Sodium hydride, 7-484 sublimation

Neither potassium nor sodium hydride dissolves in carbon tetrachloride, turpentine, ether, or benzene but both are soluble in the molten metals. The latter resembles the products obtained by P. Hautefeuille and L. Troost, which were therefore solid soln. of the hydride in the metal. When heated in vacuo, a little below red-heat, the hydrides decompose into the metal and hydrogen, and the metal sublimes. 0. Ruff gives for the decomposition of sodium hydride a temp, over 330°, and for potassium hydride a temp, over 200°. 

Disodium phthalocyanine may be prepared by the reaction of phthalo-nitrile with sodium amyloxide in amyl alcohol (10), or from sodium hydride and phthalonitrile (52). It does not sublime, and is readily demetallated by methanol and less readily by the higher alcohols (75). The complex reacts with methyl iodide in ethyl alcohol to give only the unmetallated derivative (10). 

Materials. Ethylene Oxide (EO) and pivalolactone (PVL) were dried over calcium hydride for a day before use. EO was further dried on a sodium mirror prior to passing into the reaction vessel. Dried PVL was sealed into ampules under high vacuum (I0"° mm Hg). Succinic anhydride (SA) was dried in a vacuum oven for a day and sublimed under high vacuum into ampules. Dry THF was obtained by refluxing THF on Na/K (1 1) alloy for six hours, distilling over the alloy and degassing under high vacuum in the... 

Arsenic does not combine directly with molecular hydrogen,9 and the element may be purified by sublimation in that gas. Hydrides, however, may be obtained by indirect methods (see pp. 79-84). Arsenic may be displaced by the gas from solutions of its salts at high temperatures and pressures. Thus arsenic separates in large well-defined crystals when a solution of sodium arsenate is subjected to the action of hydrogen at 25 atm. pressure 10 the action commences at 300° C., 15 per cent, of the arsenic being precipitated at this temperature, but it increases rapidly with rising temperature and at 350° C. 77 per cent, of the arsenic is liberated. Arsine is not produced in the reaction. 

Pyridine anddichloromethane are freshly distilled over calcium hydride. Triethylamine is distilled over toluenesulfonyl chloride and then calcium hydride. Anhydrous diethylether is used directly. Acetonitrile is distilled over phosphorus pentoxide and then calcium hydride. Tetra-hydrofuran is distilled over sodium metal in the presence of benzophe-none. 1-H-Tetrazole (tetrazole Aldrich, Milwaukee, WI) is sublimed before use. The preparation or purification of other reagents and solvents has been presented elsewhere (17). DNA synthesis is performed on an Applied Biosystems 380A automated DNA synthesizer. 

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