摘要:

ABSORPTION SPECTRA AND CHEMICAL CONSTI!MJTION. 571LIX.- The Relation between Absorption Spectra andChemical Constitution. Part XIV. The AromaticNitro-compounds and the Quinonoid Theory.By EDWARD CHARLES CYRIL BALY, WILLIAM BRADSHAW TUCK, andEFFIE GWENDOLINE MARSDEN.IT has been shown (Trans., 1905, 87, 1332) that the introductionof the nitro-group into the benzene nucleus produces a very markedeffect on the absorption spectrum, for, whereas the parent hydro-carbon shows a, number of closely situated absorption bands, nitro-benzene is characterised by a very strongly marked generalabsorption with only a very shallow band.* The view was putforward that this change is due to the fact that the strongresidual affinity of the nitro-group restrains the vibrations of thebenzene ring.I f , now, a second group be introduced, and thisgroup be of the so-called positive type, that is to say, one withdirecting influence to the ortho- and par&positions, the tendencyof the nitro-group to restrain the benzene ring vibrations is moreor less eliminated.* The presence of this shallow band has only recently been detected with a largespectrograph in the case of an alcoholic solution. Nitrobenzene in petroleum soh-tion does not show the band572 BALY, TUCK, AND MARSDEN: THE RELATION BETWEENWe have now examined a number of aromatic compounds derivedfrom nitrobenzene, and we find that these substances all showmore or less pronounced absorption bands, the depth and positionFIG. 1.Oscillation f requencies.26 28300032 34 36 38 4000 42full curve N/lOOOm-Nitrotoluene ( E,ltiye N/looofull curve N/lOOOp-Nitrotoluene{ dotted ,) NJ10,OOOo-Nitrotoluene{ dotted ,) lV/lO,OOO Upper curvesMiddle ,,Lower ,,,, N/lO,OOOof which depend on the character of the substituent group orgroups.The simplest cases are those of the three nitrotoluenes, wherethe second group is the not very strongly marked electropositivemethyl.The absorption curves of the ortho-, meta-, and para-isomerides are shown in Fig. 1 (full curves), and they all threABSORPTION SPECTRA AND CHEMICAL CONSTITUTION. 573show well-marked absorption bands. The differences between theabsorption as shown by the full and dotted curves will be discussedbelow under the section dealing with the effect of the solvent.TheFIG. 2.Upper Curves.Full curve a-Nitronaphthnlenc i'iL nlcohob.Dotted curve * 9 , , light petrolema.Dot and dash curve Y 9 ,, benzene.Oscillation frepucncies.26 28 3000 32 34 36 38 4000 42Lower Curves.Full curve B-Nitronaphthalene in alcohol.Dotted curve Y S , , light petrokmm.two mononitronaphthalenes also show well-marked absorption bands,as can be seen on reference to the full curves in Fig. 2. Thea-compound shows one band, whilst the /3-isomeride has three. W574 BALY, TUCK, AND MARSDEN: THE RELATION BETWEENhave also examined the absorption of the two mononitro-o-xylenes,the curves being shown in Fig. 3. Here again well-marked bandsare exhibited. It is noticeable in a, comparison of 4-nitro-o-xylenewith the nitrotoluenes that the former compound possesses a muchdeeper band than the latter. Clearly, therefore, the two methylgroups in the former substance exert a greater counteractinginfluence against t'he restraint of the nitro-group than the singlemethyl group in the nitrotoluenes.A t the same time, the relativeposition of the nitro-group and the methyl groups has a considerableFIG. 3.Oscillution frequencies.26 28 3000 32 34 36 38 4000 42Full curve 4-Nitro-o-xylene in alcohol.Dotted curve 1 ) ,) light petroleum.Dot and dash curve 3-Nitro-o-xyZene ,, abohol.2 Dots and dash curve Nitrmnesitylene ,, ,,bearing on their mutual influence. Thus, in the nitrotoluenes theortho-isomeride shows an absorption which is the shallowest andfarthest from the red, whilst the band of the para-isomeride is thedeepest and nearest the red. The small band given by 3-nitro-o-xylene is therefore attributable to the fact that the two methylgroups and the nitro-group are adjacent to one another. This isstill more strikingly exemplified in the case of nitromesitylene,which shows no band at all.This follows readily from the factthat the three methyl groups are all in the meta-positions witABSORPTION SPECTRA AND CHEMICAL CONSTITUTION. 575respect to one another; as has been previously shown, mesityleneexhibits very small absorption owing to this fact, and thereforethe three methyl groups will not be able to overcome the restraintof the nitro-group, because they of themselves also tend to restrainthe vibrations of the ring.I n the case of the two nitronaphthalenes the restraining influenceof the nitro-group on the one ring is eliminated by the second ring,with the result that very well-marked absorption bands are producedwhich are nearer the red than tliose of naphthalene itself.I n bothF ~ G . 4.O&ZZation f repueitcies.26 28 300032 34 36 38 4000 42Full cuwe 3 : 5-Dinitro-o-xylene.Dotted curve 3 : 4- Dinitro-o-xylcne.Dot and dash curve 4 : 5-Dinah-o-xyleiie.these compounds, especially in the a-isomeride, the absorption bandsare sufficiently near to the red for the substances t o be visiblycoloured.If two nitro-groups are substituted in one benzene ring, then ofcourse the influence of the positive groups must be greater inorder to produce a counteracting effect equal to that in a mono-nitro-compound.This is well shown in the case of the twodinitro-o-xylenes (Fig. 4), of which the 3 : 4-dinitro-isomeride showsa very shallow band, whilst in the 4 : 5-dinitro-isomeride th576 BALY, TUCK, AND MARSDEN: THE RELATION BETWEENabsorption band has just disappeared. Still more pronounced it?this the case in trinitro-compounds, for both the 3 : 4: 5- and the3 : 4 : 6-trinitro-o-xylenes (Fig. 5) show only general absorptionwithout even the attempt t.0 show the band evidenced by the4 : 5-dinitro-coqpound.The definite conclusion can therefore be drawn that if therestraining influence of t,he nitro-group in nitrobenzene is counter-acted by the introduction of one or more so-called positive groups,FIG. 5.Oscillation frequencies.E 26 28 300032 34 36 3a.4000 42Full curveDotted curveDot and dash curve2 Dots and dash curve3 : 4 : 5- Trir&-o-o-xyZene.3 : 4 : 6-Trinitro-o-xy2ene.A cetani Zide.Methylacetanilide.isorropesis is set up, and one or more absorption bands are produced.Further, the position and persistence of this absorption are deter-mined by the amount that the restraining influence of the nitro-group is eliminated as a result of the introduction of the positivegroups, and also by the position of the absorption band of thenon-nitra ted compound.As a further test, the spectra of mono- and di-nitrofluorene wereexamined.The first of these (I) is practically colourless, havingonly a slight cream colour, while the dinitro-compound (11) iABSORPTION SPECTRA AND CHEMICAL CONSTITUTION.577strongly yellow. These two compounds afford a rigid test of theabove conclusion, for the mononitro-compound should show aFIG. 6.Oscil latiox frequencies.26 20 300032 34 36 30 400042Full curve hTitroJEuoreize.Dotted ciirve Dinitrojhorene.strong absorption band, whilst the dinitro-compound should showvery little or no evidence of a band, since both phenyl groups havetheir motions restrained by a nitro-group. The curves are shown inFig. 6, and, as can be seen, the results are exactly as was predicted.We have also examined the absorption spectra of nitrobenzenesubstituted by other groups than methyl, as, for example, thenitrocinnamic ethyl esters.Their absorption curves are shown inFig. 7, and here tEere is a deep absorption band a t lLh=3350 inthe para-isomeride. The meta-compound shows a band at1 / A = 3850, and a step-out at 1 / A = 3200, whilst the ortho-isomerid578 BALY, TUCK? AND MARSDEN: THE RELATION RETWEENonly shows a step-out at l / h = 3 2 0 0 . There is also here a pro-gressive effect of the *CH:CH*CO,Et group from the ortho- to thepara-position as in the nitrotoluenes.FIG. 7.Upper Curves.Full curve 0- Nitrociwnamic ester.Dotted curve m-Nitrocinnamic ester.2 Dots and dash curve p-NitrocinnaaLie ester.OsciZZation frequencieg.Lower curves.Full curveDotted curveo-Cbumaric acid in alcohol.o-Coumnric acid in alcoholic NaOEt.I f now the substituent group be very strongly positive, it isevident from what, has gone before that the absorption band willtend to be nearer the red, for it must be remembered that, t,hABSORPTION SPECTRA AND CHEMICAL CONSTITUTION. 579absorption band of benzene substituted by a strong positive group,such as OMe or OEt, is generally more persistent and nearer thered than that of the xylenes or toluene.This is very strikinglyobserved in the case of nitroquinol dimethyl ether, the absorptionof which in alcoholic solution is shown in Fig. 8. The head ofthe absorption band is now at l/h=2800, which is distinctlynearer the red than the compounds previously described. TheFIG. 8.Upper Curves.Full curve Nitropino2 dimethyl cther in alcohol.Dotted curve 9 9 ,, benzene.Dot and dash curve 9 , ,, chlorofornz.2-Dots and dash curve 9 , , , Eight petroleim.Oscillation frequencies.24 26 28 3000 32 34 36 38 4000 c250 f$$100 5Lower curves.Full curve Nilroquinol dirnelh yl ether in water.Dotted curve 9 , ,, aniline.Dot and dash curve 9 9 ,, pyridine.compound, as is well known, has a strong yellow colour, and itssolution in alcohol is also yellow.It is evident that the absorptionof this compound, and therefore its colour, is capable of the sameexplanation as that put forward for the compounds previouslydescribed, that is to say, it is due to the isorropesis between theresidual affinity of the nitro-group and that of the quinol dimethylether residue. The absorption spectrum of the quinol dimethylether has already been described (Trans., 1905, 87, 1353), andshows a very deep absorption band with its head at about 1 / ~ =3445.VOL.XCVII. Q 580 BALY, TUCK, AND MARSDEN: TEE RELATION BETWEENThe question now arises as to whether the above explanation ofthe absorption and colour of the substituted nitro-compoundsshould not be perfectly general and include all the substances ofthis type, such as the nitroanilines and the nitrophenols. In thelast two classes of compounds the colour and absorption has beenattributed to their existing in the quinonoid configuration. Indeed,one of us, in conjunction with Dr. Stewart and Dr. Edwards(Trans., 1906, 89, 514), put this forward as the interpretation ofthe results obtained from the spectroscopic observation of thenitrophenols and the nitroanilines.I n the case of the former itwas judged that the sodium salts have the quinonoid formula owingto their absorption bands being so much nearer to the red thanthose of the free substances. On the other hand, from the resultsdescribed in this paper, it would seem more probable that anotherexplanation of their absorption spectra is preferable, an explanationsimilar t o that given above for the nitro-compounds, which clearlycannot exist in a simple quinonoid form. On these lines, theabsorption bands of the nitroanilines, for example, would be dueto the isorropesis between the nitro-group and the aniline residue.These bands would necessarily be very near the red owing to thefact that the absorption band of aniline is high up the spectrum(1 / A = 3500).As regards the nitrophenols and their sodium saltsthere s6ould be a considerable difference in their absorption onaccount of the great difference between the absorption of phenoland of sodium phenoxide. The absorption spectrum of phenol(Trans., 1905, 87, 1351) shows a band with its head a t 1/h=3680,whilst sodium phenoxide shows a band with head at l/h=3420. Innitrophenols, therefore, the isorropesis is between the free period ofthe nitro-group and a residue with bands at 1/~=3680, whilst inthe sodium nitrophenoxides the isorropesis is between the nitro-groupand a residue with a band a t 1/h=3420. Clearly, therefore, theabsorption of the latter compound should be much nearer the red.We thought it worth while, therefore, to undertake anew theinvestigation of these compounds with the help of the new andmuch better spectrograph than was available a t the time of theprevious investigation.We will deal first with the nitroanilinesand their alkyl derivatives. In Fig. 9 are shown the curves of3-nitro-p-toluidine, its mono- and di-methyl, and also the acetyland acetylmethyl derivatives. The free base shows a deepabsorption band with its head a t about l/h=2400, the mono-methyl derivative a band with head a t l/h=2350, whilst the headof the dimethyl compound lies a t 1 / ~ = 2 2 7 0 . While it may beurged that the absorption of the free base and the monomethylderivative is due to their existing in the quinonoid form, it iABSORPTION SPECTRA AND CHEMICAL CONSTITUTION.581difficult to see how the dimekhyl compound can exist in this form,and yet the absorption of all three is almost identical. The onlyFIG. 9.Upper curves.Full curveDotted curve iP7itromethyl-p-to22ridine.Dot and dash curve-Nitro- p- to lu2'dine.Nitrodimeth y l - p-toluidine.Osc i I Zatwn f repuen c ies.2000 22 24 26 28 3000 32 34 36 38 4000 42 4425001000250100Lower curves.Full curve Nitro~eto-p-tolz6idide.Dotted curve Nitrometh ylaceto - p - tohidide .difference between them is the slight shift of the band towardsred accompanying the introduction of the methyl groups.connexion with this, it is important to note that the bandQ Q ~theIno582 BALY, TUCK, AND MARSDEN: THE RELATION BETWEENaniline also shifts towards the red when the substance isniethylated.The heads of the bands of aniline, methylaniline, andFIG. 10.Upper curves.Full curve m - Nitroaniliite.Dotted curve m - Nit rod im et hy lnn i l i IW.Dot and dash curve p-Nitroaniline.2-Dots and dash curve p-Nitrodiineth2/la,~.ilinc.Oscil lation frequencies.3000 22 24 26 20 3000 32 34 36 30 4000 42Lower curves.Full curve Nitro-p-cresol i n alcohol.Dotted curve Nitro-p-cresetole in nZcoho2.Dot and dash curve Nitro-p-cresol i n nlcohclic NaOEt.dimethylaniline lie at 1 / A = 3510, 3450, and 3430 respectively. Itfollows that the bands of the nitro-compound will also shift whenthe latter is methylakedABSORPTION SPECTRA AND CHEMICAL CONSTITUTION.583The reduction in the absorption arising from the decrease inthe residual affinity of the amino-group caused by the introductionof the acetyl group and the acetyl and methyl groups is well shownin the two remaining curves. This is exactly analogous to thedecrease in the absorption of aniline caused by the introduction ofthe acetyl group and the acetyl and methyl groups, as shown bythe curves in Fig. 5.The absorption of n2- and pnitroanilines compared with that oftheir dimethyl derivatives is shown in Fig. 10. Exactly the sameapplies here as in the case of the o-nitroamino-compound justdescribed. There is no difference of any moment between the freecompounds and the dimethyl derivatives. The conclusion, there-fore, is forced upon us that the same explanation of the colourand absorption must be given in each.A simple quinonoidstructure is ruled out in the case of the dimethyl compounds, andhence we are compelled to abandon it in the case of the parentsubstances.As regards the nitrophenols, the same explanation without doubtis applicable to the para-isomeride as to the compounds alreadydescribed, for whilst p-nitrophenol and p-nitroanisole have thesame absorption (the bands of anisole and phenol are in the samespectral region), the band of sodium p-nitrophenoxide is shiftedconsiderably towards the red. This shift, however, is due to theshift in the absorption band towards the red when sodiumhydroxide is added to a phenol solution. In the case of theo-nitrophenols, however, the matter is complicated by the fact thatin the original paper the spectrum of o-nitroanisole differed fromthat of o-nitrophenol.I n order to elucidate this anomaly, we have examined thespectra of o-nitrophenol, o-nitroanisole, and o-nitrophenetole invarious solvents, and find that the difference is mainly due to theeffect of the solvent.As previously referred to, the influence ofthe solvent is very remarkable in the case of the nitro-compounds,and this influence will be discussed more fully below. In theoriginal paper, o-nitrophenol was shown to have two bands; these areshown in the full curve in Fig. 11, which represents the absorptionof an alcoholic solution of this compound. The solution in lightpetroleum, however, only shows one band-the one nearer the red,whilst the second band has shrunk to a step-out.o-Nitroanisolein light petroleum solution also shows one absorption band likethe parent substance in the same solvent, but a little nearer theshorter wave-lengths. In alcoholic solution o-nitroanisole onlyshows evidences of the one band nearer the red. This band isshallow, and was only detected with the new instrument. o-Nitro584 BALY, TUCK, AND MARSDEN: THE RELATION BETWEENphenetole shows the same shallow band and also a step-out wherethe second band should appear.The solution of o-nitrophenol in water is different, for the bandnearer the red has shrunk to a step-out, whilst the other band isFIG. 11.Upper curves.Full curve o - Nitrophenol i n alcohol.Dotted curve 3 ) ,, water.Dot and dash curve 2 9 ,) light pctyoleum.2-Dots and dash curve 9 ) ,, alcoholic NaOEt.is 2000 22 24 26 28 300032 34 36 38 4000 42Oscillation frcpzcencies.25010050252501005025Lower curves.Full curve o-Nitroanisole in alcohol.Dotted curve 9 s ,, light petroletun.Dot and dash curve ) Y , , alcoho 1.2-Dots and dash curve 9 9 ,, light petroletint.well marked.Now, o-nitrophenol in aqueous solution of thestrengt'h dealt with ( N j 1000) is presumably considerably ionised,and, further, this ionisation must be less in alcoholic solution andnegligible in light petroleum solution. It would seem from this anA RSORPTION SPECTRA AND CEEMICAL CONSTITUTION. 585from a comparison with the curves of the ethers that the ionisationof the nitrophenol causes the band nearer the red to shrink, whilein the non-ionised substance this band is well marked, while theband farther from the red is decreased.The absorption of sodium o-nitrophenoxide is given in Fig.11,and shows the first band well marked and the second band veryshallow. The change in the absorption when the parent substanceis converted into its sodium salt is simply a shift of both absorptionbands nearer to the red. As was pointed out above, a shift ofthis character is bound to take place, because the absorption bandof phenol also undergoes a similar shift when sodium hydroxideis added to the solution. The explanation of the absorption of thenitrotoluenes and other compounds advanced above meets this caseequally well, and there seems absolutely no reason to assume aradical change in structure such its quinonoid formation in orderto explain this shift in the absorption without any change in theNow, owing to the presence of a considerable excess of sodiumethoxide in the solution, it is very improbable that the sodiumo-nitrophenoxide is ionised to any considerable extent. This is inagreement with the observations, because the ionised or partlyionised nitrophenol in water shows a tendency on the part of thelonger wave-length absorption band t o shrink, whilst the secondband is well marked, the reverse effect being produced when thenitrophenol is dissolved in light petroleum. The sodium salt (inpresence of excess of sodium ethoxide in alcoholic solution) isanalogous to the latter case, for the shorter wavelength band isdecreased, while the other is relatively very deep.In order not to base our conclusions on one single o-nitrophenol,we have examined also m-nitro-pcresol and its ethyl ether (Fig.lo),and the results are identical with those of o-nitrophenol. Them-nitro-p-cresetole shows a band at l/h=3050 and a step-out a tabout l/h=3850; the parent substance in alcohol shows the firstband at l/h=2800, and the second band at 1/h=3650, whilst inthe presence of sodium ethoxide the two bands are shifted to1 / h = 2200 and 1 / h = 3500 respectively. In aqueous solution theabsorption is quite analogous to the case of o-nitrophenol, for theshorter wavelength band is increased in persistence, whilst the otherone is decreased to a step-out.We have also repeated the original examination of m-nitrophenoland compared it with m-nitrophenetole. As the curves on Fig.12show, the relation between the free compound, its sodium salt, andits ethyl ether is the same as in the case of the ortho-isomeride,and the Same explanation holds good. The para-compounds havetype586 BALY, TUCK, AND MARSDEN: THE RELATION BETWEENalso been examined, and their absorption curves are shown inFig. 13. Exactly the same shifts of the absorption bands mayFIG. 12.Upper curves.Full curve m-Nitrophe9i.ol in alcohol.Dotted curve 9 ) ,, water.Dot and dash curve 9 , , , light petro lewm.2 Dots and dash curve 9 1 ,, nlcoholic NaOEtOscillation freqo~,encics.24 26 28 3n00 3% 34 36 38 4000Lower curves.Full curve m-Nitrophcnelole in alcohol.Dotted curve ,Y , , iight petroleum.be noticed here, the only difference being that one deep band isexhibited in the place of the two in the o- and m-isomerides.An interesting point may be mentioned here in reference to thABSORPTION SPECTRA AND CHEMICAL CONSTITUTION.587amino- and the ONa groups. It appears from the absorption ofaniline and sodium phenoxide that the residual affinity of theseFIG. 13.Upper curvea.Pull curve p-Nitrophenol in alcohol.Dot and dash curve ,, ,, light petrolcum.Dotted curve $ 9 ,, water.2 Dots and dash curve Y Y , , akoh,olic NaOEt.OsciJEation frequencies.24 26 28 300032 34 36 38 4000Lower curves.Full curve p-Nilrophenetole in ulcohol.Dotted curve 9 9 ,, light petroleum.two groups is very nearly the same, for the heads of the bands ofthe two compounds are in the same position. The analogy betweenthese two groups has often been noticed by us in comparing th588 BALY, TUCK, AND MARSDEN: THE RELATION BETWEENspectra of compounds containing first one and then the othergroup.The resemblance between the nitroanilines and thecorresponding sodium nitrophenoxides is very striking.Perhaps one of the most important arguments against aquinonoid configuration for the nitroanilines and nitrophenols ist o be found in the fact that the absorption bands of all thecompounds described in this paper appear at the same concentrationof solution. This is the case whether the compound can or cannotexist in a quinonoid form.It must be remembered that theabsorption spectrum of p-benzoquinone shows its isorropesis band ata concentration of N / lo-, whilst all the nitro-compounds show theirbands in IV/ 1000-solution. Moreover, the shape of the absorptioncurve of quinone and those of the nitro-compounds is quite different.It therefore seems in the highest degree improbable that the shiftin the absorption bands, which takes place without any change oftype when the nitrophenols are converted into their sodium salts,is due to a radical change of structure, as is demanded by thequinonoid hypothesis. As collateral evidence it may be pointed outthat the sodium salts of the nitrophenols are extremely similar intheir absorption to the nitroanilines, and these again t o theirdimethyl derivatives.The latter cannot be written in a simplequinonoid form, and therefore the conclusion follows that none arein the quinonoid form.If the theory put forward in this paper is correct, it is evidentthat it must be applicable to all the compounds obtained bysubstituting a positive group into benzaldehyde, benzoic acid, andacetophenone, for the *CHO, *CO,H, and COMe groups are quiteanalogous to the nitro-group in &hat they tend to restrain themotions of the benzene ring. Many such compounds have beenexamined, and some have been previously published (aminoaceto-phenones, aminobenzaldehydes), and the results of the investigationare analogous to those given above for the nitro-compounds.Similarly, of course, the same explanation must be applicable tocompounds derived from benzene by the substitution of a hydroxylgroup and any other group which carries residual affinity.Forexample, in coumaric acid, where the group *CH:CH*CO,H is inthe ortho-position with respect to the hydroxyl groups, absorptionbands should appear, which should shift towards the red on theaddition of an excess of sodium hydroxide. The curves obtainedboth with and without alkali are shown in Fig. 7, and, as can beseen, the free acid shows two absorption bands, which are shiftedtowards the red in strongly alkaline solution. In cinnamic acid,where the isorropesis takes place between the residual affinities ofthe phenyl group and the unsaturated side-chain, the absorptioABSORPTION SPECTRA AND CHEMICAL CONSTITUTION.589band has its head a t 1/~=3600. In o-hydroxycinnamic acid thereare two bands with heads at 1/h=3100 and 3650, whilst in thedisodium compound the two bands have their heads at 1 / h = 2750and 3600. The shift of the bands in the latter is sufficiently largefor the substance to be strongly yellow. It is true that in thecase of coumaric acid a quinonoid formula can be written, butthere is considerable inherent improbability of this change takingplace, for it necessitates the postulation of there being a greaterattraction between sodium and carbon than between sodium andoxygen. On the other hand, the shift in the absorption whenphenol is converted into sodium phenoxide is sufficient to causethe shift when the substituted compound is so treated.A strikinganalogy betwen the amino- and ONa groups is to be found in thefact that the coumaric acid in strongly alkaline solution fluoresceswith the same yellowish-green colour as o-aminocinnamic acid.There seems therefore to be very strong evidence against aquinonoid explanation of the absorption and colour of the nitro-phenols and nitroanilines. It would seem, indeed, that this theoryis quite unnecessary. The explanation advanced in this paper, anexplanation based on the play of forces between the residualaffinities in the various intramolecular groups, has the greatadvantage in that it embraces all the disubstituted benzene com-pounds with two dissimilar substituents whether or no a quinonoidconfiguration is possible.This explanation satisfies all the factsthat have been observed, which the quinonoid theory does not,As, for example, the very small change in the absorption when anitroaniline is methylated, and that the formula of a true quinone(p-benzoquinone) is of an absolutely different type.We have also investigated the mononitro-derivatives ofbenzylideneaniline. These compounds are interesting, for whenthe nitro-group is substituted in the benzene residue a simplequinonoid structure is possible, but in the isomeric benzylidene-nitroanilines this is not the case. A comparison of the absorptionof these compounas shows that they are all strikingly similar, therebeing, however, slightly more marked absorption bands in thebenzylidenenitroanilines than in the nitrobenzylideneanilines, thatis to say, those compounds which can exist in the quinonoid formshow rather less marked absorption than those which cannot do so.It appears to us that these substances afford very strong evidenceagainst the quinonoid hypothesis.The absorption curves comparedwith that of benzylideneaniline itself are shown in Fig. 14.During the progress of this investigation a very interesting paperhas appeared by Buttle and Hewitt (Trans., 1909, 95, 1755), inwhich the constitution of the di- and tri-nitrophenols is discussed590 BALY, TUCK, AND MARSDEN: THE RELhTlON BETWEENButtle and Hewitt, basing their arguments largely on the resultsobtained in the original paper (Trans., 1906, 89, 514), attributea para-quinonoid structure rather than an ortho-one to the sodiumFIG 14.Upper curves.Full curve o- Nitrobenzylideneanilim.Dotted curve m- Nitrobenzy Zideneaniline.Dot and dash curve p- Nitrobem ylideneuniline.Oscillation f reqzcencies.26 28 3000 32 34 36 38 4000 420 00"Lower curves.Full curve Benzylideneuniline.Dotted curve Benzylidene-m-nitronnili.ILc.Dot and dash curve Benz y Zidene-p-nitroanili7zc.salt of 2 : 4-dinitrophenol.On the other hand, there isinterpreta.tion t o be given t o their results, and one whichsatisfactory than t,he one they give.anotheris morABSORPTION SPECTRA AND CHEMICAL CONSTITUTION. 591In the first place, Buttle and Hewitt assume that the absorptionspectra of the ionised di- and tri-nitrophenols would be those ofthe aci-forms of these compounds.This, however, is not the caseas far as the ortho-nitrophenol is concerned, and it would seemworth while that the absorption spectra of these substances inaqueous solution should be examined. It appears from the curvesof the two dinitrophenols that there is evidence of a second bandat about l/h=3900, which renders the compounds similar t oo-nitrophenol itself. We would therefore expect the aqueoussolution to show this second band more fully developed at theexpense of the first band. Again, our results with the solutions ofthe nitrophenols in light petroleum solution show that the spectrumof the non-ionised compound can be readily obtained in this .way.There is no doubt also that considerable importance is to bederived from a comparison of the absorption of picric acid and itsether dissolved in this solvent.The theory that we have advanced, however, offers a completelysatisfactory explanation of all the absorption results given byButtle and Hewitt. The absorption of both mono- and di-nitro-phenols is due to the play of forces between the residual affinities ofthe phenol residue and the nitro-groups. The position of theabsorption band depends on the absorption of the phenol residueand the number and position of the nitro-groups.When theabsorption of the phenol group is shifted nearer to the red byconversion into the sodium salt, so is the spectrum of the substitutedphenol also shifted in the same manner.In trinitroanisole it isevident that the single hpdroxyl group is insuscient to counteractthe restraining’influence of the three nitro-groups. When, however,the influence of the hydroxyl is enhanced by conversion into thesodium salt, then it is sufficiently powerful to overcome the restraintof the nitregroups, but the absorption produced is not so near thered as in the dinitrophenoxides.It is interesting to note that with the exception of trinitroanisole,the abnormality of which is noted above, all the nitro-compoundscontaining the hydroxyl or amino-groups in the ortho-position withrespect to the nitro-group give evidence of two bands, whilst thepara-isomerides only show one absorption band. The reason forthis is not clear, but it seems t o be characteristic of nearly allortho-disubstituted benzenes with two powerful groups of differenttype.We propose to investigate this more fully in the hopes ofdetermining the origin.There remains now to be described the very remarkable influencethat the nature of the solvent has on the absorption of the sub-stituted nitro-compounds. Although no definite relation has a592 ABSORPTION SPECTRA AND CHEMlCAL CONSTITUTION.yet been found, all our results point to the fact that an increasein the residual affinity of the solvent causes a shift in the absorptionbands towards the red. It has been known for some time that,whilst nitroquinol dimethyl ether in the solid state and in alcoholicsolution is strongly yellow, the solution of this compound in lightpetroleum is quite colourless.We have also noticed that the sameis true for a-nitronaphthalene and 4-nitro-o-xylene, Also we findthat aqueous solutions of these compounds are even more stronglycoloured than the alcoholic solutions. We have examined theabsorption spectra of many of these compounds in dserent solvents,and find that the colour changes are simply due to shifts in thepositions of the absorption bands. The solvents used were lightpetroleum, alcohol, water, chloroform, benzene, pyridine, andaniline. In the case of the light petroleum, Kahlbaum’s bestmaterial was used (b. p. 30-50@, for the determination of fat),and it was shaken for many hours with concentrated sulphuric acidin order to remove small quantities of some unsaturated substancespresent, which produce a marked absorption.After this treatmentthe material has very slight absorption in short layers. The threelast solvents have, of course, very considerable absorption, andcould only be used in those cases where the absorption band of thenitro-compound is sufficiently far from the ultra-violet.Nitroquinol dimethyl ether was examined in all the abovesolvents, and the position of the absorption band, as can be seenfrom the curves in Fig. 8, varies considerably. The position of thehead of the absorption band in the various solvents is shown in thefollowing table :l / h .Light petroleum .................... 3000Benzene ................................. 2900Alcohol .................................2800Chloroform ......................... 2750Pvridine ................................ 37302680 Water Aniline} ..............................A maximum variation of 320 units is thus shown in the caseof this substance.Again, 4-nitro-o-xylene exhibits in alcohol an absorption bandwith head at l/h=3550, whilst in petroleum solution the headlies at 1/h=3720 (Fig. 3).With a-nitronaphthalene, the position of the band is as follows(Fig. 2):l/h.Light petroleum ..................... 3200Alcohol ................................ 3100Benzene ................................. 3050In fl-nitronaphthalene, all three bands are nearer the red iCUMMINO: THE ISOLATION OF STABLE SALT HYDRATES. 593alcoholic solution than they are in light petroleum solution, as can beseen in Fig. 2.An analogous observation was made in the case of the three nitro-toluenes, for here it was found that a difference in the absorptionoccurs with the strength of the solution. As can be seen fromFig, 1 (full curves), the absorption band is most pronounced whenN / 1000-solutions are examined. If equivalent lengths of N / 10,000-solutions are observed, the absorption band is less persistent (Fig. 1,dotted curves),We would point out as a result of the observations in differentsolvents of the substituted nitro-compounds in which no quinonoidstructure is possible, that strong presumptive evidence is obtainedagainst the quinonoid configuration of the nitrophenols. Forwhereas the increase in the residual affinity of the solvent canproduce a shift in the absorption bands by so great an amountwhere no change in configuration occurs, it is not unreasonable toargue against a radical change in configuration when an increasein the residual affinity of one of the substituent groups (OH toONa) produces an exactly similar change, although perhaps some-times rather greater in amount. We feel therefore that the chainof evidence against there being any radical difference between thestructure of the nitrophenols and their sodium salts is completedby these observations, and therefore are bound to express our-selves against the quinonoid configuration of the nitroanilines andthe sodium nitrophenoxides.In conclusion, we wish to express our cordial thanks to ProfessorCrossley for his courtesy in supplying us with the nitro-derivativesof o-xplene, and also t o the Research Fund Committee of the ChemicalSociety for a grant in aid of this investigation.UNIVEILSITY OF LONDON, UNIVERSITY COLLEGE,SPECTROSCOPIC LABORATORY

