Melting, under high vacuum

Appropriate mixture of the elements heated at 600°C for 18--24h, then at 900°C for 3---4h, then repeatedly melted under high vacuum. 

Amino-5-phenylthiomethoxyacetanilide in methanol solution is heated with N,N -bis-meth-oxycarbonyl-isothiourea-S-methyl ether with the addition of a catalytic amount of p-toluene-sulfonic acid for three hours with stirring under reflux. The mixture is then filtered hot and after cooling the febantel product crystallizes out. It is filtered off, rinsed with ether and dried under high vacuum to give the final product, melting at 129°C to 130°C. 

The solvent is evaporated and the residue is dissolved in chloroform. This solution is washed with a saturated solution of K2CO3 and dried on K2CO3. The soivent is evaporated and the residue is distilled under high vacuum. The product of the condensation distills near 230°C at 2 mm Hg pressure and the corresponding dihydrochloride melts at 217° to 224°C. 

Benzyl cyanide is first reacted with 2-butylbromide in the presence of sodium amide to give 2-phenyl-3-methylvaleronitrile which is hydrolyzed by sulfuric acid to give 3-methyl-2-phenyl-pentanoic acid. 24 g of 2-phenyl-3-methyl-pentanoic acid are heated for one hour at 175° to 185°C with 30 g of 2-diethylaminoethanol and 0.5 g of sodium methylate. The excess diethyl-aminoethanol is removed in vacuo, the residue is dissolved in 300 cc of 2 N-acetic acid, the acid solution is shaken with ether and made alkaline with concentrated potassium carbonate solution and ice. The ether solution Is washed with water, dried with sodium sulfate and evaporated. The residue is distilled under high vacuum, yielding 20 to 21 g of the basic ester (60% of the theoretical) is obtained, the ester boiling at 98° to 100°C at a pressure of 0.03 mm. The hydrochloride of the ester melts at 112° to 113°C and the methobromide at 100° to 101°C. 

The 1,5-naphthalenedithiol can be further purified to a melting point of 120-121° by sublimation under high vacuum in a molecular still, followed by reprecipitation of the water-soluble disodium salt of the sublimate from excess hydrochloric acid. The pure compound obtained from 9.1 g. of product weighs 8.6 g. (76%). 

A mixture of dimethyl terephthalate (0.495 mol), 5-sodiosulfoisophthalic acid (0.005 mol), ethylene glycol (1.0 mole), and titanium tetraisopropoxide (100 ppm) was placed in a 500-ml flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a heated metal bath and the contents heated at 185°C for 2 hours, 200°C for 2 hours, and then up to 250°C under high vacuum for 2 hours. The temperature was finally increased to 270°C and a vacuum of 0.45 mmHg maintained for for 2 hours to remove unreacted diol. A high melt viscosity polymer was obtained with a glass transition temperature of 77°C with an inherent viscosity of 0.77 dl/g. 

Devolatilizing Devolatilization in a co-rotating disk chamber can be achieved by spreading the melt on the disk surfaces in a chamber under high vacuum, and collecting the foamed film in a circulating pool at the channel block where bubble rupture takes place. The partly devolatilized melt can then be fed into another chamber in series, and so on. Fig. 9.50 shows a setup of three consecutive devolatilizing chambers. 

The material tenaciously holds hydrocarbons, such as pentane, hexane, and petroleum ether, which cannot be removed even under high vacuum. The solvated crystals show hydrocarbon protons in the NM and exhibit a broad melting point. However, we have found that cyclohexane is not retained in the crystals. 

Et30+PF6 was purified by repeatedly dissolving in methylene chloride and precipitating in ether until the melting point was not raised further. It did not seem to be very hygroscopic and was stable to short exposure to air. The last traces of ether were difficult to remove even under high vacuum m.p., 142-143°C. reported (6), 137°-137.5°C. Calcd. for C6H15OPF6 P, 12.48. Found P, 12.6, 12.6. 

Deoxidation of Al by dissociation of AI2O3 according to reaction (6.24) needs extremely low values of P02 in the furnace (for instance 10-43 Pa at the melting temperature of Al and 10 35 Pa at 900°C). Such low P02 values are not easily achieved in a furnace in which P02 is usually in the range 10-,5-10-5 Pa. Therefore, deoxidation of Al observed under high vacuum does not occur by dissociation of A1203 and has been attributed to the reduction of the oxide film by liquid Al to form volatile A120 by the reaction (Laurent et al. 1988, Castello et al. 1994) ... 

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