Cooling phenols

T. Ebata, T. Walanabe, and N. Mikami, Evidence for the cyclic form of phenol trimer Vibrational spectroscopy of the OH stretching vibrations of jet cooled phenol dimer and... 

Y. Yamada, T. Ebata, M. Kayano, and N. Mikami, Picosecond IR-UV pump-probe spectroscopic study of the dynamics of the vibrational relaxation of jet-cooled phenol. I. Intramolecular vibrational energy redistribution of the OH and CH stretching vibrations of bare phenol, J. Chem. Phys. 120, 7400-7409 (2004). 

The solution of the aniline hydrochloride should be cooled to 5°C., and this temperature maintained throughout the addition of the sodium nitrite solution. External cooling has to be maintained, otherwise the heat of the reaction would cause the temperature to rise, with the consequent decomposition of the diazonium chloride and the production of phenol. If, on the other hand, the temperature is reduced to about o , diazotisation becomes extremely slow and unchanged nitrous acid may remain in the solution for an impracticably long time. 

Dissolve 15 ml. (15-4 g.) of aniline in a mixture of 40 ml. of concentrated hydrochloric acid and 40 ml. of water contained in a 250 ml. conical flask. Place a thermometer in the solution, immerse the flask in a mixture of ice and water, and cool until the temperature of the stirred solution reaches 5°. Dissolve I2 5 g. of powdered sodium nitrite in 30 ml. of water, and add this solution in small quantities (about 2-3 ml. at a time) to the cold aniline hydrochloride solution, meanwhile keeping the latter well stirred by means of a thermometer. Heat is evolved by the reaction, and therefore a short interval should be allowed between consecutive additions of the sodium nitrite, partly to allow the temperature to fall again to 5°, and partly to ensure that the nitrous acid formed reacts as completely as possible with the aniline. The temperature must not be allowed to rise above 10°, otherwise appreciable decomposition of the diazonium compound to phenol will occur on the other hand, the temperature... 

Colorations or coloured precipitates are frequently given by the reaction of ferric chloride solution with.(i) solutions of neutral salts of acids, (ii) phenols and many of their derivatives, (iii) a few amines. If a free acid is under investigation it must first be neutralised as follows Place about 01 g. of the acid in a boiling-tube and add a slight excess of ammonia solution, i,e., until the solution is just alkaline to litmus-paper. Add a piece of unglazed porcelain and boil until the odour of ammonia is completely removed, and then cool. To the solution so obtained add a few drops of the "neutralised ferric chloride solution. Perform this test with the following acids and note the result ... 

Azo-dye formation. Dissolve 2-3 drops of aniline in 1 ml. of cone. HCl and add 3 ml. of water. Shaike to dissolve any hydrochloride which may have separated and cool in ice. Add a few drops of 20% sodium nitrite solution. Add this cold diazonium solution to a cold solution of the phenol in an excess of aqueous NaOH solution. Solutions or precipitates of azo-dyes ranging in colour from orange through scarlet to dark red, according to the phenol used, are obtained. Note in particular that i-naphthol gives a brownish-red, 2-naphthol a scarlet precipitate. Catechol decomposes. 

Phthalein reaction. Place in a dry test-tube about 0 2 g. of the phenol and an equal quantity of phthalic anhydride (or acid), moisten with 2 drops (not more) of cone. H2SO4 and gently fuse together for about 1 minute. Allow to cool somewhat, and then add 10% NaOH solution in excess. 

Ltebermann Reaction To 1 minute crystal of sodium nitrite in a clean dry test-tube add 0 5 g. of phenol and heat very gently for about 20 seconds allow to cool and add twice the volume of cone. H2S04. On rotating the tube slowly in order to mix the contents, a deep green or deep blue coloration develops (some times only after i 2 minutes). Dilute cautiously with water the solution turns red. Now add an excess of NaOH solution the green or blue coloration reappears. 

For some phenols whose esters are readily hydrolysed, it is advantageous to add the powdered chloride to a pyridine solution of the phenol, warm the mixture on the water-bath for ca. 15 minutes, cool and pour into water, when the sulphonate will separate. 

C) Phenacyl and p-Bromophenacyl esters. Ammonium salts in aqueous-ethanolic solution do not however usually condense satisfactorily with phenacyl and />-bromophenacyl bromide. The aqueous solution of the ammonium salt should therefore be boiled with a slight excess of sodium hydroxide to remove ammonia, and the solution then cooled, treated with hydrochloric acid until just alkaline to phenol-phthalein, and then evaporated to dryness. The sodium salt is then treated as described (p. 349) to give the ester. Filter the ester, and wash with water to remove senium halide before recrystallisation. 

Phthalcin reaction. Fuse together very gently in a dry test-tube 01 g. of phthalimide, O l g. of phenol and 2 drops of cone. HjSO, Cool, add waier and then NaOH solution in excess. A red coloration is produced which is decolorised by acids. (Note. Succinimide gives no definite coloration in these circumstances.)... 

