Feb., 1948
COMMUNICATIONS TO THE
ticularly interesting in view of the fact that the work of Erlenmeyer, Schoenauer and Schwarzenbach3 indicates that all three hydrogen atoms of hypophosphorus acid exchange rapidly with deuterium oxide. Apparently in the deamination reaction a hydrogen atom was extracted from another aromatic nucleus, since that is the only source of hydrogen which is not equilibrated with deuterium.
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sudden but without detonation. Other experiments have shown that aluminum chloride accelerates the decomposition of aluminum hydride, On one occasion a violent explosion occurred when the residue resulting from evaporation of a dimethylcellosolve solution of aluminum hydride was varmed. The aluminum hydride was contaminated with aluminum chloride, which is known to decrease the stability of the former, and the dimethylcellosolve was impure. No explosion (3) Erlenmeyer, Schoenauer and Schwarzenbach, Helo. Chim. Acta, 90, 732 (1937); see also Franke and Man&, Ann, 6S0, 1 resulted when the experiment was repeated with (1941). purified materials. DEPARTMENT OF CHEMYSTRY Lithium aluminum hydride is considerably more UNIVERSITY OF ILLINOIS ELLIOTR. ALEXANDER stable than aluminum hydride. Approximately URBANA, ILLINOIS ROBERT E. BURGE two hundred different reactions using the former 22,1947 RECEIVED DECEMBER reagent have been carried out in this Laboratory without untoward results although nb precautions CAUSE OF EXPLOSIONS OCCASIONALLY were taken to exclude carbon dioxide. We are, OBSERVED DURING EVAPORATION OF therefore, convinced that it may be used with perSOLUTIONS OF ALUMINUM HYDRIDE fect safety if the precautions suggested by the AND RELATED COMPOUNDS facts herein reported are followed. In other words, sir : we recommend that in the reduction of organic I n experiments involving dimethyl ether solu- compounds the normal procedure of hydrolyzing tions of aluminum hydride, as well as of lithium the initial reaction product before evaporation of and sodium aluminum hydrides, explosions have the solvent be employed. If, as would rarely be occasionally occurred. The details to be de- the case, it is desired to evaporate the solvent bescribed have demonstrated that the explosions fore of the initially produced organic were caused by carbon dioxide present as an im- salts,hydrolysis the safety of the procedure should first be purity in some samples of the ether. Explosions have occurred toward the end of dis- tested by use of a small sample. GERALDINE BARBARAS tillations undertaken to remove the solvent from OF CHEMISTRY GLEND. BARBARAS DEPARTMENT dimethyl ether solutions of lithium aluminum TFIE UNIVERSITY OF CHICAGO A. E. FINHOLT hydride. That the explosions were due to an im- CHICAGO 37, ILL. H. I. SCHLESINGER purity more volatile than dimethyl ether was inRECEIVED DECEMBER 15,1947 dicated by the facts (1) that later samples of the ether taken from a cylinder caused less violent CRYSTALLINITY OF HYDRO-CELLULOSES explosions than the first few samples, and (2) ether taken from another cylinder a t no time Sir: caused these explosions. These facts, as well as Hydrolytic methods are being used a t present chemical tests to prove their absence, excluded al- for evaluating the intramolecular structure of dehydes, alcohols or peroxide as the offending im- cellulose. It has been suggested in a paper to be purity. Considerable carbon dioxide was present published in THISJOURNAL that such methods in the cylinders whose contents led to explosions; might possibly cause additional crystallization in its removal by fractionation in vacuo rendered the the initial stages of hydrolysis. We have succontents hannless. After carbon dioxide was re- ceeded in obtaining data which indicate that such introduced into the purified sample, the explo- changes do occur. Consequently, it would seem sions recurred. It was then found that diethyl necessary to reinterpret accessibility measureether solutions of lithium aluminum hydride, ments based on hydrolysis rates in terms of two which can ordinarily be safely evaporated, may competing processes : hydrolysis and further crysalso cause explosions if f i s t treated with carbon tallization. dioxide in considerable amount. The data in Table I were obtained on a beechEvaporation of dimethyl ether solutions of alu- wood pulp that had been digested in boiling 2.5 N minum hydride and subsequent slow heating of hydrochloric acid-0.6 M ferric chloride solution the residue may result in a very rapid reaction in constantly saturated with air. which, a t slightly above 40°,relatively large quanTABLE I tities of gaseous material are suddenly released, Percentage but which is not accompanied by detonation, unincrease in S ecific vol cryatdliity Time Percentage o f of booe-dry' less a large excess of aluminum chloride is present. from Sp V. treated, samples hydrocellulose, minutes destroyed ml./g. change, 7% But carbon dioxide-free ether leads to a residue 0 0 0.652 which begins to decompose slowly above 70°, if 10 4.8 .a7 aluminum chloride is not present in large amount ; 15 18 19 6.0 .646 even in the presence of a large excess of the latter 19 28 39.0 .645 (2.5 mdes/l.), the decomposition above 40° is
