Yü-Gwan Chen

“ The demand for the metal is so small that there are half a dozen concerns in the United States either willing to supply gratis any reasonable quantity for research work, or to sell it at cost. In a special report of the National Research Council on selenium (3) , it is estimated that there could be produced annually, without making any material additions to the present plants, not less than 300,000 pounds. ”

“ Sulphur compounds have similar physiological action. It is known that triphenylstibine sulphide, or sulphoform, (C6H5) 3SbS, has a curative effect in skin diseases, as it liberates “nascent” sulphur on the skin. It is equally natural to expect some organic selenium compound which liberates finely divided selenium to exert a remedial influence on animal bodies. The selenoquinazolone prepared in the course of this research and described more fully in another section of the paper, has this prospect. ”

“ The substance prepared by the above methods crystallizes from dilute alcohol in needles or prisms of dark brown color. It melts at 213.5° (corr.) . It dissolves readily in hot alcohol but on concentration sometimes forms a sticky mass with a peculiar but not unpleasant odor. It dissolves readily in alkalis and is slightly soluble in hot benzene and chloroform, but insoluble in hot water. Crystals purified from (a) were analyzed and gave the following results:
The crystals on standing in the presence of air and light decomposed with separation of finely divided selenium and methyl quinazolone. ”

“ Some experiments have been published claiming the similarity of the action of selenium and sulphur on rubber (4) (5) . The cost need not be prohibitive, since the supply could be easily increased and the price reduced provided there were a demand. In the personal experience of the writer, when working with the hydrogen selenide gas, the rubber connections of the apparatus soon turned red, and after a few hours were so [Pg 8] clear a red that visitors to the laboratory imagined that the writer was using the ordinary red rubber connections. ”

“ Synthesis of 2-methyl-4-selenoquinalozone, 2-phenylbenzoselenazole and Its Derivatives INTRODUCTION
The general conception of selenium is that it is a comparatively rare element. Few realize that it has been known for over a century and that over twenty selenium minerals, containing from one to sixty-six per cent. of the metal, are considered by the mining corporations as important. ”

“ Dimethyl selenophene was prepared from acetonyl acetone and phosphorous pentaselenide,
The compound thus obtained is stated to have the same odor as thiophene, but no mention is made in regard to its uses (28) . Selenophene was prepared from sodium succinate and phosphorous triselenide, or by conducting ethylselenide through hot tubes (29) .
Some selenazoles find application also in medicine. At present only the isoazoles are known to have physiological uses. One of them was prepared from anthraquinone selenocyanide, by the action of ammonia under pressure (30) . ”

“ It was prepared from sodium hydroxide in absolute alcohol by passing dry hydrogen selenide into the solution for about three hours. In the beginning and end of the reaction, nitrogen was used to exclude the oxygen of the air. The selenide was collected and dried in an atmosphere of nitrogen, and then in a vacuum, in presence of phosphorus pentoxide. When thus prepared, sodium selenide was colorless, but on exposure to [Pg 18] air it turns reddish and finally dark colored. ”

“ Diethyl selenide (C2H5) 2Se, is a yellowish heavy oil of unpleasant odor. It combines readily with chlorine to form a chloride (C2H5) 2SeCl2, and the latter is oxidized by nitric acid to form an oxide (C2H5) 2SeO, (39) . Diethyl sulphide is a colorless syrupy liquid, as well as diethyl amine and diethyl ether.
The gradation of color is quite pronounced in the case of selenonaphthene quinone (40) .
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It would be most natural to conclude that the chromophore :CS is more powerful than :CO, and that :CSe is most powerful of all, as shown in our study of quinazoline compounds. ”

“ The clear benzalaniline was then poured into 160 grams of selenium dust in a pyrex flask on a sand bath, the flask being connected with an air condenser as before. In order to distribute the flame to better advantage over the bath, an air space was made between the Meker burner and the bath by introducing a wire gauze. Hydrogen selenide was evolved freely. Complete reaction took three days. ”

“ Monobenzylidene Derivative
Five grams of the monoamino compound were dissolved in 200 cc. absolute alcohol with the addition of 3 cc. of benzaldehyde and the clear solution was boiled on a water-bath, with a return condenser, for two hours. After the solution was boneblacked, the yellow precipitate was recrystallized from carbon disulphide. The yield was 90 per cent.
It crystallizes in yellow plates, melting at 156.7°-157.6°C., soluble in benzene, ether, ethyl alcohol, carbontetrachloride, acetone, but difficultly soluble in ligroin. ”

“ The selenophenols do not remain unchanged in the air, but are always oxidized to the diselenides, which can be again reduced to the selenophenols. So far only the diselenides of anthraquinone and their phenols are recognized remedies (36) . ”

“ The toxicity of both the selenopyronine and the corresponding sulphur compound was compared under similar conditions in the same experiment, and it was found that the selenium dye was toxic in 1/3000 gram, but the sulphur dye was toxic in 1/2500 gram per twenty gram weight of the animal.
This physiological activity was noted years ago with the inorganic compounds of selenium and Berzelius (15) described the poisonous effect of hydrogen selenide quite impressively; “In order to get acquainted with the smell of this gas I allowed a bubble not larger than a pea to pass into my nostril ”

“ The diacetyl and dibenzylidene compounds were also prepared from these diamino derivatives. The former crystallizes in cubes from dilute alcohol; m. p., 307°C (Corr.) and the latter in beautiful yellow plates from carbon disulphide, m. p., 195°-196°C. (Corr.) . An analysis of these two compounds showed the following results,
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Dyeing with Azo Dyes
Both the monoamino and the diamino derivatives form intensely colored dyes when diazotized and coupled with phenols and aromatic amines. The dyes formed are fast to light. In the following table silk is given to represent the fabrics used. ”