摘要:

334 LI1.-A Spectroscopic Study of CJtloropJLyll. By W. J. RUSSELL Ph.D. F.R.S. and W. LAPRAIK F.C.S. THE study of chlorophyll has great fascination ; it also has its difficul-ties. We did not propose adding to the many elaborate attempts to isolate and purify this body ; but the beauty and definite character of the spectrum which it gives induced us to try whether some insight into its character and constitution could not be obtained from the study of the spectroscopic changes which it can be made to undergo ; and as one of us has already shown that in the case of the cobalt salts the spectroscope enables us to follow many chemical changes, we thought that it might be possible to interpret the spectroscopic changes of chlorophyll and so gain some knowledge of the properties and nature of this borly.The extraction of the green colouring matter from leaves was effected in most cases by breaking up the leaves in a mortar with a mixt,iire of two parts of alcohol and one of ether. The colour of the liquid thus obtained is of a dark green varying in shade according to the nature of the leaves used and the solution always has the well-known red fluorescence. This liquid when examined spectroscopi-cally gives what is known as the chloropliyll spectrum. According to Krauss it consist.s of seven bands ; the three at the most refrangible end of the spectrum are difficult as Krauss says to observe and with our source of light a gas-flame we could see in an ordinary chloro-phyll solution little or nothing of them; but under special circum-stances which will be described further on the least refrangible of the three becomes very visible.We have confined our observations principally to the four least refrangible bands. Other solvents such as chloroform disulphide of carbon benzene &c. were used occa-sionally ; they give a similar spectrum but in most cases they do not dissolve the colouring matter so readily as alcohol and ether do. The ethereal solution appears always t o give a clearer and more brilliant spectrum than the alcoholic solution. Fig. 1 sliows the spectrum of the solution obtained as above described from the majority of the leaves we have examined. Among common outdoor plants the vine and the Virginian creeper may be cited as apparent exceptions giving a different spectrum.(Fig. 2.) The second band in this case has moved towards the more refrangible end of the spectrum the band from 589 to 573 has dis-appeared and now there is a very marked band from 545 to 532. The cause of this change in the spectrum we shall explain further on. Fig. 1 then as far as it goes represents the spectrum given by th RUSSELL AXD LAPRAIK A SPECTROSCOPIC STUDY’. ETC. 335 alcohol and ether extract of most leaves. It is important at once to give a definite meaning to the term chlorophyll and we would there-fore state that we mean by it the body or bodies capable of giving this particular spectrum and of course we found our conclusions on the assumption that a particular absorption-spectrum is a complete identification of a substance. As is well known the exact position of these bands alters with the solvent used ; in all cases when no mention is made to the contrary, a mixture of alcohol and ether is the solvent we here used.Appa-rently the statement that the higher the specific gravity of the solvent, the nearer are the bands to the red end of the spectrum is not in all cases true for we find that the chlorophyll bands are nearer to the red in carbon disulphide than in chloroform. All our obser-vations have been made with a Dasaga’s spectroscope having a single heavy glass prism and the position of the bands is given in millionths of a meter reduced from the observations by graphical interpolation. Captain Abney has also been kind enough to take photogmphs of the different spectra and these agree with our eye observations.They also prove that there are no bands in the ultra-red. The first point we would note with regard to chlorophyll is that as far as our experiments go-and we have now tried a large number of different leaves-although there are apparent exceptions this parti-cular substance we call chlorophyll exists in all green leaves. If thinner and thinner strata or more and more dilute solutions of the same thickness be examined the fainter bands are seen gradually to fade out. and what is of importance the dominant band the last to disappear thins out to a band from 670 to 660. Passing over a large number of experiments on other points we shall limit our present communication as far as possible to an account of the action of acids and alkalis on this so-called chlorophyll.It is a body exceedingly sensitive to the action of acids. If for instance a mere trace of hydrochloric acid gas be introduced into the air of a test-tube containing a chlorophyll solution on shaking the tube the 628 band will be found to have moved slightly towards the blue and the next band to hare become fainter. This action of the acid, specially witlh regard t o the 628 band is very remarkable; the addi-tion of acid gradually causes this band to move bodily towards the blue, till it reaches 611-583. So constant and completeis this action t>hat the position of the bandis an indication up to a certain amount of the quantity of acid present. On adding a little more hydrochloric acid gas to the air of the test-tube and again shaking this second band will be found to have moved from 615 to 596 the 589-573 band will have disappeared and the other band at 545-532 will remain unmoved, but will hare become much darker.On still further iiicreasing th 336 RUSSELL AND LAPRAIK A SPECTROSCOPIC amount of acid the second band comes to 611-589 and now a new band appears from 573-558 and the band at 545-532 has also again increased in intensity. Further the blue end of the spectrum has considerably opened. This spectrnm Fig. 3 is permanent for on adding more acid even a large amount of liquid acid no further alter-ation takes place. The action of hydrochloric acid on chlorophyll appears then to he very definite and is well shown by the two draw-ings Figs. 2 and 3 which represent two well-marked stages ; in the first the movement of the 628 band and the disappearance of the 589 band the other two bands remaining unaltered in position; in the second (Fig.3) the 628 band has moved to its furthest extent, and a new band has appeared at 573-558 the most and least refran-gible of the four bands remaining still unaltered in position. We have described in detail these spectra for they have great interest and importance owing to the fact that these changes do not arise from the formation of any chlorine-compound but are produced by the action of the hydrochloric acid simply as an acid. Substitute any strong acid sulphuric nitric &c. for the hydrochloric acid and exactly the same changes will occur. Use a weak acid an organic acid such as tartaric citric.oxalic &c. and the action does not go beyond the first stage (Fig. 2). Carbonic acid is without action on the chlorophyll. There is also another way in which the same changes may be brought about without the presence of acid namely by the application of heat. If for instance the solution of chlorophyll be evaporated t o dry-ness on a water-bath at a temperature of 80" or above then on redis-solution it will be found to have changed and t o give no longer the original but the sccond spectrum. Let the evaporation take place at ordinary temperatures in a current of air or under the air-pump, then on at once redissolving the residue no change will have occurred ; if however after the evaporation the dry mass be kept for a short time i t will change even at ordinary temperatures.Further if the alcoholic solution be diluted with water and then boiled the body giving spectrum No 2 is formed ; and the addition of certain salts, such as mercuric chloride ferric chloride &c. causes a similar change. Alum precipitates the colouring matter and if the precipitate be col-lected washed and dried at ordinary temperatures and again dis-solved it will give the second spectrum. On the other hand basic acetate of lead precipitates the chlorophyll unchanged. Acids heat metallic solutions all act on the chloropbyll and all give rise to an identical spectrum and therefore we conclude to the same body. Further,it is of interest to note the identity of these processes with those used to coagulate albumin and consequently the probability that the change in both cases is of a similar character STUDY OF CIILOROPIIY1,L.337 Since these changes are produced by processes and reagents which differ so materially we are bound to conclude that the change is a molecular not a chemical one. I n these cases the least refrangible band does not alter for if the solution be diluted it always thins down to a band from 670 to 660 ; the other three bands on the con-trary all change the 628-607 moving towards the blue the 589-573 band disappearing and the 544-531 band becoming very much darker. I n fact although a shadowy indication of this last band is constantly visible in the normal solution it is often so small in amount that it should be regarded rather as an accidental impurity than as a necessary part of the normal spectrum.Again the essential and characteristic distinction between the two spectra Figs. 2 anci 3 is the presence in the latter of the band a t 573-558. This band as far as we know is produced solely by the presence of a strong acid in considerable excess and all specimens of chlorophyll either normal or not yield it on the addition of hydrochloric nitric or sulphuric acid. There is obviously a considerable resemblance between these three spectra but at present notwithstanding the beautiful work of Abney and Festing we can hardly deduce from these indications alone the nature and relationship between these bodies ; but from the processes used for obtaining them there can we think be little or no doubt, that they are simply molecular modifications of the original chloro-phyll and we propose a t present to designate them as a- anci 6-chloro-phyll.With regard to the different purifying processes that have been used for obtaining chlorophyll from leaves &c. in some cases the normal chlorophyll has been extracted ; in others the leavee have first been dried at steam-heat or the alcoholic solution has been boiled, and it is the or-chlorophyll that has been obtained. We have tried several of these processes and efficacious as they undoubtedly are in removing many if not ail of the numerous bodies existing in more or less intimate connection with the chlorophyll still they appear to produce really no change in the spectrum. With regard to general absorption no doubt they do produce marked effects specially a t the blue end of the spectrum ; this is well seen in the methods of purifi-cation recommended by Conrad.He obtained as he believed a separation of chlorophyll into a green and a yellow body by means of benzene. Observation shows however that the band-giving body, the chlorophyll remains quite unchanged by the benzene but that certain bodies which absorb in the blue are insoluble in this men-struum hence the change in colour. Hydrochloric acid has apparently considerable power of destroying certain of these blue-absorbing bodies for on adding this acid to an ordinary chlorophyll solution blue rays come through where befor 338 RUSSELL AND LAPRAIK A SPECTROSCOPIC the addition it was quite dark. This fact has also this application : by means of it chlorophyll can be obtained more free from blue-absorbing matter than in any other way we are acquainted with.If to an alcoholic chlorophyll solution dilute hydrochloric acid be added, a precipitate is obtained and if this be washed dried and dissolved in ether o r in a mixture of alcohol and ether it gives R solution which shows not only the bands of the a-modification but also a band a t the blue end of the spectrum which was before alluded to quite dark and distinct from 513 to 499. I n all probability this band is present in other cases but is masked by general absorption. The action of alkalis on chlorophyll is quite as marked and as charac-teristic as the action of acids. On adding either an alcoholic or an aqueous solution of potash or soda to a chlorophyll solution two effects are pro-duced one is the fading out of all except the least refrangible the domi-nant band and the other is the spread of this band towards the blue, extending from 674 to 628.The action of alkali does not however, stop here for if a considerable excess be present another and an exceedingly interesting change sets in the dominant band now from 674 to 628 dividing into two distinct bands,* one from 674 to 660 and the other from 646 to 632 ; then if sufficient alkali be present the 674 to 638 band gradually becomes fainter and fainter and ultimately the one from 674 to 628 alone remains. The same changes can be brought about with the a- and @-chlorophyll but with far more difficulty. To change these varieties the potash or soda must be stronger and the contact longer.With ammonia we believe we have broken this band up but in almost all cases ammonia is without action on these modi-fied chlorophylls and it is quite clear that as regards the action of alkalis the a- and P-chlorophylls are far more stable than normal chlorophyll. There are other and more convenient methods for pre-paring hhis one-banded modification of chlorophyll. One is to evaporate an alcoholic solution of chlorophyll to dryness over a water-bath; then treat the residue with water which washes out a soluble yellow substance varying very much in amount with different samples of chlorophyll ; and then evaporate the residue several times to dryness with a mixture of equal parts of ammonia and water. Another method is to act on the chlorophyll with a solution of copper sulphate ; the precipitate formed is washed with water until all the copper is removed then dried and dissolved in alcohol and ether.It gives a spectrum identical with that obtained by the ammonia process and like it the band is capable of being split up into two bands. In the filtrate froni the above precipitate there is always much chlorophyll remaining but this curiously enough has also been modified and * Chautard as long ago as 1836 mentions this ; he naturally concludes that it is the original dominant band split up (Compt. rend. 76 570) STCDY OF CHLOROPHYLL. 339 now gives only the one-band spectrum. When we first obtained this one-banded substance the position of this band appeared so nearly to correspond with that of the dominant band in a strong solution that we were inclined to believe that we 'had really separated the bodies giving the more refrangible bands from those which give the less refrangible; but evident,ly this is not the case; neither does i t now seem a t all probable that such a separation would be possible.We have used the term one-banded modification of the chlorophyll, and are aware of the possible ambiguity that this band can be split into two; hut this change is really brought about only by the con-tinued action of alkalis for on simply diluting the solution down even to the vanishing point of the band there is no indication of two band8 being present. The solution of this one-banded substance is still of a beautiful green colour and is very remarkable €or its stability neither a trace nor an excess of acid of any kind produces any change i n its spectrum, and i t may even be dissolved in strong snlphuric acid and reprecipi-tated by water without alteration.If the action of caustic potash or soda be pushed to an extreme for instance if chlorophyll be heated with solid potash then it is appnren tly completely decomposed the dominant band disappearing, and two hands different in position from any of the former ones being produced ; these are shown in Fig. 6. To return now to the fact of different leaves giving different spectra ; for instance when vine-leaves are treated with alcohol and ether the liquid gives strongly the a- not the normal spectrum. A s is well known the juices of the vine-leaf are very acid consequently during the extraction of the colonring matter the acid has time and oppor-tunity for action and hence the cause of what appears at first to be an anomaly.In the leaf itself the chlorophyll is in the normal con-dition for if to the bruised leaf precipitated calcium carbonate or carbonate of soda be added together with the alcohol and ether the filtered liquid then gives not the 2- but the normal spectrum ; and even without the addition of the calcium carbonate on rapidly extracting the colouring-matter from the .leaf and examining it immediately t h e spectrum is normal. It is therefore evident that although both chloro-phyll and acid are present in the leaf +they are not under such conditions that they can act on one another; but bliing them into solution and the change commences immediately.Virginian creeper Bigonia and other leaves act exactly like the vine. The acid in the Bigonia can be entirely removed by water and if the colouring matter be then extracted it gives the nornial spectrum. The way we now generally adopt in extracting the chlorophyll VOL. XLL 2 340 RUSSELL AND LAPRAIK A SPECTROSCOPIC STUDY ETC. from leaves is to add with the alcohol and ether precipitated calcium carbonate ; then whether the juice of the leaf be very acid or not is a matter of indifference. We have already stated that in all the dif-ferent leaves which we have examined the chlorophyll has been found to be in the normal condition. This applies of course only to freshly gathered leaves ; the chlorophyll in gathered leaves gradually changes, and passes over the a-modification the time required for this change varying with the leaf and with external circumstances ; whether the leaf be exposed to light or kept in the dailk does not appear to affect the result.Pear leaves after being gathered for three weeks and kept in a dry room yielded both normal and z-chlorophyll; the change apparently had just begun. The chlorophyll in some vine leaves that had been gathered less than ten days had completely passed over t o the a-modification ; but similar leaves gathered a t the same time and kept in water gave only normal chlorophgll. Remembering how easily the solid normal chlorophyll passes over to the a-modifica-tion it is evidently not necessary to suppose that the acid in the leaf is the cause of this change.The chlorophyll having passed over to the a-modi fication remains with wonderful pertinacity in the dead leaf. Dead pear leaves which Bad fallen from t,he tree seven months ago st21 gave a brilliant spectrum of a-chlorophyll and even an alcoholic and ether extract of tobacco gives this spectrum. The solutions of chlorophyll obtained by the direct treatment of leaves with alcohol and ether contain a large nnmber of substances, and the chlorophyll as well as the other bodies undergoes change on keeping. The length of time during which these solutions retain their green colour varies very much ; expose them t o light, and the rapidity of the change is enormously increased. I f acid be present in the solu-tio!i the chlorophyll quickly passes over to the a-modification and even if the extract has been made with calcium carbonate present the same change occurs only more slowly.These changes take place even in the dark. Resides this change of the chlorophyll other and more complicated changes occur. Solutions from seine leaves can be kept in the dark apparently without change for months whereas ot8hers rapidly alter and the chlorophyll disappears from them. The extract from rhubarb for instance very soon changes the solution becoming of a tolerably bright red colour and the chlorophyll bands disappearing. This red substance niid the other product.; of decom-position from their solutions do not give visible spectra and the same remark applies to a t least the majority of the colouring matters in flowers.If these green solutions be exposed to light they are with-out exception rapidly decomposed and lose entirely their green colour, becoming either red yellow or of some intermediate shade. Brillian MILLS AND BARR PRECPITATION OF THE ALUMS ETC. 341 sunshine in an hour or two will completely decompose all the chloro-phyll in a dark green solution not even a vestige of the dominant band remaining. If a solution of the a-chlorophyll dissolved in alco-hol and ether be exposed to light it is far more difficult of decompo-sition and will withstand its action for a few days. That this stability is not due to the absence of certain substances.in the solution of the a-modification is shown by dissolving some of this modified chlorophyll in a normal and readily decomposible solution when it will be found that although there will be a change of colour owing to the decomposition taking place in such a solution still the green colnur from the modified chlorophyll will long remain.A single drop of hydrochloric acid added to the green extract although it a t once changes the bright green to a darker and browner green enables the solution t o resist this action of light to a much greater extent than it could have done if no acid had been added. I n the one-lnanded modification of chlorophyll we appear to have a body on which light has no action ; solutions of this body have been, for the last three months exposed continuously to all the light and sunshine we could get and they are unchanged in colour and consti-tution ; another proof of the really wonderful stability of this substance. Again as a confirmation of the properties and formation of this form of chlorophyll a single drop of sulphate of copper added to an ordinary chlorophyll extract Tenders the green colour of the solution permanent. The very striking change of tint which occurs when a strong chlorophyll solution is very considerably diluted whereupon it changes from a dark to a light yellowish-green forcibly suggests to us the probability that the difference in shade of old leaves as com-pared with young ones is due to the same cause namely the greater or smaller amount of chlorophyll in a given area