ISSN:0368-1645    

DOI:10.1039/CT9109700571

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

CUMMINO: THE ISOLATION OF STABLE SALT HYDRATES. 593LX.--T!he Isolation of Stable Salt Hydrates, withSpecial Reference to the Stable Hydrates ofSodium Cadjonate.By ALEXANDER CHARLES GUMMING.THE actual existence of a number of salt hydrates which have beendescribed must be regarded at present as an open question. Twelvehydrates of sodium carbonate have been described, yet Ketner (Zeitsch594 CUMMING: THE ISOLATION OF STABLE SALT HYDRATES.physikal. Chevn., 1902, 39, 645) was only able to isolate three, whilstMuller-Erzbach (Ber., 1884, 17, 1427) had decided that there werebut two hydrates. This instance illustrates the need for furthercriteria of the existence of hydrates, since, according to the descrip-tions, all twelve hydrates might have been stable hydrates.Newhydrates are usually isolated incidentally in the course of solubilitydeterminations or research of a similar nature. I n general, the mainpurpose of the experiment is not the isolation of a new or of anyparticular hydrate, and a brief review of these methods will show thatthey are not for the most part well adapted to their secondarypurpose, namely, the isolation of hydrates,Solubility Method.-The solubility curve of a substance which formshydrates may show a break at a transition temperature. Crystallisa-tion above this temperature will yield a lower hydrate, or the anhydroussalt, whilst crystallisation below this temperature will yield a higherhydrate. The break in the solubility curve may, however, not beobtained, as the transition temperature may be outside the range ofconvenient or possible measurement ; thus the solubility curve forcopper sulphate (Landol t-Bornstein, Physikalisch-chemische Ta bellen,1905, p.537) offers no evidence of the existence of any hydrate otherthan the pentahydrate. Further, t.he solubility of a hydrate may inmany cases be measured in a region where it is unstable, and thismight easily lead to the non-detection of another hydrate.The existence of a hydrate may be detected by observation of atransition point from the solubility curve or by other methods, suchas the dilatometer method, but it may still remain a matter of greatdifficulty to isolate the indicated hydrate.Calorimetric Method.-The existence of a hydrate may be detectedfrom measurements of the heats of solution of the salts in variousstates of hydration (Thornsen, I'hermochemistry, English translation,1908; Donnan and Hope, Trans. Faraday Soc., 1909, 5, 244).Themethod is troublesome, and may not yield definite results, as, forexample, Donnan and Hope have shown t h a t this method does notreveal the existence of copper sulphate trihydrate, although it provesdefinitely that copper sulphate forms a monohydrate.Vapour Pressure Method.-Another method which is not open tothese objectiotls is the measurement of vapour pressures of mixturescontaining varied amounts of water. Lescoeur (Ann. Chim. Phys., 1890,[vi], 21, 511) was able to show in this way that there are only threehydrates of copper sulphate. This method is satisfactory if sufficientexperiments are performed, but i t is very laborious.Desiccation with SuZphuric Acid.-If a mixture of a salt with anexcess of water is placed over sulphuric acid in a closed vessel, it willbe desiccated until a definite hydrate is left, provided that the aqueouCUMMING: THE ISOLATION OF STABLE SALT HYDRATES.595tension of the sulphuric acid employed is below that of the hydrateand greater than that of the next lower hydrate, If sufficientexperiments are performed with various concentrations of sulphuricacid, it is possible to isolate all the stable hydrates of a salt. This isa practical method, and has found application in work by Ketner (Zoc.cit.) and others, Ketner states in a footnote that this method haslong been used ih the laboratory in Leyden.Method under Investigation.-The method which has been in-vestigated in this research is based on the same principle as that usedin Leyden, but instead of desiccating with sulphuric acid, each hydratewas prepared by desiccation with the next lower hydrate, except inthe case of the lowest hydrate, where the anhydrous salt was used asthe desiccating agent.It was shown by Andreae (Zeitsch.physikal. Chem., 1897, 7, 261)that if three hydrates are placed in a closed vessel, the highest will losewater to the lowest until there are only two hydrates in the system.It may be pointed out that this is an interesting illustration of thePbase Rule. In one experiment Andreae placed a mixture of strontiumchloride hexahydrate and dihydrate in one flask, a mixture of thedihydrate and anhydrous salt in another, and connected the twoflasks.The first mixture lost water to the second mixture until allthe hexahydrate had been converted into dihydrate, after which nofurther dehydration occurred. This obviously is a method for thepreparation of strontium chloride dihydrate. Walker and Beveridge(Trans., 1907, 91,1797) have used this device for the preparation ofp-toluidine monohydrate, and drew attention to the fact that a hydratecan be completely dried, without being decomposed, by the dehydratingaction of the next lower hydrate, the lowest hydrate being preparedby the dehydrating action of the anhydrous substance. This shouldprovide a method for the isolation of all the hydrates of any substancewhich are stable at the temperature of experiment.If a small sixpplyof moist salt is exposed to the dehydrating action of the anhydroussalt, i t should be dehydrated until the lowest hydrate is left. Thetotal quantity of water to be taken up by the anhydrous salt must beless than sufficient to convert all of it into the lowest hydrate, so thata relatively large amount should be used. When the lowest hydratehas been isolated, it may be used to prepare the next in the series, andby continuation of the process the whole series of hydrates mightbe isolated. The process might also be carried out in the reversedirection, that is, the hydrates might be prepared by hydration, usingthe next highest hydrate in each case as the hydrating agent.Onlystable hydrates have been referred to, since this method is unlikely toyield any information about hydrates unstable at the temperature ofobservation. Attention may be drawn also t o the fact that the methodVOL. XCVII. R 596 CUMMIKG: THE ISOLATION OF STABLE SA1.T HYDRATES.would fail if the temperatnre of experiment happened to be a transitiontemperature, since at a transition temperature it would be possible tohave three hydrates in equilibrium. Up to the present the onlyexperimental data on the subject are contained in the researchesof Andreae and of Walker and Beveridge. A further examination,therefore, appeared desirable, as the results would be interesting fromthe point of view of the Phase Rule.I n the course of the researchsome information was obtained as t o the rate of hydration anddehydration of hydrates under various conditions, a subject aboutwhich very little is known a t present.Hydrates of Xodium Carbonate.It was decided to apply the method to the hydrates of sodiumcarbonate. An exact knowledge of the hydrates of such a commonsubstance is obviously desirable, but very conflicting statements are tobe found in the literature. Two hydrates are well known articlesof commerce, namely, the monohydrate and the decahydrate. Hydrateshave also been described with 12, 2, '24, 3, 4, 5, 6,7, 8, and 9 moleculesof water per molecule of sodium carbonate. Another hydrate,Na,C0,,15H20, has also been described, but as i t was prepared onlyat a low temperature it may be excluded from the present discussion.All of the above hydrates from the methods of preparation andproperties given by the respective authors should be stable a t theordinary temperature, but Miiller-Erzbach (Zoc.cit.) could only isolatethe monohydrate. and decahydrate. Ketner (Zoc. cit.), by drying withvarious concentrations of sulphuric acid, obtained hydrates with 1, 7,and 10 molecules of water. Wells and Macadam, jun, (J. Amer. Chem.Soc., 1907, 29, 721), in the course of careful solubility determinations,and Donnan and Hope (Zoc. cit.), from calorimetrical analysis, foundthe same three hydrates as Ketner. These recent researches leavelittle doubt that there are only three stable hydrates of sodiumcarbonate, but in view of the earlier results, further confirmationappeared desirable, especially as none of the researches provides a rigidproof of the number of stable hydrates.EXPERIMENTAL.Preparation of Lowest Byhate.--The preparation of the lowesthydrate may be described in some detail, as the experiment wastypical of the mathod adopted.On the floor of a vacuum desiccator were placed about 100 grams ofanhydrous sodium carbonate.A small weighed quantity of thedecahydrate, spread in a thin layer on a watch-glass, was thenintroduced, and the desiccator evacuated. The apparatus was kept iCUMMING: THE ISOLATION OF STABLE SALT HYDRATES. 597a cupboard at room temperature, From time to time the substance onthe watch-glass was weighed, until no further loss in weight could bedetected.The substance on the watch-glass represented the lowesthydrate, that is, the hydrate with the same vapour pressure as themixture below, which was made up of originally anhydrous sodiumcarbonate plus the small amount of water obtained by dehydration ofthe decahydrate.TABLE I.Time in days. Weight in grams. I m s in grams. H,O per Na,COn.0 2-129 - 10.03 0.925 1 -204 1.010 0.925 1 -204 1-012 0.925 1.204 1.0MoleculesThe substance lost water until Na,CO,H,O was left, after which nofurther dehydration was detected. In all the later experiments thesubstance was roughly ground at the start of an experiment. Whenthe weight had become constant, it was ground to a fine powder, andthe experiment continued, I n no case mas a further change i n weightnoticed with hydrates of sodium carbonate. The composition wascalculated from the weight of water lost, and, as a check, the hydrateobtained was analysed, except in the firstexperiment, where this wasnot done.Hydrccte next above the Honohydrate.-An intimate mixture ofanhydrous and decahydrated sodium carbonate was made in theproportion calculated to give the monohydrate, and the mixture maskept in an evacuated vessel for three weeks before use.A smallweighed quantity of sodium carbonate was then dehydrated by a largeamount of this mixture.TABLE 11.MoleculesTime in days. Weight in grams. Loss in grams. H,O per Na&O,0 2.391 I 10.01 2.206 0.185 8 ?32 2.079 0.312 7.97 1.942 0.449 7'0213 1.941 0'450 7.0116 1.941 0.450 7.01I n this experiment the dehydrating agent was a mixture ofanhydrous and decahydrated sodium carbonates in the proportioncalculated to yield the monohydrate.As there was a remotepossibility that the monohydrate had not been formed, it was preparedin another way. The crystalline decahydrate was melted on thesteam-bath and evaporated until a sufficient quantity of the monohydrate had Peparated. This was filtered from the hot solution.Analysis showed these crystals t o have the empirical compositionNa,CO,, 1 *2H,O, that is, they were crystals of the monohydrate mixedR R 598 CUMMING: THE ISOLATION OF STABLE SALT HYDRATES.with a small proportion of a higher hydrate. A small weighed sampleof the decahydrate was then dehydrated by 100 grams of thismonohydrate..TABLE 111.Molecules10.0Time in days. Weight in grams. Loss in grams. H,O per Ns,CO,.0 2-438 -5 2,158 0.280 8.0I1 1'981 0,457 7-214 1.976 0.468 7.021 1.976 0.482 i - 0The substance was then finely ground, No further loss masdetected after seventy-three days in an evacuated vessel.Hydrate next above the Heptahydrate.--It was found that nodehydration of the decabydrate had taken place after seven daysin an evacuated vessel above a mixture of hydrates which had theempirical composition Na,C08,7.3.H,0. There is no evidence, there-fore, of any hydrate intermediate between the heptahydrate anddecahydrate.Hydration of a less Hydrated Salt.In the previous experiments a hydrate was dehydrated by a lowerhydrate until the hydrate next in the series to the lower hydratewas, obtained.'I'he process may be carried out in the reversemanner, that is, a substance may be hydrated by a higher hydrateuntil the hydrate next below the higher hydrate is formed.Hydrate next below the Decahydrate.- A small weighed sampleof the anhydrous salt was hydrated by a large supply of slightlyeffloresced decahydrate.TABLE IV.Time in days. Weight in grams. Increase in grams. H,O pcr Na,CO,.- 1.717 - -1 2.123 0.406 1'44 2.328 0-611 2 111 2-673 0.956 3'315 2.777 1.060 3 '619 2.900 1.183 4 *I25 3.238 1.521 8.228 3-305 1.588 5'539 3.540 1 '823 6.350 3 -722 2.005 6 '996 3-738 2.061 6.93216 3.i38 2.021 6 *92MoleculesThe amount of water given in the last column is cltlciilated fromthe gain in weight, on the assumption that the sample was quiteanhydrous at the beginning of the experiment, but a trace of watermust have been present, as analysis showed that the substance finallyobtained was pure Na,C0,,7H20CUMMING: THE ISOLATION OF STABLE SALT HYDRATES. 599It will be noticed that the first molecule of water was takenup very quickly, and the remainder a t R much slower rate.Thisexperiment taken alone indicates the probable existence of amono hydrate.The existence of MgSO,,GH,O was indicated in a similar mannerduring the dehydration of MgSO4,7H,O by anhydrous magnesiumsulphate. One-seventh of the water was lost in the first day, and thedehydration then became extremely slow.Hydrate next below the Heptahydi.ate.-A small weighed sample ofanhydrous s d t was hydrated with 100 grams of the heptahydrate.TABLE V.Time in days.Weight in grams. Iiicreasc in grams. H,O per Na,CO,.0 0-607 - -2 0'608 0.078 0 -7622 0909 0'102 0.9936 0.712 0'105 1 *0258 0.712 0.105 1 *02Highest Hydrate of Sodium Carbonate.-A small weighed quantityof anhydrous sodium carbonate was exposed to the hydrating actionof a saturated solution with which was mixed a large supply ofcrystals.MoleciilesTABLE VI.Time in days.12347113751-Weight in grams. Increase. in grams.0.735 -1'210 0'5851.373 0'6441 '566 0'8311.633 0.8961.753 1'0181 -853 1.1181 -985 1 '2501.985 1'250MoleculesH,O per Na,CO,.4 -75-26 -77-28 '19 '010.0110.01-The results in these tables have been expressed graphically in thediagram.The experiments were carried out a t room temperature, andthe mean temperature would be about 1 2 O .It is evident that with these hydrates, dehydration of a smallquantity of substance provides a quicker process for the preparation ofa hydrate than does the hydration method.The two curve8 showing dehydration to the heptahydrate illustratethe difference in time produced by a slight variation in the conditionsof the experiment. A first inspection of these results would suggestthat a rigid proof has been obtained that there are three, and notmore than three, stable hydrates of sodium carbonate. The existenceof the three hydrates with 1, 7, and 10 molecules of water iscertainly proved, but consideration will show that the existence o600 CUMMlNG: THE IYOLAI'ION OF S'I'AULE SALT HYDLtATES.other hydrates is possible, although very improbable.There is no proof,and at present no rigid proof is possible, that, a hydrate has not beencompletely passed over during hydration and dehydration. From thenature of the experiments this is very improbable, but it is at leasttheoretically possible, and the phenomena now to be recordedmill prove that non-formation of an intermediate hydrate is atleast a possibility.10 20 30 40 50 60Time +n days.The hydration curves start i n each case from anhydrous salt, and the dehydrationCurve A B C shows hydration with heptahydrate (Table V).Curves N M P and N R P show dehydration with monohydrate (Tables 111Curve N S T C shows dehydration with anhydrous salt (Table I).curves start in each case from sodium carbonate decahydrate.and 11).Non-formation of a Hyd~ate.-In the experiment recorded on thehydration with saturated solution to obtain the decahydrate, thefollowing phenomena were noticed.The anhydrous salt was spreadin a thin layer on the surface of a watch-glass. After one day it wasfound that some small detached portions of the s a l t had deliquesceCUMMING: THE ISOLATION OF STABLE SALT HYDRATES. 601with the formation of small drops of solution on the glass. Someof these were touched with the end of a fine platinum wire whicbhad been drawn across the surface of a crystal of sodium carbonatedecahydrate.Each drop as it was touched crystallised instantly andcompletely, which proved that a supersaturated solution had beenformed instead of the expected solid decahydrate phase. I n thecourse of the first few days all the drops crystallised, with theexception of two minute drops. These were still present a t the end ofthirty-keven days, and when these were touched they did not crystal-lise completely. The formation of the drops of supersaturated solutiona t the beginning of the experiment is mainly remarkable in t h a t therecannot have been any nucleus present t o start the formation ofdecahydrate, despite t h e fact that the floor of the vessel was coveredwith moist crystals of the decahydrate. The supersaturated solutionwould have a lower vapour pressure than the wet decahydrate system,and would therefore continue to absorb water.I n absence of anucleus of decahydrate, the absorption of water would continue, it isto be supposed, until these drops had the same vnpour pressure as thesystem below, that is, until a ‘L saturated solution ” bad been formed.This agrees with the fact that only partial crystallisation occurredwhen the drops were artificially seeded, since the liquid left after thecrystallisation must have been “ saturated solution.” If this explana-tion be accepted, “ saturated solution ” was formed without formationof the intermediate phase, the decahydrate. The experiment has beenrepeated three times, and in two-cases the solution phase was formed.I n all cases most of the salt hydrated directly to the solid hydrate,but small detached drops of solution formed in places on the glass.Nethod f o r the Isolation of a mu, Hydrate.-Prom the resultsobtained with sodium carbonate it might seem that the method out-lined in the earlier part of this paper would quickly lead t o theisolation of all the hydrates of any salt.From experiments withother salts, however, it appears that sodium carbonate is a particularlyfavourable case, and a considerable search may be necessary beforeanother salt is found which yields a series of hydrates so quicklyand completely at the ordinary temperature. Magnesium sulphateheptabydrate, dehydrated by anhydrous magnesium sulphate, lost oneseventh of its water in the first twenty-four hours, and then lost water,steadily but very slowly.A t the end of one hundred and forty-fivedays the additional amount of water lost corresponded with a loss ofonly half a molecule of water, and there was no appreciable increasein the rate of dehydration after fine grinding. With several othersalts it was found that hydration or dehydration may occur withextreme slowness. From the experience gained in this research, I amof opinion that the systematic search for all the hydrates of a sal602 CUMMING: THE 1SOLATXON OF STABLE SALT HYDRATES.would in most cases prove too tedious and troublesome t o repay thelabour. At the same time it appears probable that the existence orotherwise of any particular hydrate may be readily determined bymeans of this method.Tho method has the further important practicaladvantage that if the hydrate has any existence it will be obtained ina pure state. If the existence of a hydrate with n molecules of wateris suspected, two experiments should be performed.On the floor of a desiccator place a quantity of an artificial finelypowdered mixture which contains a little less than n molecules ofwater per molecule of anhydrous salt. On a watch-glass above itplace a little finely powdered mixture, with a little more than nmolecules of water, and exhaust the vessel. The substance on theglass will lose water until the pure hydrate is left, if there is a stablehydrate of that composition. This was the method used by Walkerand Beveridge for the preparation of p-toluidine monohydrate.Iwould suggest that a second experiment should be performed, usinga large quantity of a mixture containing slightly more than m mole-cules of water to hydrate a small quantity of a mixture with slightlyless than n molecules of water. 1.n all cases it is expedient to evacuateas thoroughly as possible. The method would probably be of value inorganic chemistry for the preparation in a pure state of substanceswhich readily dissociate into their constituents, such as iodine additivecompounds and alcohol additive compounds corresponding withhydrates (alcoholates).Suspended Tranaformation.--h curious case of suspended transforma-tion was noticed in some experiments with the hydrates of coppersulphate. The dehydrating agent was a large supply of CuS0,,H20in the form of a fine powder mixed with a emall proportion ofpowdered pentahydrate.A small weighed quantity of the penta-hydrate was to be dehydrated. Tho pentahydrate had been re-crystallised, and was ground to a coarse powder before a sample wastaken. It was found that 2.282 grams had lost in two days only0.004 gram of water, and the colorir of the crystals was unchanged.After three more days the weight was unchanged. The crystals werethen touched with a platinum spatula, which had been dipped in themixture below. No weighable quantity had been added, but a nucleusof a lower hydrate had evidently been introduced, as efflorescencestarted in two places and spread through the whole massALLMAND : AFFlNlTP RELATIONS OF CUPRIC OXIDE. 603Time in days.0251233145175182212TABLEWeight in grams.2.2822'2782'2781.9281.9141.8471-8391 *8301.795VII.Loss in grams.0-0040.0040'3540.3680'4350'4430'4520.487-MoleculesH,O per CuSO,.5.03.693'623'373.353 '313.18-__From this table i t will be seen that once the action had started,dehydration proceeded steadily, but so slowly that it had not attainedcompletion in seven months. The suspended transformation in thisexperiment is interesting, in that the vapour pressure in the apparatuswas fixed by the presence of a mixture of monohydrate with a littletrihydrate on the floor of the vessel. The initial small loss probablyindicates a trace of surface moisture, and i t is possible that onthis account the grinding did not start the formation of a lowerhydrate.CHEMISI'RY DEPARTMENT,UNIVERSITY OF EDIXBUKGH

