ACTIO?; OF PERMANOANATE OE' POTASH ETC. 111.-On the Action qf Permanganate of Potash on Urea A nzmonia and Acetamide in strongly Alkaline Solutions. By J. ALFREDWANRLPNand ARTHURGAMGEE. IT haas been pointed out by Chapman and Smith," that perrnanganate of potash in presmce of excess of alkali is an oxidizing agent of a most singular kind. It attacks alcohol much in the same way that nitric acid does producing the diatomic acids glycollic and oxalic but not aldehyde nor acetic acid. It is at the same time strangely inactive towards certain substances. Boiled with oxalic acid it does not suffer any decom- position ;and as is seen in the working of thet new method for the determination of albuminoid matter in waters it may be boiled with ammonia without the occurrence of any chemical change.The following experiments on the action of this re-agent on urea ammonia and acetamide :-Urea = CONH,NH Ammonia = NH Acetamide = COCH NH will serve as a contribution to its chemical history. Urea. The urea taken for this research was prepared by the well kriown process from ferrocyanide of potassium. One of the I * Journ. of the Chemical Society [2l T p. 302,June 1867. t Ibid. v p. 449 Sept. 1867. WANKLYN AND GAMGEE ON THE samples was proved to be pure by getting it to combine with the theoretical quantity of nitrate of mercury. Another sample was analysed by Dr. Affleck who got from it the theoretical percentage of nitrogen by Dumas' method. I. 0-100grm. of urea 1-000 , permanganate of potash 10.0 , solid caustic potash 10-0 , water was sealed up in a tube and heated to 130OC.for twelve hours. After the experiment the contents of the tube were fiee from unacted upon manganate or permanganate of potash -showing that much oxidation had taken place. On opening the tube under water there was an escape of 15-7 cub. cent. of gas. In order to ascertain whether this evolution of gas was due to the permanganate givingup oxygen or whether it was an evolution of nitrogen from the urea a gas-analysis was made. (Frankland's apparahs was employed for this and the other gas-analyses given in this paper). Volume taken.. ............ 86 After adding hydrogen.. .... 139 After explosion ............ 99 The gas therefore consisted of Oxygen........ 15-50 Nitrogen ...... 84-50 100*00 Obviously therefore inasmuch as there was less oxygen than atmospheric air contains the evolution of gas in our experiment was not evolution of oxygen but of nitrogen. The space in the digestion tube unoccupied by liquid was measured and equalled 38.1 C.C. We are thus provided with data for determining whether the permanganate had evolved oxygen and also how much nitrogen came from the urea. cub. c. Volume of gas left in tube .............. 38.1 Volume of gas escaped from tube ........ 15*7 Total volume of gas after experiment .... 53.8 ACTION OF PERMANGANATE OF POTASH ETC. consisting of 8.34 C.C. of oxygen and 45-46 C.C. of nitrogen. Now the 38.1 C.C. of air originally present in the tube when it was sealed up contained 8.00 C.C.of oxygen and 30.1 C.C.of nitrogen. We have therefore- Oxygen present originally .............. 8.00 Oxygen found after experiment .......... 8.34 No oxygen or only a trace of oxygen was set free from the permanganate. Also the urea had evolved about 15 C.C. of nitrogen gae. This amount of nitrogen is not half that which the urea con- tained (0.100 grm. urea contains 37.2 C.C. of nitrogen gas at OOC. and 760 mm. pressure). A little of the nitrogen is ac- counted for as ammonia for -0032 grm. of nitrogen was found in the tube after the experiment in the form of ammonia which was distilled of and estimated by titration. There thus remains about half of the total nitrogen to be accounted for and which must hare been converted into nitric acid.The circumstance that the 1grm. of permanganate of potash had been completely reduced to the state of bi- or sesqui-oxide of manganese and that there was no evolution of oxygen gas is in itself sufficient proof that a considerable quantity of the nitrogen of the urea had been oxidized to nitric acid. In this experiment therefore a little less than half of the nitrogen of' the urea appeared as nitrogen gas about half was oxidized to nitric acid and a small portion was found as ammonia. 11. In a second experiment the proportion of permanganate was increased the object proposed being to ascertain whether greater oxidizing effect would be the result of increasing the quantity of oxidizing agent.0950 grm. urea 1-00 , permanganate of potash 10.00 , potash 10-, water were sealed up and heated to 200OC. for four hours. After this treatment there remained much manganate still unreduced. On opening the tube there was a considerable escape of gas which WANKLYN AND GAMQEE ON THE wm lost. Not so much as *OOO1 ,grm. of ammonia wae to be found in the tube. The expeiiment was repeated in order to have an opportunity of examining the gas. 0*100gm. urea 2.00 , permanganate of potash 10.00 , caustic potash 12. , water sealed up and heated to 160° C. for one hour. Abundance of manganate of potash remained after the experiment. On open-ing under water there was an escape of gas.The total volume of gas was carefully measured and found to be 47 C.C. at 11"C. and 744 mm. pressure equal to 44.20 C.C. at 0" C. and 760 mm. On analysis :-Volume taken. ............ 160 After adding hydrogen.. .... 231.5 After exploaion ............ 20'7.5 From which is deduced- Oxygen. ........ 5-00 Nitrogen ........ 