ISSN:0368-1645    

DOI:10.1039/CT8824100334

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

MILLS AND BARR PRECIPITATION OF THE ALUMS ETC. 341 LIII.-Ort the PI*ec@itation of the Alums by Sodic Carbonate. By EDMUND J. MILLS D.Sc. F R.S. and R. L. BARR. THE behaviour of a solution of alum towards sodic carbonate is it subject of considerable theoretical as well as technical importance and extremely complicated in its nature. It therefore appeared to us that the following research-dealing as it does with a specific phase of the general investigation-might be of interest to chemists. We have been induced to submit it at this time to the Society, 2 c 342 MILLS AND BARR ON THE PRECIPITATION OF partly because it is complete in itself and partly becauso circum-stances do not permit of our pursuing it further. The particular alums we employed were potassio-aluminic and pot assio-chromic alum.1. Precipitation of Potassio-aluminic Alum. The alum employed in our experiments was an excellent commercial sample containing scarcely perceptible traces of iron and yielding very nearly the amount of alumina indicated by theory An aqueous solution of this was prepared of such verified strength as to contain 1 per cent. by calculation of aluminic sulphate or 0.2982 gram alumina in 100 C.C. The solution of sodic carbonate was made from cleaned sodium by reaction in a silver vessel with water carbonation with excess of purified carbon dioxide and evaporation a t loo" the residue being dissolved in such a proportion of water as to constitute a liquid of 093038 per cent. strength. This strength considered with reference to that of the alum solution is as 3Na,CO A&( SO,), in equal volumes.A precipitation experiment was carried out as follows The bottles containing the reagents another holding distilled water and a dry beaker were placed in a trongh of running water until their tem-perature became sensibly constant'. The requisite quantity of sodic solution was then introduced with frequent stirring into tbe beaker ; next sufficient water to make up an invariable volume of 100 C.C. ; and lastly and always 100 C.C. of alum solution. The mixture was well agitat'ed with a thermometer (whose indication was observed) and left a t rest under the same conditions for exactly an hour. At the end of this time it was filtered as rapidly as possible with the aid 9f suction. The precipitate was washed first with cold and subse-queiitly with hot water until the precipitate was free from sulphate ; it was then re-dissolved as chloride and precipitated by ammonia.The results of our experiments are recorded in the following table :-Potash alum taken in C.C. 100 TABLE I. Sodic carbonate Alumina taken in C.C. precipitated. Temperature. 20 0.0074 gram. 9-8" 30 0.0386 , 8.8 40 0.0979 , 9.8 45 0.1331 , 9.8 50 0.1664 , 9-9 60 0*219!1 , 8.8 65 0.2472 , 10.8 i 0 0.2679 , 10 2 80 0.3039 ) 8. THE ALUMS BY SODIC CARBONATE. 343 We noticed in the course of this work that the first filtrate became turbid on standing where lower quantities of carbonate had been added. 2. Pprecipitation of Potassio-chro,mic Alum. This alum was prepared by ourselves and recrystallised from water below 50' C.until it furnished on analysis very nearly the theoretical quantity of chromic oxide. The standard solution of this contained 1.1518 per cent. chromic sulphate corresponding to 0.4474 gram oxide in 100 C.C. This strength considered with reference to that of the sodic solution is as Crz(SO4) 3N*CO3 in equal volumes. The experiments were carried out exactly as in the case of the pre-ceding alum; their results are stated in Table 11. TABLE 11. Chrome alum in C.C. 100 Sodic carbo-nate in C.C. 60 65 70 75 85 95 100 110 Weight 09 chromic oxide, in precipitate. 0.0146 0.0491 0.0979 0.1520 0.2602 0.3328 0.3566 0.3894 Temperature: 7.7" 7.9 7.7 8.7 8.7 7.9 6.3 5.8 The first filtrate always became slightly turbid on standing.3. Discussiolz. On plotting out our results we soon found reason to believe that the precipitation of an alum by sodic carbonate-as we performed it, at least-takes place in three stages. First a considerable addition of carbonate is necessary before any precipitation takes place at all; secondly there is precipitation according to a continuous law until about half the alum has been thrown down; and thirdly the precipi-tation is proceeded with according to the previous law but with altered constants. Guldberg and Waage (Etudes sur Zes Afinite's chiiniyues 63) have given a particular relation between precipitant and precipitate which we believe to be general and which with a necessary linear altera-tion we have found well adapted to our numerical results, a-Potassio-ahminic BZum.-In the stage antecedent to precipitation 344 MILLS AND BARR PRECIPITATION OF THE ALUMS ETC.very nearly 19 C.C. are required. represented by the equation : The first stage of precipitation is 0.14131. - 0.0053250(47 - x) y = 1 + 0*02538U(47 - 2) ’ in which y is the weight of alumina precipitated x the number of cubic centimeters of carbonate taken i n any one experiment 0.1491 represents one-half of the total alumina constantly present in the solution and 47 is the number of cubic centimeters of carbonate re-quired to complete the semi-precipitation. In the second stage we have-0.1491 - 0.0045182(80 - .) y = 0.149.1 + 1 - 0~009s153(80 - x) ’ where the general symbols have the same meaning as before.The number of cubic centimeters of carbonate required for complete pre-cipitation of all the alumina is 80. Thus our solution just began to yield a precipitate when the aluminic sulphate and carbonate were nearly in the ratio-Al,(SO,) +(Na,CO,) ; it was about half precipitated when the ratio A1,(SO4) $(Na2C0,) was attained ; and it was completely precipitated in the proportion Al,( SO,) 9(Na2C03). This last fact is of considerable economical importance and probably even less carbonate would have sufficed had our solutions been more concentrated. We subjoin a numerical comparison of theory with experiment :-CFrbonate m C.C. 20 30 40 45 47 50 60 65 70 80 TABLE ITI. Alumina precipitated. 0-0074 gram.0.0386 ,) 0.0979 ,) 0.1331 ,, 0-1491 ,, 0.1664 ,) 0.2199 ,) 0.2472 ,, 0.2679 ,) 0.3039 ,) Alumina precipitated calc. 0.0032 gram. 0.0409 ), 0.0950 ,) 0.1318 ), 0*1491 ,) 0.1684 ,, 0.2222 ), 0-2445 ), 0.2644 ?, 0.2982 ,, Probable error of a single comparison 0.0025 gram. p-Potassio-chromic Alum.-The stage antecedent to precipitation The requires in fhis case no less than 59 C.C. of the sodic reagent WARINGTON DETERMINATION OF NITRIC ACID ETC. 345 subsequent stages are represented by the following equations in order :-0.2237 - 0.0097686(81-7 - g) 1 + 0*010083(81.7 - 2) ?J= ' 0.2237 - 0*0039040(139 - X) y = 0.2237 + 1 - 0.011873(139 - &) ' Thus our solution just began to yield a precipitate when the sul-phate and carbonate were nearly in the ratio Cr,(SO,) 2Na2C03 ; the stage of semi- precipitation was approximately marked by the ratio Cl.,(SO,j >-$( Na,C03). The completion of precipitation would have required 139 C.C. carbonate. This quantity we could not hope to comprise wit,hin our conditions though we have successfully ventured as far as 110 C.C. TABLE IV. Carbonate in C.C. 60 6.3 50 75 85 9 3 100 110 Chromic oxide precipitated. 0.0146 gram. 0.0491 ,, 0.0979 ,, 0.1520 ,, 0.2603 ,, 0.3328 ), 0.5566 ,, 0.3894 ,, Chromic oxide calculated. 0.0096 gratn. 0.0519 ,, 0.0979 ,, 0-1483 ,, 02596 ,, 0.3525 ,, 0.3568 ,, 0.3922 ,, Probable error of a single comparison 0.0019 gram. The accompanying drawing which has been constructed from the equations exhibits the entire course of precipitation of both oxides -I-l

ISSN:0368-1645    

DOI:10.1039/CT8824100341

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

WARINGTON DETERMINATION OF NITRIC ACID ETC. 345 L1V.-On the Deferiuiization of Nitric Acid as Nitric Oxide by nzeaus of its R e d i o i L with Ferrous Sults. (Part 11). By ROBERT WAEINGTOS. THE first part of this communication having been published some time ago a brief recapitulation of tlie objects and earlier stages of the investigation is probably desirable. The method proposed by Schloesing as specially applicable in the presence of organic matter consists in heating the nitrate with ferrous chloride and hydrochloric acid in an atmosphere as free from oxygci 34 6 WARINGTON ON THE DETERMINATION OF as possible collecting the nitric oxide evolved converting it into nitric acid by treatment with water and excess of oxygen and estimating the nitric acid by titration with alkali of known strength.The experiments a t Rothamsted haPe had for their object to ascertaiu the amount of accuracy attained by this method when applied to the determination of very small quantities of nitric acid in the presence of organic matter. I n all these experiments the nitric oxide produced has been collected over mercury and its quantity determined by gas analysis this being undoubtedly the most exact method available. I n the earlier experiments (Trans. Chem. Soc. 1880 468) it was shown that some of the simpler modifications of Schloesing’s process comrnonly employed give very low results when the amount of nitric acid present is but small and that this error is increased by the presence of sugar. By adopting Schloesing’s later improvement of cmducting the reaction in a small’bulb retort through which a stream of carbonic acid could be passed much better results were obtained.Using nitre containing 1.4 mgrm. of nitrogen 93-94 per cent. of the nitrogen taken was obtained as nitric oxide; the presence of con-siderable quantities of sugar and other forms of organic matter was also now without influence. This indifference to the presence of organic matter was apparently due to the retort being heated in a chloride of calcium bath and its contents boiled to dryness in every experiment thus ensuring a complete reaction. The errors of deficiency still perceptible were in all probability, due to the presence of a trace of oxygen in the retort this oxygen beiug introduced in the carbonic acid gas or in the other materials employed.The improvements to be now described consist for the most part of precautions taken to avoid as far as possible the entrance of oxygen ; these improvements have been long in use in the Rotham-sted Laboratory but time has only lately been found for the execution of test experiments showing the value of the alterations made. The apparatus now employed is quite similar to that formerly figured (Trans. 1880 477) with the only difference that the bulb retort in which the reaction takes place is now only 19 inch in diameter thus more exactly resembling the form employed by Schloesiq. A bulb of this size is sufficient for the analysis of soil extracts ; for determinations of nitrates in vegetable extracts a larger bulb is required. The chief improvement consists in the use of carbonic acid as free as possible from oxygen.The carbonic acid generator is formed of two vessels. The lower one consists of a bottle with a tubular in the side near the bottom ; this bottle is supported in an inverted position, and contains the marble from which the gas is generated. The upper vessel consists of a similar bottle standing upright ; this con NITRIC ACID AS NITRIC OXIDE ETC. 347 tains the hydrochloric acid required to act on the marble. The two vessels are connectad by a glass tube passing from the side tubular of the upper vessel to the invert2d mouth of the lower vessel ; the acid from the upper vessel thus enters below the marble. Carbonic acid is generated and removed a t pleasure by opening a stop-cock attached to the side tubular of the lower vessel thus allowing hydrochloric acid to descend and come in contact with the marble.The fragments of marble used have been previously boiled in water. The boiling is conducted in a strong flask. After boiling has proceeded some time a caoutchouc stopper is fixed in the neck of the flask and the flame removed; boiling will then continue for some time in a partial vacuum. The lower reservoir is nearly filled with the boiled marble thus prepared. The hydrochloric acid has been also well boiled and before it is introduced into the upper reservoir it has dissolved in it a moderate quantity of cuprous chloride. As- soon as the acid has been placed in the upper reservoir it is covered by a layer of oil. The apparatus being thus charged is at once set in active work by opening the stop-cock of the marble reservoir; the acid descends, enters the marble reservoir and the carbonic acid produced drives out the air which is necessarily present a t starting.As the acid reservoir is kept on a higher level than the marble reservoir the latter is always under internal pnessure and leakage of air from without cannot occur. The presence of the cuprous chloride in the hydrochloric acid not oiily ensures the removal of dissolved oxygen but affords an indication to the eye of the maintenance of this condition. So long as the acid remains of an olive tint oxygen will be absent ; bub should the acid become of a clear blue-green it is no longer certainly free from oxygen and more cuprous chloride must be added.A further slight improvement adopted since the last communica-tion consists in the use of freshly-boiled reagents which are employed in as small a quantity as possible. When boiling the hydrochloric acid i t is well to add a few drops of ferrous chloride in order more certainly t,o remove any dissolved oxygen. The mode of operation is as follows :-The apparatus previously described is fitted together the long funnel tube attached to the bulb retort being filled with water. Connection is made with the glass stop-cock of the carbonic acid generator by means of a short stout caoutchouc tube provided with a pinch-cock. The pinch-cock being opened the stop-cock is turned till a moderate sheam of bubbles rises in the mercury trough ; the stop-cock is left in this position and the admission of gas is afterwards controlled by the pinch-cock pressure on which allows a few bubbles to pass a t a time.The heated chloride of calcium bath is next raised so that the bulb retort is almost sub-merged; the temperature shown by a thermometer which forms par 34s WBRINGTON ON THE DETERNINATION OF of the apparatus should be 130-140". By boiling smdl quantities of water or hydrochloric-acid in the bulb retort in a stream of carbonic acid the air present is expelled ; the supply of carbonic acid must be stopped before the boiling has ceased so as to leave litkle of this gas in the retort. Previous to very delicate experiments it is advisable to introduce through the funnel tube a small quantity of nitre ferrous chloride and hydrochloric acid rinsing the tube with the latter re-agent; any trace of oxygen remaining in the apparatus is then consumed by the nitric oxide formed arid after boiling to dryness, and driving out the nitric oxide with carbonic acid the apparatus is in a perfect condition for a quantitative experiment, Soil extracts may be used without other preparation than concen-tration.Vegetable juices which coagulate when heated require t o be boiled and filtered or else evaporated to a thin syrup treated with alcohol and filtered. A clear solution being thus obhained it is concen-trated over a water-bath to the smallest volume in a beaker of smallest size. As soon as cool it is mixed with 1 C.C. of a cold saturated solution of ferrous chloride and 1 C.C.of hydrochloric acid both reagents having been boiled and cooled immediately before use. I n mixing with the reagents care must be taken that bubbles of air are not entangled ; this is especially apt to occur with viscid extracts. The quantity of ferrous chloride mentioned is amply sufficient for most soil extracts, but it is well perhaps to use 2 C.C. in the first experiment of a series ; the presence of a considerable excess of ferrous chloride in the retort is thus ensured. With bulky vegetable extracts more ferrous chloride should be employed; to the syrup from 20 grams of mange1 sap I have usually added 5 C.C. of ferrous chloride and 2 C.C. of hydro-chloric acid. The mixture of the extract with ferrous chloride and hydrochloric acid is introduced through the funnel tube and rinsed in with three or four successive half cubic centimeters of hydrochloric acid.Tlie contents of the retort is then boiled to dryness a,little carbonic acid being from time to time admitted and a more considerable quantity used a t the end to expel any remaining nitric oxide. The most con-venient temperature is 140" but in the case cf vegetable extracts it is well to commence a t 13Uo as there is some risk of the contents of the retort frothing over. The gas is collected in a small jar over mercury. As soon as one operation is completed the j a r is replaced by another full of mercury and the apparatus is ready t o receive a fresh extract. A series of five determinations with all the accompanying gas analyses, may be readily performed in one day.The bulb retort becomes encrusted with charcoal when extracts rich in organic matter are the subject of analysis ; it is best cleaned first with water and then by heating oil of vitriol in it NITRIC ACID AS NITRIC OXIDE ETC. 349 Mercury contrary to the statement in most text-books is gradually attacked by hydrochloric acid in the presence of air ; the mercury in the trough is thus apt to become covered with a grey chloride and i t is quite necessary to keep the store of mercury in contact with sul-phuric acid to preserve its mobile condition. The gas analysis is of a simple character; the gas is measured after absorption of the carbonic acid by potash and again after absorption of the nitric oxide the difference giving the amount of this gas. For the absorption of nitric oxide a saturated solution of ferrous chloride was for some time employed.This method is not, however perfectly satisfactory when the highest accuracy is required, the nitric oxide being genemlly rather underestimated except the process of ahsorption is repeated with a fresh portion of ferrous chloride. The error is greater in proportion to the quantity of un-absorbed gas present. Thus with a mixture of nitrogen and nitric oxide containing little of the former absorption of the nitric oxide by successive treatment with oxygen and pyrogallol over potash showed 97.8 per cent. of nitric oxide ; while the same gas analysed by a single absorption with ferrous chloride (after potash) showed 97.5 per cent. of nitric oxide. With a mixture containing more nitrogen the oxygen method showed 65.9 per cent.of nitric oxide ; while one absorption with ferrous chloride gave 64.2 per cent. and a second absorption,. in which the ferrous chloride was plainly discoloured 66.2 per cent. The use of ferrous chloride as an absorbent for nitric oxide has now been given up and the oxygen method substituted. All the measure-ments of the gas are now made without shifting the laboratory vessel ; the conditions are thus favourable to extreme accuracy. The chief source of error attending the oxygen process lies in the small quantity of carbonic oxide produced during the absorption with pyrogallol ; this error becomes negligible if the oxygen is only used in small excess. The difficulty of using the oxygen in nicely regulated quantity may be removed by the use of Professor 0.Bischof’s vecently-invented “ gas delivery-tube.” This may be made of a test-tube, having a small perforation half an inch from the mouth. The tube is partly filled with oxygen over mercury and its mouth is then closed by it finely-perforated stopper made from a piece of wide tube and fitted tightly into the test-tube by means of a covering of caoutchouc. When this tube is inclined the side perforation being downwards the oxygen is discharged in small bubbles from the perforated stopper, while mercury enters through the side opening. Using this tube the supply of oxygen is perfectly under control and can be stopped as soon as a fresh bubble ceases t o produce a red tinge in the laboratory vessel. The trials made with this apparatus have been very satisfac-tory 350 WARINGTON DETERMINATION OF NITRIC ACID ETC.In the follom-ing table will be found a number of test experiments made with nitrate of potassium by the method just described. The gases were analysed the same day in which they were obtained save in the case of Experiments 3 and 7 in which the analysis was made on the following day. In Experiments 3,4 and 7 the nitric oxide was absorbed by ferrous chloride ; in all other cases the oxygen method was employed. The gas found in each stage of the analysis is €or convenience reckoned as nitric oxide and expressed in milligrams of nitrogen. Test Experiments with known quantities of Nitre coizducted i n an A tniosphere of Carbonic Acid free front Oxygen.NO. 1 2 3 4 5 6 7 8 8 10 11 12 Nit,rogen t,aken as nitre, milligrams. 5 *092 5 '092 2 *828 2 -828 2 '560 2 -560 1 *414 1 *023 1 019 1 -019 0 -512 0 -505 Gas obtained expressed as milligrams of iitrogen. Total gas after potash. 5 -080 5.050 2,824 2.774 2 522 2 *585 1 -411 1 -040 1,081 1 -031 0 *539 0 *519 Nitric oxide absorbed. 5 -042 5 .(I23 2 *790 2 *746 2 -505 2.563 1 *381 0 *992 1.003 0.985 0-516 0 -496 Gas left unabsorbed. 0 -038 0.027 0 *034 0 028 0 -017 0.022 0 030 0 *048 0.078 0 a046 0 .Od3 0 *023* Nitrogen found as nitric oxide for 100 taken. 99 '0 98 -6 98 *7 97 -1 97 -9 100 -1 97 -7 97 '1 98 -4 96 -7 100 -8 98 '2 The figures show that the modifications introduced have issued in a considerable improvement in the result the small quantities of nitrogen taken having yielded an average product of 98.4 per cent. This favourable product does not show any diminution even when only half a milligram of nitrogen is the subject of experiment. In Experi-ment 9 0.2 gram of cane-sugar was added with the nitre but without affecting the result. We have thus in the reaction proposed by Schloesing a means of determining very small quantities of nitric acid with considerable accuracy even in the presence of organic matter ; but to accomplish this the various simplifications consisting in the omission of the stream of carbonic acid and the collection of the gas over caustic soda, must be abandoned and special precaut)ions must be taken to exclude all trace of oxygen from the apparatus. that found in the diiplicate experiment No. 11. * The unabsorbed gas was L>st in this experiment j it is reckoned as the same a