ISSN:0368-1645    

DOI:10.1039/CT9109700593

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

ALLMAND : AFFlNlTP RELATIONS OF CUPRIC OXIDE. 603LXI.-Afinity Relations of Cup~ic Oxide and ofCupric Hydroxide.By ARTHUR JOHN ALLNAND.IN the course of a recent paper (Trans., 1909, 95, 2151), the authorshowed that crystalline cupric hydroxide when treated with concen-trated alkali solutions at the ordinary temperature, or when shakenwith dilute aqueous ammonia at 2 5 O , loses its water and is convertedinto cupric oxide. According to these facts, crystalline cuprichydroxide is unstable with respect to cupric oxide and the givenaqueous solution at the temperatures in question, whereas the reversehas been thought to be the case. To decide this point tensimetricand electrometric experiments were undertaken. If in reality crystal-line cupric hydroxide constitutes an unstable system at the ordinarytemperature, it must have n higher vapour pressure than water, orthe alkaline and ammoniacal solutions referred to, and yet it appearsto be perfectly stable in dry air.Secondly, it must also be moresoluble than cuprio oxide, and the system Pt cuzo alkali should give 604 ALLMAND : AFPIKITY RELATIONS OFa lower single potential difference value then the system Pt 1 Cu(Ho)2alkali, although it is not certain a priori t h a t the solubility differencewill be sufficlently great to be detected.cu,oTensimetric Experinzents.A tensimeter was filled with all the ordinary precautions. Onebulb contained a sample of ‘( Becquerel” cupric hydroxide (Compt.rend., 1852, 34, 573), which had been dried a t looo, bottled, and subse-quently left in a dessicator over calcium chloride.The other bulbcontained phosphoric oxide, and the indicating liquid in the U-tubewas olive oil. The tensimeter was placed in a thermostat at 2 5 O .Readings were taken over some four months, at the end of whichtime the cupric hydroxide had undergone no marked change in colour.The following table contains the results,TABLE I. Temperature 2 5 O .Time of observation.September 27Y I 289 ) ‘293 9 47 6November 2300ct);ber 2:, 207 9 15) I 29December 1, I 7,, 9f f 112 8 15I f 21January 59 ) 20Reading in mm. of olive oil.Filled and sealed : kept limhs in connexion.Allowed oil to flow into U-tube ; placed in789-109-1 09-1013-1413-14.thermostat.Took out, and allowed limbs to stand inconnexjon 15 hours.Replaced. Beading rosevery slowly.3-43-4. Put limbs once more in connexion for 3hours. Replaced.8-42-32-32< 2< 21.5. Put limbs into coiinexion once more for 241.5hours. Replaced.The vapour pressure of water at 25’ is about 33.5 mm. of mercury,whilst the highest pressure observed in the tensimeter was about13.5 mm. of olive oil. This supported the view that cupric hydroxideis the stable system. It was, however, possible that the dehydrationdid not commence, owing to powerful opposing reaction resistances,and that by the addition of some quantity of a decomposition productthese reaction resistances could be overcome. A second tensimeterwas therefore filled, containing in one limb a mixture of cupriCUPRIC OXIDE AND OF CUPRIC HYDROXIDE. 605hydroxide together with cupric oxide, prepared by the action ofaqueous ammonia at 2 5 O on cupric hydroxide.The measurementsobtained are given in the following table :TABLE 11. Temperature 25".Time of observation. Reading in mm. of olive oil.December 2 Started> 9 7 9Y Y 9 9.59 9 15 11.51 ) 11 11.5, 9 21 12.5Y 9 20 1-5Januniy 5 13.5. Placed limbs in connexion for 24 hours.Replaced.It will be seen that the figures are pritctically identical with thosein table I, furnishing further evidence in favour of the view thatcrystalline cupric hydroxide is stable with respect to copper oxide andwater. The fact that the same two final figures-13.5 mm.and1.5 mm.-occur in both tables points t o their corresponding with twodefinite equilibrium states. It has been already shown (Zoc. cit.) thatcrystalline cupric hydroxide contrains more wnter (in the ratio 1.07 : 1)than is demanded by the formula Cu(HO),, and that i t is improbablethat this excess is physically held or adsorbed. It was suggestedthat the excess may be due to the presence of srriall quantities of ahigher hydrate, such as Cu0,2H20. If that view be taken, we canperhaps ascribe the- higher of the two vapour pressures observed tothe presence of this hydrate, and write :P H ~ O at 25' for Cu(HO),,zH,O t Cu(HO), + xH,O= 0 9 mm. mercury.(The specific gravity of olive oil is taken as 0.9.)I n any case it is highly probable that the lower vapour pressuremeasured corresponds with the dehydration of cupric hydroxide tocopper oxide and water, and we can write :P H ~ O at 25' for CU(HO)~ CuO + H,O(fresh)= 0.1 mm.of mercury.Electrometric Measurements.The electrode measured was always of the type P t I ;:> alkali.With the exception of a few experiments carried out with N-potassiumhydroxide and N/lO-sodium hydroxide, the electrolyte employed wasN-sodium hydroxide (carbonate-free). The electrode vessels wereadapted for shaking and similar to those already described (Zoc. cit.),whilst the measuring apparatus-galvanometer, Weston elementGO6 ALLMAND : AFFINITY RELATIONS OFmetre bridge-calls for no remark. The electrodes were gentlyrevolved on a wheel, shaken, and taken off and measured againstcalomel electrodes a t various intervals for some length of time.Allreadings were made at the ordinary temperature, namely, 17'. Thepotential of the N-calomel electrode was taken as + 0.282, volt at 17",the liquid potential difference bet ween N-potassium chloride andN-sodium hydroxide as 0.020 volt,I n the first experiments, cupric oxide was used, prepared bythorough ignition of cupric hydroxide or cuprous oxide over a Bunsenburner. Now the single potential difference given by the systemCu(Ho)2 N-NaOH is - 0.074 volt (Zoc. cit.), and judging from Ptthe results of the vapour-pressure measurements, the combination I cu20Pt I :$ N-NaOH should give a more positive value, correspondingwith a tendency for the change CluO+H,O -+ Cu(HO), to takeplace. As a matter of fact, the behaviour of the electrodes was asfollows.They commenced (read the day after setting up) by givingconsiderably more negative values than the cupric hydroxide elect rode,and then slowly fell, becoming more and more negative, and in somecases finally reaching or approaching an asymptotic value. Forexample, an electrode set up containing N-sodium hydroxide andcupric oxide, prepared by igniting cuprous oxide, gave the followingreadings.TABLE 111. Temperature 17".Days after setting up. Single potential Pt 1 ,C-$N-N~OH.134567810111214- 0'096 volt- 0.109 ,,-0'112 ,,0.117 ,,-0,118 ,,-0'119 ,?-0'120 ,,-0'120 t o - 0 119-0.120 to -0.119 ,,- 0'121 to - 0'122-0.114 to -0'115 volt,,,)The rate of fall of potential was very different in different cases, aswas also its extent.The first explanation which suggests itself isthat the electrode is not acting reversibly. Of electrode systems inwhich the reaction taking place is not the complete discharge ofan ion to a neutral substance, but only an increase or decrease in thenumber oE ionic charges, it is known that but few behave reversibly, andthis is particularly the case in alkaline solutions. On the other hand,the particular reaction Cu" Cu' + @ is reversible in acid solutionCUPRIC OXlDE AND OF CUPRIC HYDROXIDE. 607and there is every reason from the behavionr of tile P t cu(K0)2 I cn,o . -alkali electrode to assume that it is also reversible in alkaline solution.Luther (Zeitsch.Elektrochem., 1907, 13, 289) has declared the criteriaof irreversibility of an electrode to bo (amongst others): (1) fluctuationsin potential value; (2) two electrodes in the same solution givingdifferent values ; (3) changes on shaking, and (4) changes in concentra-tion of the electrolyte not bringing about the corresponding theoreticalpotential changes.I n the present case, the variation in potential mas always adirected one-a fall. To test the second point an electrode vesselwas made up containing two electrodes (one blank and one plxtinised)about 2 cm. apart, dipping into the same mixture of depolariser andelectrolyte. They were measured over a period of five weeks, duringwhich time the potential fell by 0.025 volt, and they always agreed towithin 0.0004 volt.It was further found t h a t shaking never alteredthe potential of any electrode by more than a millivolt, and theoriginal value was restored within a minute or two on standing.Pt cu(Ho)2 alkali electrodes gave the theoretical change on alteringthe concentration of the alkali (slight deviations could be otherwise I cu,oexplained), and a few experiments carried out with P t 1 ::$ alkali. -electrodes, using alkali of different concentrations, gave indication ofthe same behaviour. That cupric hydroxide is really far more solriblethan cupric oxide is also shown by the fact t,hat, whereas the formerwhen shaken up with alkali and an excess of finely-divided copper iscompletely converted into cuprous oxide within a few days, cupricoxide was found to be only altered slightly by a month's shaking.Itseems justifiable to assume therefore that the electrode is actingreversibly, and giving the true potential corresponding with the relativeconcentrations in the solution at any moment of Cu" and Cu' ions.This being so, the only other explanation open is that some kind ofchange is taking place in the copper oxide, rendering i t less soluble.This view seems particularly plausible, as cupric oxide is not crystallinebut amorphous, and as such is subject to the phenomenon of ageing,Which is bound up with a progressive decrease in solubility. Thenature of t h i s process is still obscure. It has been regarded as theresult of a slow crystallisation taking place in the amorphous mass,looking on the latter as a supercooled liquid.This does not seem veryprobable, as the solubility of the material should not then apprecisblyalter until completely changed into crystalline substance. Thephenomenon is particularly well marked in the cases 'of precipitatedcolloidal substances (Zeitsch. anorg. Chem., 1899, 20, 185 ; 1900, 25155; 1901, 27, 390; 1901, 28, 474; 1903, 3 0 , 331; 1904, 38, 377;1904, 4 0 , 428; 1905, 46, 333, etc.). It is there accompanied by aprobable loss of water, and by a striking decrease in the bulk andsurface of the precipitate, and Hantzsch (Zeitsch. anorg. Chem., 1902,3 0 , 338) has ascribed the lowering in solubility to both chemical andphysical reasons, the former depending on the supposed molecular dehy-dration which accompanies the ageing, and the latter being due to thegreat decrease in surface which is the result of the spontaneous coagu-lation of the material.Ostmald (Zeitsch. physikal. Chern., 1900,34, 395)had previously advanced the conception of dependence of solubility onsurface or size of grain to account for the differences displayed betweenthe red and yellow forms of mercuric oxide, and the idea mas furtherextended t o other substances (all crystalline) by Hulett (Zeitsch.physikul. Chern., 1901, 37, 385), Hulett and Allen ( J . Amer. C’henz.SOC., 1902, 24, 667), and von Steiriwehr (Zeitsch. Ekktrochem., 1906,12, 578). It has been lately shown (Trans., 1909, 95, 2151, andunpublished work of the author) that the initial decrease observedin the single potential readings of the system Ptand Hg I HgO alkali can be ascribed to a spontaneous diminution insolubility due to the same cause.In the present case the author is disinclined to adopt t h a t explann-tion.As mill be seen, the difference between the highest and lowestvalues experimentally obtained with the Pt 1 ::$ alkali electrodes is0.093 volt, which corresponds with a ratio of solubilities in the twocases of about 40 : 1. On the other hand, the greatest ratio in whichthe solubility of a substance has been increased by alteration of thesurface conditions is 3 : 1 (Hulett, Zoc. cit.). Further, the colloidalhydroxides to which Hantzsch has applied Ostwald’s conception docertainly shorn a very remarkable diminution of surface when ageing,whilst the samples of copper oxide with which the author has workedundergo no such change.A more probable explanation is that the phenomenon is due togradual polymerisation of the molecules of the copper oxide, and thata t any moment between the time of preparation of the fresh substanceand the time of complete ageing w e have a solid solution containingtwo (or more) kinds of molecules of different complexity in proportionswllich do not correspond with the equilibrium ratiosi Assuming, then,that the more complex riiolecule is the less soluble, and that the freshlyprepared material has an undue preponderance of simple molecules, thesolubility of a sample of copper oxide will slowly fall, until a valuehas been reached corresponding with the equilibrium concentrations ofthe differerit kinds of molecules.When shaken up with somethinCUPRIC OXIDE AND OF CUPRIC HYDROXIDE. 60-9which can exert a solvent action, the velocity of the process will beincreased. Alkali solutions must have that effect, owing t o the slightamphoteric nature of the copper oxide; and it is found by experiencethat left to itself, the oxide alters very slowly indeed, but that it agesin contact with alkali, and more rapidly in a concentrated than in adilute alkaline solution. We will adopt this polymerisation conceptionas a working hypothesis. 'l'hen it is very probable that the equilibriumof the different kinds of molecules will shift with increase of tempera-ture, and in favour of the less associated molecule, the formation ofwhich is probably accompanied by absorption of heat.Further, therate at which equilibrium is reached mill be greater the higher thetemperature ; and consequently, until equilibrium has set in,determinations of solubility, potential difference, dissociation pressure,etc. (all of them related quantities) will yield results depending to agreater or less extent on :( a ) Temperature of preparation of sample.( b ) Time during which it was kept at that temperature.(c) Rate of passage from temperature of preparation to temperatureof measurement.And the influence of the temperature of measurement will be a two-fold one, due to :( a ) The change of solubility, etc., of each different kind of moleculewith change of temperature, and( b ) The variation in the relative proportions of the different kindsof molecules with change of temperature.I n Fig.1, temperature is plotted along the abscissa and along theordinate solubility or dissociation pressure of the oxide. AB wouldrepresent the curve supposing all t h e molecules to be simple, and CL)supposing them all to be complex, whilst EP is the actual equilibriumcurve, which moves nearer to AB as the temperature rises, correspond-ing with a decrease in the proportion of the more complex molecules.With the simple assumptions already made, i t is possible to tracequalitatively on the above curve the behaviour of any sample ofcopper oxide on heating or cooling or measurement.Let, for example,the line AEC correspond with 17O, a t which temperature a specimenof copper oxide is made by withdrawing water from cupric hydroxide.It mill initially have the dissociation pressure corresponding with A.This will fall pretty rapidly a t first along the line AE. Supposewhen the point Q is reached the oxide be heated to a temperaturet,'. If no further polymerisatioii were t o take place, its path wouldbe along the line ab. Polymerisation will continue, however, and themore rapidly the higher the temperature (although the closer proximityof the curves ab and Ec at the higher temperature will tend todiminish the rate of change). The actual path followed then will fal610 ALLMAND : AFFINITY RELATIONS OFbelow ab, but close to it if the temperature be raised rapidly.If thetemperature be raised very slowly, then the equilibrium curve Ec will bereached proportionately sooner, and followed until c is reached. A tintermediate or variable rates of increase ol temperature, the linebc may finally be struck, or the curve Ec cut, and a point below it,such as d, ultimately reached, Hence, a t the temperature t,O theinitial dissociation preFsure given by the oxide may be equal to, greaterthan, or less than the equilibrium value.FIG. 1.37" 350" t," 700" 1000"We mill now attempt to interpret the single potential readingswhich were obtained for the system Pt N-NaOH in terms ofthe conception developed above.1. Value of Point A (Fig.1)-This is not given directly byelectrometric measurements, but can be deduced from the tensimeterreadings already discussed.We have :P H ~ O at 25' for Cu(HO), CuO + H,O~ 0 . 1 rnm. mercury,andpH20 at 25' for pure water=23*5 mm. mercuryCUPKIC OXIDE AND OF CUPRIC HYDROXIDE. 611Hence the decrease in free energy of the reactionCUO + H20 -+ CU( HO)(freshlypreparrd)93.5 at ,"jO is IZT In 5-0- 1= 0.06 log. 235 volt-faradays= 0.06 x 2-37 volt-faradsys.It will not be very diffeiaent a t 17".If the cellcurrent in cellf--- -were to be set up, the chemical result for the passage of o m faradaywould be the same reaction, namely :[fresh CuO] + [H20] -+ [Cn(HO),].Hence E.M.F. = 0.06 x 2.37 volts= 0.148 volt.We know that Pt Cu(Ho)2 N-NaOH= - 0.074 volt I CU20Therefore,= + 0.068 volt.2.Value of Point E (Fig. l).-For this valiie the author hastaken the lowest figure reached in any of the measurements, that is,-0.154 volt. It. was obtained with a sample of cupric oxide pre-pared by ignition of cupric nitrate. As the accompanying figure (2)shows, it was approached asymptotically, which fact supports theview that it represented the true equilibrium value. The other curveon the same diagram 'was given by a sample of oxide obtained byignition of cuprous oxide. Although not followed to the end (theelectrode vebsel broke), it appears likely that it would have reachedthe same limiting value. As we shall see later, there is anotherreason for thinking that - 0,154 volt is very near the correct value.3.Samples of Oxide aged at 950-1000°.-Some cupric oxide (i),prepared by igniting crystalline cupric hydroxide, was placed ina platinum crucible and heated in a platinum-wound electricheaterat 800-900" for 3 hours.,, 900-950 ,, 1 hour.,, 950-1000 ,, 3 hours.,, 1000' ), 1 hour.VOL. XCVII. Y 612 ALLhZSND : AFFINITY RELATIONS OFA second sample (ii), also from cupric hydroxide, was similarlyheatedat 800-900" for 14 hours.,) 950-970 ,, ? :: ), 900-950 ,)In both cases the oxide was allowed to cool in the furnace aftershutting off the current. The following readings resulted, usingelectrodes containing the above oxides.FIG. 2. 1 - 0.08- 0-10- 0.14TABLE IV. Temperature 17'.Time after setting "p.1 day2 days5 9 79 9 )13 , 720: 1 922 7 )29 7 )36 9 7Potential Pt 1 :$ N-NaOH in volts.- (ii)-0)-0.061 Volt- - 0.063 Volt-0.064 ,, --0.067 9 , --0.076 ), -- -0.073 ) )- - 0.078 ),- -0.081 ,,__ -0.084 ),Referring to Fig. 1, it is seen that for a high temperature, such as1000°, a t which equilibrium will be quickly reached, and a t which theproportion of simple molecules is comparatively high, the copper oxidedissociation pressure will correspond with a point such as e. If suddenlychilled, the ratio of the different molecular species would remainunaltered, and the falling dissociation pressure would follow the linee$ When measured electrometrically at room temperature, a veryhigh initial value would result.If cooled moi-e slowly, as waCUPRIC OXIDE AND OF CUPRIC HYDROXIDE. 613actually the case, the curve EF would probably be followed for sometime and then gradually left, the path eyh being taken. The point, h,finally reached would correspond with the initial potential value,- 0461 volt, given by these oxide samples. It is interesting t o noticethat these samples of oxide when first measured were unstable withrespect to cupric hydroxide, the potential Pt 1 ::$'), N-NaOHbeing -0.073 volt.4. Samples of oxide prepared by iynition of cupric nitrate, cuprichydroxide, or cuprous oxide in un open porcelain crucible over a Bunsenfiame.-The results of some of the preparations are shown in table 111and in Fig. 2. Other figures were as follows :TABLE V.Temperature 17".1 . setting up. a. b. C. cl.Time in days after- 0.097 - 0.107- 0.107 -- O.llO> 1 - 0.10323 - 0,1234 - 0.125 - 0.115 -- 0'118 - - - 0.1091- 0'112J- - 0.114- - 0.114 - 0.115)- 0.106 14- - 0'113 2330 - - - 0.115- 0.118 37- - -- -.-- - -These preparations were never subjected to such a high temperatureas those discussed under (3), and they were also cooled far morerapidly. During this process one would expect them to follow nearlythe line kl, falling a little below it only. The value l correspondswith the initial figure of -0,097 to -0.107 volt given in the table.The differences observed will be the result, amongst other things,of differences in time of heating, rate of cooling, etc.5. Samples of Oxide aged at 350°.-Two samples of crystallinecupric hydroxide contained in porcelain crucibles were heated ina nickel-wound electric heater to 330-350' for twenty hours.Thecrucibles were then taken out and allowed to cool. Two electrodeswere made up and measured in the ordinary way.(a) - 0.135 (2nd day) ; - 0.134 (13th day).(6) -0.133 (3rd day); -0.133 (10th day); -0.136 (17th day).There was thus hardly any alteration during the time of measure-ment, and, moreover, the two sets of figures agree very well withone another. From this fact we conclude t h a t equilibrium wasprobably reached in the two cases, and frozen by the rapid cooling,They gave :s s 614 ALLMAND : AFFINITY RELATIONS OFduring which the dissociation pressure would follow the line nzm.Thus, a low initial value would result,6.Xcmples of Oxide prepared at low tei,a~eratures.--Oxide wasprepared by dehydrating cupric hydroxide with aqiieous ammonia at25" and with aqueous potassium hydroxide a t 70'. The potential valuesof electrode systems containing preparations of oxides thus made onlyfell very slowly; although in one case measured for five weeks,values lower than -0.117 volt were never reached, as the tableshows :TABLE VI. Temperature 17".Potential difference Pt I :$ N-NaOH in volts. Time indays after A \setting up. 1. 2. 3. 4. 5. 6.123456789101112131416181925283235- 0'099- 0.100- 0'102- 0.105- 0~100)---- 0.105- 0.105---- 0.107- 0.107 - 0.108- 0.111- 0.113- 0.112---7.- 0.102--- 0.108- 0.111---- 0.111-- 0.114-- 0.116----- 0.116--It is evident thatreference to Fig.1 can interpret satisfactorily theinitial values given by the different electrodes, but gives no explanationof the reason for the very diEerent rates of ageing a t 17" of samplesof copper oxide which have been heated to different temperatures. Ithas been seen that oxide which has been heated to 1000° alters slowlyand regularly, that oxides which have been prepared at temperaturesof 700-800' age a t varying speeds, and that oxides heated onlyto 350' or below alter very slowly indeed. It is probable that thesedifferences are due to variations in the nature of the surface ofthe material or to similar causes, but more it is impossible to say.Apart from this point, if the view developed here that the changesobsenved duribg ageing are the result OF polymerisation be accepted ascorrect, it is obvious that electromotive measurements may prove to bCUPRIC OXIDE AND OF CUPRIC HYDROXIDE.615a very valiiable method for the investigation of the molecularcomplexity of certain solid substances.It should be meutioned here that Immerwahr (Zeitsch. Elektrochem.,1900-1, 7 , 477), Johnson (Trans. Amer. Electrochem. Xoc., 1902, 1,187), and Lorenz and Hauser (Zeitsch. anory. Chem., 1906, 51, 81)have all worked on electrodes of the type Cu I CuO alkali, which,however, have been shown by the author to be unstable, owing tocuprous oxide formation.It is interesting to note that Immermahrfound that oxide prepared from copper nitrate gave much morenegative values than oxide prepared by precipitation from hot aqueoussolution by alkali.Calculations of Afinity Values.We are now in a position to understand the relationships t o oneWe have the following another of cupric hydroxide and cupric oxide,three potential differences at 17' :Pt 1 &:: N-NaOH= + 0.068 volt.1 . 4 (Calculated approximateprobable value)= - 0.074 volt.The change [Cu(HO),] -+ [CuO] + [H,O].absorbs(Crystslline) (Fresh) (Liquid)96540 x [O*OSS - ( - 0*074)] joules= 96540 x 0.142= 13700 joules.The change [Cu(HO),] --+ [CuO] + [H,O].(Crystalline) (Stabilised) (Liquid)yives out 96540 x [ - 0.074 - ( - 0.154)] joules.= 96540 x 0.08= 7720 joules.If, however, the stabilised copper oxide is prepared directly from thecupric hydroxide, fresh solid cupric oxide, not an aqueous solution, beingthe intermediate stage, we are dealing with two successive reactions :( a ) reversible formation of fresh [CuO], absorbing 13700 joules, and ( b )irreversible formation of stabilised [CuO], giving out 21420 joules ;and dehydration cannot set in except when the aqueous vapourpressure of the system is kept below 0.1 mm.Then it will takeplace very slowly, its rate being determined by that of the reaction :CuO (fresh) -+ CuO (stabilised).When, however, the change Cu( HO), --+ CYuO(stabi1ised) + H,O ha616 ALLMAND AFFINITY RELATIONS OFan opportunity of taking place without the intermediate for mation of“ fresh ” cupric oxide, it will set in.This will happen, for exaiuple,if t h e cupric hydroxide is treated with some solvent, such as anammoniacal or alkaline solution, when the rate of reaction will dependon the concentration of the electrolyte, increasing with it. Thesaturated solution of cupric hydroxide is unsaturated with respect tothe non-polymerised “ fresh ” cupric oxide, but supersaturated withrespect t o the polymerised “aged” cupric oxide, and this willsettle out.From the data contained in this paper and in the author’s previouspublication, we can calculate the free energy of the reaction :[CU] + [CUO] -+ [CU2O].(Stahilised)If one faraday is furnished by the combinationCurrent in cellthe total chemical effect will be given by the above equation.Now we know that Cu I Cu,O N-NaOH = - 0,344 voltand Pt 1 :,PO(aged)N-NaOH = -0,154 volt,therefore the E.M.F.of the above combination is 0.190 volt, andthe free energy change of the reaction concerned96540 x 0.19= 4370 calories.4.1y caloriesThe total energy of the same reaction, calorimetrically determined,is 3600 cals. It should be noticed that, whereas the free energychange is deduced for cupric oxide which has become stabilised at theordinary temperature, the value of the total energy change used holdsfor copper oxide which was very probably not stabilised when workedwith. The two values are therefore not strictly comparable. It isnot, however, likely that the irreversible molecular changes due topolymerisation or depolymerisation at constant temperature are boundup with changes of any magnitude in the total energy of the substanceconcerned.This view is borne out by the fact that it is possible to calculatewith considerable accuracy the dissociation pressure of cupric oxide a thigh temperatures from electromotive measurements carried out at theordinary temperature (see the ensuing calculations), making use of thecalorimetrically determined value of the total energy change, andassuming it to be const:tnt over the whole temperature range. Bythe author’s conception, the molecular complexity of the cupric oxidCUPRIC OXIDE AND OF CUPRlC HYDKOXIDE.617is supposed to change essentially with the alteration in temperature.If this is accompanied by any marked change in total energy, suchcalculations would not be possible.Let us next consider the elementPt CuO (stabilised) alkali H2 I Pt.Current in cell +---I cu20It can be regarded as a H2-02 cell in which hydrogen at atmosphericpressure combines with oxygen furnished at the dissociation pressureof cupric oxide a t the temperature in question, and from our data wecan calculate this dissociation pressure.We know that, at 17",(stabilised) N-NaOH = -0,154 volt= - 0.810 volt.I CU20PtPt I H, N-NaOHHence the E.M.F. of the above cell at 17" is 0.656 volt.Putting the E.N.F. of the H2-0, cell a t 17" at 1.232 voltwe get :0.656 = 1.232 + 0-058 - log po2,4whence log po, = - 39 *7 = 40.3, andp02 at 17O for 4Cu0 -+ 2Cu20 + 0,= 2 x 10-40 atmospheres.By the use of the simple formula (26) given on p.69 of Haber'sThernaodynmics of Technical Gas Reactions, we can also calculate thedissociation pressures of cupric oxide at higher temperatures.Putting in A=O, 5"=290°, R = 2 , &= 67200, log.po2 = - 39.7,we get : k = - 48.9.If we now extrapolate to 1030" (1303" abs.), we obtainlogpo, = i . 4 2 ,or p a t 1030' for 4CuO -+ 2Cu,O + 0,= 0.26 atmosphere=200 mm.Experimental determinations by Wohler and Frey (Zeitsch. Elektro-chem., 1909, 15, 34) and by Foote and Smith (J. Amer. Chem. SOC.,1908, 30, 1344) give 170-lS0 mm. at 1030". The coincidence fallswithin the limits of experimental error as far as the electrometricmeasurements are concerned, and is much better than could beexpected, taking into consideration the approximate nature of thecalculation involved.This agreement affords additional support tothe correctness of the figure - 0,154 volt for the equilibrium value a t17' of the electrode potential Pt 1 :$ N-NaOH618 ALLMAND AFFlNITY RELATIONS OFIf, on the other hand, we calculate the dissociation pressure ofcupric oxide at the two temperatures mentioned from purely thermaldata by means of Nernst's well-known formula :(log. Po, = ~ - ' + 1.751og. I'+ gas),4-57 1'we get at 170" : yo, = 2.5 x atmosphereat 1030": poZ = 0.66 mm.I n both cases the values are far too low, but the discrepancy isWe can also calculate the free energy changes ( A ) for several other(i) A for [H,] + 4[0J --+ [H,O] = 2 x 1.232 x 96540 jonles.considerably greater at room temperature than at 1030O.reactions.We know that at 17O :(atmospheric (atmospheric (liquid)pressure) pressure)(ii) A for [Cii2O] -+ [HJ -+ ~ [ C U ] + [H,O] = 3 x 0,469 x(atiiiospheric (lic~uid) 96540 joules.(iii) A For 2[CuO] + [H2] --+ [Cu20] + [H,O] =- 2 x 0-656 x(stabilised) (atmospheric (lirillid) 96540 joules.pressure)pressure)By subtraction we get :(iv) A for 2[Cu] + &[O,] -+ [Cu20] = 2 x 0.763 x 96540 joules(atmospheric = 35200 calories.(v) A for [Cn20] + &[lo,] -+ 2[CuO] = 2 x 0.576 x 96540 joules(atmospheric (stabilised) = 36500 calories.(vi) A for [CU] + 4[0,] -+ [CuO] = 1.339 x 96540 joules(atmospheric (stabilised) = 30850 calories.With (iv) and (vi) we can compare the corresponding total energy(iv) ~ [ C U ] + &[O,] (atmospheric pressure) = [Cu20] + 40800 cals.(vi) [Cu] + $LO,] (atmospheric pressure) = [CuO] + 37200 cals.I n conclusion, a few remarks may be made concerning a phenomenonnoticed by Wohler in his studies of the thermal dissociation of oxidesof copper, palladium, platinum, and iridium (Bey., 1903, 36, 3475 ;Zeitsch.Elektrochem., 1905, 11, 836; 1906, 12, 781 ; 190S, 14, 9 7 ;1909, 15, 34). It was sometimes observed that the equilibriumoxygen pressure of a sample of oxide kept at constant temperaturedid not remain constant, but gradually fell. As the oxides in questionwere partly decomposed UKI der the conditions of measurement, heattributed this drop in pressure t o solid solution formation setting inbehween the still undecomposed oxide and i t s solid reaction product.Theprobability of this explanation being the true one cannot be gainsaid,pressure)pressure)pressure)changes. These have been calorimetrically determined, and gave CUPRIC OXIDE AND OF CUPRIC HYDROXIDE. 619but some of his experiments on cupric oxide were also carried out wibhsamples of material which were kept under an excess oxygen pressureuntil the first reading mas taken, and where very little opportunity ofcuprous oxide formation was consequently presented. In spite of thatfact, high initial va,lues which rapidly fell were noticed, and thesevalues did not represent states of equilibrium as the later onesobtained did, that is to say, if the pressure were slightly increased ordecreased, i t did not adjust itself again to its original value.Wohlerattributed these pressure changes also to solid solution formation, dueto the minimal amounts of cuprous oxide produced, in which case thedissociation pressures of pure cupric oxide would lie higher still. Itis quite possible, however, that they may be due to two other causes, asfollows :(I) High initi+l dissociation pressures given by the finest of thecopper oxide particles present. In two samples of oxide microscopic-ally examined by the author, one, prepared from copper nitrate, provedto have a large number of particles down to 1-2p in size, and theother, made from copper hydroxide by dehydratidn with ammonia at25", consisted to a great extent of particles of dimensions less than0.5p In both cases the solubility in aqueous solutions of the particleswould be affected by their size ; and Schoch (Amer.Chem. J., 1903,29,31 9) has further shown, experimentally, that the initial dissociationpressure given by yellow mercuric oxide, with its large proportion ofvery finely-divided material, greatly exceeds for that reason thepressures given by the red oxide, or by the yellow oxide which hasbeen heated for some time.(2) According to the conception which has been used to explain theexperimental results of this paper, freshly prepared copper oxide willalways contain an excess of the less complex molecules, and will there-fore have a higher dissociation pressure than a copper oxide in whichthe different molecular species have come to equilibrium. Thiscircumstance may be the cause of the lowerings of pressurementioned.It is also possible that the same cause may biing about the veryrapid fall of the initial dissociation pressure which was sometimesnoted by Wohler during his experiments with iridium dioxide.Theywere ascribed by him to the presence of the unstable iridiumsesquioxide.I n any case, isolated examples apart, the variations in potentialshown by an electrode system containing samples of copper oxidewhich have been subjected t o varying thermal treatment must,undoubtedly, have their counterpart in variations ill oxygen diseocia-tion pressures determined at higher temperatures ; and under suitableexperimental conditions, there is no doubt that such effects could b620 ALLMAND : AFFINITY RELATIONS OF CUPRIC OXIDE.isolated and studied.If not avoided they will certainly seriouslyaffect dissociation and affinity measurements, although less so than atlow temperatures, owing to the more rapid setting up of equilibrium.It will perhaps be objected that the possibility of solid solutionformation is not excluded from the author's measurements. Thelikelihood of such a complication is very small. None of the copperoxides worked with could be affected before measurements werestarted-they were never heated above 1000°, a t which temperaturetheir dissociation pressure is less than 100 mm., and particular carewas taken thoroughly to ignite those samples which were made fromcuprous oxide. We should need some positive evidence beforeadmitting the possibility of the formation of solid solution during themeasurements, at such a low temperature, and with the very smallCu" and Cu' ionic concentrations in the electrolyte. Moreover, thedifferent initial values given by different samples of oxide would notbe thereby explained.Summary of Results.(1) Freshly prepared cupric oxide ages with time, and its freeenergy content thereby falls.(2) This ageing is attributed t o increasing molecular complexity,not to crystallisation or t o surface changes.(3) The explanation given accounts qualitatively for the electro-motive behaviour of samples of copper oxide which have been subjectedt o varying thermal treatment, and may perhaps cast some lighton phenomena noticed in the determination of dissociation pressures ofcertain oxides at higher temperatures.(4) By means of tensirnetric and electrometric measurements, it hasbeen shown that crystalline cupric hydroxide is stable with respect tofreshly prepared cupric oxide, and unstable with respect to old samplesof cupric oxide.(5) The decreases of free energy involved in the following reactionshave been measured or calculated for 17".(i) [Cu(HO),] -+ [CaO] + [H,O].(fresh) (liquid)(ii) [CuOl -+ [CuO] (irreversible).(iii) [Cu] + [CuO] --+ [Cu20].(stabilised)(iv) ~ [ C U ] + +[Of] . --+ LCu20].(fresh) (stabilised)(atmosphericpressure)(4 [Cul + 4II02l .--+ ["UOI.(atmospheric (stabilised)presiureSOLUBILITIES BELOW AND ABOVE CRITICAL TEMPERATURE. 621(6) The dissociation pressure of cupric oxide at 1030" has beencalculated and found t o agree satisfactorily with Bxperimentalresults.The author wishes, in conclusion, t o offer his siucere thanks toProfessor Donnan for advice and criticism received during the progressof this work.MUSPRATT LABORATORY,UNIVERCIITY OF LIVERPOOL