95-00 100*00 Allowing for the nitrogen originally present in the tube when it was sealed up which may be done by taking the 5 per cent. of oxygen to be the measure of atmospheric air we shall arrive at the result that 33.68 C.C. at OOC. and 760 mm. is the quantity of nitrogen furnished by the urea. Thus we have :-0.100 grm. urea give 33.68 C.C. of nitrogen. Theory requires that 0.100 grm. urea contains 37.2 C.C.of nitrogen. We arrive at the startling result that by increasing the pro-portion of permauganate we put a stop to the oxidation. This fact so singular at first sight would appear to indicate that the oxidation of urea by permanganate is quick but super- ficial whilst the oxidation at the expense of manganate is slower but deeper. Obviously (as will be apparent on referring to the actual quantit'ies of permanganate and urea employed) ACTION OF PERMANBANATE OF POTASH ETC. there would still remain unattacked urea in the first experiment after the permanganate had exhausted itself and passed intornan- ganate. In the second experiment on the contrary there was enough permanganate to transform all the urea into carbonic acid w+ter and nitrogen without suffering deoxidation lower than to the stage of manganate and nitrogen once in the free state is beyond the reach of oxidizing agents.For some interesting considerations concerning the difference of action between permanganates and manganates we would refer to Chapman and Smith‘s paper which we cited ah the begin- ning of this notice. Thus far we have been dealing with very concentrated solu- tions at temperatures considerably above the boiling-point of water. Taking weaker solutions and operating at about 100°C. we meet with a similar decomposition only slower. The following experiment illustrates this we dissolved 4.75 milligrammes of urea in about 400 C.C. of pure water added a little carbonate of soda about 5 grm. of caustic potash and about 0.5 grm.of permangnnate of pot:tsh and distilled for a very long time. A slow evolution of ammonia took place. Ultimately this evolution became very slow arid then stopped. The quantity of ammonia obtained was estimated by the Nessler test and amounted to 0.575 milligramme. Theory requires 2.692 milligrammes. About 22 per cent. of the nitrogen in the urea was obtained in the form of ammonia the rest of course being either evolved as nitrogen gas or converted into nitrate. An experiment on a still smaller quantity of urea gave a very similar result. Here the remark may be made that this result is hardly compatible with Mr. Dugald Camp- bell’s statement published in the ‘‘Laboratory,” which is in effect that a weak solution of urea gives up all its nitrogen in the form of ammonia when it is partially decomposed with carbonate of soda and then attacked with potash and perman- ganate of potash.If Mr. Campbell did not get off the full quantity of nitrogen in the form of ammonia by the treatment with carbonate of soda he would not get the full quantity on employ in g permanganat e. Urea being resolved into carbonic acid and ammonia by the simple assimilation of water ACTION OF PERMANGANATE OF POTASH ETC. CONH,NH + H,O = CO + 2NH it might be supposed that an oxidizing agent applied to urea in presence of water would in effect operate on the ammonia; and on this ground it was necessary to study the oxidation of ammonia. Experiment I.-0-050 grm. of NH,CI 2.00 grm.of permanganate of potash 10.00 grm. of caustic potash 10-grm. of water was heated to 15OOC. for an hour and a half. Opened the tube ; only minute traces of gas escaped. The gaseous con- tents of the tube were analysed :-Oxygen = 23.00 Nitrogen = 77-00 100-00 showing that the minute evolution of gas was evolution of oxygen and not of nitrogen. The residue in the tube con- tained only 00033 grm. of nitrogen in the form of ammonia; therefore there had been oxidation of most of the ammonia to the state of nitric acid. In a second experiment sulphate of ammonia was substituted for the chloride of ammonium the other things being the same and the proportion the same. The temperature was a little higher than in the first experiment.Result no ammonia and no gas. A cetamide. I. 0-050 grm. acetamide 1-00 grm. permanganate of potash 10. grm. caustic potash 10. grm. water sealed up and heated to 160' C. for one hour. After the experiment there remained abundance of man-ganate but some peroxide of manganese had been deposited. No gas was given 06and only 0*0005 grm. of ammonia was found in the tube. The appearance of peroxide of manganese WANKLYN AND SCHENK’S SYNTHESIS OF CAPROIC ACID. 31 proves that reaction had taken place Nitrates or nitrites must therefore have been formed. The results arrived at in this paper are the following :-Urea and great excess of permanganate in presence of much caustic potash gives all the nitrogen in the form of nitrogen gas.Urea with less permanganate gives part of the nitrogen as gas and part as nitric acid. Ammonia whether as chloride or sdphate is totally oxidized to nitrates when heated with great excess of permanganate and alkali. Acetamide behaves like ammonia. These reactions occur at temperatures above the boiling-point of water. The foregoing result has an important bearing on the rational formula for urea and goes a long way to show that it is not the amide of carbonic acid. Ammonia and the amides yield nitrates on oxidation with alkaline permanganate. Urea if it were really carbamide should do the same but it gives nitrogen gas instead. Moreover urea as is well known is not resolved into ammonia and carbonic acid with anything like suflicient ease to admit of its being carbamide. We are f NH therefore led to write C NH for urea. It is marsh-gas OH L wherein imidogen amidogen and peroxide of hydrogen replace hydrogen. This formula is not new. Very simple and natural changes in this formula express the passage from urea to cyanate of ammonia and to carbarnide. The following formulae express the relation between guani- dine and urea :-Ouanidine Urea.