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decomposed by carbon dioxide. Wislicenus proposes the formula
CH,.co.CH.CO.O.C,H, for the original compound, according to which it is ethyl succinylsuccinate, a derivative of succinylsuccinic acid. The metallic compounds are explained by supposing the hydrogen atoms of the groups CH to be replaced by the metals, the hydrogen in these groups having a somewhat acid character. It seems to me that the great stability of the ether which we have above recognized speaks against this formula. Most acids, which consist of atoms grouped in the manner indicated by the above formula, are decomposed by boiling with barytawater, whereas we have seen tbat this substance may be boiled with baryta-water without undergoing decomposition. It is true that we know very little concerning bibasic acids of this structure, and it is possible that what is true of the monobasic acids is only partially true of the bibasic. Be this as it may, it is certain that the experiments thus far published will not permit the positive conclusion that the above formula is the true one, and further investigations would be called for whether the formula is correct or not.
3. Action of phosphoric Chloride upon the body C, H, O.
With the hope of learning something more definite concerning the nature of the oxygen atoms contained in the substance under examination, I next undertook the study of the action of phospboric chloride upon it. At first I employed two molecules of the chloride to one molecule of the substance. Wben the two are brought together in a dry vessel, no action ensues until heat is applied. If the mass is very gently heated, the substance C, H, O, melts, and immediately reaction commences, and continues then without the further aid of heat, until the contents of the retort form a clear, bomogeneous liquid. The reaction is accompanied by an evolution of chlorhydric acid, the amount of which, however, was such as to leave me in doubt whether this was a necessary product of the reaction, or was formed from the secondary decomposition of the phospborus compound which distilled over. The oxichloride of phosphorus was distilled off by gentle heat, and the oil in the retort then treated with water. Decomposition soon began and there resulted a solid, insoluble product. On examination this proved to be the original substance C,,H,Oc. As the amount of this product was comparatively considerable, I at once concluded that a chloride had been formed by the first reaction which by its decomposition with water yielded the mother-substance. This conclusion proved subsequently to be erroneous, in such a way as to show that the first error in judg. ment was partially excusable. In a second series of experi. ments, I employed four molecules of the chloride to one molecule of the substance, and thus reached new results. The same phenomena accompanied the reaction, that were noticed in the case already described. The direct product was a clear, yellow oil. This was treated with a little cold water. At first the oil simply fell to the bottom of the vessel, but in a short time decomposition commenced, and gradually the oil disappeared, a solid product remaining in its stead. On being filtered off and examined, the solid product proved to be a new acid, comparatively easily soluble in water. In the filtrate there was also contained a considerable quantity of the new substance, which was extracted by shaking with ether. The new acid crystal. lizes out of the concentrated aqueous solution in lamina which are colored yellow. In alcohol it is exceedingly easily soluble. It dissolves in a little potassic carbonate, and is precipitated from the solution on the addition of a few drops of chlorhydric acid.
As this product is easily soluble in water, it is plain that it escaped me in the first experiinent, by remaining dissolved in the water which served for the decomposition of the chloride, a sufficient quantity of water having been employed to dissolve the whole of the product, if the conversion of the substance C,H,O, into the chloride had been complete. That which was really found in the first experiment was simply a part of the original substance, which had not been acted upon by the chloride of phosphorus.
If we attempt to distil the chloride for the purpose of purification the mass is completely carbonized. A few drops of a colorless liquid boiling at a high temperature pass over, but the quantity of this liquid is too small to admit of an examination. It is decomposed by water, and the product is solid. It was impossible to determine the nature of the solid, owing to the small quantity obtained. It is not probable that it was succinic acid, for, in that case, the chloride from which it was obtained would have become solid at a low temperature, whereas it remained liquid even when cooled down to 0°.
If the product of the action of phosphoric chloride on the substance C, H, O, is heated for some time, it gradually becomes solid, or nearly so, and then has the appearance of a translucent resin. I analyzed this compound, but the numbers obtained did not agree in different analyses. It appears, thus, that condensation and decomposition of the chloride are caused by heat.
As the most important result of these experiments with
phosphoric chloride, then, we see that, if four molecules of the chloride are caused to act upon one molecule of the substance C,H,O., a liquid chloride is formed which is decomposed by water yielding a new acid. I have not yet studied this new acid, and can, therefore, not state in what manner it is derived from the original substance. As it can apparently be prepared in any desirable quantity with comparatively little trouble, its examination will probably give interesting and positive results.
In addition to the results already recounted, I will mention the following:
1. Acetyl chloride exerts no influence upon the substance C,,,,06. It simply dissolves it when gentle heat is applied, but, on cooling, the unchanged substance crystallizes out. This result could be anticipated with considerable certainty, as the presence of alcoholic hydroxyl in the substance was not at all probable. Still the experiment was necessary to prove the fact, no matter how probable it might appear.
2. Ammonia does not act upon the substance either in aqueous or alcoholic solution. v. Fehling (loc. cit.) states that with ammonia the body yielded a bright yellow compound crystallizing in needles. I endeavored in vain to obtain such a compound. I first boiled the substance with very strong aqueous ammonia; it remained unchanged. I then conducted dried ammonia gas into an alcoholic solution of the substance. The solution turned deep yellow in color, but I was unable to extract from it anything save the original substance. This indeed, sometimes crystallizes in needles—a fact which may have misled v. Fehling. By analogy we should expect the formation of a compound with ammonia corresponding to the metallic compound described above. It is possible that some change in the conditions may lead to its formation.