ISSN:0368-1645    

DOI:10.1039/CT9109700603

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

SOLUBILITIES BELOW AND ABOVE CRITICAL TEMPERATURE. 621LXI1.-Solubilities Below and Above the CriticalTemperature.By DAN TYRER.IT was fir& observed by Hannay and Hogarth in 1879 (Chcm. News,40, 256) that a solution of a salt, when heated to a temperature abovethe critical point of the solution, does not necessarily deposit thedissolved salt on the disappearance of t'he liquid phase. They showed,for example (Chem. News, 1880, 4 1, 103) that a solution of potassiumiodide in ethyl alcohol could be heated to a temperature of about 100'above the critical temperature of the solution without the depositionof the dissolved salt.Pictet (Compt. rend., 1895, 120, 26) heated solutions of borneol,cineol, and terpineol in ether to temperatures above the critical pointwithout the precipitation OF any of the solute.P.Villard (Chem. News, 1898, 78, 297, 309) found that easilyvolatile solids, like iodine and camphor, will dissolve appreciably atthe ordinary temperature in compressed gases, such as oxygen andmethane.Centnerszwer and Tetelow (Zeitsch. BZektroche?n., 1903, 9, 799)have made some interesting experiments on the solution of anthra-quinone in liquid sulphur dioxide; they found that if a certainquantity of anthraquinone is heated in a sealed tube with a particularquantity of liquid sulphur dioxide, the following phenomena occur :(I) The liquid expands and then diminishes in volume, owing toevaporation, until all the liquid just disappears a t temperature t,.(2) As the temperature rises further, the quantity of anthraquinoneleft undissolved diminishes, and then liquid reappears at.temperaturet 2 -(3) The solid anthraquinone passes entirely into solution in theliquid a t temperature t,622 TYRER : SOLUBILITJES BELOW AND ABOVE(4) The liquid phase finally disappears at teniperature t,.Obviously in the above, the solubility of the antliraquinone in thevapour of the siilphur dioxide increases with rise of temperature,Centnerszwer and Tetelow made a f e w measurements of solubility in amixture of the liquid and vapour of the sulphur dioxide, but theresults are not of much interest here. The solubility would be due toa large extent t o the mere mechanical mixing of the vapour of theanthraquinone with the sulphur dioxide.The above experiments show clearly t h a t the phenomenon of solutionis not peculiar t o the liquid state, but, under certain conditions, thevapour of a liquid may dissolve solids in the same manner as a liquidsolvent.As no quantitative measurements of such solubilities seem to exist,it appeared to be of interest t o make some determinations.I ncommencing this work I had the following objects in view :(I) To determine the solubility of some non-volatile salts in liquidsolvents from the ordinary temperature t o the critical point.(2) To continue the solubility curve through and beyond thecritical point, and to find if there were any discontinuity at the criticalpoint.(3) To determine the solubility i n the vapour above the criticalpoint under different conditions of temperature and density of t h esolution.Method of Experiment.There seems to be only one practicable method of determiningsolubilities a t high temper'ttures near the critical point.This method isthe indirect one of starting with a mixture of the solvent and solute inknowii proportions and determining, by slowly raising the teniperature,the miniuium temperature of complete dissolution. Obviously thismethod is most accurate when there is a moderate change of solubilitywith change of temperature, and least accurate when this change isvery small. The efficiency of the method does, of course, dependlargely on the general efficiency of the apparatus and details ofworking.Apparatus.The sealed tiibes containing the mixture of solute and solvent wereheated in a specially constructed, electrically heated air-bath.Thisconsists (see Fig. 1) of a series of cylinders, A , B, C, and 11, madeof sheet-iron. The cylinder C is wrapped closely with thin iron wire(diameter 0.5 mm.), whichconducts the current and heats the bath. Itis insulated from t h e metal cylinder by a wrapping of asbestos paperThe heat radiatses first to cylinder E", and then to a thick (&-inch)iron cylinder E, in which fits closely, but loosely, another iron cylindeTHE CRITICAL TEMPERATURE. 623F, of the same material. Through all the cylinders are cut two pairsof opposite windows. By the handle at the side, the innermost cylinder,F, can be turned and the windows shut off. This serves the doublepurpose of keeping the temperature in the interior more uniform, andalso of protecting the apparatus from damage by a bursting tube.Onto the ends of the cylinder, R, can be screwed thick iron caps, thronghone of which passes a thick iron tube, T, which carries a thermometer.The sealed glass tubes are held in the interior by a clip to the tube Z',FIG. 1.-I In--Pand the ends of the sealed tube are visible through the windows. Thetube T' can, moreover, be raised or lowered by a screw, and thusany portion of the sealed tube brought into view. To prevent externalloss of heat as much as possible, the space between cylinders A and Bis packed with asbestos wool, and the windows in these cylinders arefitted with panes of glass. The terminals of the heating wire arebrought to two insulated copper cylinders, X , X ' , forming slidingcontacts with thick brass wires through which the current is brought.The ends of the outermost cylinder, A , are covered by sheet-iro624 TYRER : SOLTJBILITIES BELOW AND ABOVEplates, to which are fastened disks of asbestos board.The wholeapparatus j s mounted on stands, and rotated on the pivots by means ofa small motor attached by a rope to the pulley P. This serves thedouble purpose of agitating the liquid and salt inside the sealed tube,and of destroying convection currents of air in the interior of thebath and thus ensuring uniformity of temperature.This bath gives very good results. By varying the externalresistance to the current, the temperature can be varied from theordinary temperature to 400°, or can be maintained constant for anylength of time to O9lo at low temperatures and to about 0.3' at hightemperatures (350').The sealed tubes were made from glass tubing, the thickness of thewalls of which varied from about 2.0 mm.t o 4 mm. The capacity ofthe tubes was, on the average, about 30 C.C. The strength of sealedtubes depended largely on good clear glass free from surface scratches,and, of course, on the thickness and diameter. Tubing more than4 mm. thick, and of a moderate diameter, mas inconvenient to work inthe blow-pipe flame.The thermometers used were mercury thermometers reading to Oslo,but a t high temperatures i t was not found practicable to read to lessthan 0.25'.They were carefully graduated by comparison with astandard thermometer.It was found necessary in preparing the tubes to introduceparticular quantities of the solvent and solute, so as to give a particularpercentage concentration when saturated. Direct weighing of thesolvent became, on this account, impracticable, and the solvent was,therefore, run out of a very carefully graduated burette consisting ofa narrow tube with capillary exit-tube, which could be projected intothe open end of the tube that was being prepared. I n readingthe volume of the solvent added, correction was made for roomtemperature.Sodium Iodide und Ethyl Alcohol.The sodium iodide was purified in t h e ordinary way by recrystallisa-tion from a mixture of distilled water and alcohol.The last traces ofmoisture were removed by placing the partly dried salt in a bulb-tube and heating in a current of air until constant in weight.The ethyl alcohol was commercial " absolute " alcohol, from whichthe last traces of water were removed by repeated treatment withsodium followed by fractional distillation. I n order to prove that noreaction took place between the sodium iodide and the alcohol a ta high temperature, a solution containing a known weight of sodiumiodide was heated in a sealed tube to 300' for several hours. Aftercooling, the contents of the tube were analysed, when the originalquantity of sodium iodide was found to be presentTHE CRITICAL TEMPERATURE. 625The sealed tubes were prepared as follows : A selected piece of glasstubing was carefully and thickly sealed a t one end, and drawn out t oa narrow constriction a few inches from the other end.The capacityof the tube was then ascertained by running in mercury from aburette to a point in the constriction where the tube mas subsequentlysealed off, The tube was then cleaned and dried, and the requisiteamount of sodium iodide added from a weighed bulb-tube havinga, long tube as neck, which was projected into the open end of thetube being prepared. To prevent an explosion in the tube betweenthe air and the alcohol vapour when sealing off, the air was displacedby dry carbon dioxide, As a rule, the tubes were not evacuated,except those heated to the higher temperatures. The presence ofa small quantity of carbon dioxide was found, by blank experiments,not to affect the solubility to any measurable extent.The requisiteamount of alcohol was then added from the burette, and the tube thensealed off at a point in the constriction.I n preparing a tube for adetermination of the solubility in theliquid at a high temperature, where the density of the vapour is quiteappreciable, it was necessary to add such an amount of alcohol thatby thermal expansion the amount of liquid existing in the stateof vapour a t the temperature of the determination mould benegligibly small,To a certain point it was found that the solubility increased withrise of temperature, and in determining a minimum temperatureof dissolution within this range, the temperature was first raisedquickly and a rough idea of the dissolution temperature obtained,Then the tnbe mas cooled to about five degrees below this point.,and raised very slowly with constant rotation of the bath untilthe point was found a t which the last trace of salt just dissolved.The wholo experiment required, on the average, between four andfive hours.A t a higher temperature the solubility was found to decrease withrise of temperature, and in this case the temperature was raisedquickly until some salt separated from the solution.The temperatureof dissolution was then found as before, but by cooling insteadof heating.If the amount of alcohol added exceeded a certain critical quantity,then before the critical temperature was reached the solutionexpanded and filled the tube completely.At this point therewas a break in the curve and a new curve began. Similarly, if theamount of alcohol added fell short of this critical quantity, the liquidwould diminish in quantity, and, finally, all be vaporised before thecritical point was reached. Again, there was a break in the solubilitycurve, and a new curve of solubilicy in the vapour began626 TYRER : SOLUBILITIES BELOW AND ABOVEResults.The numerical results of the solubility of sodium iodide in liquidalcohol from the ordinary temperature to the critical point are givenin the following table. The values are calculated from a carefullydrawn and smoothed curve of the experimental results, which areindicated in Fig. 2.FIG.2.Xolubility of sodium iodide in ethyl alcohol from ordinary temperature to temperaturesabove the critical point.0 2 30-+- Temperature.Xolubility of Sodium lodide in Liquid Ethyl Alcohol from the OvdinaryTemperature to the Critical Point.Solubility.Parts by weight ofsodium iodide dissolvedTempera- in 100 parts of ethylture. alcohol.10" 43.77 +O-0430 44'25 +O*lO50 44-50+0'0580 45.0 k0.1100 45.1 k0.1120 45.2 +O-1160 45.0 k0.2200 42.3 k0.3180 44'3 +0'2Solubility.Parts by weight ofsociium iodide dissolvedTempera- in 100 parts of ethylture. alcohol.220" ' 38.5 +, 0.3230 36.2 f 0.4240 32-7f0-4250 26.2 f0-5255 21 '0 +_ 0.8260 10 -8 +, 0 *8261 -5 8-62 0'05(Critical temperatureof solution)The probable accuracy of the numbers is appended.From 250°to 261-5O there is an enormous fall in the solubility, and the accuracyof the determinations in this range is much impaired on this a.ccount.The point at which the meniscus of a saturated solution just disTHE CRITICAL TEMPERATURE. 627appears is 261.5'. This, it will be noticed, is very considerablyhigher than the critical point of the pure solvent, On reference tothe curve (Fig. 2) it will be noticed that the solubility increaseswith rise of temperature to about 140', and then decreases, a t firstslowly and then more rapidly, until the curve becomes almost vertical.A t 261.5' the liquid phase ceases t o be distinguishable from thevapoiir, and here there is a break in the solubility curve. Thisdiscontinuity is more apparent than real, as will be pointed out later.I n order to show the phenomenon of the slow disappearance of themeniscus, a tube of given volume must contain approximately adefinite amount of solvent.The amount of solvent contained in atube of given volume is expressed in terms of the concentration of thesolvent when all the liquid has disappeared, that is, the amount ofsolvent contained in unit volume. The critical concentration wasfound t o be 0.365, but this figure is only approximate, as the point isvery indistinct, concentrations of 0.370 and 0-360 both giving thecritical phenomenon of the slow disappearance of the meniscus. I fthe concentration of the solvent exceeds 0.365 gram per c.c., theliquid will expand and fill the tube entirely.If the Concentration ofthe solvent is, for example, 0.45 gram per c.c., the saturated solutionwill just fill the tube completely a t 2 5 5 O , and a t this point there is abreak in the curve, and, on continuing, the almost horizontal curveindicated is obtained. Similarly, a solution of concentration of thesolvent of 0.4 gram per C.C. fills the tube completely a t 259O, andanother curve branches out, which it will be noticed has a smallergradient than that of concentration 0*45. The critical curve ofconcentration 0.365 slopes still less. If now the concentration of thesolvent is below the value 0.365, the liquid boils away before thecritical point is reached. If, for example, the concentration is 0-1gram per c.c., the liquid just completely evaporates at 242O, and thenthere is a drop in the solubility from 31.9 per cent.in the liquid toabout 0.5 per cent. in the vapour. Temperature up to about 325' hasno measurable influence on the solubility in the vapour of this par-ticular concentration. A solution of concentration of the solvent of0.2 gram per C.C. also gives a curve parallel to the abscissa; the curveof concentration 0.3 has a very slight gradient.The numerical results of the solubility in the vapour at varyingconditions of temperature and concentration are given in the followingtable. The numbers express parts by weight of sodium iodide whichdissolve in 100 parts of ethyl alcohol.VOL. XCVII. T 628 TYRER : SOLUBILITIES BELOW AND ABOVESolubility of Sodium Iodide in.the Vapour of EtiJ.92 Alcohol d o v e thoCritical Point.Concentration of the Solvent.0'3 0.365 0-4 0.45 0.485.1+_0*05 8%+_0-05 11*6*0*1 17*.3+_0*2 21*6+_0-45 '1 8 '35 11-5 17.0 -5.0 8.2 11.0 16.5 -4.9 8'0 10.54.8 7.7 10-24.7 7.5 9 -7- -- - - -The above figures are calculated from the smoothed curves ofobserved results. The probable accuracy in the first series at 262' isappended. The accuracy of the remaining numbers is only com-parative, that is, it depends on the accuracy of the first series.Determinations in the vapour were very difficult to make. Owingto the homogeneity of the solvent above the critical point, the mixingof the solvent and solute was less efficient than in the liquid state,where the solvent was not wholly homogeneous.The salt had, more-over, a peculiar aptitude foricrystallising on the sides, but this difficultywas largely overcome by placing in the tubes small pieces of platinumfoil, which, falling up and down the tube, assisted the dissolution. Itwas found that the process of dissolution in the vapour was muchaccelerated by keeping the temperature a t the point at which theliquid disappeared, so that the undissolved salt remained moist, and thesaturated liquid solution would completely evaporate without deposi-tion of the dissolved salt. The following way of testing whether thesolution in the vapour was saturated or not proved very useful. Ifthe bath were kept vertical for a short time, the upper part of thetube would become slightly hotber than the lower part, with the resultthat the vapour within the tube would expand locally, and, if saturated,would deposit a thin, crystalline film of salt on the sides of the hotterportion of the tube.Indeed, it was possible in this manner t o distilthe solid salt from one portion of the tube to another. It was foundimpossible to continue the determinations above about 310°, for, inorder t o ensure a fair degree of accuracy, it was necessary to use fairlylarge tubes, so as to hold moderato amounts of the solvent and solute,and with increase in size of the tube, the strength decreased.The curve of solubility in the vapour a t 262O showing, the relationbetween solubility and concentration of the solvent is given inFig. 3.It will be noticed that the solubility diminishes regularly withdecrease of concentration, becoming practically zero at a concentrationof about 0.05 gram per C.CTHE CRITICAL TEMPERATURE.629Potassium Iodide and Methyl Alcohol.The potassium iodide was purified by recrystallisation, and com-pletely freed from traces of moisture by heating in a bulb-tube in acurrent of air until constant in weight. The methyl alcohol was thecommercial '' absolute " alcohol, which was freed from last traces ofFIU. 3.J'olubility curve of sodium iodide in vapmr of ethyl alcohol at 262'.h 5 0.4 Q & 0.35B 0.20 2 4 6 8 10 12 14 16 18 20 22 24water by keeping it over excess of anhydrous copper sulphate for afortnight, and then fractionally distilling. A sample, kept for monthsafterwards i n a sealed tube with a little anhydrous copper sulphate,did not affect the colour of the latter, although it dissolved a little toa blue solution.The general method of investigation was the sameas in the previous case, and it is only necewary to give here thethe numerical results and curves, No reaction was found to takeplace between potassium iodide and methyl alcohol even at 300'.T T 630 TYRER : SOLUBILITIES BELOW AND ABOVESolubiZitg of Potaasium Iodide in Liquid Methgll BEcoIbl f?*oqn theOrdinary Temperature t o the Critical I'oivd.Tempera -ture.15"305080100120140160180Solubility.Parts per 100 ofmethyl alcohol.14.50 f 0'0516'20 f 0.0518.9 f0.0622.5 +_0.0825.0 k 0 .129'2 k0.1530.7 f0-22'1'2 k 0 . 130.6 k 0 . 2Solubility.Tenipera- Parts per 100 ofture. methyl alcohol.200" 29.1 f 0.2220 27.5 f 0'2240 24.8k0.3245 22.6 +_ 0 -5247 21.0k0.5250 13'8 k 0-6252.5 7 -6 +_ 0 - 1(Critical temperatureof saturated solution)FIG. 4.Solubility curve of potassium iodide i i z met7Ly1 alcohol fyonz wdinnyy tempemtiweto 310".4036322824&ro 8 20840The above figures are calculated from a smoothed curve ofexperimental numbers. The probable accuracy is appended. Thecritical concentration of the solvent was found t o be about 0.36, butthis point is even more indistinct than in the previous case. The aboveresults are shown graphically in the curve in Fig. 4. It will be seenthat the solubility first increases to about 170' and then decreases.The rate of decrease during the range 240-250' is exceedingly great.The rest of the curve will be easily understood from the explanationgiven in the case of sodium iodide and ethyl alcohol.The numerical results for the solubility in the vapour are given inthe following tableTHE CRITICAL TEMPERATURE.631Solubility of Potassium Iodide in, Vapour of Methyl Alcohol above theCritical Point.Temper:t- Concentration.ture. ------------ 70 . 1 0.2 0'3 0.36 0.4 0 -45252" t0.3 1.0f0.05 3'7+_0*1 7'!+0*1 11%+_0*1 IS*l+_0.2- 270 - 5 3 3.5 4 '4 11 '5280 - 7 3 3'4 7.3 11.3290 -- 7 7 3'4 7.2 11.0300 - 7 9 3.3 7.0--- -The above figures represent the solubility in parts by weightThe accuracy of the numbers beyond the first series is dependent ondissolved in 100 parts of the solvent,.FIG.5.0 *5ttre accuracy of the numbers in the first series; the relation betweenthe soluhility in the vapour at 252O and the concentration of thesolvent is shown in the curve in Fig. 5 . The curve is similar to thatobtained in the case of sodium iodide and ethyl alcohol.Discussion of Results.The first and most interesting point to notice is that the solubilityin the vapour is a function of concentration of the solvent. Anextension of this idea to the liquid state explains the very great an632 JONES AND WHITE: A SUPPOSED CASE OFrather sudden fall of solubility in the liquid just below the criticaltemperature. For over this range the rate of expansion of thesolution is very much greater than at lower temperatures. It alsoexplains the apparent discontinuity in the solubility curve at thecritical point, for just previous to the critical point the solvent hasbeen undergoing a great decrease in concentration, and when this pointis reached this decrease, of course, stops and the concentration of thesolvent remains practically constant (the slight expansion of the glassbeing neglected), with the result that the solubility remains nearlyconstant. If we imagined the concentration of the solvent to decreasepast the critical point at the same rate as before, and if we plot thesolubilities for the concentrations thus obtained, we get no discontinuityat the critical point, but a perfectly uniform curve.The second point to notice is that the solubility in the vapourdecreases with rise of temperature, although the concentration remainsconstant, and, further, that this decrease is greater for the graater con-centrations of the solvent. This would suggest the formation ofhydrates in the solution which dissociate under the influence of heat.If the process of solution is due to an attractive force between themolecules of solute and solvent, then we should expect, as is herefound to be the case, that the solubility a t constant temperature wouldvary directly with the concentration of the solvent.I n conclusion, I desire to express my thanks to Prof. H. B. Dixonand Dr. A. Lapworth for much kind advice and interest taken inthe work.THE CHEMICAL DEPARTMENT,THE UNIVERSITY,MANCHESTER