ISSN:0368-1645    

DOI:10.1039/CT8824100345

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

351 LV.-Ojt the Deternzination. of Nitric Acid in Soils. By ROBERT WARIKGTON. As the nitrogen contained in cereal and in many other crops is a t lenst in greatest part derived from the nitrates of the soil the quan-t,ity of nitrates present in a soil becomes for many purposes a measure of the assimilable nitrogen which the soil contains. Investigations as to the increase or diminution of the nitrates of the soil under various circumstances of manuring culture or season have been for some time past in progress a t Rothamsted. As a part of this work atten-tion has naturally been directed to perfecting the methods employed for determining nitrates in soil. Some results of the experience thus acquired it is proposed to lay before the Society. 1. Collection of the Soil Samples.A fair sample of soil is best taken by driving into the ground a, short iron tube of the dept'h which it is desired the sample shall represent. When the upper edge of the tube is level with the surface of the ground the soil tilling the tube is cut out and constitutes the sample. If a sample of the second depth is desired the earth sur-rounding the tube is cleared away and the tube is once more driven down till its upper edge is a t the level which the lower edge pre-viously occupied. By proceeding in this way the soil may be sampled to any required depth. The iron tube should be wide enough to prevent any abnormal consolidation of the soil within it else the length of the tube will not exactly represent the depth of soil taken. The method here indicated has been employed by Messrs.Lawes and Gilbert during the last 25 years; the tubes made use of are rect-angular and 9 inches deep ; the smallest is 6 inches square. I n sampling a soil for nitrates it is advisable to extend the collection to a considerable depth as although nitrates are formed a t the surface, they are readily washed down by rain and distributed by diffusion ; the whole range of soil available to the roots should therefore if possible be iricluded. If only a comparatively small depth of soil can be sampled it is very necessary that the sampling should be done after dry weather when the nitrates are nearest the surface. 2. Trentmed of the Soil Samples. The first step to be taken is to bring the soil as quickly as possible If this is not done the quantity of nitric acid to a dry condition 352 WARINGTON ON THE DETERMINATION OF Treatment of soil.---1. Dricd in water-oven 90" 2. Dried in stove 38" . . . . 3. Dried in air ZOO . . . . . . 4. Xept in bulk 7 months, then dried in air found may greatly exceed that existing in the original soil as nitri-fication will be continually in progress while the soil remains damp. Experience has shown that it is not unimportant a t what tempe-rature the drying is effected. If a wet soil is dried in a water-oven at a temperature approaching loo" the nitrates present will be more or less destroyed. This destruction is probably due to deoxidation by the organic matter present and will be in proportion to the mass of the soil its wetness and its richness in organic matter.While, however drying in a water-oven occasions loss of nitrates drying by mere exposure to air is equally likely (in the case of surface soils at least) to occasion a gain in nitrates the drying being so slow that a, sensible amount of nitrification rn%y occur. The following test experiments have been made to ascertain the influence of various modes of drying :-An arable loam# representing the first 9 inches from the surface was passed through a sieve with meshes half an inch diameter to separate stones ; the sifted soil weighed about 280 lbs. The fine mould of this soil contained about 18 per cent. of water. The sol1 was well mixed and divided into several por-tions. One-eighth was dried in the water-oven for 24 hours a t about 90" ; one-eighth was dried in the stove room a t 38" ; one-eighth was dried by exposure to air during 17 days at a mean temperature of 10.2" ; one-half was placed in a bag and kept in an outer shed during seven months (October to April).The whole of the samples were finally powdered and sifted and all visible roots removed. The nitrogen existing as nitric acid was then determined in all the samples by the Crum-Frankland method. About four years afterwards the deter-minations were repeated using the modification of Schloesing's method now adopted for soil analysis ; the results are given in Table I. Water. -p. c. 0.99 2 *13 3 a53 4 '22 TABLE 1.- Variations in the Quantity of Nitrates present i n Soil resultiny froin Dlferent Modes of Dryimg. I Analysed 1878. Nitromen as ni-trates fn dry soil, Crum-Frankland method.per million. 1.08 4 *88 6 '04 a -90 Annlysed 1892. Wat,er. p. c. 1 '57 2 .23 3 '12 3.62 -~ ~ ~~ Nitrogen as ni-trates in dry boil, Suhloesing method. per million. 4 -17 5 *6% 6 9 7 9 -18 * The Rothamsted soil to which all the experiments here quoted refer may be described as a heavy loam with a clay subsoil NITRIC ACID IN SOILS. 353 The analyses made by the Crum-Frankland method show a wide range of variation in the quantity of nitric acid found the amount being least when the soil was dried in the water-oven and most when the soil had been left in bulk for several months and was finally sifted and powdered without the iise of artificial heat. The later analyses of the same series of soils by the Schloesing method show much less variation in the contents of nitric acid but the differences all lie in the same direction as before.The want of agreement in the two series is principally due to the much greater amount of nitric acid found by Schloesing’s method in the case of the soil dried in the water-oven ; we shall see presently that this higher result is probably more correct than that shown by the Crum-Frankland process. We shall probably have no difficultly in concluding that the quan-tity of nitric acid found in the soils numbered 3 and 4 is in excess of that originally present the process of drying in these cases having afforded more or less opporhnity for nitrification ; hut the facts before us do not prove that the nitrates found after drying in the water-oven were too low.The following experiments snpplement those just quoted, and show the influence of heat and moisture in diminishing the amount of nitrates in a soil. I n a dry powdered sample of arable soil representing the first 9 inches from the surface nitric acid was in the first place determined. Three quantities of this soil were then taken each of 300 grams. One lot was treated with 60 C.C. of water free from ammonia the water being care-fully added so as not to destroy the open texture of the soil; the moistened soil was then made into a cubical mass and placed in the middle of a basin. The second lot was similarly treated placed loosely in a beaker which it nearly filled and covered with a clock-glass.The third lot was gradually introduced into a similar beaker containing 130 C.C. of water ; the soil in falling through the water parted with most of its air ; the water was sufficient to slightly cover the mass of soil. This beaker was also covered by a clock-glass. The three soils were then placed in a large water-oven for about 24 hours ; the water was in actual ebullition during eight hours. The quantities of nitric acid found before and after this treatment were as follows ; the analyses were all made by Schloesing’s process : 354 WARINGTON ON THE DETERMINATION OF TABLE II.-Infiuence of Heat and Joisture i n reducirtg the Nitrates present in Soil. Treatment of soil. 1. Original soil . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Ditto moistened and quickly dried in water-oven .. . . . . . . 3. Ditto moistened and slowly dried in water-oven . . . . . . . . 4. Ditto thoroughly wetted and heated in water-oven . . . . . . Nitrogen as nitrates Iwr million of soil. 8 '08 7 '78 6 *34 1.83 It appears from these figures that with the particular soil in question little error was introduced by heating in the water-oven if only drying was quickly effected; but where as in Experiment 3 the escape of water was hindered B very distinct reduction of nitrates took place. The fourth experiment proves t h a t ,in the case of a mass of soil sntu-rated with water a comparatively short exposure to a high temperature is sufficient to destroy most of the nitric acid present,. Other experi-ments made a t Rothamsted ( J o w .Bo?J. Ag7-i. S~C. 1881 332) have shown that a soil kept saturated with water will lose nitrates even a t ordinary temperatures and similm facts have been noticed by Schloesing and others. As drying wet soil at a high temperature thus tends to a loss of nitrates while slow drying a t low temperature admits on t'he other hand of their production the follo.wing coume has been adopted at Rothamsted :-The soil is broken up immediately it is received from the field and spread in trays in layers about 1 inch in thickness ; the trays are then placed in a stove room kept at about 55" ; the drying is usually completed in 24 hours. As the temperature of the room is one a t which nitrification by an orgnnised ferment does not occur it is probable that very little production of nitric acid takes place during the operation.After drying stones and roots are removed and the soil is finely powdered and placed in bottles. Soil samples thus pre-pared are not absolutely dry but the small amount of water present is apparently insufficient to allow of organic change. 4 3. Preparation o f a Watery Extract. The mode of extracting the nitrates employed by Bousshqpult and still recommended in works on agricultural analysis is to take 500-1000 grams of the soil add its own weight of water (twic3 its weight is recommended by Wolff) and shake thoroughly ; after standing a portion of the fluid is removed for analysis. This mode of proceedin NITRIC ACID IN SOILS. 355 demands a considerable amount of soil the extraction occupies a good deal of time and the extract obtained is weak and turbid.Moreover some :%mount of uncertainty will generally attach to the calculated relation between the weight of soil taken and the nitric acid found; for if the soil is moist it will be difficult to decide how much of this moisture is diffusible water and how much exists as hydrates ; while if the soil has been dried at loo" a part of the water added will doubtless combine with the soil and cease to form part of the solu-tion. Grandeau (Trait4 d'dxalyse des Xatitkes Agricoles 1877 157) has proposed to extract the nitrates by simple percolation ; but as accord-ing to his directions four hours are required to extract 50 grams of soil while the resulting extract measures 150 c.c. the advantages offered seem very small.The method now employed at Rothamsted is to extract the soil by per-colation on a vacuum filter. A funnel 42 inches wide is made by cutting off the top of a Winchester qiiart bottle ; at the bottom of this funnel a disc of copper gauze is laid and on this two discs of filter-paper each slightly wider than the one beneath. The filter is first moistened and the dry powdered soil is then introduced ; 200-500 grams are usually taken according to the supposed richness of the soil in nitrates. If the soil is of loose texture it is shaken firmly together but with a clay soil consolidation is better avoided. The funnel is now connected by a caoutchouc stopper and glass tube with a strong flask water is poured on the soil and the flask is put in connection with a water-pump.The water descends through the soil and is collected in the flask. When 100 C.C. have passed through it may be concluded that all nitrates have been extracted. The collection of this extract may take from 10 minutes in the case of a surface soil of loose texture to 45 minutes in the case of a subsoil. The extract is nearly clear. Second extracts have frequently been taken but no chlorides or nitrates have been found in them. The small volume of the extract in which all the chlorides and nitrates of a soil may be obtained if the soil is taken dry and percolation is conducted on a vacuum filter is truly astonishing. In an experiment already published (Jour. Roy. Agri. Soc. 1881 3291 7 lbs. of dry powdered soil were placed on a filter similar to that just described, the soil forming a column 8 inches in height ; the filter was then put in connection with the pump and water applied to the surface of the soil.In 24 hours the water had descended through the column of soil, and percolation commenced. It was found that the first 50 C.C. of extract contained more than three-quarters of the chlorides and nitrates present in the soil while in the first 150 C.C. the whole of the chlorides and 98.8 per cent. of the nitrates were found. It would YOL. YLI. 2 356 WARINGTON ON THE DETERMISATION OF appear that as a column of water descends through a dry powdered soil i t dissolves the soluble salts at its lower edge and pushes this solution before it till the area of discharge is reached. If the soil were wet instead of dry a much larger extract wonld be required t o obtain all the chlorides and nitrates as it would then be necessary to displace all the water present in the soil.4. Aitalysis of the Soil Extract. The watery extract obtained by the method just described is placed in a small basin and evaporated nearly to dryness on a water-bath. The extract is usually acid to litmus and when highly concentrated may be strongly so. I have usually made the solution slightly alkaline with lime-water before evaporation but some test experiments with and without lime-water have not shown that this treatment is of any importance. The extract from an arable soil yields when concentrated, a very small quantity of pale-brown syrupy liquid ; a pasture soil being much richer in organic matter yields a much more considerable extract.The extract from a soil which has been dried at a high temperature is much richer in organic matter and apparently also in some saline constituents than the extract from the same soil dried a t a low tem-perature. Thus the extract (100 c.c.) from 300 grams of the soil dried in the water-oven (Experiment 1 Table I) gaye a dry residue of 0.239 gram while similarly prepared extracts from the soils dried at 10" and a t 38" gave only 0.107 and 0.104 gram of soIid matter. The temperature a t which a sample of soil is dried thus considerably affects other ingredients besides the nitrates. Two methods have been employed at Rothamsted in recent years for determining the quantity of nitric acid in soil extracts.The earlier determinations were made by the well known Crum-Brankland method in which the concentrated fluid is introduced into a tube of special construction mixed with If times its volume of concentrated sulphuric acid and shaken wihh mercury the reiulting nitric oxide gas being then measured. Test experiments made with this method have been already communicated to the Society (Trans. Chern. Soc., 1879 375). In applying this method to the analysis of soil extracts it was soon found that the amount of soluble organic matter present was far too great at least in the case of extracts from surface soils for its convenient or accurate me ; much froth was produced in the shaking tube and the results obtained were proved to be below the truth.The effect of organic matter in diminishing the amount of nitric oxide obtained has been already pointed out in the communication just referred to NITRIC ACID IN SOILS. 357 Further experiments with soil extracts showed however that the greater part of the organic matter could be removed by treatment with alcohol. The mode of operation was to concentrate the watery extract from the soil to a small bulk then add several times its volume of strong spirit and filter. The bulky precipitate was well washed with spirit and the filtrate and washings evaporated to dryness. The residue left had the appearance of a thin varnish ; this was dissolved in a few drops of water and introduced into the shaking tube. A later improvement consisted in the introduction of a single drop of dilute hydrochloric acid into the shaking tube before commencing the agitation; by this means the attack on the mercury is much intensified and the evil influence of organic matter diminished.When using this small quantity of hydrochloric aoid no instance has occurred of a subsequent development of gas in the laboratory vessel of the gas analysis apparatus due to an incomplete reaction in the shaking tube. To ascertain whether the organic matter in a purified soil extract had any influence on the result test experiments were made. Extracts were prepared in the usual way from a pasture soil proved to contain no nitrates ; to each of these extracts 10 C.C. of a solution of nitre were added ; the extracts were then concentrated purified with alcohol and analysed with the addition of hydrocliloric acid.In some cases the TABLE 111.-Determinations of Nitric Acid by the Crum-Frankland Method. Nitre Solutions alone and mixed with Soil Eztracts. Nitrogen found. Total gas reckoned as nit,ric oxide. 10 C.C. Normal Nitre Solution. 1. Nitre only 2. Ditto 3. Ditto 4. Nike evaporated with 1st extract from soil 5. added to alcohol extract 6. evaporated with 1st extract from soil 7. added to alcohol extract 8. evaporated with 2nd extract from soil 9. D;';to ditto 10. Ditto ditto 11. Nitre added to alcohol extxact 10 C.C. 2 Nitre Solution. 12. Nitre evaporated with 2nd extract from soil 13. added to alcohol extract 10 C.C. + Nitre Solution. 14. Nitre added to alcohol extract milligrams.1.368 1.369 1 -370 1 *354 1 ' 4 7 1 '593 1.569 1 -263 1 '279 1 *297 1 *330 0 -166 0 -234 0 -037 2 D 358 WARINGTON ON THE DETERMINATION OF nitre was not evaporated with the original extract but added to the residue left on evaporating the alcohol extract any possible reduction of nitrates during the evaporation or loss during treatment with alcohol was thus avoided. I n several of the experiments a second extract from the soil was made use of. The results will be found in Table 111. The normal nitre solution employed contained in 10 C.C. 1.388 mgrms. of nitrogen. In the above results the whole of the gas obtained on shaking with mercury has been reckoned as nitric oxide; this however is not absolutely the case. When using the Crum-Frankland method in the presence of organic matter any gas produced before shaking with mercury cannot safely be removed from the tube as this gas may consist in great part of nitric oxide (Trans.Chem. Soc. 1879 383) ; indeed in some soil extracts rich in organic matter two-thirds of the whole gas has been evolved before shaking. That some gas other than nitric oxide was produced was proved on several occasions. Thus a soil extract precisely similar to that employed in Experiments 4 and 5 but without nitre when shaken with sulphuric acid yielded gas which would have been reckoned as 0.051 mgrm. of nitrogen. Of the large gas obtained in Experiment 6 0.257 mgrm. was found to be unabsorbed by ferrous chloride. There is no doubt therefore that the quantities of nitrogen calculated from the volumes of the gas are rather higher than those actually obtained.In the experiments in which 10 C.C. of normal nitre solution were added to the soil extract the nitrogen introduced was on the whole fairly recovered on analysis. The resulta are not nearly so good when we turn to the smaller quantities of nitre. In Experiment 13 about two-thirds of the nitrogen added is recovered on analysis and in Experiment 14 less than one quarter ; in both these experiments the reaction was pushed as far as possible the solutions being heated in the shaking tube and reshaken. In the earlier investigation of the Crum-Prankland method already referred to the same fact appeared ; a small quantity of nitric acid suffering a greater absolute loss from the presence of sugar than a large quantity.When applying the method to actual soil analysis the same truth is manifest an increase in the quantity of soil taken producing an increase in the percentage of nitric acid found when the soil is poor in nitrates. The Crum-Frankland method having proved only partially satis-factory trkls were made with the method recommended by Schloesing for the determination of nitrates in organic extracts namelr heating with ferrous chloride and hydrochloric acid and collection of the nitric oxide evolved. A general investigation of this method has been already published (Xrans. Chem. Soc. 1880 468) ; a description o NITRIC ACID IN SOILS. 359 1. Nitre only 2. ,) evaporated with 1st extract from soil 8. ) added to extmct after evaporation 4., only 5. evaporated with 1st extract from soil 6 . Diko ditto improvements recently adapted will be found in the present volume, pp. 345-350. The method has been found to yield excellent results in the presence of organic matter. With this method a few test-expe-riments with soil extracts have been made the same soil being used as in the preceding series. The extracts were used without purification with alcohol. The results will be found in Table IT. milligrams. 2.713 2 -699 2 -691 1 *325 1 *325 1 -376 TABLE IV.-Determhations of Nitric Acid by Schloesing’s Method. Nitre Solutions alone and nzixed with Soil Extracts. Nitrogen found 1 as nitric oxide. I The quantity of nitre solution employed in Experiments 4 to 6 was rather less than that used in the experiments quoted in Table 111.The results obtained are seen to be quite satisfactory the known quantity of nitrate added being fully recovered on analysis; the organic matter present in the soil extract is apparently with this method entirely without effect on the result. As the organic matter of soil has no influence when the analysig is made by Schloesing’s method while it lowers the result even after treatment with alcohol when the Crum-Frankland method is em-ployed it follows that the same soil analysed by these two methods will give somewhat higher results by the former than by the latter ; this has uniformly proved to be the case when duplicate determinations have been made. This fact will serve to explain the discrepant results found in Table I.We have apparently in Schloesing’s method a really satisfactory means of determining nitrates in soil. The soil extract requires in this case no preliminary purification but may be analysed as soon as concentrated. The method is equally capable of determining large or small quantities of nitric acid while the amount of nitric oxide produced is ascertained with the greatest precision by gas analysis. Full details respecting the conduct of this method will be found in the papers above referred to. The indigo method for determining nitric acid is quite unsuitable for soil analysis. I n an earlier communication (Trans. Chem. Soc. 1879 360 SAKURAT. ON METALLIC COMPOUNDS 588) some comparative determinations by the indigo and Crum-Prank-land methods were given ; I may here add a few comparative deter-minations by the indigo and Schloesing methods of the nitrates in an arable soil showing that the indigo method fails even in the analysis of the extract from a clay subsoil. The figures represent the nitrogen existing as nitrates per million of soil. Schloesing’s Indigo method. method. First 9 inches from surface 8.08 6-18 Second , 9 498 3.78 Third , 2-66 2.03 9 , The nitric acid shown by indigo is in the first 9 inches 64.1 per cent. in the second 9 inches 7.5.9 per cent. and in the third 9 inches 76.3 per cent. of the truth the result improving somewhat as the amount of organic matter diminishes