3. Hydrogen in the nascent state (from tin and chlorhydric acid) does not act upon the substance. If the group CO is present, it is difficult to see why this should not be converted into the secondary alcohol group CH.OH by the action of hydrogen.
4. A solution of potassic permangunate, as well as dilute nitric acid, oxidize the substance very slowly. The products of the oxidation I have not yet examined. In connection with the oxidation by means of potassic permanganate a peculiar phenomenon was noticed which deserves mention. I have stated that the oxidation took place slowly; the product was not an acid, so that the manganic oxide formed was precipitated ; but, further, the substance oxidized was insoluble in water, so that the manganic oxide, being produced in contact with the faces of the insoluble crystals, was deposited in even layers upon them, forming thus a complete envelope, and giving a genuine pseudomorph. I was at first deceived by this strange pseudomorph, believing it to be the product of the oxidation. It was insoluble in water, and appeared to be insoluble in alcohol. I found, however, afterward, that the alcohol dissolved the central portions of the pseudomorphs leaving the envelopes unchanged in form.
5. The substance was heated with water at 150° in a sealed tube. At this temperature decomposition took place, but not at a lower temperature. The products of the reaction were alcohol, and a solid, white crystalline substance which conducted itself in some respects like succinic acid. The alcohol was detected by placing the whole product in a flask and distilling with water. The distillate was tested by Lieben's reaction* for the formation of iodoform.
The experiments wbich have thus been described do not suffice to enable us to judge positively in regard to the structure of the substance under investigation. I have stated above the view held by Wislicenus, and also my objections to this view. It remains yet to be decided whether my objections are well founded, and this can be done only by the aid of new experiments.
No. V. On the action of Ozone on Carbon Monoxide ; by Ira
REMSEN and Mase S. SOUTHWORTH. One of the most remarkable examples of so-called nonsaturated compounds is carbon monoxide. If we accept the hypothesis of constant valence, the compound CO must possess free affinities, or, as some chemists believe, the two affinities of the carbon-atom, which are not saturated by the oxygen atom, must exercise an influence upon each other. We can not ex. plain this case by assuming that two carbon-atoms are joined together by two affinities each, for we know that the formula of carbon monoxide is CO, and not C,0, or a higher multiple, and, accepting this formula, it is plain that we cannot assume a double union of carbon atoms in the compound.
If, on the other hand, we accept the hypothesis of variable valence, believing that the valence of an element depends upon circumstances, we shall look in vain for circumstances which, in the one case, can cause the bivalence, in the other the quadrivalence, of the carbon-atom. A difference in temperature certainly does not cause the difference in valence. The atom
* Annalen der Chemie, Suppl. VII, 218.
of carbon is quadrivalent toward oxygen at the ordinary tem. perature and under ordinary conditions. How otherwise shall we explain the formation of carbon dioxide in the processes of decay, fermentation, etc. ? But the atom of carbon is just as positively quadrivalent at high temperatures. .
The comparative ease with which carbon monoxide takes up chlorine appears to prove that it possesses free affinities. But if we accept this as a proof of the existence of free affinities in carbon monoxide, we have still better grounds for believing that free affinities are present in ethylene, for this gas combines with chlorine much more readily than carbon monoxide does. Still the view is commonly held that in ethylene the two carbon-atoms of the molecule are united by the mutual action of two affinities of each atom.
These considerations show that the nature of carbon monoxide is, as yet, bilt very unsatisfactorily understood. The first question which suggests itself is this: How far are we justified in considering carbon monoxide as a body possessing free affinities?
If we attempt to answer this question entirely without prejudice, we see that the principal experiment which is supposed to prove the existence of free affinities in carbon monoxide is the above mentioned experiment with chlorine. Oxygen does not combine with carbon monoxide at the ordinary temperature. This is readily understood, for, in order that the carbon monox. ide and oxygen may combine by direct contact of the two substances, the oxygen-molecule must first be decomposed into its constituent atoms. An interesting experiment in this connection has been described by E. Ludwig, * who shows that carbon monoxide is oxidized by chromic acid at the ordinary temperature forming carbon dioxide. In this case carbon monoxide is active enough to separate one atom of oxygen from chromic acid and to employ it for the formation of carbon dioxide.
We have occupied ourselves with an experiment similar to that described by Ludwig, and have obtained a different and unexpected result. It appeared to us to be of interest to know whether, at the ordinary temperature, ozone has the power to transform carbon monoxide into the higher oxide. According to the views which are commonly held concerning the nature of the substances experimented upon, the transformation mentioned could be predicted with a tolerable degree of certainty. Particularly is this the case, if we consider the result of Ludwig's experiment, for usually ozone gives up its extra atom of oxygen with still greater readiness than chromic acid does. There is indeed no substance in the whole field of chemistry which furnishes us with a better means for obtaining
* Annalen der Ch. u. Pharm., clxii, 47.