 

Benzohydrol has been obtained by reducing benzophenone with sodium amalgam,1 with metallic calcium and alcohol,2 with hydrogen in the presence of a catalyst,3 with zinc, aluminium or sodium in strongly alkaline solutions,4 with zinc dust and alcoholic potassium hydroxide solution,5 and electrolytically.6... 

A solution of 5 (20 mmol) in CH2C12 (100 mL) was treated with liquid NH3 (100 mL) and while the NH3 was refluxing the mixture was stirred for 5h in a flask fitted with a dry-ice condenser. The NH, was then allowed to evaporate at rt and the CH2C12 solution was washed with H20, dried and evaporated in vacuo to leave the 2-(aininoacetamido)benzophenone 6. 

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