ISSN:0368-1645    

DOI:10.1039/CT8824100351

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

360 SAKURAT. ON METALLIC COMPOUNDS LV1.-COMMUNICATIONS FROM THE LABORATORY OF THE UNIVERSITY OF TOKIO JAPAN. Metallic Compounds containing Bivalent Hgdrocarbon Radicals. Part 111. By J. SAKUKAI F.C.S. WEEN monomercuric methylene iodide (see this Journal 1880 Trans., 658) and mercuric chloride were mixed together and the mixture was covered with alcohol a reaction took place after some time whereby another new organometallic compound of the class under considera-tion was formed. I n order to obtain this body quickly and in a state of purity the following plan was adopted :-Monomercuric methylene iodide was mixed with merciiric chloride in the proportion of 468 (= CH,HgI,) to 271 (= HgC1,) parts by weight niid both in a state of fine powder and the mixture was coho-bated with alcohol for an hour i n a flask fitted with an upright con-denser.On cooling the alcoholic solution deposited a coiisiderable quantity of a white shining crystalline substance. On addition of water to the contents of the flask a further deposition of the crystals took place together with mercuric iodide. They were washed witii water till free from mercuric chloride then digested with a stron CONTAINING BIVALENT HYDROCARBON RADICALS. 36 1 solution of potassic iodide in order to dissolve out the mercuric iodide, and finally washed with water till the washings showed no turbidity with nitrate of silver. The residue was dried first between blotting-paper and then over sulphuric acid. When dry it was digested with hot ether and the ethereal solution on spontaneous evaporation left behind a mass of substance beautifully crystallised in thin shining plates of silk-white colour and having a slight mercurial odonr, common to the organometallic compounds.The presence in it of mercury iodine and chlorine as well as of carbon was distinctly indicated by the ordinary methods. The compound is soluble in ether chloroform and alcohol but quite insoluble in water. It melts at 129" yielding on cooling a slightly yellowish mass which remelts a t the original temperature. Heated with a solution of iodine in potassic iodide it yields an oily liquid having a sweetish smell like that of chloroform. As in the analyses of the other organometallic bodies described in previous papers the Rmount of iodine needed for the decomposition of this compound was determined by a standard solution of soclic thiosulphnte and the mercury as sulphide.The results are recorded below :-I. Ir. Substance taken. . 0.152000 0.1 7400 Iodine taken 0.2 78500 0-30510 , left 0.176088 0.18582 , needed 0.102412 9.11928 Also mercuric sulphide . . - 0*10800 From these numbers it appears that the amount of iodine needed for the decomposition of 100 parts of the compound and the quantity of mercury therein contained are as follows :-I. Ir. Mean. Iodine needed 67.37 67.356 67.363 Mercury. . - 53.500 53.300 These numbers agree with those calculated for the formula CHZHgIC1 viz. :-Iodine needed 67.46 Mercury 33.12 From the mode of its preparation as well as from the analytical results there is no doubt that the new compound is monomerczwic methylene chloriodide and formed in the following way :-CHZHgI2 + HgC112 = CHZHgIC1 + HgTC1.Now since monomercuric methylene iodide was proved to hav 362 SAKCRAI ON METALLIC COMPOUNDS ETC. t'he formula I(Cl&)HgI a question naturally arises as to which of t'he iodine-atoms is replaced by chlorine in the new compound. This question was answered by the facts derived from the study of the reaction which the compound undergoes with iodine. If it is to be represented by the formula I(CH,)HgCl then iodine would decom-pose it into methylene iodide and mercuric chloride thus-ICH HgC1 I I 1 If on the other hand it has the constitution Cl(CHJHg1 then the action of iodine upon it would be to produce methylene chloriodide and mercuric iodide thus :-CICH HgI 1 I 1 The oily liquid before mentioned as the product of the action of iodine upon monomercuric methylene chloriodide was found, on purification to contain both iodine and chlorine.It boils at 129" and has a density of 2.49 at 20". A determination of iodine and chlorine in it was made with the following results :--556 gram of the liquid was decomposed by nitric acid and silver nitrate in a sealed tube; the resulting mixture of silver iodide and chloride weighed 1.202 grams. The whole of the silver was then reduced to the metallic state by nascent hydrogen dissolved in nitric acid and precipitated as chloride which weighed *921 gram. From these data the amounts of iodine and chlorine were calculated as follows :-Iodine.Chlorine. 70.15 21-30 On account of the number of operations which the analytical pro-cess involved and of the indirect ways in which the determinations had to be made a little discrepancy between the above figures and those calculated for methylene cliloriodide which follow may perhaps be overlooked without fear of serious error. Iodine. Chlorine. CHJC1 71.95 20-11 Methylene chloriodide has now I believe been obtained and de-scribed for the first time. Its physical properties are such as might be inferred from the close analogy between iodine and chlorine. Its boiling point for instance is very nearly the mean of the boiling points of methylene iodide and niethylene chloride :-Metbylene iodide 181" C. chloriodide 139 chloride 4 PERKIN ON THE COMBUSTION OF ETHER ETC. 363 Having established the fact that the above oily liquid is methylene chloriodide we now come to the conclusion that monomercuric methylene chloriodide has the latter of the two formulae previously mentioned viz. CI(CH,)HgI

