Water melting

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. 

Phenylpropanolamine. - With catalyst prepared as previously described from 0.5g of palladium chloride and 3g of charcoal, it was possible to reduce two portions of 9.8g of isonitrosopropio-phenone (0.06 mol), dissolved in 150 cc. of absolute alcohol containing 7. Og of hydrogen chloride, to phenylpropanolamine in from 145 - 190 minutes with yields of the isolated chloride from 9.4g to 11. Og, or 84 to 98% of the theoretical. After recrystallization from absolute alcohol the salt melted at 191°. The free base was obtained by treating an aqueous solution of the hydrochloride with alkali on cooling, the liberated amino alcohol solidified and after recrystallization from water melted at 103°."... 

Lead Telluride. Lead teUuride [1314-91 -6] PbTe, forms white cubic crystals, mol wt 334.79, sp gr 8.16, and has a hardness of 3 on the Mohs scale. It is very slightly soluble in water, melts at 917°C, and is prepared by melting lead and tellurium together. Lead teUuride has semiconductive and photoconductive properties. It is used in pyrometry, in heat-sensing instmments such as bolometers and infrared spectroscopes (see Infrared technology AND RAMAN SPECTROSCOPY), and in thermoelectric elements to convert heat directly to electricity (33,34,83). Lead teUuride is also used in catalysts for oxygen reduction in fuel ceUs (qv) (84), as cathodes in primary batteries with lithium anodes (85), in electrical contacts for vacuum switches (86), in lead-ion selective electrodes (87), in tunable lasers (qv) (88), and in thermistors (89). 

Then 21.89 g of the hydrochloride salt was dissolved in 600 ml of 80% aqueous ethanol. With the addition of a palladium carbon catalyst, this solution was hydrogenated at room temperature under a hydrogen pressure of about 1.1 atmospheres. After 2 mols hydrogen had been absorbed, the catalyst was filtered off and the filtrate was evaporated in vacuo until crystallization occurred. Then the crystals were dissolved by heating in the smallest possible quantity of water and after cooling, the crystallized substance was filtered off, washed with water and dried in vacuo. The yield was 6.80 g, i.e., 39% of the theoretically possible yield. The resultant product recrystallized from water melted at 203° to 204°C. 

There is obtained a yield of 14 grams of crude 2-(p-acetylaminobenzenesulfonamido)-6-methyl pyrimidine, which on recrystallization from alcohol and water melts at 238° to 239°C. The crude product is hydrolyzed by suspending it in 400 cc of 2 N hydrochloric acid and warming until solution is complete. The solution is neutralized with sodium carbonate and the precipitated 2-(sulfanilamido)-6-methyl pyrimidine is removed by filtration. The latter on recrystallization from alcohol and water shows a melting point of 225° to 226°C. 

Water melts at 0°C and boils at 100°C both these temperatures are much higher than the melting and boiling temperatures of other substances that have a compositions similar to that of water. 

In this Laboratory, several potential liquid-phase treating agents have been studied at 225-275°C—that is, at temperatures well below 325°C, which appears to be the initiation temperature for pyrolysis of the coals studied here. Working with Wyodak coal in a ZnC -water melt at 250°C, Holten and coworkers (2,3) discovered that addition of tetralin increased the pyridine solubility of product to 75%, compared to 25% without tetralin. About 10 wt-% of water is required in the melt, because pure ZnC melts at 317°C. 

The structure of ice is shown in the diagram. The crystal structure of ice is essentially tetrahedral. When water melts, the hydrogen bonds are progressively broken. The molecules pack closer together and so an initial reduction in volume of the liquid occurs before the usual expansion effect from raising the temperature is observed. Water, therefore, has its maximum density at 4°C. 

More recent quantum-based MD simulations were performed at temperatures up to 2000 K and pressures up to 30 GPa.73,74 Under these conditions, it was found that the molecular ions H30+ and OH are the major charge carriers in a fluid phase, in contrast to the bcc crystal predicted for the superionic phase. The fluid high-pressure phase has been confirmed by X-ray diffraction results of water melting at ca. 1000 K and up to 40 GPa of pressure.66,75,76 In addition, extrapolations of the proton diffusion constant of ice into the superionic region were found to be far lower than a commonly used criterion for superionic phases of 10 4cm2/s.77 A great need exists for additional work to resolve the apparently conflicting data. 

Experiments.—(a) Acetyl chloride is added drop by drop to aniline. Accompanied by strong hissing, a vigorous reaction occurs which ceases as soon as an approximately equal volume of the chloride has been added. The liquid is cooled in water while five volumes of water are added. A copious precipitate of acetanilide is thrown down the amount can be increased by rubbing the walls of the vessel with a glass rod. The precipitate is filtered ofE and crystallised from a little hot water. Melting point 115°. 

The residue in the flask is then filtered at the pump while hot, and the filtrate is strongly acidified with concentrated hydrochloric acid. When the acid filtrate is cooled the by-product of the reaction, benzoic acid, separates in glistening plates. These are filtered with suction, and recrystallised from boiling water. Melting point 121°. Benzoic acid is somewhat volatile with steam. 

Experiment.—Qninol from Quinone. Suspend about 2 g. of quinone in 50 c.c. of water and while shaking frequently saturate the suspension with sulphur dioxide. Keep for some time and then extract the now colourless liquid twice with ether, dry the ethereal extract with calcium chloride, and evaporate the ether. The residue of quinol crystallises. Recrystallise it from a little water. Melting point 169°. Warm a sample with dilute sulphuric acid and a few drops of dichromate solution the odour of quinone is emitted. 

For example, when one mole of water melts, it absorbs 6.02 kj of energy. 

N-phenylglycine org chem C8H5NHCH2COOH A crystalline compound, moderately soluble in water, melting at 127-128°C used in dye manufacture (indigo). en fen-arglT,sen )... 

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