Dry testing

Place a small quantity (t.e., about o-i g.) of the following substances (finely powdered) in a clean dry test-tube and add about I ml. of cone. H2SO4. Note any reaction in the cold, and then warm gently. Note any effervescence and any pronounced blackening (as distinct from mere darkening in colour). 

Dinitrobenzoylation. To 0 5 g. of powdered 3,5-dinitro benzoyl chloride (preparation, p. 240) in a dry test-tube, add 2 ml. of dry methanol and warm the mixture until a clear solution is obtained. Cool and filter off the solid ester which separates. Recrystallise from petroleum (b.p. 60-80 ), and take the m.p. (M.ps., pp. 536, 537.)... 

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. 

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-... 

Formation of Biuret., and Biuret reaction. Place 0 2 g. of urea in a dry test-tube, heat very gently just above the m.p. and note the production of ammonia. After 1-2 minutes the liquid suddenly solidifies with the formation of biuret ... 

Fluorescein reaction. Fuse together in a dry test-tube o-i g. of succinimide, O l g. of resorcinol and 2 drops of cone. HjSOi, Cool, add water and then NaOH solution in excess. A green fluorescent solution is obtained. 

Methiodide formation. Place 2 drops of dry pyridine in a dry test-tube, add 4-5 drops of methanol, and 2 -3 drops of methyl iodide. 

Physical Properties. Benzene, C H, toluene, C Hj-CH, and petrol (a mixture of aliphatic hydrocarbons, e.g., pentane, hexane, etc.) are colourless liquids, insoluble in and lighter than water. Benzene and toluene, which have similar odours, are not readily distinguishable chemically, and their physical constants should therefore be carefully noted benzene, m.p. 5 (solidifies when a few ml. in a dry test-tube are chilled in ice-water), b.p. 8i toluene, m.p. —93°, b.p. 110°. Petroleum has a characteristic odour. 

Obtain five small dry test-tubes (75 x 10 mm. ) and introduce 1 ml. of the following alcohols into each ethyl alcohol, n-butyl alcohol, jcc.-butyl alcohol, cycZohexanol and butyl alcohol. Add a minute fragment of sodium to each and observe the rate of reaction. Arrange the alcohols in the order of decreasing reactivity towards sodium. 

Method 2. Mix 1 0 g. of 3 5-dinitrobenzoic acid with 1 5 g. of phosphorus pentachloride in a small, dry test-tube. Warm the mixture gently over a small smoky fiame to start the reaction when the reaction has subsided (but not before), boil for 1-2 minutes or until the solid matter has dissolved. Pour the mixture while still liquid on a dry watch glass (CAUTION the fumes are irritating to the eyes). When the product has solidified, remove the liquid by-product (phosphorus oxychloride) by transferring the pasty mixture to a pad of several thicknesses of filter paper or to a small piece of porous tile. Spread the material until the liquid has been absorbed and the residual solid is dry. Transfer the 3 5 dinitrobenzoyl chloride to a test-tube, add 0-5-1 ml. of the alcohol, and continue as in Method 1. 

Place 1 0 g. of the monobasic acid and 2 g. of aniline or p-toluidine in a dry test-tube, attach a short air condenser and heat the mixture in an oil bath at 140-160° for 2 hours do not reflux too vigorously an acid that boils below this temperature range and only allow steam to escape from the top of the condenser. For a sodium salt, use the proportions of 1 g. of salt to 1 5 g. of the base. If the acid is dibasic, employ double the quantity of amine and a reaction temperature of 180-200° incidentally, the procedure is recommended for dibasic acids since the latter frequently give anhydrides with thionyl chloride. Powder the cold reaction mixture, triturate it with 20-30 ml. of 10 per cent, hydrochloric acid, and recrystallise from dilute alcohol. 

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. 

Dissolve 1 0 g. of the compound in 5 ml. of dry chloroform in a dry test-tuhe, cool to 0°, and add dropwise 5g. (2-8 ml.) of redistilled chloro-sulphonic acid. When the evolution of hydrogen chloride subsides, allow the reaction mixture to stand at room temperature for 20 minutes. Pour the contents of the test-tube cautiously on to 25 g. of crushed ice contained in a small beaker. Separate the chloroform layer and wash it with a httle cold water. Add the chloroform layer, with stirring, to 10 ml. of concentrated ammonia solution. After 10 minutes, evaporate the chloroform on a water bath, cool the residue and treat it with 5 ml. of 10 per cent, sodium hydroxide solution the sulphonamide dissolves as the sodium derivative, RO.CgH4.SO,NHNa. Filter the solution to remove any insoluble matter (sulphone, etc.), acidify the filtrate with dilute hydrochloric acid, and cool in ice water. Collect the sulphonamide and recrystallise it from dilute alcohol. 

Place in a dry test-tube 0 -5 g. of the compound and an equal bulk of pure phthahc anhydride, mix well together, and add 1 drop of concentrated sulphuric acid. Stand the tube for 3-4 minutes in a smah beaker of concentrated sulphuric acid or oil previously heated to 160°, Remove from the bath, allow to cool, add 4 ml. of 5 per cent, sodium hydroxide solution and stir until the fused mass has dissolved. Dilute with an equal... 

Solubility in ether. Use 0 -10 g. of solid or 0 -20 ml. of a liquid in a dry test-tube and proceed exactly as in testing the solubility in water, but do not employ more than 3 0 ml. of solvent. 

Fuming sulphuric acid test. Place 2 ml. of 20 per cent, fuming sulphuric acid in a dry test-tube, add 0 -5 ml. of the hydrocarbon and shake vigorously. Only the aromatic hydrocarbon dissolves completely heat is evolved, but excessive charring should be absent. 

Sodium test. Treat 1 ml. of the compound with a amall thin slice of freshly cut sodium (handle with the tonga or with a penknife) in a small, dry test-tube (75 X 10 mm. or 100 X 12 mm.). Observe whether hydrogen is evolved and the sodium reacts. (If the compound is suspected to contain water, dry it first with a little anhydrous calcium or magnesium sulphate.)... 

Acetyl chloride test. In a small, dry test-tube treat 0 -5 ml. of the compound with 0-3-0-4 ml. of redistUled acetyl chloride and note whether reaction occurs. Add 3 ml. of water and neutralise the aqueous layer with solid sodium bicarbonate. Look for a product different from the original alcohol. 

Miscellaneous Fastness Tests. The fastness to hot pressiag, ISO 10S-X1 /, test is similar to the fastness to dry heat test except that the time of pressing is 15 s (again at 150, 180, and 210°C), and the test can either be carried out dry when a damp cotton fabric containing its own weight of water is placed on top of the dry test fabric, or wet when the test fabric also contains its own weight of water. 

Diying te.st.s. Drying tests should be conducted in those diyers still under consideration. These tests will determine the optimum operating conditions and the product characteristics and will form the basis for firm quotations from equipment vendors. 

On the basis of the results of the drying tests that establish size and operating charac teristics, formal quotations and guarantees shoiild be obtained from diyer manufacturers. Initial costs, installation costs, operating costs, produc t quality, diyer operability, and diyer flexibihty can then be given proper weight in final evaluation and selection. 

Dry test 24-h cold-water soak 6-h boil test ... 

Depth loading The deposition of particles mainly within the filter interstices, rather than on the filter surface. Desiccator A sealed container containing a water-absorbing substance such as silica gel or calcium chloride used to dry test materials in the laboratory,... 

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