ISSN:0368-1645    

DOI:10.1039/CT8824100360

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

PERKIN ON THE COMBUSTION OF ETHER ETC. 363 LVII.-Bonze Observations on the Luminous Imomplete Combustion of Ether and other Organic Bodies. By W. H. PERKIN F.R.S. WHEN evaporating ether in a shallow vessel 011 a somewhat strongly heated sand-bath it is always observed that vapours irritating to the eyes are formed. Some time since when coiiducting an operation of this kind in the evening when it was nearly dark a pale blue flame was seen floating about on the surface of the sand and yet not ignit-ing the ether which was being evaporated. The experiment was repeated several times and always with the same result This phenomenon which appears to have been almost lost sight of has been previously observed. It was first noticed by Sir Humphry Davy (Gmelin's Hundbook of Chemistry 8 179-180) who found that when a hot spirally wound platinum wire was introduced into a mixture of ether vapour and air it became red-hot and in a dark room a pale phosphorescent light was observed above the wire especially when it ceased to glow.Doebereiner noticed the same thing but states that the blue lambent flame ceased when the platinum became red-hot. He also remarks that when ether is dropped into a retort heated on the sand-bath to 100" and upwards or into A platinum capsule exposed to the vapour of boiling water Leidenfrost's phenomenon (the sphe-ro'idal state) is produced accompanied by a blue flame visible only in the dark and not capable of setting fire to other bodies tear-exciting vapours of lampic acid being formed. As will be seen further on the temperature of loo" mentioned by Doebereiner is insufficient to produce the blue flame.Boutigny in 1837 observed that this phenomenon took place equally in a metal or porcelain dish heated to R temperature a little below that of fusing lead or about 260" lampic acid being formed a t the same time. Miller also mentions that the glowing extremity of a glass rod or piece of porcelain held over ether, exhibits a small blue flame and forms a large quantity of acid. Although the foregoing facts are known it was thought that it would be interesting to make a few more experiments on this remark 364 PERKIN ON THE LUMINOUS INCOMPLETE able kind of combustion and to see if other bodies besides ether were capable of producing the same effect. The temperature a t which ether begins to burn with this blue flame is about 260° and any temperature between that and a dull red heat may be used.The higher the temperature however the morelikely is ordinary combustion to set in. There are several ways by which this phenomenon may be produced on a sufficiently large scale to exhibit a t lectures. The most simple way is to project ether from a wash-bottle on to a thick iron plate heated nearly to dull redness ; but it is better to use a thick iron dish heated over a Bunsen burner and after the gas has been turned off or the lamp so screened that no light escapes into the room to make the jet of ether play on various parts of the surface; in this way a con-siderable mass of blue flame may be obtained. The best way of showing this flame however is to take a copper or iron ball about 2 or 3 inches in diameter provided with an eye so that it may be suspended from a wire heat it t o dull redness and as soon as i t has cooled so as to be nearly invisible in the dark place it over a dish about 4 inches in diameter containing several filter-papers well drenched with ether.As the ball approaches the ether a beautiful blue flame will form passing over its heated surface upwards for several inches. The ball may be let right down into the ether without causing ordinary combustion. This peculiar combustion of ether may also be shown in a glass tube. A large tube is taken about 4 cm. in diameter GO or 70 cm. long bent a t right angles about 15 cm. from the end this is fixed, with the bend downwards in a clamp and some ether poured into it, but not sufficient to prevent a free current of air from passing through the tube.On heating tbe longer arm of the tube with a Bunsen burner a draught is instituted and when the walls of the tube are suficiently heated a blue light will be seen on putting out the lamp. If the tube be now shaken to increage the volatilisation of the ether a blue flame will fill the arm of the tube and issue out into the air. It then often enters into ordinary combustion at the opening and the peculiar effect of the combustion of ether in two manners may be seen at tnhe same time; the blue flame inside the tube is however much masked by the luminosity of that outside. The experiment soon after-wards comes to an end by the ordinary name passing down to the ether when it is necessary to close the tube to extinguish it.This blue flame from ether has a comparatively low temperature. The fingers may be placed in it with impunity. It will not char paper or ignite carbon disulphide and a lncifer match held in it at first becomes only phosphorescent and is some time before it is ignited. Ether Fapour burning with this blue flame when in large qnantities COMBUSTION OF ETHER ETC. 365 or more especially when in a confined space rapidly increases in tem-perature and quickly enters into ordinary combustion. As it appeared from some small experiments that this kind of com-bustion was attended with the production of but small quantities of carbonic anhydride a quantitative experiment was made to settle this point.The arrangement was as follows :-A Woulff’s bottle containing ether was provided with a tube opening under the liquid so that when air was aspirated through it it would be saturated with the ether vapour. This was connected by ordinary quill-tubing with a piece of combus-tion-tube about 20 cm. long laid in a thick metal trough and heated with a Bunsen burner. Connected with this by means of a tube bent a t right angles was a large test-tube cooled in a freezing mixture of ice and salt to condense ether and other products. To this was attached a Liebig’s bulb full of concentrated sulphuric acid to absorb any uncondensed vapour of ether and other bodies and then a weighed potash apparatus for the absorption of carbonic anhydride. Lastly, this was connected with an aspirator of known capacity.On drawing air through the ether the blue flame formed in the heated piece of combustion-tube and travelled backwards and forwards but never passed from it. After the operation had gone on until several litres of air had been aspirated it was stopped the potash-bulbs weighed and the gas in the aspirator measured and analysed (it was nearly pure nitrogen). In this way it was found that the amount of oxygen consumed amourited to 1.313 gram and the carbonic anhydride produced to only 0.133. The liquid condensed in the test-tube in the freezing mixture was fractioned and found to consist chiefly of aldehyde and ether a small quant.ity of an oil boiling above looo and apparently crotonic alde-hyde was also present.On making experiments with other bodies it has been found that the luminous appearance accompanying incomplete combustion is not peculiar to ether though so far as observations have been made it appears to be the best example we have. Acetic aldehyde is the next best and gives a very beautiful blue flame when the vapour passes over a heated copper ball. The alcohols up to amylic give but traces of blue flame methylic alcohol giving iione. The following results were obtained with the hydrides :-Pentane gave a trace of flame ; hexane a considerably better result ; heptane a still greater improve-ment ; and this increase was found to go on up to solid paraffin which, when thrown on a heated surface or fused on a hot metallic ball, gives a good blue flame.Benzene and its homologues give no result ; neither do phenol and cresol 366 PERKIN ON THE COMBUSTION OF ETHER ETC. With the fatty acids no result is obtained with the two lower mem-bers of the series but it begins with propionic acid which gives a very small effect. Butyric acid acts however somewhat better. Stearic acid when heated becomes luminous at about 250° and this increases gradually in intensity ; with the temperature at 290" blue flames appear and when heated somewhat higher the vrtpour enters into ordinary combustion. Oleic acid behaves in the same way as stearic becoming quite visibly luminous at 2.50-260" ; blue flames form at 310" after which it soon catches fire. Benzoic cinnamic and phthalic acids give no result. Olive and linseed oils and white wax behave like oleic acid when heat,ed.Spermaceti shows this effect very well and is a very suitable sub-stance for its exhibition a t a lectnre. It may be shown in two wa.ys : first by throwing pieces on ft strongly heated iron plate ; these form luminous patches as they melt ; but by far the best way is to bring it in contact with the upper side of a strongly heated metallic ball suspended by a wire; then a's it melts and flows over the ball it produces it beautiful effect the vapour evolved being also luminous. Spermaceti, when heated in a dish becomes luminous and this effect increases with the temperature ; a t 300" pale-blue flames flicker over its surface, and at about 360" it ignites. On cooling the luminosity gradually decreases and it is difficult to find the point a t which it perfectly fades away but it may be seen even as low as 130".This is true of all the other bodies which have been tried in this manner. It was thought of interest to see to what extent carbonic anhydride was given off from some of these bodies of high molecular weight when in a luminous state. Some solid paraffin was therefore taken for this purpose. It was heated in a retort up to about 160-170", air being drawn throng11 it ; the products were freed from water and organic matter by passing t.hrough sulphuric acid and then passed through potash to absorb t'he carbonic anhydride the amount of air passed being calculated from that in the aspirator which was analysed. The experiment showed that 0,3816 gram of oxygen had been used, and only 0.025 of CO formed a resnlt similar to that which was obtained i n tlie case of ether. We thus see that with the paraffins fatty acids and probably alcohols, their power of producing this phenomenon increases with their mole-cular weight and that bodies of tlie aromatic series do not possess this power. The blue flames and the luminous appearance which result from imperfect combustion are no doubt similar to ordinary phosphoi-escence produced during the imperfect combustion of phosphorus the only dif HUMMEL AND PERKIN ON SOME NEW COMPOUNDS ETC. 367 ference being that while these various substances require to be heated, phosphorus shows this phenomenon at ordinary temperatures. The physical properties of the blue flame produced by different substances seem to be the same. The light is too feeble to examine in detail with the spectroscope; but no bands are seen