ISSN:0368-1645    

DOI:10.1039/CT9109700621

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

632 JONES AND WHITE: A SUPPOSED CASE OFLXII1.-A Supposed Case of Stereoisomeric TervalentNitrogen Compounds.By HUMPHREY OWEN JONES and EDWARD JOHN WHITE.IN 1896 (Ber., 29, 1462) von Miller and Plochl described twoisomeric compounds, C,,H,,ON, obtained by the interaction ofm-4-xylidine and acetaldehyde in dilute hydrochloric acid solution :these differed in crystalline form, melting point, solubility, andstability. The more soluble and more fusible form, melting at102q hereinafter called the a-form, was partly converted into the@-form, melting at 131°, by crystallisation from solvents, by solutionin acids, or by heat. Both compounds gave the same oxime, benzoySTEREOISOMEKIC TERVALENT NITROGEN COMPOUNDS. 633derivative, and condensation product, (C,,H,3N)2, with xylidine,also the same 2 : 6 : 8-triniethylquinoline was obtained from both.The two isomeric compounds were therefore considered to have thesame structural formula, namely, C,H3Me,*NH*CHMe*CH2*CH0,and it was suggested that they differed only in the disposition ofthe three groups around the tervalent nitrogen atom.It is remarkable that the observations on this interesting caseof isomerism have not been extended, especially on account of itsimportant bearing on the stereoisomerism of nitrogen.The present paper contains a short account of a reinvestigationof these compounds, and of the preparation of similar compoundsfrom other amines.The method of preparation has been improved, and it has beenfound that the properties of the compounds agree generally withthose described by Miller and Plochl, but with the importantdifference that neither isomeride i s transformed into the other bythe action of solvents or of heat.This fact renders the hypothesisof stereoisomerism untenable, but the nature of the isomerism isstill a problem of general interest.Although no transformation is effected by heat or inert solvents,it is brought about readily by the action of acids. I n dilute acidsolution the a- and &forms are converted into the same equilibriummixture, consisting of approximately two parts of the a- to onepart of the P-compound, which is also the composition of themixture obtained in the preparation of the substances in the firstinstance : this equilibrium mixture in acid solution changes into2 : 6 : 8-trimethylquinoline, slowly a t the ordinary temperature, andrapidly on heating.I n addition to yielding the same oxime, benzoyl derivative, andcondensation product with xylidine, the two isomerides gave thesame benzylphenylhydrazone and the same methyl derivative,C,H,Me,~NMe*CHMe-CH,-CHO.The only difference in chemical properties which the two com-pounds have been found to exhibit is in their behaviour towardshydrogen chloride and towards nitrous acid.When a solution ofthe a- or 8-compound in ether or benzene was treated with hydrogenchloride, a compound of the composition C,,H,,ON,HCl was pre-cipitated in each case; that from the a-form melts a t 85O, whilst thatfrom the 8-form melts at 135--136O, and is identical with theproduct obt.ained by the action of aqueous hydrochloric acid.The difference in the products of the interaction of the twocompounds and nitrous acid is remarkable ; both compoundsyielded a non-basic substance which gave Liebermann's nitroso-reaction; but whereas the product obtained from the &form wa634 JOBES AND WHITE: A SUPPOSED CASE OFcrystalline and had the composition CI2Hl8O2N2, that from thea-form was oily and could not be obtained pure.The absorption spectra of the two forms have been examined,and the curves obtained are very nearly but not quite identical.Similar isomeric compounds have been prepared from p-toluidineand $-cumidhe.As regards the cause of this case of isomerism, it is clear thatthe a- and &compounds cannot be stereoisomeric, since each is toostable towards heat, and under the influence of solvents, and oftwo compounds differing only in the disposition of the groupsaround the tervalent nitrogen atom, one would inevitably be veryunstable. Yet any structural difference between the compoundsmust be slight and easily removed, since so many derivatives areidentical, and the absorption spectra are so nearly the same.I nall cases the a-compound is distinctly more reactive than theP-compound, but in two cases only are the derivatives of the twoisomerides diff erenfj, namely, the hydrochlorides and nitroso-compounds.the a-compound, andThe adoption of the formula C,H,Me,*NH*CHMe*CH,*CHO forfor the P-compound, affords a satisfactory explanation of all thefacts observed, with the exception of the action of nitrous acid.The hydroxytrimethyleneimine ring present in the P-compoundwould be unstable, especially towards acids, just as the trimethylene-imine ring has been found' to be (Howard and Marckwald, Ber.,1899, 32, 2031), and under the influence of acids or otherreagents would undergo fission, so that the product obtained fromthe P-compound with hydroxylamine, benzoyl chloride, benzyl-phenylhydrazine, or methyl iodide would be identical with thatobtained from the a-compound.Certain suggestions might be made to account for the differentproducts obtained by the action of nitrous acid, but the experi-mental evidence is insufficient to discriminate between them.Bothcompounds are insoluble in acids, so that it is improbable thateither is an ester or a salt.The products obtained with hydrogen chloride would be thesimple additive products, different for the a- and P-forms: thereis no evidence of the formation of an ammonium salt of the typesimilar to that formed from cotarnine (Dobbie, Lauder, and Tinkler,Trans., 1903, 84, 598)STEREOISOMERIC TERVALENT NITKOGEN COMPOU NDM. 6.35EXPERIMENTAL.The method given by Miller and Plijchl for obtaining the mixtureof the two isomeric compounds consists in mixing xylidine, dilutehydrochloric acid, and acetaldehyde, keeping the mixture for oneday, and then fractionally neutralising it.A dark resinous sub-stance is first formed, and is removed, after which a red oil, repre-senting the isomeric mixture, separates.This is extracted withether, and the crystalline product is obtained from the etherealsolution after concentration, part of it by addition of liglitpetroleum, and the remainder by keeping t>e gummy motlierliquor for some days, when a further crop of crystals separates.In this way 20 grams of xylidine yield 17 grams of yellow, solidproduct.Several difficulties were encountered in repeating the preparationas above described. There is no definite stage in the neutralisationof the acid solution to separate the resinous from the oily pre-cipitates, and in reality a complicated succession of precipitates ofdifferent degrees of colour and consistency is obtained. Con-sequently, either the yield of solid product is small, owing to thegreater part of the crystalline material having been removed alongwith the “ resin,” or less resin ” is separated and the crystallinematerial is only very slowly obtained from the impure etherealsolution.Moreover, in addition to the two crystalline, isomericsubstances, and to the dark-coloured, uncrystallisable substance,which is probably ethylidenexylidine, C,H,Me,-NXHMe, a thirdcrystalline substance is invariably present in the product, theso-called bimolecular ethylidenexylidine, C,,H,,N,. Miller andPlijchl seem to have overlooked its presence, but it is formed inconsiderable quantity, 20 grams of xylidine yielding about 4 grams,and of this amount a large proportion must inevitably have beenpresent in their 17 grams of crude product.It was found possible, however, by modifying the original methodof preparation to overcome both difficulties simply and successfully,and thus obtain a better yield of the product as a white, crystallinesolid.The modified process depends on the fact that both thecoloured, uncrystallisable impurity and the bimolecular ethylidene-xylidine are soluble in light petroleum and dissolve very readilyif the light petroleum is present at the time of their precipitation,whereas the isomeric substances are only very sparingly solublein the cold solvent. The method is as follows.Xylidine (10 grams) was poured into Erlenmeyer flasks containingtwice the equivalent quantity of hydrochloric acid diluted withwater to 120 C.C.A slight excess (11 c.c.) of acetaldehyde wa636 JONES AND WHITE: A SUPPOSED CASE OFadded, and the mixture kept in the stoppered flasks at the ordinarytemperature for at least eighteen hours.* About 40 C.C. of lightpetroleum were now added, and the requisite amount of alkalifor complete neutralisation was poured in quickly, the flask beingvigorously shaken. The red petroleum solution contained theimpurities, and after a few minutes the isomeric mixture separatedas a white, crystalline cake on the surface of the water-layer. Thesolid product was collected, washed with light petroleum and water,and dried.The crystalline mixture, 1 2 grams of which are thus obtainedfrom 10 grams of xylidine, melts at 84-8707 and consistsapproximately of 8 grams of the a- and 4 grams of the 6-isomeride.The composition in this and other cases is approximately deducedfrom the residue of P-compound left after extracting the moresoluble a-compound from a weighed quantity of the mixture,allowance being made for the P-compound, which is removed atthe same time.Miller and Plochl obtained the less soluble &form by fractionalcrystallisation from ethereal solution and the a-form by mechanicalseparation. The following method was found much more suitablefor the preparation of the P-compound.The amount of benzenerequired to dissolve the more soluble component was added tothe mixture (60 C . C . of benzene for 12 grams of mixture), and aftershaking for about half an hour. the solid residue was removedby filtration.After one recrystallisation from benzene, nearly4 grams of pure substance were obtained.The a-isomeride is very difficult to separate in a state of purity.The method of mechanical separation is unsuitable for obtaininglarge quantities of the pure substance. This is chiefly becauseneither compound shows much tendency to crystallise in largeindividual crystals. Various solvents were tried, and many modi-fications were made in the conditions of crystallisation andseparation, but in every case only a very small proportion of eachproduct consisted of separable crystals. Even under the mostf avourable conditions the crystallised mixture is mainly made upof masses which consist of radiating clusters of both kinds ofcrystals, and cannot be detached so as to admit of mechanicalseparation.For the same reason, although there is an appreciabledifference of density, namely, 1-13 and 1.19 for the a- and &formsrespectively, the method of separating by means of B liquid ofintermediate density was also unsuccessful. Since, as will be seenlater, the a-form is not transformed by the action of inert solvents,* Longer keeping than eighteen honrs, even for several days, has no furthernfluenee on the nature or quantity of the productsSTEREOISOMERIC TERVALENT NITROGEN COMPOUNDS. 637it should be possible to separate it by fractional crystallisation.Repeated crystallisation from various solvents never gave specimenswith a higher melting point than 96-99O, whereas the purea-compound melts a t 103-104O.The explanation of this un-doubtedly lies in the relative solubilities of the two compounds.The solubilities in various solvents, including benzene, ether,acetone, and alcohol, were determined, and it was found that, ineach of these cases, the ratio between the solubilities of the com-pounds has very nearly the same value, namely, about 4 : 1. Itfollows that the more soluble component cannot be purified by asimple process of crystallisation until a solvent is found for whichthe two solubilities are either more nearly equal or more discrepantthan they are in the above cases. The difficulty caused by thisaccidental uniformity in the relative solubility of the two isomerideshas not yet been overcome. A t present the only means of obtain-ing the pure a-compound is by mechanical separation followedby crystallisation; this is very slow and tedious, but enough ofthe pure a-compound has been obtained in this way to allow of aninvestigation of its properties.Melting Point.-The melting points given by Miller and Pliichlare 1 0 2 O and 1 3 1 O for the a- and &compounds respectively.It isnow found that the a-form melts a t 103-104°, and the &format 127-128O. I n both cases, especially the former, the meltingpoint is much affected by the presence of impurity. It. is note-worthy, in connexion with the question of transformability, thatthe melting point of individual rhombohedral crystals picked outfrom the crystalline mixtures is never more than 99-l0lo, and isusually considerably lower ; therefore, after mechanical separation,the crystals of the a-compound must be recrystallised before thesubstance can be obtained quite pure.Crystalline Form-The crystals of the a-isomeride havecommonly a rhombohedral appearance, but are often elongated, andare then not so easily distinguished from those of the &form.Thelatter are flat needles, differing from the former in possessingmarked cleavage, the cleavage fragments being diamond-shaped.Both kinds of crystals occur usually as radiating clusters of smallindividuals.8oZubiZity.-The a-compound is easily soluble in acetone, benzene,ether, or alcohol, these solvents being arranged in descending orderof solubility. It is very sparingly soluble in cold, but moderatelyso in hot light petroleum, and insoluble in water.It is readilysoluble in dilute acids. The solubility of the P-isomeride, as alreadystated, is in all these cases proportionately less, the ratio being verynearly constant at. 1: 4638 JONES AND WHITE: A SUPPOSED CASE OFAbsorption Spectra.-These were observed by Mr. bJ. E. Purvis,and are described in the paper following this. The curves forthe two isomerides are very nearly but not quite identical. Thespectra of the corresponding p-toluidine derivatives, the pre-paration and properties of which are described later, show veryclearly a difference of precisely the same nature as that observedin the xylidine derivatives.It is impossible to draw very definite conclusions from theseresults as to the constitution of the two compounds, but it isextremely probable that two substances, with absorption spectraso nearly the same, would only differ slightly in chemical con-stitution.TransfoT?TWEbiZitY.-Miller and Plochl state that the 8-compoundis stable, but that the a-compound is (( partly " transformed intothe other form by (i) simple crystallisation from solvents; (ii)keeping in acid solution for some time; (iii) heating above itsmelting point.It w a found that no transformation could beeffected either by solvents or by heat.I n addition to showing that the pure a-compound could berecrystallised several times' without changing the melting point,the following more stringent experiments were made. Solutionsof the purified substance, melting at 103-104°, in different solvents,such as benzene or light petroleum, were heated to looo in sealedtubes for several hours, after which the substance was recoveredabsolutely unchanged.The effect of heat alone was examined by heating the a-form inan air-oven to l l O o (at higher temperatures quinoline formationtakes place very rapidly).The substance was then washed withlight petroleum in order to remove any trimethylquinoline whichhad been formed, and the residue again proved to be unchangedsubstance, melting a t 103-104O.The 8-compound was submitted to the same treatment and foundto be equally stable.Action of A cids.-The two compounds are, however, transformedon treatment with acids. The a-form is much more easily dissolvedby dilute hydrochloric acid than the B-form, but on keeping inacid solution each form is transformed into an equilibrium mixture,which has the same composition as the mixture obtained whenthe substances are prepared in the ordinary way by the con-densation of xylidine and aldehyde in acid solution.In cold diluteacid the change is slow, needing several days for completion, buton warming the solution, the equilibrium is attained in a fewminutes. I n all cases when either the a- or the P-compound isdissolved in acid and reprecipitated by the addition of alkali, thSTEREOISOMERIC 'I'ERVALENT NITROGEN COMPOUNDS. 639quantity of base recovered is considerably less than the amountdissolved, owing to the formation of 2 : 6 : 8-trimethylquinoline,which takes place very readily under the influence of acids.Action of Hydrogen Chloride.-The a- and B-compounds weredissolved in dry ether or benzene, and dry hydrogen chloride waspassed into the solution, when a white precipitate separatedimmediately.The a-form yielded a deliquescent product, which sintered at80°, and melted with frothing at 85O:0.2755 gave 0.6345 CO, and 0.1910 H,O.0'2579 ,, 0.1654 AgCl. C1=15*8.C,,H1,ON,I3C1 requires C = 63-3 ; H = 7.91 ; C1= 15.7 per cent.The aqueous solution was acid t o litmus, and on the addition ofalkali an oil separated, which crystallised after some time.Thecrystals melted at 8S0, and were a mixture of the a- and &forms.The &form yielded a white, crystalline precipitate, which meltedwithout decomposing at, 1 3 5 4 36O, and could be recrystallisedfrom alcohol or water unchanged.The same substance is producedby allowing a solution of the base in aqueous hydrochloric acidto evaporate spontaneously, when it separates in long, needle-shapedcrystals :C = 62.8; H = 7.7.0.2715 gave 0.6220 CO, and 0.1895 H,O.0.2855 ,, 0.1865 AgC1. C1=16*1.C,,H,,ON,HCl requires C = 63.3 ; H = 7.91 ; C1= 15.7 per cent.The aqueous solution, on the addition of alkali, deposited acrystalline solid, which melted at 125O, and consisted of the B-form.Formation of Trimethylquino1ine.-The action of heat or ofstrong acids is, as stated by Miller and Plochl, t o decompose thecompounds with formation of 2 : 6 : 8-trimethylquindine. Thus,if the a-compound is heated t o 120° in an air-oven for half anhour and the residue distilled in a current of steam, a 50 percent.yield of trimethylquinoline will be found in the steam dis-tillate as large, crystalline plates, melting at 4546O. TheP-compound requires heating to 150° for about two hours t o givea similar yield.Acids, even when cold and not very concentrated, slowly effectthe same transformation, and the change takes place completelyif either of the compounds is warmed for a few minutes withconcentrated hydrochloric acid. This effect of acids is alsoillustrated by the action of d-camphorsulphonic acid. Dry acetonesolutions of the two bases were mixed with dry acetone solutionsof d-camphorsulphonic acid, with the object of preparing thecamphorsulphonates.A crystalline product separated in eachcase, melting after purification at 229--231°, but when examinedC = 62.8; H = 7.8640 JONES AND WHITE: A SUPPOSED CASE OFwas found to be a camphorsulphonate, not of the original bases,but of 2 : 6 : 8-trimethylquinoline. I f ether is added to the solutionimmediately after mixing, colourless crystals separate, which meltat a low temperature (about 1 0 3 O ) , but these change rapidly intothe camphorsulphonate of 2 : 6 : 8-trimethylquinoline.Aldehyde Reactions.-Miller and Plochl lay stress on the factthat both compounds reduce ammoniacal silver solutions, takingthis as indicating their aldehydic nature. The silver reductiondoes actually take place, but in neither case so readily as thatbrought about by the simple amines, such as xylidine itself. Thetest, therefore, is valueless.Both compounds do, however, condensewith hydroxylamine, benzylphenylhydrazine, and xylidine, andthese condensations will now be described.Condensation with Hydroxylu?nine.-The method of preparingthe oximes described by Miller and Plochl was found to give goodresults. Both compounds give a 60 per cent. yield of the samecompound, which, when crystallised from alcohol, melted at163--166O, Miller and Plochl’s value being 1 6 5 O . As the analysisgiven in the original paper is somewhat unsatisfactory, the follow-ing analytical results are appended :0.1785 gave 0.4570 CO, and 0.1450 H,O.C,,H,iON, requires C = 69.9 ; H = 8.75 per cent.Since the isomeric compounds are both transformed into amixture in acid solution, attempts were made to condense themwith free hydroxylamine in alcoholic solution. Under these con-ditions, however, no reaction occurred, and the unchanged. baseswere isolated.Condensation with Xy1idine.-Both substances can be condensedwith xylidiiie by simply mixing calculated quantities in alcoholicsolution, and heating on the water-bath in a sealed tube, or in aflask provided with a reflux condenser.The condensation productis very sparingly soluble in alcohol, and in about three hours, inthe case of the a-compound, it separates out as a white, crystallineprecipitate, the yield being about 25 per cent. of the theoretical.The /3-isonieride gives an equal yield after about six hours’ heating.This method of condensation is found considerably quicker andsimpler than Miller and Plochl’s method of heating the reagentssuspended in a large quantity of water and afterwards proceedingto isolate the condensation product.The only information available with regard to this condensationcompound, the so-called bimolecular ethylidenexylidine, is to befound in a short paragraph in Miller and Plochl’s paper (Zoc.c i t . ,p. 1467), therefore a few supplementary details are given here.The compound crystallises in isolated, flat, six-sided plates withC = 69.8; H = 9.0STEREOISOMERIC TERVALENT NITROGEN COMPOUNDS. 641vitreous lustre, and melts a t 144-145c; Miller and Plochl give147O. It is moderately easily soluble in cold light petroleum,thereby differing from the isomeric compounds; it is easily solublein benzene, ether, or dilute acids, and very sparingly so in alcohol.No analyses or molecular weight determinations for the con-densation product appear to have been published, but it hasundoubtedly the formula C20H26N2, as the following results show :0.2070 gave 0.6185 CO, and 0.1660 H20.0.415, in 17.50 benzene, gave A t = - 0*400°.Miller and Plochl assume that the constitutional formula isC6H,Me,*NH.CHMe*CH,*CH:N*c6H~Me,.Its empirical formulashows it to be a bimolecular polymeride of the simple Schiff's base,C,H3Me,*N:CHMe, and the method of preparation and generalproperties render the above constitutional formula prima facieprobable.In addition to the method of preparation described above, twoother methods may be employed.It is formed along with theisomeric bases when xylidine is condensed with acetaldehyde inacid solution, as has already been mentioned, but it is mostconveniently prepared by the direct condensation of xylidine withacetaldehyde in alcoholic solution. The calculated quantity ofacetaldehyde is slowly added to an alcoholic solution of xylidineat Oo, when the product separates first as a red oil, but in a fewminutes solidifies t o a jellow mass, which is collected and purifiedby recrystallisation from alcohol.The compound is readily soluble in dilute acids, but in acidsolution it slowly decomposes into xylidine and the equilibriummixture of the isomeric compounds, the reaction occurring in thefirst method of formation being thus exactly reversed.It wouldtherefore appear that, in acid solution, there is an equilibriumbetween the three substances, bimolecular ethylidenexylidine andthe two a- and P-compounds.Condensation with Benzylphenylhydrazine. - The compoundswere dissolved in alcohol, calculated quantities of benzylphenyl-hydrazine added, and the solutions allowed to evaporate. Gummyresidues were left, which crystallised after several days. Aftercrystallising from alcohol, it was found that the same derivative,melting at 120-121°, was obtained from both compounds:C = 81.5 ; H = 8.9.M.W. =296.C2,H26N, requires C = 81.6 ; I€ = 8.84 per cent. M.W. = 294.0.1597 gave 0.4725 CO, and 0.1148 H,O.C=80*6; H=7*98.requires C = 80.9 ; H = 7.82 per cent.Reaction with BenzoyE Chloride.-The reaction with benzoylchloride takes place readily on adding excess of benzoyl chloride toa benzene solution of either compound in presence of a large excessC,,EL,,N642 JONES AND WHITE: A SUPPOSED CASE OFof 10 per cent. sodium hydroxide solution. The mixture is shakenvigorously during the addition of the benzoyl chloride, and finallyshaken until all the benzoyl chloride has disappeared. After twoor three hours, a white, crystalline product separates and floats onthe benzene solution, and represents a 72 per cent. yield of thebenzoyl derivative, which, after crystallising from alcohol, meltsat 149-150°. It is sparingly soluble in ether or benzene, andquite insoluble in dilute acids.On the latter account, the com-pound must be an imino- and not a hydroxy-derivative, since thebasic character of the original substances has evidently beendestroyed by the introduction of the benzoyl group.Reaction w i t h Nitrous Acid.-In this case the two compoundsshow a remarkable difference of behaviour. Both compounds, whendissolved in cold dilute hydrochloric or acetic acid and treatedwith potassium nitrite solution, gave precipitates which, aftercareful washing, gave Liebermann’s test for nitroso-compounds.Both compounds would therefore appear to be secondary bases,but there is this difference. In the case of the a-compound theprecipitate is a yellow, oily substance, which cannot be obtainedcrystalline, whilst the &compound gives a t once a faintly yellow-coloured, crystalline precipitate.The latter was recrystallisedfrom ether and light petroleum, and obtained in plates, melting at112-113’ :0-1100 gave 0.2635 CO, and 0.0715 H,O.C,,H,,O,N, requires C = 65-45 ; H = 7-27 per cent.-4ction of Methyl Iodide.-The a- and j3-compounds react slowlywith methyl iodide, forming sometimes a gummy substance, whichafterwards becomes crystalline, and sometimes forming a crystallineproduct directly.The products were readily soluble in alcohol, and appeared tobe mixtures.The aqueous solutions have an acid reaction, and on treatmentwith sodium carbonate or sodium hydroxide each compound yieldeda small quantity of oily precipitate, which crystallised on keeping;this was readily soluble in ether, but very sparingly so in lightpetroleum.On repeated crystallisation from a, mixture of etherand light petroleum, the products from the a- and B-compoundsseparated in fine needles, melted at 4 5 4 6 * , and were apparentlyidentical. It seems probable that this is the methyl derivative,C,H,Me,*NMe*CHMe-CH,-CHO. . This product resembles2 : 6 : 8-trimethylquinoline in some respects, but the solubility inlight petroleum discriminates between them, since the quinolinederivative is readily soluble in this solvent.Other pure compounds have not been separated from the productsC = 65.3 ; H = 7.22STE:I1EOISOMERIC TERVALENT NITROGEN COMPOUNDS. 643of the action with methyl iodide, but on repeated recrystallisationthe melting point varied from 215O to 230°, and the composition wasapparently that of a mixture.It is probable that in each case theproduct is a mixture of the methyl iodide additive compounds of2 : 6 : 8-trimethylquinoline and of the tertiary base mentionedabove, together with the hydriodide of the latter.Analogous Compounds from other Anlines.-Several amines,including aniline, 0- and p-toluidines, 0- and p-xylidines, &nd+-cumidine, were treated with acetaldehyde in acid solution in thesame manner as m-4-xylidine. The precipitates obtained byneutralisation in presence of light petroleum varied considerablyin appearance. In two cases, those of p-toluidine and t,!-cumidine,the precipitate was slightly coloured and crystalline, but theother amines gave products which were viscous and dark coloured.The products obtained from p-toluidine and $-cumidine were frac-tionally crystallised, and found to consist of mixtures of twoisomerides corresponding with the a- and P-xylidine isomerides,along with compounds corresponding with bimolecular ethylidene-xylidine.I n the q-cuniidine product, the latter derivative pre-dominates, and it is probable that, with many of the other bases,the isomeric pairs of compounds only form a very small part of theproduct, the regular condensation product being the polymerisedSchiff's base.The P-compound isolated from the p-toluidine product consistedof small, colourless plates, melting a t 164-167O, readily separatedfrom the a-compound by crystallisation :0.1570 gave 0.4265 CO, and 0.1185 HiO.C,,H,,ON requires C = 74.57 ; H = 8.47 per cent..The a-compound can be obtained by recrystallising the moresoluble product and picking out the stout plates, which melt a tC= 74.1 ; H = 8.38.108-110' :0.1673 gave 0.4555 CO, and 0.1295 H,O.From the cumidine product the derivatives isolated were :The less soluble P-con~pound, melting a t 110-112° :0.2112 gave 0.5875 CO, and 0.0760 €I,O.The a-compound melts a t 80°.The bimolecular Schiff's base, soluble in light petroleum, wasIt closely resembles theC = 74.23 ; H = 8-60.C,,H,,ON requires C = 74.57 ; H = 8-47 per cent.C=75-3; H=9*25.C,,H,,ON requires C = 76.0 ; H = 9.27 per cent..also isolated, and melted at 160-161O.corresponding xylidine compound in its properties :0.1727 gave 0.5140 C02 and 0.1415 H,O.VOL. XCVII. u uC=81*2; H=9*4.C&H,,,N, requires C = 81.98 ; H = 9.3 per cent($44 PUKVIS : ABSORPTION SPECTRA OF P-TOLUIDINE, M-XYLIDINE,These results show that the cause of the isomerism is not in anyway connected with the benzene nucleus in m-4-xylidine, but isapparently general.The expenses of this investigation have been defrayed by meansof a grant from the Government Grant Committee of the RoyalSociety, for which we are glad to make this grateful acknowledg-ment.USIVERSITY CHEMICAL [>AUOILATORP,CAMBRIDGE

