NaOH solutions

Raney nickel A special form of nickel prepared by treating an Al-Ni alloy with NaOH solution. The nickel is left in a spongy mass which is pyrophoric when dry. This form of nickel is a most powerful catalyst, especially for hydrogenations. 

NaOCl. Formed (with NaCl) from CI2 plus cold NaOH solution. Forms hydrates. Aqueous solutions are used as bleaches and antiseptics. 

Na2S20j. Obtained NaOH solution saturated SO2 at 100 C. Forms 7 and 6 hydrates. Used in photography. 

Racemic acid, ( )-tartaric acid, is a compound of the two active forms. M.p. 273 C (with IHjO), m.p. 205°C (anhydrous). Less soluble in water than (-t-)-tartaric acid. Formed, together with mesotartaric acid, by boiling (4-)-tartaric acid with 30% NaOH solution, or by oxidation of fumaric acid. Potassium hydrogen racemate is very insoluble. 

The hydrolysis of as little as 0 5 ml. of the ester can be carried out in the combined reflux-distillation apparatus shown in Fig. 38 (p, 63). Pass a stream of cold water through the vertical condenser. Place in the 10 ml. pear-shaped flask 0 5 ml. of the ester, 5 ml. of 10% NaOH solution and one or two minute fragments of unglazed porcelain and heat the mixture gently for 15 minutes so that the vapours do not rise more than about half-way up the vertical water ondenser. Now run the water out of the ver ical condenser, insert a thermometer at the top, and pass water through the inclined condenser. Heat the flask sufficiently strongly to collect 1--2 ml. of distillate. This is dilute ethanol. 

NaOH solution until the mixture attains a uniform orange... 

Dissolve 2 g. of anthranilic acid in 12 8 ml. of 5% aqueous sodium hydroxide, or in 16 ml. of A -NaOH solution in a 50 ml. conical flask. (It is essential that the concentration of the hydroxide solution is accurately known.) Add i-6 ml. of dimethyl sulphate, and shake the securely-stoppered flask vigorously. 

Place about o-i g. of the following substances in a boiling tube and add about 5 ml. of 10% aqueous NaOH solution. Note any reaction in the cold. Then add a small piece of unglazed porcelain (to prevent bumping ), and boil gently for a few minutes. Note any further reaction. 

These compounds require a more concentrated NaOH solution (e.g., 30%) for a quick reaction on a test-tube scale. 

Ferric chloride solution sometimes contains a large excess of HCl which would interfere with the following reactions. If it is very markedly acidic add dil. NaOH solution, drop by drop, to the ferric chloride solution until a small but permanent precipitate of ferric hydroxide is obtained. Filter this off through a small fluted filter paper, and use the clear filtrate. The latter is still not quite neutral owing to hydrolysis, but this feeble acidity does not interfere with the tests given below. 

Note. For a very weak acid, the ammonium salt of which may dissociate rapidly on heating, conversion into the sodium salt rs recommended. Place o-1 g. of the acid in a boiling-tube and add NaOH solution until the mixture is just alkaline to litmus-paper. Add dil. HNO3 until just acid and then a slight excess of ammonia until again just alkaline. Add a piece of unglazed porcelain, and boil until the odour of ammonia is removed, and then cool. 

To a few drops of the ester, add 0 2 g. of hydroxylamine hydrochloride and about 5 ml. of 10% NaOH solution and gently boil the mixture for 1-2 minutes. Cool and acidify with HCl, cool again and then add a few drops of FeClj solution. A violet or deep red-brown colour develops immediately. 

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. 

Action of sodium hydroxide, (a) Warm 1 ml. of acetaldehyde with a few ml. of cone, (c.g., 30%) NaOH solution. A yellow resin, having a characteristic odour of bad apples, is formed. Paraldehyde slowly gives a yellow resin. 

Reduction of ammoniacal silver nitrate. Place about 5 ml. of AgNOj solution in a thoroughly clean test-tube, and add 2-3 drops of dil. NaOH solution. Add dil. ammonia solution, drop by drop, until the precipitated silver oxide is almost redissolved, then add 2 - 3 drops of formaldehyde or acetaldehyde. A silver mirror is formed. 

Nitroprusside reaction. Add 1 ml. of a freshly prepared solution of sodium nitroprusside to the aldehyde or its solution. Add dil. NaOH solution in excess a red coloration is produced. 

Isocyanide reaction. Since chloral hydrate is readily converted into chloroform by alkali, it will give the isocyanide reaction. To a few crystals of the solid add about 5 ml. of alcoholic NaOH solution and a few drops of aniline, and heat the disagreeable odour of phenyl isocyanide, C H(NC, is rapidly detected. 

Action of sodium hydroxide. Does not undergo the Cannizzaro reaction. It dissolves in dil. NaOH solution, giving a yellow solution from which the aldehyde is precipitated unchanged on acidification. If heated with cone. NaOH solution, salicylaldehyde slowly undergoes atmospheric oxidation to salicylic acid. 

Solubility in sodium hydroxide solution. See Section 4, p. 329. Note also that phenols dissolve in NaOH solution to give phenoxides. 

I. Fluorescein test. Fuse together carefully in a dry test-tube for about 1 minute a few crystals of resorcinol and an equal quantity of succinic acid or a succinate, moistened with 2 drops of cone. H2SO4. Cool, dissolve in water and add NaOH solution in excess. A red solution is produced which exhibits an intense green fluorescence.-f-... 

Iodoform reaction. To 0 5 ml. of lactic acid add 10% NaOH solution until alkaline to litmus. Then add 5 ml. of 10% KI solution and 10 ml. of freshly prepared sodium hypochlorite solution and mix well. A yellow precipitate of iodoform separates out almost immediately in the cold. 

Reduction of ammoniacal silver nitrate. Add i drop of dil. NaOH solution to about 5 ml. of AgNO, solution, and add dil. NH solution drop by drop until the silver oxide is almost redissolved. Add AgNO, solution until a faint but permanent precipitate is obtained (see p.525). Then add 0 5 ml. of a neutral tartrate solution. Place the tube in warm water a silver mirror is formed in a few minutes. 

Fenton s reagent. To a solution of tartaric acid or a tartrate add 1 drop of freshly prepared ferrous sulphate solution, i drop of hydrogen peroxide solution and then excess of NaOH solution an intense violet coloration is produced, due to the ferric salt of dihydroxyfumaric acid, HOOC C(OH) C(OH)COOH. 

Sulphuric add test. Heat 0 5 g. of citric acid or a citrate with 1 ml. of H2SO4 CO and COg are evolved and the mixture turns yellow, but does not char. Acetone dicarboxylic acid, OC(CH2COOH)g, is also formed, and is tested for after heating the mixture for 1 minute cool, add a few ml. of water and make alkaline with NaOH solution. Add a few ml. of a freshly prepared solution of sodium nitroprusside and note the intense red coloration (see Test 4 a) for ketones, p. 346). 

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