ISSN:0368-1645    

DOI:10.1039/CT8824100363

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

HUMMEL AND PERKIN ON SOME NEW COMPOUNDS ETC. 367 LVII1.-CONTRIBUTIONS FROM THE DYE-HOUSE OF THE YORKSHIBE COLLEGE. On some New Compounds of Hcematein and Brazilein. By J. J. HUMMEL and A. G. PERKIN. WHILE engaged in the preparation of specimens of the colouring prin-ciples of logwood we devised a very simple method for obtaining hEematein in the crystalline state in tolerable quantity which induced us to investigate some of the reactions of this colouring matter. In order to prepare pure crystalline haemate'in commercial logwood extract is dissolved in a small quantity of hot water and after cooling, ammonia is added in slight excess to the syrupy solution. The solu-tion of the ammonia-compound of hsmatoxylin thus formed is then exposed to the air for two or three days with occasional stirring in order to convert it into the corresponding compound of btffmate'in ; or this change is effected more rapidly by the aspiration of air through the solution for several hours.A dark purplish precipitate of the ammonia-compound of haemstein is gradually deposited. This is col-lected on a filter and well pressed. About 40 grams of this precipitate are now dissolved in a litre of hot water and from 30-160 C.C. of strong acetic acid (sp. gr 1.04) added. After heating the mixture for some time on the steam-bath (in order to dissolve as much as possible of the amorphous hEmatei'n precipitate which has been formed) it is cooled completely and filtered. The amorphous htffmate'in residue ou the filter may be treated with hot dilute acetic acid in a similar manner three or four times and the con1 bined fil tmtes evaporated over the steam-bath.A s the solution becomes concentrated minute glittering crystals of hEema te'in appear." In order to separate these from the accompanying impurities the * Crystals are also readily obtained when the filtrate from the haemate'in-ammonia compound is precipitated with excess of acetic acid the solution atered and evaporated 368 HUMMEL AND PERKIN ON SOME NEW COMPOUNDS liquid is allowed to cool and mixed with a little acetic acid which retains these foreign matters in solution but leaves the haematein crystals for the most part undissolved. The latter are collected on a filter washed three or four times with acetic acid then with water, and dried. Thus prepared haemate'in has the form of exceedingly minute crystals having a spIendid pale yellowish-green metallic lustre.When viewed under the microscope they appear by transmitted light as very thin reddish-brown rhombic plates forming occasionally stellate groups. Rubbed with a glass rod they yield a reddish-brown powder. Haemate'in is very sparingly soluble in water alcohol ether, and acetic acid. Alkalis dissolve i t readily ; ammonia dissolves it with a rich brown-violet colour ; while its strong alkaline soda solution has a rich purplish-blue colour. On exposure to the air the colour of these alkaline solutions gradually becomes red and finally brown the colouring matter being apparently destroyed. It is worthy of notice that when a very dilute solution of sodium hydrate is added to haematei'n the latter dissolves with a bright red colour and only when excess of sodium hydrate is added does the colour become purplish-blue.Analyses of crystalline hemateiln gave the following numbers :-0.1270 gram gave 0.3002 gram of CO and 0.0478 gram of OH,. 0.1210 , 0.2838 , GO and 0.0466 , OH,. 0.1128 , 0,2635 , GOz and 0.0419 , OH,. These numbers give percentages agreeing with the formula C16HI206. Carbon . . . . 64.00 64-47 63.94 63.71 Hydrogen . . 4.00 4-18 4.28 4.12 Theory. I. 11. 111. The haemate'in crystals a,s obtained in the above manner are anhydrous and evidently identical with those described by Halber-stadt and Reis (Ber. 14 Sll) who obtained them by extracting aged Campeachy logwood with ether but were unable to obtain them from commercial logwood extracts.Action of Sulphuric Acid on Hmmatein. Accoi-ding to Baeyer (Ber. 4 457-.555) haemateh is probably a member of the group of bodies termed phthale'ins and possibly stands in a close relationship to galle'in. Since this latter body when heated for some time with concentrated sulphuric acid to 200° yields a new green colouring matter termed coeruZei'n it seemed possible that by treating haemate'in in the sam OF HBXATEIN AND BRAZILEIN. 369 way a similar product might be formed ; but experiment proves that under these conditions the hmmate'in is more or less completely de-stroyed and yields no new colouring matter. Hmmatejin however, dissolves readily in cold concentrated sulphuric acid with evolution of heat producing a dark reddish-brown solution which when left at rest for some time becomes filled with lustrous yellow prismatic crystals.When this solution is poured into cold water it gives a reddish-brown precipitate which resembles ferric oxide and seems hitherto to have been mistaken for unchanged amorphous haemate'in (see GmeZin's Org. Chem. 10 293). After washing free from acid, however it is found to dissolve in sodium hydrate solution with a redd ish-purple colour whereas hmmate'in as already stated gives a purplish- blue solution. It also dyes mordanted calico in shades quite different from those yielded by hmmate'iu viz. with alumina mor-dants if weak it gives a dull red ; if strong red inclining to choco-late ; and with weak iron a slate. It is evident therefore that a new body is produced.By adding hot glacial acetic acid very gradually and with constant stirring to the sulphuric acid solution of hmmate'in until it is diluted to the extent of two or three times its bulk there is gradually thrown down an orange-coloured crystalline precipitate. It is collected on a filter washed with glacial acetic acid until free from sulphuric acid, and dried. The product thus obtained forms an orange-coloured crystalline powder which under the microscope is seen to consist of minute transparent prisms. On analysis it gave the following numbers :-0.1120 gram of substance gave 0.2073 gram C02 and 0.0331 gram 0.1153 gram of substance gave 0.2120 gram CO and 0.0341 gram 0.2325 gram of substance gave 0.1477 gram of BaS04.OH,. OH,. These numbers give percentages agreeing with Theory. I. 11. Sulphur . . . . 8.42 - -Carbon . . . . 50.53 50.47 50.12 Hydrogen 3.16 3.28 3.29 The formation of this body which we propose to hcematei'n sulphate may be represented t,hus :-the formula 111. -8.72 call acid iso 370 HUMMEL AND PERKIN ON SOME NEW COMPOUNDS I t is insoluble or nearly so in alcohol ether and benzene but in strong acetic acid it dissolves to a small extent forming a yellow solu-tion. It is little soluble in cold ammonia solution but on heating it dissolves with a dirty claret colour. Its sodium hydrate solution has a reddish-purple colour. Both solutions become brown on exposure to air very much more rapidly indeed than the corresponding solutions of hmnate'in.When acid isohemate'in sulphate is washed with alcohol its colour becomes redder and the filtrate is found to contain a considerable quantity of sulphuric acid. With water it becomes darker than with alwhol but the same separation of sulphuric acid takes place. In order to examine fhis reaction the following preparations were made :-(1.) A portion of acid isohematein sulphate was treated with alcohol then with water again with alcohol and then ether and dried. (2.) A second quantity of this substance was treated with water, washed until no more sulphuric acid passed through and dried. (3.) A third quantity was placed in contact with ordinary alcohol (about 80 per cent.) and left to stand for some days. In the course of a few hours the yellow product became covered with dark-coloured patches which were found to consist of crystals, and after two or three days the whole producf was found to be con-verted into these crystals which by reflected light have a beautiful metallic lustre and when seen by transmitted light appear as plates having a dark orange-red colour.This colour is heightened by polarised light. Analyses of these preparations gave the following numbers :-Preparati0.n 1.-0*1109 gram of substance gave 0.2382 gram GO, 0.1092 gram of substance gave 0,2357 gram GO and 0.0333 gram P?*eparutimz 11.-0-1137 gram of substance gave 0.2469 gram of Prepuration II1.-0.1059 gram of substance gave 052282 gram CO, and 0.0339 gram OH,. OHZ. CO and 0.0325 gram of OH2. and 0.0358 gram OH2. 0.1009 gram of OHp These numbers substance gave 0.2167 gram COz and 0.0340 gram agree moderately well with the formula OF HBMATEIN AND BRAZILEIN.37 1 Prep. I. Prep. 11. Prep. 111. r-E"- 1 I-- 7 Carbon . . 58.77 58.5Fi 58.85 39.22 58.63 58-57 Hydrogen . 3.67 3.38 3.38 3.17 3.75 3-74 Prom the ready manner in which acid isofiiaemate'in sulphate gives up part of its sulphur as sulphuric acid it is evident that it is not an ordinary sulphonic acid but has more the character of an acid sul-phuric ether. The remarkable fact however is that with water i t gives up only two-thirds of its sulphur yielding the above peculiar body. On boiling it with magnesium carbonate a large quantity of mngne-sium sulphate is formed together with a crystalline magnesium deriva-tive which when freshly prepared is seen to have a metallic lustre.This compound however is still found to contain a small quantity of sulphur. After removal of the magnesia by an acid the product dyes mordants simiIarly to the original sulphuric product but the colours are much duller. Theory. I. 11. I. 11. It is proposed to examine this product further. Action of Eydi-ochloi-ic Acid on Hmtituteh. When hzemate'in is heated in sealed tubes with hydrochloric acid (sp. gr. -1195) for some time to loo" the rich crimson colour of the solution gradually changes to a dirty yellow and the mixture is found to contain minute crystals. As soon as the reaction is considered terminated which is after several hours' heating the tubes are opened and the contents evaporated to dryness in a dish over the steam-bath.The product which consists of a dark almost black crystalline powder showing an olive-green metallic lustre when viewed under the microscope may be purified by heating it with water slightly acidu-lated with hydrochloric acid in which it easily dissolves and filtering. On adding hydrochloric acid to the rich orange-coloured filtrate an orange precipitate is obtained and if the whole be now boiled so as to redissolve the product there is deposited on cooling a red powder, which appears under the microscope to consist of minute transparent orange-red needles. This substance was found to contain chlorine. On analysis the following numbers were obtained :-0.1239 gram of substance gave 0.2729 gram of C02 and 0.0402 gram 0.1277 gram of substance gave 0.2808 gram of CO, and 0.0411 gram 0.2169 gram of substance gave 0.0873 gram of AgCl.0.2053 gram of substance gave 0.08.56 gram of AgCl. VOL. XI". 2 F: OH,. OH, 372 HUMMEL AND PERKIN ON SOME NEW COMPOUXDS These numbers give percentages agreeing with the formula C,H110,Cl. Theory. I. 11. 111. IT. Carbon . . . . 60.28 60.07 59-96 - -Hydrogen . . 3.45 3-60 3.57 - -Chlorine. . . . 11.15 - - 10.59 10.82 The formation of this body may be expressed thus :-C16H12O6 + HCZ = CI~~H,~O~CL + OHp This was found to take place almost quantitatively as will be seen 0.2904 gram of hamatein heated with concentrated hydrochloric acid, from the following experiment :-increased in weight 5.74 per cent. Theory requires 6.13. We propose to call this substance Isohcernatein Chlorhydrin.It dissolves easily in water forming an orange-coloured solution which is rather strongly acid owing to the separation of hydrochloyic acid and if repeatedly evaporated and redissolved loses most of its chlorine It is less soluble in alcohol than in water. Wit.h alcoholic potash it gives a reddish-violet solution which soon changes and becomes slaty and afterwards of a blackish-brown colour the intensity quickly diminishing. With concentrated sulphuric acid it evolves hydrochloric acid gas, and is converted into acid isohaemate’in sulphate. It dyes mordants in a similar manner t o the sulphuric compound but much more freely, and the shades are rather brighter in tone. Action of Hydrobromic Acid on Hcematean. When haematein is heated in sealed tubes with strong hydrobromic acid the coyresponding isolzcematein monobromhydrin is produced.The product consists of a dark mass of microscopic needles. On analysis it gave the following result :-0.2572 gram of substance gave 0.1274 gram of AgBr. The percentage from this agrees closely with that required by the formula C16H1,06Br. Theory. I. Bromine . . . . 22.03 21 60 The reaction may be expressed thus :-ClsHl& + HBr = C16HI1o5Br + OH2. Isohamatein bronihydrin dissolves in alkalis with a violet colollr OF HEEMATEIN AND BRAZILEIN. 373 and altogether in its general properties resembles the chlorine com-pound. IsohmmteTn. If to an aqueous solution of isohcenzateitz chlorhydri~~ or Bronzhydrin enough argentic hydrate be added to remove the chlorine the dark orange solution becomes somewhat less bright and darker in colour.This solution when concentrated on the water-bath and then evapo-rated to dryness over sulphuric acid leaves isolzceinatein as an amor-phous mass with a green metallic lustre. This product has not yet been obtained perfect'ly pure and quite free from chlorine but on analysis it gives numbers indicating that it has the same composition as hEmatein. The formation of this body may be expressed thus :-C16HllC105 + AgHO = C,,H,,Os + AgCl. It is however an isomeride of that body and differs from it con-siderably in its properties as the following comparison will show :-Solution of caustic alkali . . . . . . , sodium carbonate . . Ammonia . . . . . . . .. . . . . . . . . . Ammonium sulphide . . . . . . . . Solution of lead acetate . . . . . . IIaemate'in. --Blue-violet colour. Redd ish-p urple colo ur. Bright red-purple. Nearly decolorised but quickly becoming pur-ple when placed on bibulous paper and exposed to the air. Blue violet precipitate. Isohaemate'in. --Red-violet oolour. Purple. Dull red-purple. A red-purple precipi-tate. Red-purple precipitate. Isohamate'in dyes mordants much in the same way though not so It freely as isohaematein chlorhydrin and not a t all like haematein. is also more soluble in water than that colouring matter. Crystalline brazile'in is obtained from commercial Brazilwood ex-tracts by a method exactly similar to that employed for the prodnctioii of crystalline haematein only that it is necessary after treating the extract with ammonia to expose the solution to the air for a greater length of time the oxidation in this case taking place more slowly.Obtained in this manner brazile'in has the form of very minute dark crystals having a grey metallic lustre and forming when rubbed a, brown-red powder. Under the microscope they appear as thiii reddish-brown rhomhic plates sometimes grouped logether in th 374 HUMMEL AND PERKIN ON SOME NEW COMPOUNDS form of rosettes but for the most part they are detached and lens-shaped with the points of the lens cut off obliquely. It is very slightly soluble in cold water but more so in hot the solution having a pale yellowish-pink colour with a distinct greenish-orange fluorescence ; alkalis dissolve it forming rich carmine-red solu-tions which although much more stable than t,he corresponding com-pounds of hamatein gradually become brown when exposed to the air.There is but little difference in the d o u r of the ammonia and sodium hydrate solutions of brazilein. Dried at 130" it gave on analysis the following numbers :-0.1071 gram of substance gave 0,2644 gram GO2 and 0.0408 gram 0.1024 gram of substance gave 0.2531 gram GO2 and 0.0390 grain OH,. OH,. These numbers give percentages agreeing with the formula Theory. 1. I I. Carbon 67.60 67.30 67.46 Hydrogen. . 4.22 4.22 4% But dried at 100" these crystals were found to contain one molecule of water which is given off at from 130" to 140". 0.1137 gram at 100" became 0.1071 gram at 130".0.1090 , 100" , 0.1054 at 130". Theory. 1. 11. 3-96 3-97 6.O-5 Analysis of samples dried at 100" gave the following numbers:-0.1193 gram of substance gave 0.2790 gram GO, and 0.0485 gram 0.1386 gram of substance gave 0.3231 gram CO,. These numbers give percentages agreeing with the formula OH,. Ci,HnOa,OHz-Theory. I. II. Hydrogen. . 4.63 4.51 - Carbon 63.57 63-78 63.57 Action of Xulphuric Acid on Brazileijz. Brazilein grs dually dissolves in cold concentrated sulphuric acid, forming a dark orange-coloured solution which when dilute has OF HBMATEIS AND BRAZILEIN. 375 very marked olive-green fluorescence. On long standing the solution becomes filled with lustrous yellow rhombic needles. I f the solution be poured into water a bright orange-coloured amorphous precipitate is thrown down which represents a new body.By adding t o the sulphuric acid solution hot glacial acetic acid in small quantities at a time and with constant stirring the new product is gradually thrown down in the form of minute crystals. These are thrown on a filter thoroughly washed with glacial acetic acid and dried. Thus obtained it consists of a n orange-coloured crystalline mass, seen under the microscope to consist of transparent flat needles. On analysis the following numbers were obiained :-0.1191 gram of substance gave 0.2297 gram CO, and 0,0364 gram 0.1055 gram of substance gave 0.2037 gram C02 and 0.0325 gram 0.1102 gram of substance gave 0.2111 gram CO, and 0.0534 gram OH,. OH,. OH,. These numbers give percentages agreeing with the formula Theory.I. 11. 111. Carbon . . . . 32.74 52.59 52-68 52-24 Hydrogen . . . . . . 3.29 3.39 3.42 3.36 The formation of this body may be expressed thus :-This acid isobrazilei'n sulphate as we propose t o name it is only slightly soluble in boiling glacial acetic acid but very solu-ble in alkalis. Its ammonia solution has a rich carmine colour, almost identical with that of the corresponding solution of brazilein. Its soda solution is somewhat bluer in tint. Both solutions rapidly become brown when exposed to the air very much more rapidly than the alkaline solutions of brazilei'n. On treatment with alcohol these crystals become bright scarlet in colour and on filtering the filtrate is found t o contain sulphuric acid in considerable quantity.Under the microscope the product now appears as brilliant red needles. On analysis this body gave the following numbers :-It is slightly soluble in water alcohol and acetic acid 376 HUMMEL AND PERKIN ON SOME KEW COMPOUXDY 0.1158 gram of substance gave 02436 gram of CO, arid 0.0400 0.0712 gram of substance gave 0.1478 gram of CO, and 0.023'3 0,1433 gram of substance gave 0.2970 gram of (20 and 0.0452 gram of OH,. gram of OH,. gram of OH,. These results give numbers corresponding with the formula C16H1205 2( c 16Hllg } s 0 4 ) . Theory. I. 11. 111. Hydrogen 3.55 3.83 3.73 3.50 Carbon 56.90 57.13 56.61 56.50 The sulphuric derivatives of brazilein dye mordants differently from brazile'in itself and yield colours somewhat like those of garancin.Action of Hydrochloric Acid o n Brazileiu. Brazile'in digested in sealed tubes with concentrated hydrochloric acid at 100" behaves in a very similar manner to haematein. The reaction however takes place much more slowly. The solution which at first has a bright scarlet colour gradually changes to a dirty yellow, and crystals separate out. As soon as the reaction has terminated which is generally after eight or ten hours' heating the whole is evaporated to dryness over the steam-bath. The product consists of a very dark brown crystal-line mass having a violet lustre. Under the microscope it exhibits the form of small prisms having the colour of potassium bichromate by transmitted light. On analysis it gave the following numbers :-0.1436 gram of substance gave 0.3335 gram of CO and 0.0473 0.1179 gram of substance gave 0.2725 gram of C0 and 0,0387 These numbers give percentages agreeing with the formula gram of OH,.gram of OH,. CdLO4C1. Theory. I. 11. 63.03 Carbon 63.13 63.28 The formation of this subsfance may be expressed thus :-Hydrogen. . 3-66 3.65 3.64 C16HyZ05 + HC1 = C1GHI104Cl + OH, OF HEMATEIN AND BRAZILEIS. 377 Isobrazilein chlorh ydmh as we have named this body dissolves readily in water forming an orange-coloured solution which is acid to litmus-paper and contains free hydrochloric acid. Its alkaline solii-. tions have a slight greenish fluorescence. Action of Hydrobroniic Acid o n Brazilein. On adding fuming hydrobromic acid in excess to brazile'in it itis-solves to a small extent and a t tbe same time changes the undissoIvecl portion to a beautiful carmine.On heating the mixture in a sealed tube to 100" this substance mostly dissolves forming a red solution, which gradually changes into an orange-yellow coloured liquid. After heating for five or six hours the undissolved portions of the product are seen to consist of crystals. On cooling. most of the product sepa-rates out as crystaiq which when seen under the microscope appear as flat oblique prisms their colour by transmitted light being like that of potassium bichromate b u t darker. On analysis the following numbers were obtained :-0.1576 gram of substance gave 0.3190 gram of C02 and 0.0460 0.1613 gram of substance gave 0.3260 gram of C02 and 0.0498 gram of OHz.gram of OH2. These numbers give percentages agreeing with the formula C16HlI04Br. Theory. I. 11. Carbon 55-33 55.2 54.9 Hydrogen 3.17 3.23 3.40 The formation of this body which we have named Isobmzi7&'7?, bromhydrin may be expressed thus :-C16H1205 + HBr = Cl6HllO4Br + OH?. When ground logwood is boiled for some time with dilute sulphuric or hydrochloric acid and then well washed it dyes mordants in R similar manner to the hemate'in derivatives. This is probably owing to the formation of an analogous haematoxylin derivative which osidises during the process of dyeing. Brazilwood also behaves in a similar matter when trea8ted with acids. Other acids besides those mentioned namely oxalic tartaric &c., yield evidently analogous compounds.Nitric acid too appears to give a similar compound but it is diEcult to control the reaction. Heated t80 120" with phthalic anhydride for some time hematei'n yields also new colouring matter 378 HUMMEL AXD PERRIN ON SOME NEW COMPOUNDS ETC. Further experiments on the action of these various substances on haematein are in progress. The tinctorial power of the new compounds is much greater than that of the original haemate'in and brazile'in and a very noteworthy point is that the colours are much faster withstanding the action of a boiling soap-solution and a weak solution of bleaching powder tolerably well especially those derived from the brazilein. During the dyeing process the whites are considerably soiled and this in most cases is probably due to the liberation of the acids from the compounds when in contact with water the liberated acid causing the mordant to dissolve and then attach itself to the un-rnordanted portions of the cloth.The new haemate'in compounds give on cotton mordanted with alumina a dull red inclining to chocolate with strong iron a black, with weak iron a slate arid with mixed alumina and iron mordant a full chocolate. The sulphuric derivatives of €mematein however produce shades with alumina mordants somewhat redder than the ot'her products. Soaping renders all the colours produced by these compounds rather bluer in tone. The brazileiin derivatives with the same mordants give shades resembling those of the haematein compounds. They possess how-ever a much more lively red tint and in fact remind one of the corre-sponding garancine shades.The foregoing resnlts show how very similarly hamatein and brazile'in behave towards reagents and confirm the views of Lieber-mann respecting their relationship ( B e y . 9 1883). The ease wit8h which they exchange one and only one hydroxyl for chlorine or bromine when treated with the corresponding haloid acids and the rea,diness with which the resulting products give up these elements again when treated with water or bases is remarkable and points out that this hydroxyl is not phenolic but most probably alcoholic. The fact that these bodies when giving up their chlorine (ir bromine on treatment with silver oxide or other bases do not regenerate haema-tein or brazilein but yield substances isomeric with them shows either that some change takes place in the molecule itself or else that it becomes polymerised.The fact that the products are more soluble in water than either hEmatein or brazilci'n is perhaps rather against this latter view but in the case of the sulphuric derivatives polymeri-sation is believed to take place. As already stated these substances appear to be somewhat analogous to the acid sulphuric ethers and in fact they are decomposed by water with separation of sulphuric acid, even more readily than these bodies ; but this decomposition is onl THOMSON AND POPPLEWELL ON THE CRYSTALLISATION ETC. 379 partial and results in the formation of products which cannot be repre-sented as derived from less than 3 mols. of the original colouring matter. It is therefore inferred that acid isohaemate'in sulphate should be represented not by the formula and the analogous brazilein compound as products are moreover difficultly soluble in most fluids? which also points to the same fact. Although it has been up to the present found impossible to produce from haemate'in a body similar to the coerulejin obtained from galle'in, it does not prove that haematein does not belong to the class of phthale'ins. On the contrary our experiments appear rather to confirm this view of Bneyer as among the phthale'ins there are several which are already known to form somewhat peculiar com-pounds with sulphuric and hydrochloric acids e.g. fluoresceiii and phthale'in-orcin (Ber. 7 1213 -1214) quinol-phthale'in (Ber. 11, 71.5) and homofluoresce'in (Ber. 13 547). The formation instability and composition of these compounds apparently show that they are analogous to the acid-compounds of hsernatein and brazile'in described in this paper