ISSN:0368-1645    

DOI:10.1039/CT9109700632

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

($44 PUKVIS : ABSORPTION SPECTRA OF P-TOLUIDINE, M-XYLIDINE,LXIV.-The Ahsoiytion Spectra of p- Toluidine,m-Xylidane, rx,nd of their Condensation I’roductswith Acetaldehyde.By JOHN EDWARD PURVIS.WITH regard to the preceding investigations of Jones and White,it appeared to be of some interest to study the absorption spectraof the compounds they obtained in order (1) to compare the spectrawith those of ptoluidine and of m-4-xylidine, and (2) to comparethe spectra with each other so as to differentiate, if possible, thesuggested linking of the nitrogen atom.The absorption spectrum of p-toluidine has been examined byHartley (Trans., 1885, 47, 685), and he found two bands in thedilutions he employed, one range being h 3171 - h 2701, and theother h 2568 - h 2310.The absorption curves have been investigatedby the method and apparatus used by Purvis and Foster (Proc.C a d . Phil. SOC., 1908, 14, 381), and the results confirm Hartley’sobservations. It will be noticed (Fig. 1) that there are two bands,and that before the appearance of the band on the less refrangibleside, the one on the more refrangible aide of the spectrum dis-appears as the thickness of the solution increases.The spectrum of m-4-xylidine has not hitherto been studied, andfrom the absorption curve it will be seen that the bands are similarto those of p-toluidine. The differences are that the weightingof the molecule has produced a slight shift of the bands towardsthe red end of the spectrum, and also that the bands are notquite so persistent, the difference in this respect being greater forthe more refrangible band.The bimolecular ethylidenexylidine (in.p. 144--145O), the con-stitutional formula of which may be writtenC6H,&1e2*NH CHMe*CH,*CH :N*C6H3Me2AND OF THEIR CONDENSATION PRODUCTS WITH ACETALDEHYDE. 645was examined, and from the absorption curve (Fig. 1) i t will benoticed that there has been a great shift of the band towards thered end of the spectrum, and that only one band was cbserved,the persistency of which was considerably diminished. The bandon the more refrangible side occurring in m-4-xylidine was notFIG. I.Oscillation frequencies.32 34 56 38 40 42Continuous curve p- Toluidiiie.Dotted curve rn-Xy Zidine.Dot and dash curve Bimolecular etkylidencxylidine.observed; and, although more diluted solutions of N/1000 andiV/ 10,000 strengths were also examined, there were merely indica-tions of this second band.The effect of the union of the twosimilar xylidine residues by the aliphatic group has been to reducethe persistency of the bands and not to destroy them.The condensation product of p-toluidine and acetaldehyd646 PURVIS : ABSORPTION SPECTRA OF P-TOLUIDINE, M-XYLIDINE,(a-form, m. p. 108-110°), C,H,Me*NH*C€IMe*CH,-CHO, wasexamined; and as regards the general form and persistency, thecurve (Fig. 2) shows the presence of only one band, very similar tothe band of p-toluidine on the less refrangible side of the spectrum.This band is shifted more towards the red end as a result of thep- Toluidine derivatives.Continuous curve a- C’ompoz~nd.Dotted curve &Compound.FIG. 2.Oscillation frequencie3.30 32 34 36 38 40weighting of t’he molecule, and the second band on the morerefrangible side has disappeared.The corresponding P-compound (m.p. 164-1 6‘i0), the suggestedconstitutional formula of which is :was also examined, and it will be not’iced that the absorptioncurve (Fig. 2) is similar to that of the a-isomeride both in formand position, although i t is slightly less persistentAND OF THEIR CONDENSATION PRODUCTS WITH ACETALDEHYDE. 647The condensation product of mr4-xylidine and acetaldehyde(a-f orm, m. p. 103-104O) , C,H,Me,*NH-CHMe*CH,*CHO, wasexamined, and on comparing the curve (Fig. 3) with that ofm-4-xylidine, it is noticeable that only one band is visible, thepersistency of which is greater than that of the latter substance,and also greater than that of the corresponding compound obtainedfrom p-toluidine.The band on the more refrangible side hasFIG. 3.Oscillation frequencies.30 32 34 36 38 40m-4-Xylidine derivatives.Continuous curve a- Compound.Dotted curve B- Compound.Dot and dash curve a-Compound with hydrochloric acid.disappeared, exactly similar to the effect in the correspondingsubstance obtained from ptoluidine.The P-co,rnpound (m. p. 127-128O), the constitutional formulaof which, i t is suggested, may be648 PURVIS : ABSORPTION SPECTRA OF P-TOLUIDINE, M-XYLIDINE,was examined, and the absorption curve (Fig. 3) is not unlike thatof the a-compound, although it is not quite so persistent.Thereis therefore precisely the same kind of difference between these twosubstances as between the two corresponding substances obtainedfrom ptoluidine.It has been noticed by Hartley (Zoc. c i t . ) , Baker and Baly(Trans., 1907, 91, 1122), and Purvis (Proc. Carnh. Phil. Soc.,1908, 14, 436) that the effect of adding hydrochloric acid to thebases, pyridine, lutidine, and trimethylpyridine respectively wasto produce a marked increase in the persistence of the absorptioncurves. The author has also shown (Proc. Cnm'b. Phil. Soc., 1908,14, 568) that in tetrachloro-2-aminopyridine and tetrachloro-4-aminopyridine the absorption curves differ widelv in theirpositions and persistencies, the orientation of the amino-groupdetermining the nature and extentl of the absorption ; and, further,that the substitution of atoms forming part of a side-chain does notexert the same marked influence on the absorption of light aswhen the substitution takes place in the nucleus (Trans., 1909, 96,I n order to test how far the vibrations of the aromatic ring ofthe compounds of the present investigation are affected when thenitrogen atom is part of a side-chain, the absorption curve wasstudied when hydrochloric acid was added to the a-compound(m.p. 103-104°) obtained from m-4-xylidine. The results show(Fig. 3) that the form and persistency of the curve are notdifferent from those of the latter compound. There is only agreater shift of the band towards the red end, caused by theweighting of the molecule by the acid.They confirm the viewthat the position and linking of the nitrogen atom in the ring orthe side-chain is of considerable importance in determining theabsorption of light.Further, it will be noticed that in the bimolecular ethylidene-xylidine the linking of the nitrogen atom of the two xylidinegroups is different. On one side it is linked with two atoms ofcarbon and an atom of hydrogen; and on the other side it islinked with two atoms of carbon. I n the latter case the linking ofthe nitrogen atom with a carbon atom of the aliphatic residue is adouble one. The effect has been to reduce the absorption, andtherefore the persistencies of the bands, although the general formof the curve has been retained.The effect of t,Ee nitrogen linking in the a-compound obtainedfrom p-toluidine has been to obliterate the more refrangible band,whilst the less refrangible one remains very similar to that of theparent substance both in form and persistency.The curve obtained294)AND OF THEIR CONDENSATION PRODUCTS WITH ACETALDEHYDE. 649from the P-compound is also very similar, the only difference beingthat it is not so persistent. This difference probably indicates somealteration in the linking of the nitrogen atom,. which may be inthe direction of the suggested formula.As regards the a- and P-compounds obtained from m-4-xylidine,which correspond with the a- and &compounds obtained fromp-toluidine, similar remarks apply, for the persistence of the curveof the &compound is not so marked as that of the a-compound.The phenomena observed in the two series of compounds areprecisely similar in this respect; and the linking of the nitrogenatom appears to be exactly the same.It is not clear, however, how far these results assist the suggestedformulze of the @-compounds.We might have expected a somewhatdifferent form of curve in compounds containing two rings ofsuch different types. A t the same time, there can be little doubt-that the nitrogen atom is a determining factor in the absorption,and the suggestion that i t is linked to three separate carbonatoms in these compounds, whereas in the isornerides it is linkedto two carbon atoms, derives some support from the different per-sistencies of the bands. I n such linkings the tendency would beto influence the vibrations so that less light would be absorbed,and it would be manifested in a decreased persistence of theabsorption band.It is also conceivable that the vibrations of thearomatic ring are more fundamentally influenced by the com-bination with the nitrogen atom than are those of the aliphaticring; or, in other words, if the aliphatic parts of the compoundsare considered as displacing the hydrogen atoms of the amino-groups, the small differences shown by the curves may be explainedby the previous observations that there is less influence on thevibrations of the nucleus in such a case than when the displacementtakes place in the nucleus itself (Trans., 1909, 95, 294).General ResuZts.The general results of the investigation show :1.That the absorption curves of p-toluidine and m-4-xylidineare very similar. The chief differences are the slightly decreasedpersistence of the bands of mc4-xylidine, and the shifting of thebands of the heavier molecule towards the red end of the spectrum.2. That the combination of two ~n-4-xylidine residues throughacetaldehyde produces a greatly decreased persistence of the twobands and also a greater shift towards the red end.3. That the isomeric substances obtained by the union ofp-toluidine or of m4-xylidine with acetaldehyde produce a dis-appearance of the more refrangible band found in the aromati650 PURVIS : ABSORPTION SPECTRA.compounds ; and that the isomeric substances show differences inthe persistence of the remaining band, the origin of which may beexplained from a consideration of differences in the nitrogenlinking.4. That the addition of hydrochloric acid to these derivedcompounds has no effect on the form and persistence of the absorp-tion band, thereby indicating that, the vibrations of the nucleus arenot influenced by an alteration in the valency of the nitrogen ofthe side-chain.UNIVERSITY CHEMICAL LABORATORY,CAhf BRIDGE

