Лако-красочные материалы — производство

The diagram in Figure 28 best explains the procedure. Naphtha­lene is placed in flask B, which is heated to 110°C., and a stream of moist air is passed through the gas introduction tube (A). The presence of water vapor is important for the oxidation. The necessary air is most Fig. 28. Apparatus for preparation of […]

Pumice is broken up into pieces about 3 mm. in size and screened, using a sieve that retains the 3-mm. pieces. The more uniform the pieces are, the better. This pumice is placed in a hot solution of ammonium vanadate which is as concentrated as possible. When the pumice is thoroughly impregnated, it is removed […]

Phthalic Anhydride from Naphthalene by Catalytic Oxidation54 The heat of combustion of naphthalene is +1234 kilocalories per mole, and of phthalic anhydride, +450 kilocalories per mole. The catalytic oxidation of naphthalene can easily be carried out in the laboratory, although the amount of phthalic anhydride which can be prepared in one operation is insignificant. It […]

OH но/N OH (NH4),SO, + NHS COOH OH HO /N OH CO-NH, The most important starting materials for the preparation of galla­mide and gallic acid are gallnuts and sumac (Rhus coriaria). The tan­nins from these are split either into sugar and gallic acid by the action of sodium hydroxide, or into sugar, gallamide, and gallic […]

The difficultly soluble sodium salt from the first step is dissolved in 300 cc. hot water, and the free sodium hydroxide present is neutralized with dilute hydrochloric acid. The resulting solution is added during the course of 30 minutes to 200 grams of iron turnings which have been etched with 20 cc. 40 per cent […]

Hydrolysis of 2,6-dichlorobenzal chloride is much more difficult than that of benzal chloride itself. In contrast to the latter, 2,6-dichloro — benzal chloride is not hydrolyzed either by water and iron or by cal­cium or potassium hydroxide, even under pressure at 150°C. The hy­drolysis to the desired aldehyde is effected with concentrated sulfuric acid, although […]

The laboratory chlorination of dichlorotoluene to form diehloro — benzal chloride is very simple. Chlorine is passed into boiling, dry dichlorotoluene, in sunlight if possible, until the original weight of 161 grams has increased 69 grams. With these quantities, the chlorination is easily completed in 2 hours. The reaction flask must be equipped with an […]

A solution is made of 141.5 grams (1.0 mole) of 2,6-ehlorotoluidine in 1 liter of water and 450 grams of 30 per cent hydrochloric acid by heating to 80°C. and then cooling to 30° with stirring. Enough ice is then added to lower the temperature to 5°. Some of the hydrochloride crystallizes out. Diazotization is […]

Nitrochlorotoluene is reduced by the Bechamp method, adding 100 grams of the nitro compound during the course of 2 hours to a boiling, constantly stirred mixture of 100 grams of finely powdered iron, 200 cc. water, and 20 cc. technical hydrochloric acid. 20 grams of soda ash is then added, and the apparatus is heated […]

(a) Benzal Chloride In a chlorination apparatus such as that shown in Figure 5 (page 63), 460 grams (5 moles) of toluene containing 10 grams of phos­phorous pentachloride is heated to boiling, and chlorine is run in until the gain in weight is 345 grams. Sunlight or ultraviolet light generally facilitates smooth chlorination of the […]