ISSN:0368-1645    

DOI:10.1039/CT8824100367

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

THOMSON AND POPPLEWELL ON THE CRYSTALLISATION ETC. 379 LIX.-On the Crystallisation from Supersaturated Solutiom of certain Cornpound Xalts. By JOHN M. THONSON and W. POPPLEWELL BLOXAM ; King’s College, London. IN a paper published in the Chemical Society’s Journal May 1879 on “ The Action of Isomorphous Salts in producing the Crystallisation of Supersaturated Saline Solutions,’’ I pointed out that if a mixture of dimorphous salts be taken a separation of the salts may be effected within certain limits by touching the solution with a crystal of one or other of the salts this separation being limited by and depending on the relative solubilit.ies of the different salts contained in the solution. The subject of the present paper is a continuation of these observa-tions employing in this case supersaturated solutions of double salts, VOL.XLT. 2 6 380 THOMSON AND POPPLEWELL ON THE CRYSTALLISATION where it was possible to obtain such and acting on them with nuclei consisting of one or other of the component salts in order to find whether any disruption of the compound has taken place by the action of the nucleus. The method of carrying out the experiments was exactly the same as that employed before and fully described in my first paper the nucleus being added to the solution to be experimented on by one of two methods (1) the nucleus being obtained by crys-tallisation from a supersaturated solution and in this condition retained in the syphon-tube in the neck of the flask till required for use or (2) the nucleus being added directly from its mother-liquor in a bulb-tube suspended in a similar manner in the neck of the flask.In all these experiments as before the substances were purified with the greatest care and the admission of part.icles from the externa.1 air most carefully guarded against. The first group of salts experimented with consisted of certain of the double chlorides bromides and iodides of mercury with the COT-responding salts of the alkali-metals. The results obtained with these bodies are detailed in the following table :-Substance in solution. > 9 HgBrz(NHaC1),,3H,0 . . 9 9 Hg12 ( KI) 99 HgC12(NH4Cl)~,3H,O . . HgBr2(NH4Br),,:{H2O . 7, Nucleus added. HgCl (prismatic) HgC1 (deposited from hot solution) NH4Cl. . HgBr (depositedin thecold) HgBr2 (deposited from hot (NH4)Br.. solution) HgL (needle-shaped crys-KI tals) HgBr,(NH4Br)z,3H,0 HgC1 (prismatic). . NHhCl Result. Active. Both active and Inactive. Active. Both active and Inactive. Active. Inactive. Active . Active. Inactive. inactive. inactive. It is very difficult to obtain many double salts of the halogen acids in a state of supersaturation and the field for experiment with them is therefore limited. I n the cases described above however there are several points to be noticed. With these double salts the salt of the heavy metal invariably caused the cr.ystallisation of the double salt FROM SUPERSATURATED SOLUTIONS ETC. 381 whereas the constituent containing the alkali-metal had no action.It was however impossible to determine whether the salt causing crys-tallisation did so by first inducing the deposition of the salt a,nalogous to itself in the solution. Experiments me being carried out to endeavour if possible to determine the primary action which takes place ; it is, however a somewhat difficult one to examine. It may also be observed that when the mercuric chloride orbromide existed in the nucleus in its true prismatic form crystallisation at once took place but that when its deposition from its solution took placeat a higher temperature the results were various. On examining this point I find that the crystalline forms of the mercuric chloride and bromide change when so deposited which may readily account for the alternation in those cases.The crystalline form also of the double salt is more nearly allied to the form of the heavy metallic salt than to the constituent containing the alkali-metal. Finding that a double salt consisting of mercuric cyanide with ammoniam chloride ( HgCy2,NH,C1) existed forming a good super-saturated solution I made experiments in order to compare it with the double salts before mentioned ; when the following results were obtained :-Substance in solution. Nucleus added. ResuIt. HgCy2,NH,Cl HgCy2 Active. NH4C1 Active. Y, In this case there is a distinct difference from the halogen salts employed in the first-mentioned experiments both components pro-ducing the crystallisation of the double salt. It seems probable therefore that the double salts formed from these monobasic acids although they form good supersaturated solutions, are not so firmly united together as to withstand the disturbing in-fluence of certain of their constituents ; but that the disruption pro-duced by them is not sufficient to cause the decomposition of hhe body, and consequently the double salt is deposited.In the case last men-tioned also of the double cyanide and chloride both salts are deposited as the final result of the crystallisation. In experimenting with mercuric iodide this substance was intro-duced by means of a pipette-sha.ped tube and the iodide strongly steamed by boiling the flask before it was allowed to cool. The next double salt examined was ordinary potash-alum AlK( S04)2,12H20, as this salt undergoes supersaturation with very great ease and may be taken as a good instance of a fhoroughly well defined double salt from a bibasic acid.The following results were obtained : 382 THOMSON AND POPPLEWELL ON THE CRYSTALLISATION Substance in solution. Substance added. Result. A1K(SOaj2~12H2,O . . A1,3(SO4),18H20 Inactive. 9 . . . . &SO4 . . . . Inactive. showing thaf neither of the constituents from which the double alum is originally derived has any action upon its supersaturated solution. This is the more interesting when it may be remembered that the late Dr. Graham held the view that potash-alum might be split up into its constituenh by the process of dialysis. The alum solution used in my experiments was saturated a t 90" C. Other Observations OIL Supersaturated Alum Solutions.-In connec-tion with the main object of the examination of these solutions certain other experiments were made which yielded results of sufficient interest to warrant their being mentioned.Cold saturated solutions of potas-sium and aluminium sulphates a t a temperature of 15" C. were mixed together when it was observed that considerable rise in temperature took place amounting generally with the mass of substance used to about 15". At the same t>ime a deposition of crystals took place which on exarniuation were found to be alum corresponding to the composition AIK( S0&12H20. These experiments were repeated many times the result always being the same. Some very curious peculiarities were observed with an alum aolntioii saturated at 95" a temperature slightly higher than that at which the ordinary solutions were prepared.This solution was stoppered with cotton-wool in the ordinary way and set aside to cool. When it had attained a temperature nearly that of the surrounding air small opaque cryshls began to form in the liquid and crysfallisation gradually proceeded without however the production of he&-currents in the liquid which is so marked an accompaniment of the more rapid crystallisation from a supersaturaied solution. In about four hours the whole contents of the fiask except a thin layer a t the bottom, were apparently perfectly solid and the fiask quiiie cold On touching the solid however with a glass rod and finally stirring the pasty contents of the flask a great evolution of heat took place equal to that observed in the ordinary crystallisation of a supersaturafed solu-tion of aluui.The formationof the crystals in this case was extremely peculiar and appeared to be accompanied by some contraction causing the mass to creep away from the sides of the flask which contraction might possibly account for the non-evolution of any large quantity of heat during solidification. As the same phenomenon was observed with this solution over and over again on its cooling I determined to examine the crystals de-posited by suddenly breaking the flask and washing its solid contents with ice-cold water. This was accordingly done and the crystallin FROM SUPERSATURATED SOLUTIONS ETC. 353 mass after air-drjjing yielded on analysis numbers very closely corre-sponding with ordinary alum.An examination of the crystalline form of the body deposited showed however that the aggregation of the crystals was quite diEerent from the formation deposited from a proper supwsaturated solution the crystals being small and arvanged in tree-like forms like ammonium chloride. I t is difficult however to examine them accurately as on touching or moving they are converted into the usual octohedra of alum From these last-mentioned ex-periments it would appear that above say go" the limit of supersatu-ration for alum is passed. There is also some indication of a, dimorphous form of alum existing. Another fact with regard to this alum-solution may be mentioned viz. that after it had solidified on immersing the cold flask in boiling water to remelt the salt it was observed ; first that the water continued to boil and secondly that the contents of the flask underwent reliquefaction after about ten minutes' immersion ; whereas in ordinary cases the solution of the same quantity of deposited alum is very gradual and would take about sixty minutes.I was anxious to compare the alum experiments with the double sulphates formed from protoxides of the same group siich as the double sulphates of iron and zinc with potassium sulphate of the general formula M"Kz(S04)z6H,0 but it was found that these sul-phates have no tendency to undergo supersaturation-at least to an extent sufficient for our experiments. I next prepared a supersaturated alum solution by dissolving equi-valent quantities of A1,(SO4),l8Aq and K,S04 in a quantity of water exactly corresponding with that which would have been necessary for the solution had crystallised alum been used instead of the consti-tuents separately.It was found however that with the two salts taken separately in the manner described the quantity of water was not sufficient for their entire solution and had to be increased by an amount corresponding with nearly one-half of the original quantity taken before perfect solubility could be obtained. With this solution, however i t was found that neither crystals of A12(SOI)3,18Hz0 nor K2S04 were a t all active; but the moment it was touched with A1K(S04),,12H20 the liquid became filled with crystals of alum. Being unable to obtain good supersaturated solutions of the double sulphates represented by the general formuh M"Rz( S04)26Hz0 and M"M"&( SO4>,l2H2O which have been described by Vohl (Annulen, 95) I determined to try some experiments with a double sulphate of zinc and copper known as Lefort's salt the composition of which, according to that author is Zn3Cu(S04),H20 and which will undergo recrystallisation without decomposition.Quantities of this salt were dissolved in rather less than half thei 384 THOMSON AND POPPLEWELL ON THE CRYSTALLISATION weight of water zinc sulphate (ZnS04,7H20) and copper sulphate (CuS04,5H20) being employed as the nuclei. In these cases both the constituents were active in causing crystal-lisation that from the zinc sulphate nucleus being more rapid than that from the copper sulphate nucleus.An examination of the crystals deposited showed that they were crystals of the double salt and their deposition presented some very peculiar phenomena. When the zinc sulphate was employed the crystals of the double salt are formed first in long shaped needles closely resembling those of ZnS04,7H20 ; this form is retained till the crystallisation is very nearly at an end but shortly afterwards the crystals gradually begin to change and break up into truncated needles exactly similar to Lefort’s salt. In the case of the copper sulphate nucleus the deposition of the salt was slower and the crystals though not doubly oblique like CuS04,5H20 were truncated needles and never came down in long needles as in the first mentioned case. The deposit here was also found to be the double salt.From these experiments it will be seen that the nucleus in certain cases exercises a determining influence on the crystals of the body deposited in a manner similar to some other cases mentioned in my first paper. This I think may be due at least in the case of the zinc sulphate to the nucleus of that salt beginning the action by sepamting first ZnS04,7H20 crystals ; but the forms of both the constituents being to a certain extent similar it gradually induces the crystallisation of the copper salt as well and the double salt is deposited. Some curious pbenomena were to be observed in the deposition of t9he crystals from these solutions when the nucleus became detached from the introducing tube and fell to the bottop of the flask.In such catses when the nucleus was moved along the bottom of the flask by slightly inclining it crystallisation was observed to take place first along the line upon which the nucleus had travelled and it was some little time before crystallisation extended in other directions through-out showing that crystalline activity had been induced directly by the nucleus. Experiments with iMicrocosmic Salt Na(NHJ HPO4’4Aq. The experiments on solutions of this body were made in the same way as on the other substances the nuclei being added both with the syphon-tube and with the bulb-tube. Substance in solution. Nucleus added. Result. NaNH4HP04,4H20 . . Na,HP04,12H20 . . Inactive. 7 . . (NH4)2HPO,. . . . . . 7 79 Na4P,O . . . . . . . . 2 9 . . (NH4)H2P04 . .. - 7 FROM SUPERSATURATED SOLUTIONS ETC. 385 I t was found extremely difficult to obtain the ammonium phosphates free from sodium many weeks being taken up in preparing good samples. They were filially obtained by neutralising perfectly pure phosphoric acid by ammonium carbonate. There are also several points with regard to the composition of the ammonium phosphates, which require further investigation. In the case of microcosmic salt on attempting t o form it from cold saturated solutions of the disodic and diammonic phosphates the same result was observed as in the case of alum the solution when brought in contact undergoing a considerable rise in temperature and crystals of microcosmic salt being deposited. The rise in temperature in these cases was less than in the alum experiments being generally an increase of from 10" t o 12".In connection with these double phosphate experiments others were made with the double arsenate of sodium and ammonium with the following results :-Substance in solution. Nucleus a,dded. Result. NaNH4HAa04.4H20 . . Na,HAs04,12H20. . Inactive. 9 . . (NH~)ZHASO~,A~~ . ,9 Ili these cases both constituents were inactive to the double salt as in the case of the alum and the phosphates. Actiow qf the Constituents on Swpersnturated Solutions of Double Tar-trates and Citrates. It is not easy to find double salts of organic acids which will undergo supersaturation without passing i iito a gummy consistency which precludes experiment. The substances however which we have been able to employ are the double tartrate of sodium and potas-sium or Rochelle salt (KNaH4C40s,4Aq) ; the double potassium and sodium citrate K,Na3(H5C607)2 ; and the double magnesium and sodium citrate MgNaH,CeO,.The methods of adding the nuclei were similar to those employed in the other cases as the constituents undergo supersaturation with great readiness. With Rochelle salt the following results were obtained :-RNrtH,C4O&Aq . . K2H4C406 . . Inactive. 9 NaZH4ClO6 - Active. The sodium tartrate was specially made and perfectly purified. In all these cases crystallisation from the sodium tartrate took place but never from the potassium tartrate. It now became important to examine if possible the composition of the crystals which were gradually deposited from the nucleus.For this purpose experiment 386 THOMSON AND POPPLEWELL ON THE CRYSTXLLISATION ETC. were carefully performed in flasks containing the Rochelle salt to which the nuclei of neutral sodium tartrate were added by means of the syphon-tubes. The crystals gradually and slowly formed from the point of the syphon-tube and were allowed to grow till a considerable cluster had formed and a great part of the salt had been thus removed from the solution in the flask. The deposit adhering to the syphon-tube was withdrawn from the mother-liquor removed from the flask, washed with ice-cold water pressed between blotting-paper air-dried, and analysed. On analysis the deposit gave numbers closely agreeing with the composition of Rochelle salt. Now it is to be observed that the crystals forming the deposit here in no wise resemble those of Rochelle salt but closely resemble those of sodium tartrate giving us evidence of the probable dimorphism of Rochelle salt.We have also to note that if the crystals formed by the nucleus of sodium tartrate are allowed to grow till the contents of flask are nearly solid and then rinsed from the mother-liquor this mass being then stirred a sudden and considerable amount of heat is evolved as in the case of the alum solution.before mentioned After stirring the mass and examining the crystals by the microscope they present the appearance of ordinary Rochelle salt. At present it is difficult to see why the sodium tartrate should be active and the potassium salt inactive but i t may be remarked that the solubility of the sodium salt is less than that of the potassium salt which may perhaps account for its activity.A corresponding result has been observed with the citrate of potassium and sodium in which the sodium citrate has always proved active whilst the potas-sium salt is inactive. Here also the solubility of the potassium salt is greater than that of t'he corresponding sodium salt. In the case however of the double magnesium and sodium citrates, the results were different both of the constituent salts proving inactive to the double salt. From these experiments it will be seen that the double salts of monobasic acids apparently suffer disruption more easily than the salts from acids of higher basicity like sulpburic and phosphoric acids ; but that in the case of the first of these two latter acids salts may exist, like Lefort's salt which is acted upon by the constituents.It will be observed however that such salts indicate more of molecular than of atomic grouping in their constitution whereas in the true alum and double phosphate we have a firmer union of the salts. This is also I think to be observed in the salt's from the organic acids. By it)s mode of formation and its composition the double sodium and potassium citrate appears more like a molecular grouping of the constituent salts and both constituents are capable of causing disruption whereas in Rochelle salt and the magnesio-sodi MO RLEY ON OXTPROPYLTOLUIDISE. 387 citrate there is evidence of a closer binding of the component salts. In the case of Rochelle salt only one constituent produces disruption, and in the-case of the magnesio-sodic citrate neither constituent has any action. It is to be hoped that further experiments carried out on these solutions may assist in the examination of the condition of such salts when in a state of solution. I am a t present engaged on certain experiments with regard to the amount of heat evolved in the crystallisation of these compound salts and compring the numbers obtained in the different groups of salts. These experiments take much time to carry out but I hope soon to be in a position to lay the results before the Society