ISSN:0368-1645    

DOI:10.1039/CT9109700644

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

65 1ANNUAL GENl$KATI MEETING,MARCH 1 STH, 19 10.Prof. HAROLD 13. DISON, M.A., Ph.D., P.N.S., in the Chair.3lr. J. S. S. BRAME and Dr. N. V. SIDGWIUK were appointedScrutators, and the ballot was opened for the election of Oficers andCouncil for the ensuing year.The Report of the Council on the progress of the Society duringthe past twelve months was presented by the PRESIDENT, and theTreasurer, after making a statement as t o the Society’s income andexpenditure for 1909, proposed a vote of thanks to the Auditors,which was seconded by Mr. A. C. CHAPMAN and acknowledged byDr. J. A. VOELCKER.The adoption of the Report of Council together with the Ba!anceSheet and Statements of Aecounts for the year ended Docember 31st,1909, proposed by Dr. G. MUGOWAN and seconded by Dr.H. EBERETONBAKER, mas put t o the Meeting and carried unanimously.REPORT OF THE COUNCIL.The Council is again in SL position to report favourably on theprogress of the Society, as indicated by an incrdase in the number ofFellows and in the list of papers comrnunicsted.On the 31st December, 19OS, the number of Fellows was 3,950.Jluring 1909, 160 Fellows have been elected and 7 were reinstated, thegross total thus being 3,117. The Society has lost 25 Fellows bydeath; 43 have resigned; the election of 2 Fellows has become void,and 44 Fellows have had their names removed from the List for non-payment of Annual Subscriptions.The total nutuber of Fellows, therefore, at the 31st December, 1909,was 3,003, showing a net increase of 53 over the preceding ycar.VOL.XCVII x 652 ANNUAL GENERAL MEETING.The names of the deceased Fellows, with the dates of their election,are :K. Bannister (1871).J. Castell-Evans (1 903).E. J. Cox (1S86).C. B. Dudley (1898).C. Ekin (1864).J. Fuller (1886).C. Graham (1862).El. E. Harrison (1883).W. H. Hudleston (1871).S. H. Johnson (1866).J. J. Kielty (1903).L. Mond (1872).F. Norton (1854).G. E. Perry (1888).E. A. Pontifex (1848).T. H. Redwood (1887).W. B. Roberts (1880).W. J. ltussell (183 1).W. Stewart (1872).F. Stocks (1874).C. Thomas (1871).H. E. Thomas (1874).Sir T. Wardle (1875).A. F. Watson (1893).J. H. Wilson (1878).The following Fellows have resignedE. W. Bealoy. C. P. Hines.H. J. Brown.E. Houghton.‘I. S. Busher. A. Howard.E. Catherall. R. S. Hutton.E. Cleminshaw. A. J. Hyder.A. J. Cook, A. James.J. W. Daniels. W. H. M. Jones.J. H. Davidson. J. Leicester.F. R. Dudderidge. A. G. Levy.E. J. Fairhall. R. D. MacKechnie.C. Gordon. W. Mackectn.J. H. Gough. A. McMullen..H. W. Harrie.J. W. Helps. *C. Muller.C. A. MacMunn.J. M. Murray,P. G . PennymoreH. Richardson,H. E. Richardson.J. Richardson.*C. J. Smith.T. Southern.W. S. Templeton.R. Tervet.A. Tighe.S. Tolson.A. J. Webb.G. H. West.F. G. Wiechmann.and Professor Dr. Georg Lunge, whose name has been transferredfrom the list of Fellows t o that of the Honorary and Foreign Members,The number of those Fellows elected previous t o the year 1860 hasbeen diminished still further by the death of Mr.Fletcher Norton,elected on December 18th, 1854, of Mr. Edmund Alfred Pontifex,elected December 4th, 1848, and of our distinguished Past-President, Dr. William James Russell, F.R.S., elected March Srd, 1851.The number of Honorary and Foreign Members a t the close of1909 was 34. One election has taken place, and the Society has t omourn the loss of Professor Emil Erlenmeyer, and of Professor Julius* Included among the seven reinstated FellowsANNUAL GENERAL MEETING. 653Thomsen, who passed away early last year, making the total number ofHonorary and Foreign Members at December 31st, 1909, amount to 33.The Council has much pleasure in congratulating the followinggentlemen, who, during the past year, have reached their Jubilee asFellows of the Society :Prof.Dr. Heinrich Debus, F.R.S.Mr. Thomas Fogg.Dr. A. G. Vernon Harcourt, P. 8.8.Mr. Josiah W. Kynaston.Dr. Hugo Muller, P.K.S.Mr. Thomas W. Salter.MY. John Spiller.During the year 1909, SO0 scientific communications have beenmade to the Society, 327 of which have been published already in theTransactions, and abstracts of all have appeared in ths Proceedings.The volume of Transaclions for 1909 contains 2,219 pages, ofwhich 2,133 are occupied by 236 memoirs, the remaining 86 pagesbeing devoted to the Obituary Notices, the Wolcott Gibbs andMendelheff Memorial Lectures, the Report of the International Clom-mittee on Atomic Weights, the Report of the Annual General Meeting,and the Presidential Address; the volume for the preceding yearcontains 222 memoirs, which occupy 2,188 pages.The Journal for 1909 contains 4,946 abstracts, which extend t o3,040 pages, whilst the abstracts for 1908 numbered 4,978, and occupied2,112 pages. The abstracts for 1909 may be classified as follows :PART I.No.ofl’ages. AbstractsOrganic Chemisjtry. ............................. 980 1,781General and Physical Chemistry ...........Inorganic Chemistry ...........................Mineralogical Cliemis try ....................Physiological Chemistry .....................Chemistry of Vegetable Physiology andAgriculture.. ...............................Analytical Chemistry ........................9535651445773046221,060 3,165Total in Parts 1.and 11. ............... 8,040 4,946s x 654 ANNUAL GENERAL MEETING.Since the last Annual General Meeting, three Memorial Lectures,dealing with tho life-work of deceased Honorary and Foreign Membershave been delivered. On the 3rd of June, 1909, Dr. Prank WigglesworthClarke paid this tribute to tho lute Professor Wolcott Gibbs; SirWilliam Tilden delivered the NendeldeE Memorial Lecture on October2 lst, arid Sir Edward Thoiape reviewed the thermochemical and otherresearches of Professor Julius Thomsen in u discourse given beforothe Society on February 17th, 1910.The year 19 11 marking the hundredth anniversary of Avogadro’scelebrated memoir, the Council has voted a contribution of 210 fromthe funds of the Society towards the international commemoration ofthe event.Fellows have been invited also to participate in thecelebration of Professor Korner’s seventieth birthday, which willbe recognised on behalf of the Society by the presentation of anilluminated address of congrdtulatio J in May next.The rapid growth of the Library since the contents of the rooms atBurlington H-ouse were vitlued, has necessitated the preparation of afresh estimate of replacement cost ; this has now been completed, and a11arrangement based thereon will be concluded with the InsuranuoCompany.During the past year’the Chemical Society has become indebted tothe Society of Dyers and Colourists for the gift of a reproduction inbronze of the plaque by Mr. F. W. Pomeroy, R.A., representing thelate Sir William Perkin.Professor Meldola has added to the collec-tion of photographs an interesting one OF the Jury (Paris Exhibition,l900), which included among its members the late Professor Mendeltieff,and the Society has also received valuable gifts of books fromMrs. J. Wilson, Mr. A. Gamble, and Mr. F. Stocks.In chronological order, Past-Presidents the Rt. Hon. Sir HenryRoscoe, Sir William Crookes, Dr. Hugo Miiller, and Dr. A. G. VernonHarccurt have more than completed fifty years of Fellowship, whilstProfessor William Odling, who has now been for sixty-two years aFellow, and became President in 1873, is the sole survivor of the sixPast-Presidents who were entertained to a banquet in 1898. Desiringto do honour to these gentlemen in the 11am~ of the Society, theCouncil, through the President, has invited them to a banquet t obe held during the ensuing summer, believing that a considerablenumber of Fellows will be glad to assist a t this interestingcommemoration, details of which will be announced forthwith.With the object of meeting a widely expressed desire, the Report ofthe International Committee on Atomic Weights will in future, it ishoped, be published in September instead of in January.This willrender it imniediately useful to College teachers a t the beginning ofeach new Session. In order to adapt the list of amended AtomiANNUAL GCENERAI; MEETING. 655Weights t o the requirements of students, it is now printed on paper aswell as on cardboard.The Council desires to place on record its high appreciation of thevaluable services rendered to the Society by Dr.M. 0. Forster, whonow retires from the position of Honorary Secretary, which he hatsheld for the last six years. Dr. Forster has given unspzringly bothhis time and his energy to the work of tho Society, and has eveis beenactive in promoting its highest interests.The number of books borrowed from the Library during the ymr1909 was 1,548, as against 1,339 in the previous year ; of these, 347were issued by post, as against 338 in the preceding year.The additions t o the Library comprise: 142 books, of which 7 2were presented, 41 S volumes of periodicals (representing 243 journals),and 80 pamphlets, as against 159 books, 412 volumes of periodicals(representing 245 journals), and 36 pamphlets last year.The income of the Society for the yesr shows an increase of2252 10s.10d. over that of last year, the amounts being &7,387 8s.and 27,134 17s. 2 d . respectively, whilst the expenditure has risenfrom ,€6,834 15s. to 27,028 39. 5d. This Iesves in tho Treasurer’shands a balance of A2359 49. 7d. on the year’s working, whichtogether with the balance of $300 saved in 1908 has enabled theCouncil to authorise the purchase of X700 Canadian 34 per cent. stock.In the balancc-sheet for this year there appears for the first time avaluation of the Library, Furniture, Bronzes, Busts, &c. This hasbeen based on a complete inventory which has now been made inorder to be used as the basis for the new Fire Insurance Policy whichwill be arranged in June next, when the present policy expires.Thanks Go the care of the Publication Committee and the Editor,the net cost of the annual publications (taking account of theirincreased sales) only shows a rise of about 225, and this, be i t noted,includes the preparation for the next volume of the Decennial Indexeswhich is now fairly under way.The cost OF indexing no longerappears as R seEarate item in our accounts, as it has been entirelytaken over by the Editor and is included in his salary. Therehas been a reduction-of nearly &lo0 in the cost of the Annual Reports,whilst house expenses and repairs cost about 250 less than last year.The chief items i n the expenditure which are not of annual occurrenceare the new cases for the Library costing .€93 lOs., and the balance ofthe Dinner account, which was no less than &70 9s.6d.From the Research Fund grants were made amounting in all t oS369, and as this year there was the further outlay on theLongstaff Medal and its accompanying Honorarium, the expenditureexceeded the income by &34 17s. Id., this deficit being met fromthe balance in hand. During the last six years grants have bee656 ANNlJAL GENERAL MEETING . ANNUAL GENERAL MEETIKU . 657INCOME AND EXPENDITURE ACCOUNT FOR THE YEAR ENDED 3 1 s ~ DECEMBER. 1909 .Income .To Life Compositions . . . . . . . . . . . . . . . . . . . . . .. Admission Fees ........................ .. Annnal Sulmriptions-Rereiveil in advance.oil arrnnnt, of 1909 ...... .. hiring 1909 .. 1909 . . . . . . . . . . .. 190s . . . . . .9 9 . . . . .. 1907 . . . . . .Lraa amonnt included in last year's Income. . . . . . . . . . Arrears as per last Balance Sheet. . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .being vslnation . . . . . . . . . . . .Add Arrears n t date : 1909 8442 ; 190s 8 2 0 ; 1907 €2. estimated to .. Laily Snbsrrihers ....................................... .. lnvenimcrits :-realisc as per Balance Sheet .........................Dividei:ds on i ( i 7 3 0 Metropolitan Consolidated 34 per Cent . Stock81620 148.3d. Carditf Corporation 3 per rent . Stock... .. f l O B O London and North Western Railway 3 per cent .Debentnre Stock ............................. 81400 India 2 t per cent . Stock . . . . . . . . . . . . ... .. E2400 Bristol Corporation 2$ per cent . Dehenture'itock .. €4341 Midland Railway 2$ per cent . Preference Stoi.1~ .. 61200 Leeds Corporation 3 per cent . Stock ...... .. €1200 North British RRilwny 3 per cent . DebentnreStock ................................... ..... el500 Transraal 3 per rent . Gunranteed Stnck' . . . . . ... Income Tax Recovered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Interest on Deposit Account . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... Publications :-Sales :Journals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .Proceedings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .General Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Memorial Lectures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Library Cataloguc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Atomic Weight Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Annual Reports on the Progress of Chemistry . . . . . . . . . . . . . . .Lers Pnhlishers' Commission . . . . . . . . . . . . . . . . . . . . . . . . . . .Procecds of Advert. isoments in Joiirnal . . . . . . . . . . . . €42 1R 3Lrrs Commission . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 9..Sale of Royal Society Proceedings .. Sale of Waste Paper........................... .................................... .. Snbscriptions from other Societies :-Society of Chemical Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Hociety of Pnblic Analysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . .E b . d . ... ...... 2 5 5 0 0 ... 4152 n o ... 3 6 0 0 0 ... i n n o4757 0 0of ... 3 1 0 0 0E23:6281 . d .0 0o n4127 n nExpenditure .ExDenses on account of Journal and Proceedines :-Salary of Editor. inrlu ling Indexin; . . . . . . . .Salnry of Sub-Editor . . . . . . . . . . . . . . . . . .Editorial Postages . . . . . . . . . . . . . . . . . .Abstractors' Fees . . . . . . . . . . . . . .. . . . . .Printing of Journal ....................Illustrations ...........................Bnuding . . . . . . .....................Printing of Adveriisements . . . . . . . . . . . . . . .Wrappers and Addressing . . . . . . . . . . . . . . .Distribution of Journal . . . . . . . . . . . . . . . . .Authors' Copies . . . . . . . . . . . . . . . . . . . . . . . .Insurance of Stock a t Clay's . . . . . . . . . . . . ..... ... ... ... ... ... ... ... ... ... ... .... . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .Printing of Proceedings .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Banding .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. jF 0 0 - 47Ri ," Distribution ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... Annual Reports on the Proqress of Chemistry,. Purchase of back numbers of Journal . . . . . . . . . . . . . . . . . . . . . . . . .. List of Fellows . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... Library Expenses :-. . . . . . . . . . . . . . . . . . 222 16 n20 1; 249 3 133 2 256 15 0 Salary of Librarian and Assistant . . . . . . . . . . . . . . . . . . . . . . . . . . .102 17 li Books and Periodicals . . . . . . . . . .., . . . . . . .., . . . . . . . .. , ..3 t 1 0 Binding . . . . . . . . , . . . . . . . . . . . , .. , . . . . . . . . . . . . . . . , , . . . .42 7 li New Bookcases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54 0 4 Indexing for International Catalogue .. . . . . . . . . . . . . . . . . . . . . . . .A1 13 0 .. Subscription to Avogadro Memorial . . . . . . . . . . . . . . . . . . . . . . . . .. Balance of Dinner Account ..................... .., ......Salary of Assistant Secretary .., . . . . . . . . . . . . . . . . . . . . . . , , ..Salary of Office Assistant ......... ., . . . , .. , .. . . . . . . . . .1 s 5 11 - 643 5 .. Administrative Expenses :-Wages (Commissionaire. Housekeeper. and Charwomaii'j' . . . . . . . . .Pension. Mrs . Hall . . . . . . .. . . . . . . . . . .., . . . . . . . . . .., ...Coal and LightingFIouse Expenses and Repairs . . . . . . . . . . . . . . . . . . .., . . . . . . . .Tea Expenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Insurances . . . . . . . . . . . . . . . . . . .Accountants' Charges. balance for 1908' .., ... .., . . . . . . . . . . . .ComiKission on d;?covery of h o m e Tax .....................Honorarium for Valuation of LibraryPostages . . . . . . . . . . . .., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Furniture . . . . . . . . . , . . . . , . . . . . . . . . . . . . . . . . , , ,Xiscellaneous Expenses . . . . . . . . . . . . . . . . . , .. , .. , . , . . . . , . ,9 3 0 .. Balance. being excess of Income over Expenditure.carried to Balance0 15 0 Sheet ... .., ... , ............................. , . . . . .860 0 113(i 11 1113 5 0, 3 1 7 617 <150 4 61075 1 5 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 1 n . Jim ..........................................103 3 5 Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Stationery . . . . . . . . . . . . . . . . . , . . . . . . . . , . . . . . . . . , . . . . . . ni2 12 4.. .. ...36 9 6ion0 1 10 --S R O12 i i20 0 B€7387 S 08 8 . d .545 1 5 0200 0 022 1 3 2485 1 8 52983 0 910 5 1 1.5 7 7 826 1 2 0118 1 3 655b 1 8 1174 1 2 67 0 0 ..8477s.? .d .0 3203 4 611 a 44 2 11 4261 18 2421 14 2d 1 8 9G I 4 6141 5 0240 8 1 144 1 1 703 1 0 0 .. 522 1s ti3 0 0 01 0 0 07 0 9 6260 0 036 0 0160 2 630 0 035 1 2 1 055 1 7 927 2 1 09 1 5 25 5 021 0 01 1 1 82s 0 0T D 1 6 116 1 3 57.5 6 05 11 618 5 1 .. S60 0 1350 4 7f 7 3 8 7 s 0I have examined the abnve Acennnta with the Bnoks and Vonchers of the Society. and certify them to be in accordance therewith . I have also veriEed the Balance a t the Bankersand the Investmonts .2 5 . Q~JEEN VICTORIA STREET.LONDON. E.C.2nd March. 1910 . W . B . EEEN.Chavfered AccountantApproved- J . AWOUSTW VCELCKER.VICTOR H . YELEYFREDERICK B . PdU'ER Linb ilitics.To Subscriptions received in advance .. . . . . . . . . . . . . . ?75 0 02 s. tl. € s. tt.,, Cash received on Account of Annual Report, Vol. VI.(not published) . . . . . . . . . . . . . . . . . . . . . . . . . . 27 10 ci, , Sundry Creditors . . . . . . . . . . . . . . . . . . . . . . . . . . 1130 14 0,, Research Fund :-As per last Balance Sheet . . . . . . . . . . . . . . . . . . 10510 12 5Less Excess of Expenditure over Income for the year 34 17 1 -- 10475 15 41190s 19 l o1 , Chemical Society : Excess of Assets over Liabilities :-As per last Balance Sheet.., . . . . . . . . . . . . . . . . . . 19945 11 10Add Excess of Income over Expenditure for the year 359 4 7____- 20304 70 5$32213 lti 3By Investments (value whcnf6730 Metropolitan€1050 London a ncent. DebentureEl520 14s.3d. Cardiff$1400 India 24 per;62400 Bristol CorporationZ.1341 Midland Railway$21200 Leeds Corporationf1.500 Trarisvssl 3 per€1200 North BritishSt,ock . . . . . . . .(Estimated present615177 ,, Stindry Debtors :-Society of Public AnalystsAdvertising Agw tsblessrs. Gurney & JacksonTelephone Deposit!, Subscriptions in Arrear,,, Insurance paid in advance ,, Cash a t Bank :-Deposit L4ccountCiirrcnt Account ,, Cash iu hand . . . . ., , Research Fund :-Investmetits (valuef1000 North BritishPreference Stockf4400 Metropolitan61034 Great Westernture Stock . . . . .81142 lGs. New South81122 Metropolitan2 ockf'>:& M~&T;; Railw&€SOB Victoria 3 per,, Cash a t Bank . . . . .(Estiuiated presentFund Iuvestments,xoTE.-The estimatedexclusive of theown publications,Furniture.&c.RESEARCH FUND INCOME AND EXPENDITURE ACCOUNT FOk THE YEAR-~ ~~ - ~- -A m m e .s t f . ,S 6 . 11. I By Grants to-E. C. C . Baly ......J. A. N. Friend . .C:. Gilling ................................G. 9. Hibbert . . . . .H. Hibbert . . . . .To Dividends on :-- I j21000 North British Railway 4 par cent. No. 1 PreferenceStock . . . . . . . . . . . . . . . . . ... 37 17 10 ... 145 13 2&lo34 Great Western Railway 2 4 ~ e r cent. Debenture Stock 24 10 1$4400 Ivletrogolitan Consolidated 34 per cent. Stock’21142 16s. New South Wales f & r cent. Stock ......... 38 8 5€1122 Metropolitan Water Board 3 per cent. “ B ” Stock 31 17 431365 Midland Railway 24 per cent. Debenture Stock ...32 6 112606 Victoria 3 per cent. Stock .................. 22 17 4 -- 327 11 4Repayment of Research Grants :-C. Smith . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 9J. A. N. Friend . . . . . . . . . . . . . . . . . . . . . . . . . 4 5G. Young . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Y 4 0W. 1%. Patterson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 0 1 1 -- 12 1 1Income Tax Recovered . . . . . . . . . . . . . . . . . . . . . . . 17 5 10Balance being Excess of Expenditure over Income carriedto Balance Sheet ........................... 34 17 I&391 15 4E. Hope ......‘1‘. 31. Lowry ...H. McCoinbieA. N. MeldrnniW. H. Mills ...A.G. Perkiir ...R. Robinson ...J. L. SiinonseiiMiss I. SmedleyC. Sinith ......R. Storev ......J. J. SttdboronghJ. F. Thorpe ...\V. E. 8. TurnerA, J. AllinandR . Alpern ......D. Bain ......... ...I . . ......... ... ............ ...... ... ... ...G . 13arcer . . . . . . . .T. V. Barker ......A. Clayton ...Mss 11. E. DoiwonJ. C. Duff .........H. D. Gttrdner ...A. Holt .........J. Lister . . . . . . . . .P. May . . . . . . . . .W. Parry . . . . . . . . .R. H. Pickard ......0. Senter .........5. Smiles .........J. A. Sinythe ......D. Tiiomson ......C. K. Tinklcr . . . . .G. T. Morgan ........ Cost of Longstaff Medal .. Cornn~issioii 011 RecoveryCliecque book.. Longstaff Honwariuiii................................I have exaillined the above Account with t,he Books and Vouchers of the Society, and certify i t to be in accordancethe Bankers and the Investinents.2nd March, 1910. Chartered Accountant.W. B. KEEN660 ANNUAL GENERAL MEETING.made to 183 out of 216 applicants, the total amount applied forhaving been $2,845, of which 31,673 was granted, and of this 257has been refunded. I n return, 160 papers have appeared in ourTransactions, 18 in the Proceedings, and 22 in other journals.A vote OF thanks to the Treasurer, Honorary Secretaries, ForeignSecretary, and Council for their service during the past year wasproposed by Dr. BERNARDYER, seconded by Mr. E. GRANT HOOPER,and acknowledged by Dr. M. 0. FORSTER, the retiring Hon.Secretary.The PRESIDENT then delivered his address, entitled '' The Union ofHydrogen and Oxygen in Flame." Dr. A. G. VERNON HARCOURTproposed a vote of thanks to the President coupled with the r6qUeStthat he would allow his address to be printed in the Transactions.The motion was seconded by Sir EDWARD THORPE and carried withacclamation, and acknowledged by the PRESIDENT.The Scrutators having presented their report, the PRESIDENTdeclared that the following had been elected as Officers and Councilfor the ensuing year :President : Harold B. Dixon, M.A., F.R.S.vice-Presidents who have $filled the Ofice of President : H. E.Armstrong, Ph.D., LL.D., F.R.S. ; A. Crum Brown, D.Sc., LL.D.,F.R.S. ; Sir William Crookes, D.Sc., F.R,S. ; Sir James Dewar, M A . ,LL.D,, F.R.S. ; A. Vernon Harcourt, M.A., D.C.L., F.R.S. ; RaphaelMeldola, 4'. K.S. ; H. Muller, Ph.D., LL.D., F.R.S. ; W. Odling, M.A .,M.B., F.R.S. ; Sir William Ramsay, K.C.B., LL.D., F.R.S., ; J.Emerson Reynolds, Sc.D., M.D., F.R.S. ; The Rt. Hon Sir Henry E.Roscoe, LL.D., F.R.S. ; Sir Edward Thorpe, C.B., LL.D., F.R.S. ; SirWilliam A. Tilden, D.Sc., F.R..S.Vice-Presidents : J. ,Norman Collie, Ph.D., F.R.S. ; J. J. Dobbie,M.A., D.Sc., F.R.S.; M. 0. Porster, D.Sc., Ph.D., F.R.S. ; F. StanleyKipping, D.Sc., Ph.D., F.R.S. ; A. Liversidge, LL.D., F.R.S. ; J.Walker, D.Sc., Ph.D., F.R.S.Treaszcres* : Alexander Scott, M. A., D.Sc., F.R.S.Secretaries: A. W. Crossley, D.Sc., Ph.D., F.R.S. ; G . T. Morgan,Foreign A'ecretary : Horace T. Brown, LL.D., F.R.S.Ordinary Members of Council : Julian L. Baker ; George T. Beilby,F.R.S. ; William A. Bone, D.Sc., Ph.D., F.R.S. ; Adrian J. Brown,M.Sc. ; Julius B. Cohen, Ph.D., B.Sc. ; Charles E. Groves, F.R.S. ;J. T. Hewitt, M.A., D.Sc., Ph.D. ; H. R. Le Sueur, D.Sc. ; Alex.McKenzio, D.Sc., Ph.D. ; J. C. Philip, D.Sc., Ph.D. ; Sir BovertonRedwood, D.Sc.; A. E. H. Tutton, M.A., D.Sc., F.R.S.D.Sc