Benzylthiouronium salts. Add 0 5 g. of sulphanilic acid to 10 ml. of water and 5 ml. of 10% NaOH solution, zndgently warm the shaken mixture until a clear solution is obtained. Cool, add 1 drop of phenol-phthalein solution, and then add dilute HCl dropwise with shaking until the pink colour is just discharged. Now add very dilute NaOH solution until the pink colour yt/rZ returns. Cool and add with shaking a solution of 0-5 g. of benzylthiouronium chloride in 5 ml. of water. The thiouronium salt rapidly separates filter at the pump, wash with water, drain and recrystallise from ethanol. Colourless crystals, m.p. 185°. (M.ps., p. 548.)... 

Add dil. H2SO4 until the solution is acid to litmus. Cool, and scratch the sides of the vessel with a glass rod a white precipitate indicates an aromatic carboxylic acid or uric acid, or a solid phenol insoluble in water (e.g., i- or 2-naphthol). If a precipitate is obtained, filter off through a Buchner funnel, wash with water, recrystallise if necessary and identify. 

Dissolve 1 g. of the secondary amine in 3-5 ml. of dilute hydrochloric acid or of alcohol (in the latter case, add 1 ml. of concentrated hydrochloric acid). Cool to about 5° and add 4-5 ml. of 10 per cent, sodium nitrite solution, and allow to stand for 5 minutes. Add 10 ml. of water, transfer to a small separatory funnel and extract the oil with about 20 ml. of ether. Wash the ethereal extract successively with water, dilute sodium hydroxide solution and water. Remove the ether on a previously warmed water bath no flames should be present in the vicinity. Apply Liebermann s nitroso reaction to the residual oil or solid thus. Place 1 drop or 0 01-0 02 g. of the nitroso compovmd in a dry test-tube, add 0 05 g. of phenol and warm together for 20 seconds cool, and add 1 ml. of concentrated sulphuric acid. An intense green (or greenish-blue) colouration will be developed, which changes to pale red upon pouring into 30-50 ml. of cold water the colour becomes deep blue or green upon adding excess of sodium hydroxide solution. 

Equip a 500 ml, three-necked flask with a separatory funnel, a mercury-sealed mechanical stirrer and a reflux condenser. Place a solution of 21 g. of sodium hydroxide in 200 ml. of water and also 47 g. of pure phenol in the flask, and stir the mixture cool the warm mixture to about 10° by immersing the flask in an ice bath. Place 63 g. (47 ml.) of dimethyl sulphate in the separatory funnel. 

Cautiously add 250 g. (136 ml.) of concentrated sulphuric acid in a thin stream and with stirring to 400 ml. of water contained in a 1 litre bolt-head or three-necked flask, and then dissolve 150 g. of sodium nitrate in the diluted acid. Cool in a bath of ice or iced water. Melt 94 g. of phenol with 20 ml. of water, and add this from a separatory funnel to the stirred mixture in the flask at such a rate that the temperature does not rise above 20°. Continue the stirring for a further 2 hours after all the phenol has been added. Pour oflF the mother liquid from the resinous mixture of nitro compounds. Melt the residue with 500 ml. of water, shake and allow the contents of the flask to settle. Pour oflF the wash liquor and repeat the washing at least two or three times to ensure the complete removal of any residual acid. Steam distil the mixture (Fig. II, 40, 1 or Fig. II, 41, 1) until no more o-nitrophenol passes over if the latter tends to solidify in the condenser, turn oflF the cooling water temporarily. Collect the distillate in cold water, filter at the pump, and drain thoroughly. Dry upon filter paper in the air. The yield of o-nitrophenol, m.p. 46° (1), is 50 g. 

To a mixture of 10 g. of the compound and 3-5 ml. of 33 per cent, sodium hydroxide solution in a test-tube, add 2-5 ml. of 50 per cent, chloroacetic acid solution. If necessary, add a little water to dissolve the sodium salt of the phenol. Stopper the test-tube loosely and heat on agently-boiling water bath for an hour. After cooling, dilute with 10 ml. of water, acidify to Congo red with dilute hydrochloric acid, and extract with 30 ml. of ether. Wash the ethereal extract with 10 ml, of water, and extract the aryloxyacetic acid b shaking with 25 ml. of 5 per cent, sodium carbonate solution. Acidify the sodium carbonate extract (to Congo red) with dilute hydrochloric acid, collect the aryloxyacetic acid which separates, and recrystallise it from hot water. 

Place 10 g. of clean sodium (cut into small pieces) in a 500 ml. round bottomed flask fitted with a double surface reflux condenser. Introduce 100 g. (127 ml.) of absolute ethyl alcohol and allow the reaction to proceed as vigorously as possible if the alcohol tends to flood the condenser, cool the flask momentarily with a wet towel or by a stream of cold water. When all the sodium has reacted, add 40 g. of pure phenol. Distil ofif the... 

Methylation with diazomethane may be carried out as follows (FUME CUPBOARD )-. Dissolve 2-3 g. of the compound (say, a phenol or a carboxylic acid) in a little anhydrous ether or absolute methanol, cool in ice, and add the ethereal solution of diazomethane in small portions until gas evolution ceases and the solution acquires a pale yellow colour. Test the coloured solution for the presence of excess of diazomethane by removing a few drops into a test-tube and introducing a glass rod moistened with glacial acetic acid immediate evolution of gas should... 

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