ISSN:0368-1645    

DOI:10.1039/CT8824100379

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

MO RLEY ON OXTPROPYLTOLUIDISE. 387 LX. - On Ozyprop y 1 to1 uidine. By H. FORSTER MORLEY M.A. Fellow of University College. PROPYLENE oxide dissolves an equivalent quantity of paratoluidine, producing a fall of some 15" in temperature. The solution was heated in a water-bath for four hours and the viscid liquid thus formed was submitted to distillation ; i t contained no propylene oxide, and only a drop or two of toluidine but the thermometer rose rapidly to 380" remained constant for some time at 285-288" and finally reached the boiling point of mercury before the liquid had all passed over. The portion boiling above 360" contains no doubt dioxypropylene-t oluidine. The chief portion (285-296") solidified after some time and was analysed after recrystallisation from a small quantity of benzene.11. -256 gram gave 17.7 C.C. N a t 11" C. bar. press. 782 at 13". I. *a68 gram substance gave 0.7166 gram Cot and 2243 gram H,O. Whence Calculat,ed for oxy propy ltoli tidine. Found. C 72-73 7292 H . . . . . . 9-09 9-30 N 8.48 8-39 VOL. XLT. 2 388 MORLEY ON OXYPROPYLTOLUIDINE. The numbers agree therefore with the formula-N( C&O) (GH7) H, and the reaction may be represented by the equation-NHz.CyH7 + CsHGO = NHC7H,(CaHGOH). A better yield is obtained by avoiding the use of heat and simply allowing the solution of toluidine in propylene oxide to stand for some days at the ordinary temperature. The limpid liquid then becomes gradually viscid and at length the new base crystallises out. It may be separated from the mother-liquor by filtration and pressure and recrystallised from light petroleum oil when it is obtained in the form of slender needles.In this way 20 grams of the base were obtained from 46 grams of toluidine. A third method consists in converting the bases into oxalates and separating them by cry stallisation from water. The oxalate of the new base is very soluble ; that of toluidine is as is well known nearly insoluble while other oxalates present have in-termediate solubility. Oxypropyltoluidine melts at 74" and boils with slight decomposition at 293" (corr.) ; it has not much tendency to become coloured when exposed to air ; it is insoluble in water but soluble in benzene ether, alcohol and petroleum. I have not been able t o obtain its chloride sulphate chloroplatinate, or chloroaurate in crystalline form.If the base be dissolved in aqueous osalic acid and the solution con-centrated by evaporation crystals of the oxdate are formed ; these may be recrystallised from water or spirit when they form pearly plates melting at 151". The analysis of these crystals gave the following result :-I. *2686 gram was decomposed by CaCl and the calcic oxalate 11. ,2495 gram gave as combustion -5176 GO and -1558 gram H,O. converted into lime by ignition -059 gram CaO. Calculated for ~l,Hl,N 0 H2C204. Found. C 56-47 56.58 H 6.67 6-94 HZCZOI 35.29 35.2 hIORLEY ON OXPPROPPLTOLCIDISE. 389 The compound is therefore the acid oxalate of oxypropyltoluidine, and it appears to be the only one capable of existing €or if excess of base (2 mols.) be dissolved in spirit and mixed with an alcoholic solu-tion of oxalic acid (1 mol.) the acid oxalate crystallises out first and afterwards the free base separates in needles.It is to be observed that the neutral oxalate of p-toluidine is not known. When the oxalate is heated to 150" it melts and then gives off water carbonic oxide and carbonic acid and leaves a non-crystal-lisable syrup which is only partly basic (solnble in aqueous oxalic acid) ; the insoluble part begins to boil at about 270". I had hoped to find among the products of this reaction a base of the formula CloHI3N formed from oxypropyltoluidine by dehydration, and possibly belonging to the quinoline series but I have not succeeded in isolating such a base.I will take this opportunity of dewribing the-Distillation of 0x~~r~~y.Etri.nzethyZammonizcm Hydrate. This base which I have described elsewhere (this Journal 38, 877) resembles ordinary neurine in its behaviour when heated ; it first froths up giving off trimethylamine then propylene-glycol and other liquids come over and finally carbonic acid is evolved. The products were passed first into a cold tube then through dilute hydric chloride next through lime-water and finally into bromine (which did not however absorb any olefine). The platinum salt of trimethylamine obtained from the hydric chloride solution was ignited. -3544 gram contained ,1314 gram platinum. Theory. Found. Pt 37.38 3 7.08 The chief portion of the liquid distillate is propylene-glycol recog-nised by its boiling point sweet taste and miscibility with water, alcohol and ether. It is formed by the equation-N(C&LOH) (CH,),OH = N(C&)3 + CJL(OH), 390 MORLEY ON OXYPROPPLTOLUIDINE. The propylene-glycol is however mixed with small quantities of volatile bases produced by secondary reactions but of which I have not obtained sufficient for identification

ISSN:0368-1645    

DOI:10.1039/CT8824100387

出版商:RSC    

年代:1882

数据来源: RSC

摘要:

391 LXI.-O~L gome Hulogen Compounds of Acetylene. By -R. T. PLIMPTON Ph.D. RERTHELOT has shown that acetylene unites with the halogen elements, forming compounds of the formuh C,H2X2 and C2H2X4. Of such derivatives the di- and tetra-chlorides and bromides and a di-iodide are known ; also an iodide C2H2L obtained by the action of iodine upon silver acetylide. The present paper contains a few additional observations upon some of the above and on the preparation and properties of the remaining tli-derivatives i.e. the chlorobromide chloriodide and bromiodide. The acetylene needed for the following experiments was obtained by burning coal-gas in the apparatus described by Jungfleisch (BUZZ. SOC. Chim. 31 482) passing the products through ammoniacal cuprous chloride solution and decomposing the precipitate with hydrochloric acid in the usual way.Acetylene Bromides. By the actioii of bromine on acetylene Berthelot obtained a di-bromide boiling a t 130° and a tetrabromide. Under ordinary condi-tions however when the gas is passed through bromine the products are as shown by Reboul (Cowpt. r e d . 54 1229) and Sabanejeff ( A n n u l e n 178 112) the tetrabromide and a small quantity of zt solid body C2HBr3 crystallising in laminae and melting at 174". I obtained the same results. By treating the tetrabromide mixed with its own volume of alcohol, with zinc powder as recommended by Sabanejeff (Bey. 9 1441) a, considerable quantity of dibromide was prepared. It boiled a t 110-ill" and did not solidify a t -17'. Its specific gravity a t 0" was 2.268.The results of some experiments upon the action of tertiary amincs on this bromide have already been communicated (Trans. 1881, 536). Acetylene Iodides. The di-iodide was prepared by passing acetylene over iodine moistened with alcohol (Sabanejeff Awnden 1'78 109). The absorp-tion is very slow. On removing the iodine a semi-fluid mass was obtained which when crystallised from alcohol yielded long elashic needles of the di-iodide melting a t 73". This body is remarkably VOL. x u . 2 392 PLINPTON ON SOME stable and may be distilled without decomposition. Roiling point 192" (corr.). On distilling the alcoholic mother-liquor a further por-tion of the solid iodide volatilised together with some iodoform and the residue when precipitated with water yielded a small quantity of the liquid isomeric iodide described by Sabanejeff.It solidified readily in ice. Acetylene Ch loriodide. Acetylene chloriodide C2H,ClI may be prepared in bhe same way as the corresponding ethylene compound obtained by Maxwell Simpson (Proc. Boy. SOC. 11 590; 12 278) but the absorption of acetylene by a solution of iodine monochloride in hydrochloric acid is by no means rapid and must be aided by continual shaking. The solution of iodine chloride was prepared by passing chlorine over iodine nntil liquefaction had taken place dissolving t,he product in four or fire times its volume of hydrochloric acid and treating the resulting brown solution with chlorine until it no lcnger lost colonr. The absorption-bottles were shaken up vigorously during the passage of the acetylene and as soon as some quantity of the chloriodide had been formed the absorption became tolerably complete.The crude chloriodide was washed dried and distilled. Between 117-120" about two-thirds of the liquid passed over; the thermometer then began to rise and separation of iodine began. The residue could not be distilled without decomposition even under greatly diminished pressure ; neither was it possible to separate anything by means of a freezing mixture On distilling a t the ordinary pressure much iodine was liberated the thermometer rising gradually from 120" to 170". Towards the end of the distillation some fumes of hydriodic acid were noticed and a small quantity of carbonaceous matter remained.The iodine was removed with thiosulphate and the liquid was redistilled. By repeatting this treatment a further considerable quantity of chloriodide was obtained only a few drops of a higher boiling liquid remaining. Possibly the compound C2H2C113 is formed and on distilling breaks up into C2€12ClI and I2. The chloriodide was obtained as a heavy liquid becoming pink on exposure to light with an odour like that of ethylene bromide. It boils a t 119" (thermometer in vapour). Specific gravity at 0" = 2.2298. Analysis gave the following results :-0.4237 gram chloriodide yielded 0.8517 gram AgI + AgCl. Loss Correspond- of Keight on treatment with chlorine 0.2062 gram. ing to HALOGES COMPOUX'DS OF ACETYLEXE. 393 Calculat.ed Found. for C,H@. I 67.57 67-37 C1 18.83 18.82 ((311) .86.28 86.2 Treated with alcoholic potash acetylene chloriodide yields a gas Bromine displaces the iodine yielding acetylene chlorobromide and which precipitates ammoniacal cuprous chloride. other products. Acetylene Chloro byonaide. When acetylene is passed through an aqueous solution of bromine chloride an oil separates which begins to boil a t about 130" when some bromine is set free and the temperature rises quickly to 230° a t which point most of the liquid distils over. Compounds containing more than two halogen-atoms are formed and this is also the case when dilute solutions are employed. As the chlorobromide was not to be obtained by direct combina-tion experiments were made with acetylene dibromide which was heated with several metallic chlorides but with a negative result.Henry (Bey. 3 598) has prepared ethylene chlorobromide by treating the chloriodide with bromine (3-4 mole.) and this method was found t o answer in case of the acetylene compound ; only as the product is here unsaturated bye-products are formed by addition of bromide and iodine. On adding bromine (2 mols.) drop by drop to acetylene chloriodide under water the mixture becomes dark and much heat is evolved. If sodium thiosulphate is then added until the iodine which at first precipitates has redissolved and the liquid is dried and distilled pure chlorobromide passes over from 80-85". To obtain complete decomposition of the chloriodide it is necessary to employ the bromine in the proportion of at least 2 mols.to 1 of chloriodide. The product of the reaction contains besides the chlcro-bromide at least two other bodies richer in halogens. One of these begins t o decompose with separation of iodine and bromine as soon as the thermometer reaches 90". Efforts to isolate this substance by cooling the liquid in a freezing mixture were unsuccessful nothing separating out and distillation with steam also failed to eflect the purpose. It is possibly the compound C2H2C1Br21 for it decom-poses on dist,illation giving off iodine arid bromine and yielding a further quantity of chlorobromide C2H2C1Br. The other addition-product distils over above 200" and is a heavy oily liquid smelling like acetylene tetrabromide ; it is a chlorobromide perha,ps C2H2C1Rr,. The formation of these bye-products of course greatly diminishes the 2 H 394 PLIMPTON ON SOJIE yield of chlorobromide.I n one experiment 20 grams of chloriodidc were treated with 18 grams of bromine and the mixture after cooling, was left at rest for an hour. After removina the halogens with thio-sulphate the product weighed 25 grams. On distilling some chloro-bromide was separsted between 80-go" and the tliermometer then rose gradually to 190° when the separation of iodine and bromine ceased. The distillate 90-190° was then twice redistilled and treated with thiosulphate ; it yielded on fractionation a further quantity of chlorobromide making tfhe total amount obtained 5 grams. Analysis gave the following results :-I. 0.4278 gram substance decomposed with nitric acid and silver 11.0.3497 gram gave 0.8236 gram silver salts. Loss of weight Loss of weight,, nitrate yielded 1.0016 gram mixed silver salts. after treatment with chlorine 0.1097. 0.1101. 111. 0.3539 gram gave 0.8318 gram silver salts. Corresponding to Calcuht ed I. IT. 111. for C2H2C1Br. (ClBr) 81.57 82.04 81.8 81.62 Br - 56.39 55-92 56-53 c1. . - 25.47 25.63 25.09 Acetylene chlorobromide is a volatile liquid with a pleasant ethereal odour boiling at 81-82'. It is isomeric with the chlorobromethyleiie obtained by Hugo Miiller (this Journal 1864 [ii] 420) by the act'ion of potassium cyanide on chlorethylcne bromide and also by Denzel (Liebig's AnnaZeiL 195, 206) who treated the same compound C2H3C1Br2 with alcoholic potash. The compound obtained by these chemists differs greatly from acetylene chlorobromide; it boils a t 62" has an excessively pungent odour aad polymerises with great ease.Its constitutional formula has been proved to be CH2 - CClBr. The body de-scribed above must therefore possess the symmetric constitution CHCI-CHBr as indeed might be expected from its mode of forma-tion and boiling point. Warmed with alcoholic soda acetylene chlorobromide gives off a gas which explodes spontaneously doubtless chloracetylene. Sp. gr. at 0" = 1.8157. Acetylene Bromiodiide. This compound is formed together with other products on passing The solution was prepared by treating iodine with bromine mixed acetylene through an aqueous solution of bromine iodide HALOGEN COMPOUNDS OF ACETYLEXE. 395 with four or five times its volume of water warming the mixture leav-ing it a t rest and pouring off from the excess of iodine.On passing acetylene through this solution it was found that to obtain absorp-tion the bottles must be shaken continuously. As no convenient mechanical arrangement was a t hand for the purpose another plan was adopted. Several large bottles were fitted with stopcocks some solution was placed in each the air exhausted and acetylene allowed to take its place. From time to time the bottles were shaken and coiinected with a supply of acetylene. The black oil which separated was freed from iodine and bromine by washing it with thiosulphate solution. On distilling it decom-posed with sepai-stion of iodine ; the same took place on exposure to light.Distillation in a current of steam however caused only a slight decomposition the liquid becoming claret-coloured and a por-tion of i t passing over with the greatest ease. There remained in the retort a reddish oil which refused to volatilise. Towards the end of the distillation a small quantity of a crystalline substance came over, having the odour and properties of acetylene iodide. The distilhte was freed from iodine and fractionally distilled. After four distillations i t yielded the following chief fractions 110-115" consisting of acetylene dibromide 145-150" acetylene bromiodide, and a few drops 160-190" which solidified in ice and contained free iodine and hjdriodic acid. The fraction 145-150" dist.illed chiefly between 147-148". Analysis gave the following results :-0.3045 gram substance decomposed with nitric acid and silver Loss of weight nitrate yielded 0-5537 gram mixed silver salts.on treating with bromine vapour 0.0619 gram. Calculated Found. for C2H2BrI. (I&) . . . . . . . . . . . 88-97 88.8 I . . 54.91 58.050 Br 34.12 34.33 Acetylene bromiodide is a heavy colourless liquid which becomes red on exposure to light. Its specific gravity a t 0" (when solid) is 2.750 and at 17.5" 2.6272. It boils without decomposition a t 150" (corr.) and solidifies at about + 8". Heated with alcoholic soda it gives off it gas having the properties of bromacet ylene. The oily liquid which remained after distilling off the bromiodide and other products in a currelit of steam became claret-red on stand-ing; it refused to solidify or deposit anything a t - 12".On distilla-tion it decomposed with separation of iodine and bromine leaving some carbonaceous matter and the distillate was found to consist of acetylene dibromide which is easily volatile with steam and therefor 396 PLINPTON ON SOME could not have existed as such in the original liquid. Analysis of the original liquid gave iodine 36 per cent. bromine 56 per cent. or about two equivalents of iodine to five of bromine. These numbers approach those required for the formula C2H2Br31 which requires iodine 3 2 3 per cent. bromine 61 per cent. The decomposition noticed makes it probable that the liquid in question consists mainly of a bromiodide of this formula. The following table contains the boiling points and specific gravities of the halogen-derivatives of acetylene described in this paper and of the isomeric substituted ethylenes ; on the opposite side are the corre-sponding ethylene and ethylidene compounds.It will be seen that the boiling points of the mixed halogen-compounds of acetylene in each case lie midway between those of the corresponding simple derivatives. This being also true of the ethylene-compoixnds (Henry) one may ca,lculate the boiling point of ethylene iodide as 19T" which differs from that of acetylene iodide by 5". Taking the middle column of differences of boiling point corresponding to H? and regarding only the symmetric compounds the differences augment as the molecular weights diminish from five in the case of iodides to thirty in that of the chlorides. This does not appear to be the case with the dissymmetric compounds. As would be expected the specific gravities of the acetylene derivatives are slightly greater than those of the corresponding ethylene derivatives. The experiments described in this paper were made in the laboratory of University College London TABLE. Diff. Formula. C&J2 C2€I& (?) -C2H2BrI C2H2BrI C2H,ClI C2HZClI CPH2Br2 C2H2 Br2 CzHpBrCl C2H,BrCl CzH2Cl C2H2Cl sp. Gr. --3 *303 at 21" 2-9/12 , 21" 2-75 , 0' -2'23 at 0" -2 -268 at 0" -1 '815'7 at 0" ---B. P. 19P --150" -119" -110" 91" 81-2" 62" 55" 37O Di5. ---12 -22 -21 19 26 23 30 21 B. P. dec. 179-80" 163" 142" 141' 118" 131" 1 loo 103" 85" 8 5" 5 8" --In each pair ~f isQmerides the eymmetzic compound i

ISSN:0368-1645    

DOI:10.1039/CT8824100391

出版商:RSC    

年代:1882

数据来源: RSC