ISSN:0368-1645    

DOI:10.1039/CT9109700651

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

DIXON : THE UNION OF HYDROQEK AND OXYGEN IN FLAME. 661PRESIDENTIAL ADDRESS.Delivered at the ANNUAL GENERAL MEETING, March 18th, 1910.l3y HAROLD R. DrxoN, M.A., Ph.T)., F.R.S.IN his presidential address last year, my distinguished predecessorin this Chair quoted with approval that clever definition whichdistinguishes a theory from a hypothesis -f‘ a theory is a suppositionwe hope to be true; a hypothesis is a supposition we expect to beuseful.” I do not know whether the majority of scientific peoplehope that the theories they employ are true; I feel very sure theybecome convinced of their truth by a long habit of using them.Supposition’s that have stood the criticism of Time, and have beentuught to u s as accepted theories, take possession of our mindswhether we will or no.I have heard St. Claire Deville, whoprofessed his disbelief in all theories, lapse unconsciously into theatomic theory in moments of controversy. Such theories becomealmost an essential part of our mental apparatus, and perhaps nogreat harm results if the majority of us believe in them as an articleof scientific faith. we expect tobe useful.” I n its inception it is a more or less piausible guess-often arrived a t by analogy. We try it (with proper scepticism) tosee if it will “ work.” If it serves we try it again with less mentalreserve. The hypothesis suggests certain consequences undercertain conditions; if we find these consequences follow in a fewtrials we are apt to regard our hypothesis as verified,” and webegin to think in terms of it-especially if we have published it..By and by our hypothesis becomes crystallised in our system, antii f further consequences are not in accord with ib, we-to reform thelanguage of the unreformed Chamber-disregard the consequences.But the hypothesis, however useful it may be as a means of winningnew facts, or new views of facts, is by no means proved to be trueby successful prediction.We must be continually on our guardlest we become the bondmen of our own hypotheses, although I donot think that we Britons, as a race, are the worst offenders.“Chemists,” wrote Stas, “ t h e instant they see certain facts arereproduced with an uppenranwe of regularity, believe this is a simplenatural law; moreover, they have contracted the habit of con-sidering that the law has been demonstrated the moment they havemade any measurements not greatly differing from it.”The danger lies in the hypothesi662 DIXON : THE UNION OF FIY~ROGEN AND OXYGEN IN FLAME.I am not claiming for myself exemption from the commoninfirmity.I have made hypotheses, and very possibly have allowedthem to bias my judgment. Moreover, I have suffered what Huxleycalled that great tragedy of science--“ the slaying of a beautifulhypothesis by an ugly fact.” But I regard this as a proper anddesirable ending, and am glad t o have helped in the “happydispatch,” not only of my own, but of those of some of my fellow-workers.I would urge, then, t h a t i t is the present wsefdness of thehypothesis, not its truth, t h a t is important: we ought to value i tonly so long as it is a working hypothesis, that is, is guiding andsuggesting work in the laboratory.We ought, indeed, to do unt,oour hypotheses as we would do unto professors-other professors-inan ideal university. The moment the hypothesis ceased to workin the laboratory it should be quietly superseded.My text might have been illustrated from almost any branch ofchemistry; I have chosen the union of hydrogen and oxygen in flame,partly because I am more familiar with this subject, and partlybccause the reactions involved are comparatively simple. It wasmainly with the hope of finding, among these or other gases,reactions simple enough to be interpreted and to throw light (‘onthe course of a chemical change,” that I started these researchesunder the guidance of Mr.Vernon Harcourt more than thirty yearsago. Though I have, no doubt, wasted much time, I have neverregretted the choice of subject, and have never been tempted toturn aside.The Direct Union of Hydrogen and Oxygen.I first studied the union of hydrogen and oxygen in flame a.spart of the investigation on the mode of burning of carbonmonoxide. When steam, either present to start with or formed inthe flame, was found to be necessary for the propagation of a flamein carbon monoxide-oxygen mixtures, I ventured on my f i r h thypothesis-I think a moderate one. I f there is some constitutionaldisability preventing oxygen from direct combination with carbonmonoxide, may not the latter take oxygen from steam, and thehydrogen, so liberated, re-form steam by direct union wit.h oxygen.I need not a t this point discuss what special disability preventsthe oxygen from burning the carbon monoxide directly.Manyhypotheses Eave been made to account for it, for example, that theoxygen, per se, is too stable (Lothar Meyer, Beketoff), or that gasesonly react in equal volumes (Mendeleeff). With the aid of severalof my old students I have shown, in communications to this Society,that neither the stability of the oxygen, nor the “law of equaDIXON : THE UNION OF HYDROGEN AND OXYGEN IN FLAME. 663iiiolecules,” can be the cause, for carbon monoxide will not explodewith ozone, with chlorine monoxide, or with nitrous oxide.Ontlic other hand’, the dried gases unite readily ujithout in&uming intlic presence of red-hot platinum, and in the burning of driedcyanogen the carbon monoxide first formed will burn in excess ofoxygen-either prolonging the flame, as in explosions, or burningwith a separate flame, as in the Smithells’ flame-separator. Steam,then, is cessary for the burning of carbon monoxide only under.certain corrditions. How does it act ? Carbon monoxide was foundto take o ygen from steam and liberate the hydrogen when thetwo were ieated together in a variety of ways. I n explosion ofmixtures I f carbon monoxide, oxygen, and steam, in which theoxygen was insufficient for complete combustion, the steam wasfound to give up its oxygen to burn the excess of monoxide.Moreover, the propagation of the flame through the mixture wasfound to increase in velocity the more steam was added up to6 per cent.of the mixture. It was therefore possible for thecarbon monoxide to take oxygen from steam in a flamc, and ifthe liberated hydrogen united directly with oxygen, water wouldbe re-formed, and the whole operation be completed by therepetition of some simple cycle.So the next point to investigate was-Does hydrogen unitedirectly with oxygen in a flame, or does it only do so through thedecomposition of or by the intervention of water?My first experiments on the union of hydrogen and oxygen werehigh temperature experiments. I found that an clectric spark,which would fire a damp mixture of hydrogen and oxygen, wouldalso fire a similar mixture however carefully dried.Many differentelcotrodes were tried, and they were submitted to every process Icould devise to prevent the possibility of steam being formed inor on the surface of the electrode. The spark always determinedexplosion. Moreover, I have analysed (on a rapidly-moving film)the flame of an explosion in electrolytic gas from its starting pointa t the spark as it spreads into the unburnt gas. The experimentswere made in exactly similar tubes, all other conditions being thesame-except that, in each pair, one tube was well dried and theother was moist. I n no case could any difference be detectedbetween the dried and moist gases either in the initiation or tlicspread of the flame.Dr. Brereton Baker, than whom I could citeno more careful or patient experimenter, has come to the same con-clusion. But it may be objected: “ Some steam molecule may existin the path of the spark, and that starts the reaction; once started,the water formed serves to spread the flame.” We cannot, of course,prove that no stcam molecules exist in the dried gas-indeed, 664 DIXON : TEE UNION OF HYDROGEN AND OXYGEN IN FLAME.should say it was very probable that there are some. But we havesome evidence as to the proyress of the reaction in the explosion ofhydrogen and oxygen, and that evidence w0 can use to test thepoint whether the flame, once started, is propagated by direct unionof hydrogen and oxygen molecules, or whether that union onlytakes place through’the intervention of a steam molecule.Both Moritz Traube and Professor Armstrong have put forwardthe view (on different grounds) that for the formation of steamthere must be a simultaneous reaction between three molecules :H, + OiH, + 0,.Now, the “ explosion-wave ” is a true physico-chemical constant.The genius of Berthelot was not at fault when he described theadvancing locus of high pressure and of rapid chemical change asZ’onde explosive.The “ wave ” was propagated, according t oBerthelot, from layer to layer by successive shocks between themolecules, resulting in chemical action ; so that the explosion-wavediffered from a sound-wave in that the former varied, not only withthe physical, but with the chemical nature of the gaseous mixture.The maximum velocity of the explosion-wave could be predicted,said Berthelot, by calculating ths mean velocity of the gaseousproducts before they had lost by conduction or radiation any of theheat of the chemical change.My own work on the explosion-wavebegan in an attempt to confirm or disprove my hypot.hesis thatsteam was the “carrier” of oxygen in the explosion of carbonmonoxide and oxygen. The results obtained led me to use theexplosion-wave as a, means of tracing the course of other changes ingases. For instance, it was found most useful in showing that thecarbon in gaseous compounds of carbon was not burnt directly tocarbon dioxide in explosions, but, in every instance that could betraced, the carbon dioxide, appearing as an end-product, had beenproduced by a secondary and not by a primary reaction in thewave-front.After many experiments on the diluting effect ofvarious gases on the propagation of the explosion-wave, I was ledto advance a “ workipg hypothesis ” somewhat different from thatof Berthelot. I n my hypothesis the gases are not burnt ‘( cold,” butthe unburnt molecules are heated in the wave-front by ‘‘ shock,”and so are burnt (‘ hot,” and consequently the product is raisedto a higher temperature. A formula based on this hypothesis wassuccessful in predicting the velocities of the explosion-wave in anumber of different gasesDIXON : THE UNION OF HYDROGEN AND OXYGEN IN FLAME. 665Velocity of explosion-wave.Gas mixture. Calculated. Found.H, + 30, 1740 17122H, + C1, 1832 1849C,N, + 0, 2725 2728C,N, + 0, + 2N, 2166 2163C,H,+20,+8N, 1727 17348H, 3- 0, 3554 3535I find it very hard to believe that these extremely closeapproximations can be mere coincidences.There are probably many cases in which the reactions are notso simple as the above.I find that the explosion-wave in a mixtureof equal volumes of ethane and oxygen does not give the sameproducts as are obtained in the explosion of ethylene, or ofacetylene, with its own volume of oxygen. The ethane is not burntwholly to carbon monoxide and hydrogen, but appears to form (asProfesor Bone has shown at lower temperatures) acetaldehyde andsteam, the acetaldehyde yielding methane and carbon monoxide.For other gaseous mixtures, especially those in which steam isformed a t a very high temperature, the formula gives a higher valuethan the rate found.For instance, the found velocity of theexplosion-wave in electrolytic gas is a long way below that given bythe formula. I “ explained ” that by t.he further supposition thatthe dissociation of steam was appreciable in the explosion-wave ofelectrolytic gas. I n support of this view, I showed that about1 per cent. of unburnt gas* remained behind after the explosion-wave had gone by, and proved that this could not be attributedto the cooling effect of the walls.I do not believe to-day in the truth of my working hypothesisof the explosion-wave. It embodied a number of assumptions, someof which I have myself shown to be erroneous.But I still think itwas sufficiently parallel to the truth to be useful: I made no higherclaim for it.The theory of the explosion-wave is not to-day dependent on thehypotheses of Berthelot and myself. Sufficient experimental datawere secured to allow a mathematical treatment of the subject.Professor Schuster was the first to suggest that Riemann’s equationfor the propagation of an abrupt variation in the density andpressure of a gas might be applied to the propagation of theexplosion-wave, since the necessary uniformity of type is maintainedowing to the continued reinforcement of the wave by the successivechemical changes. In 1899 Mr. D. L. Chapman, acting on thissuggestion, worked out from Riemann’s equation an expression for* Mem.Manehester PhiE. Soc., 1888. The fact was rediscovered in 1897 byF. Eniich (Monatsh., 18, 6), who attributes it t o the cooling action of the walls666 DIXOK : THE UNION OF HYDROGEN AND OXYGEN IN FLAME.the propagation of the explosion-wave, making, of course, ailassumption as to the specific heats of the gases formed at the tem-perature of the explosion. He pointed out how it might bcpossible to use the easily determined velocities of the explosion-waveto give the specific heats of the gases concerned. I n 1906 ProfessorJouguet, without knowing Mr. Chapman's work, developed onsimilar lines a very complete theory of the explosion-wavc.sa I-Ichas most justly chastised the wal:t of mathematical rigour in myhypolhesis and in that of Berthelot.We have reached the rightresult, he says, by a kind of chemical intuition. But as our resultshave led to M. Jouguet's generalisation, I, for one, will hope theverdict of my fellow-chemists will be: " Guilty, but please do itagain." Fundamentally, I think, M. Jouguet and I have the sameconception. We both think there is a preliminary heating up of thegas just before it burns; we both think that the wave-front ismoving as a sound-wave with a velocity, relative to the unburntgas in front, t w i c e that calculated from the ordinary heat of com-bustion of the gases. But whereas I had supposed this increasedvelocity should be set down to increased temperature, M. Jouguetpoints out that the burning gas is driven forward e n masse with thcvelocity of sound, and the wave-front is travelling like a sound-wave in this moving gas, and therefore has a motion relative to theunburnt gas in front double that of a sound-wave in the burninggases.The theoretical conclusions of M.Jouguet concerning the forwardmotion of the gas behind the wave-front are entirely borne out bymy photographic analysis of the explosion-wave. One can showthe retardation of a sound-wave meetilag the on-rushing burninggas; one can show that a sound-wave, following a little behind thcwave-front, travels with almost the same velocity as the explosion-wave itself.One other point of some importance: I found experimentallythat an increase in the initial temperature of the unburnt gas wasaccompanied by a diminution in the rate of explosion.Myformula did not account for this, but. I find the equations ofM. Jouguet lead to this result, when a moderate rise in the specificheats of the products of combustion is assumed.Messrs. Chapman and Jouguet have raised the very importantquestion whether the specific heats of gases at high temperaturescan be calculated backwards from the observed velocities ofexplosion. I would point out that a determination of the velocityof the explosion-wave for one mixture would not definitely fix thespecific heats of the products of combustion. For instance, if we* Joiiriut.1 de Mathe'matipes, 1905-6DIXON : THE UNION OF HYDROGEN AND OXYGEN IN FLAME. 667ttake the simple case where cyanogen burns t o carbon monoxide andnitrogen :the velocity of the explosion-wave was found to be 2728 metresper second when the initial temperature was 10’.Working back-wards from the observed velocity, I find that the mean specific heatof the products may lie betweenCZN, -k 0, == 2CO + N,0.5 1 0.61000 10004.5 + --T and 4-5 + -T,according as the compression of the gases is assumed to be more orless. The observed rate corresponds with the following pressuresand temperatures :Specific heat of CO and N,.4*5+ --TPressure in atins. Temperature, C.57.21 5966” 0-51100051.21 5736” 0.5510004*5+ -- T4.5 + O?oT100047‘16 5541”But by measuring the velocity of the explosion-wave when thismixture is “damped down” with inert nitrogen, or with argon,it is possible to limit the range of specific heats correspondingwith the observed velocities, and also to compare the specific heatsof nitrogen and argon at high temperatures.I am makingexperiments on these “ retarded ” explosions.The exceptions to the application of Chapman’s and of Jouguet’sequations-for example, in the explosion of carbon monoxide andoxygen, where we believe on other grounds that steam intervenes;or in the complete burning of carbon compounds, where we haveother reasons for believing that the formation of carbon dioxide isa secondary action-appear to me greatly to strengthen the viewthat the flame is propagated as a wave.If, then, the flame in explosions of gases is really propagated id9a pressure-wave, that is, by collisions of molecule with molecule,the chemical change involved in the wave-front must also proceed bythese collisions; and since the wave dqes not wait for the rareoccurrence of a triple collision, the primary chemical change mustbe uni- or bi-molecular, n o t termolecular.As Sir Joseph Larmor *has put the case, “Imagine the scale of magnitude of a gas a t apressure of one atmosphere to be magnified so that the diameterof each moving molecule becomes about one inch, there will bein the model roughly about one molecule in each cubic foot, andMem. illanchester Phil.soc., 1908.* “On the Physical Aspects of the Atomic Theory.”VOL. XCVII Y 668 DIXON: THE UNION OF HYDROGEN AND OXYGEN IN FLAME.a molecule will have to travel about a hundred feet before it,encounters another one.Such binary encounters will thus happenwith some frequency, and from some of them combination mayensue. But the chance of three molecules coming together simul-taneously is negligible; the only way in which a termolecularcombination can arise is by one of the molecules attaching to itselfanother, and this pair going off together to meet a third. . . . Itappears to be commonly recognised that direct termolecular com-binations occur seldom; the inference from the present line ofargument is that in gaseous reactions they do not occur at all.”It has been suggested that Sir J. J. Thomson’s hypothesis-thatchemical action in gases begins on the surface of condensed particlesof liquid water-might be applied to the explosion-wave.I findit difficult to believe either that sufficient water particles can existin the dried unburnt gas to allow the flame to proceed a t theobserved velocity, or, if such condensation really took place, thatthe velocity of explosion would not be increased by the addition ofwater vapour.To sum up, I believe the reaction between hydrogen and oxygenin an explosion is a direct one, and does not take place throughthe intervention of steam, for three reasons, namely:(i) That well-dried mixtures of electrolytic gas always explodewith a spark;(ii) That the velocity of explosion in a well-dried mixture isgreater than when steam is added;(iii) That the explosion-wave is propagated as a pressure-wavethrough the gas.The Union of Hydrogen and Oxygen at Low Temperatures.Whether steam or water facilitates the slow combustion ofhydrogen and oxygen below the inflammation temperature isanother question.The most careful experiments made to decidethis question are those of Dr. Brereton Baker. In 1902 he describedto this Society experiments in which he showed that when thegreatest care had been taken to purify the gases, the moist gasesexploded when the tube containing them was heated in a flamewhile the dried gases did not,. I n some of the tubes which did notexplode, a small quantity of steam had been formed, and in onetube, which had been dried for two days only, water was visiblyproduced by slow combustion.I n another experiment Dr. Baker heated a fine silver coil inthe dried gases, and succeeded in melting it without exploding themixture.The importance of these experiments induced me to repeat themDIXON : THE UNION OF HYDROGEN AND OXYGEN IN FLAME, 669and Dr.Baker was good enough to assist me by placing at mydisposal an ingot of his pure silver, and some of his fifteen-timesrecrystallised barium hydroxide. To provide against the infirmitiesof age, I enlisted the services of Dr. E. C. Edgar (whose work onthe atomic weight of chlorine proves his manipulative skill) to makean entirely independent series of experiments. As our experimentshave not been published, perhaps I may be permitted to give abrief summary of them here,The tubes, in which the gases were collected, were made of Jenaglass; into the walls of these were fused platinum hooks, fromwhich hung coils of thin silver wire carefully drawn from Dr.Baker’s ingot. The tubes were connected by a glass joint eitherdirectly to the electrolytic vessel, or to a condenser and dryingtube sealed to that vessel.The tubes, as well as the other parts ofthe apparatus, were cleaned by hot chromic and nitric acids andby steaming; they were finally dried in a current of air.The tubes were filled with electrolytic gas by placing them in atrough holding pure mercury (Fig. l), and partly evacuating themuntil the mercury rose nearly to the silver; the gas was then slowlyadmitted. After several repetitions of this operation, the piecea1’ Y 670 DIXON: THE UNION OF HYDROGEN AND OXYGEN IN FLAME.of phosphoric oxide (redistilled in oxygen) were introduced, andthen the last traces of air were eliminated by again emptying andfilling.I n other tubes no mercury was admitted, but after the admissionof phosphoric oxide the glass was sealed off, and the air pumpedout, while the tube and silver coil was maintained at a red heat.On cooling, the electrolytic gas was admitted, the pumping repeated,and the tubes, after being finally filled, sealed off.For the “ dry ”experiments, forty days were allowed before the silver coil washeated.Dr. Edgar agrees with me in the following observations-(i) thata higher temperature was required to start the reaction in thedried than in the moist gas; (ii) that combination occurred bothin the moist and in the dried gases, and that liquid water wasdeposited in the lower (cool) portion of the tube.In four experiments performed by Dr.Edgar, he finally fusedthe silver wire without exploding the dried gases. His account,written at the time, says : “ I n each experiment, after the mercuryhad risen almost to the silver, the wire was fused withoutexploding the gases.” I can entirely confirm this description. Iwatched the mercury rising in the tube and drops of water con-densing; on raising the temperature of the wire, the mercury rosemore quickly, and finally the silver fused without an explosionwhen the mercury was near the coil. I confess I did not think atthe moment that;, when the silver fused, the gas in the heatedupper portion of the tube must have been mainly steam.Onreflection it was clear that the experiment should be tried ofattempting to melt the silver by rapid heating. Two of the tubeswhich had been drying for forty days exploded when the coil wassuddenly heated to a bright red-heat. Our experiments show that,with the purity and dryness we were able to obtain (no doubt lessperfect than in Baker’s experiments), hydrogen and oxygen donot unite so readily as moist gases in contact with a heated silverwire, but such gases can be exploded by a sufficiently hightemperature.Professor Le Chatelier has defined the ignition point of gasesas that temperature at which the initial flameless combination heatsup the gas (more or less rapidly) until it inflames. ProfessorNernst has given a similar definition.Below the ignition point,combination occurs, but the heat evolved is not sufficient to over-come the cooling effect of the surroundings. I n a tube heated to540°, for instance, electrolytic gas slowly combines, the amountof steam formed in unit time gradually diminishing as the changeproceeds. A t 560° the heat evolved by the more rapid combinatioDIXON : THE UNION OF HYDROGEN AND OXYGEN IN FLAME. 671self-heats the mixture to the inflammation point.. I f the gas,however, can be maintained at 560° by contact with a sufficientlylarge surface, the combination proceeds as before, but more quickly.I n those experiments, such as those of M. HBlier, in which electro-lytic gas is drawn over small pieces of heated porcelain, exposinga very large surface to the gas, temperatures of 800° and highercan be employed without producing explosion.I n the experiments which Dr.Coward and I published last yearon the ignition point of gases, we brought together hydrogen, heatedin an inner tube, and oxygen, heated in an outer tube: we foundit necessary to use a wide outer tube for the oxygen, and a certainrapidity of flow of the hydrogen in the inner tube in order toobtain a constant ignition point. When the region where theheated gases mingled was removed from contact with a heatedsurface, a minimum ignition temperature was obtained. When thegases met close to a heated surface, the ignition point was raised.That electrolytic gas can combine isothermally at high temperaturesif the surface contact is large is a sufficient explanation of theseobservations.Now the question raised by Dr.Baker is this: Is the initiationof slow combustion in electrolytic gas, and. the velocity of thereaction when it is started, influenced by the presence of steamor water particles? I n his latest experiments he has found thatwhen moist hydrogen and nitrous oxide are kept at 530°, thepresence of an ionising agent, such as thoria or radium bromide,greatly increases the rapidity of the reaction; in the carefullydried gases the ionising agent had no effect.Although I agree with Dr. Baker that steam (or water) inter-vmes in the initial action of hydrogen on oxygen at moderatetemperatures, I do not think it necessary for the propagation ofa flame once started in the mixture.There are many similardifferences in gaseous reactions. Light will not explode driedhydrogen and chlorine, it does so in presence of water; but oncestart a flame in mixed hydrogen and chlorine, and it is propagatedas an explosion-wave through the dried gases. A platinum wireheated to whiteness will not fire a mixture of cyanogen and oxygen,flameless combination taking place round the wire; but a sparkimmediately sets up the explosion-wave in the same mixture.What is the First Product of the Union of Hydrogen and Oxygenin Flame?Do hydrogen and oxygen directly form steam, or do they formhydrogen peroxide in a flame? I f we accept the view ofMendcEeff that all primary reactions between different substance672 DIXON: THE UNION OF HYDROGEN AND OXYGEN IN FLAME,are bimolecular-a view enforced by Sir J.Larmor for gaseousreactions-we must suppose that a collision between a hydrogen andan oxygen molecule can only result in the primary formation ofhydrogen peroxide, or in the formation of steam and a free oxygenatom.The following reasons, among others, have been brought forwardfor the view that hydrogen peroxide is the first product in flame :(i) That hydrogen peroxide is found in the water rapidly con-densed from a hydrogen flame;(ii) That the mixture of equal volumes is more sensitive to aspark;(iii) That the mixture in equal volumes has a lower ignitionpoint than any other mixture.(I.) As, I think, Moritz Traube first showed, a jet of burninghydrogen playing on to the surface of water produces peroxidein the water.Some years ago, when I repeated Traube’s experi-ment, I thought that the mere heating of the water would producesome peroxide, but I found afterwards that this was incorrect. Itrequires some burning to take place near the surface of the water.But the presence of the peroxide in the condensed water might beexplained either by its direct formation from hydrogen and oxygen,o r by the union of the liberated oxygen atom with a molecule ofwater. Those who favour the first view consider tho peroxide tobc dihydroxyl, H-01-0-H, those who take the second view considerthe peroxide t o bc oxygenatcd water, r <I>=O.HThere are rcactions of hydrogen peroxidc (and o f a llralineperoxides) which may be appealed to in support of both views:possibly both forms may exist in solution.The second formulaseems to me to be supported by the remarkable researches OPCarl Harries 011 the decomposition of ozonides by water, in whichhe shows that the loosely joined oxygen atoms attach themselvesto water molecules to produce hydrogen peroxide quantitatively.The recent experiments of Manchot * confirm the olderobservations that ozone as well as hydrogen peroxide exists ina hydrogen flame. I f the ozone is formed owing to the liberationof an oxygen atom, hydrogen peroxide may be formed by theunion of an oxygen atom with steam. Engler’s experiment ofburning a hydrogen jet so as to bore a hole into ice, showsplenty of peroxide in the condensed water in the hole.I haverepeated this experiment both with ice and with a lump ofsolid carbon dioxide. When a large jet of hydrogen is used,* Ber., 1909, 42, 3948DIXON : THE UNION OF HYDROGEN AND OXYGEN IN FLAME. 673burnt with an outside blast of air, and a very small jet ofnitrous oxide is introduced into the centre of the hydrogen flame,a piece of ice may be introduced so that it is surrounded byhydrogen, and a hole may be bored in it by the small central jetof nitrous oxide burning in hydrogen. The central jet may thenbe fed by oxygen, and the samples of condensed water compared.While the oxygen produces plenty of peroxide, only a trace is foundin the water condensed from the nitrous oxide flame. This, ofcourse, only shows that in the burning of hydrogen and nitrousoxide, steam is formed directly without the splitting off of anoxygen atom.In the explosion-wave the greatest velocity of propagation is notgiven by electrolytic gas.The addition of hydrogen increases thevelocity of the wave so long as it is set up in tho mixture; this,of course, is due to the mobility of the hydrogen. But the factthat the addition of equal volumes of oxygen and nitrogen t oelectrolytic gas retards the wave exactly in proportion t o theirdensity is an argument that hydrogen peroxide is not the primaryproduct of the change, for the two gases appear to be equallyinert to the mixture 2H,+ 0,.Ifhydrogen peroxide were directly formed, the immensely high tem-perature of the flame and the very rapid cooling behind the flameshould be precisely the conditions most favourable for a high yieldof the endothermic peroxide.I have carefully examined theproducts of combustion of the explosion-ma.ve in such mixture, andcould detect no peroxide. On the other hand, when the explosion-wave traverses electrolytic gas, about 1 per cent. of unburnt gasis left behind, showing how rapid the cooling is.II. The experiments of Emich on the sensibility to expIosion bysmall sparks of different mixtures of hydrogen and oxygen led himin 1897 to suggest that hydrogen peroxide was the first product ofthe reaction on the ground that the mixture in equal volumes w amost sensitive to the spark. In a later paper (1900) hbe withdrewthis conclusion, although his work is still quoted as an argument infavour of the direct formation of peroxide.Whether or not alocal heating of a small mass of gas by a, spark will set up generalinflammation must depend inter alia on the rate a t which heat isconveyed away from the heated region; a gas richer in the rapidlymoving hydrogen molecules will convey heat away more quicklythan one poorer in hydrogen. Dr. Coward has recently foundtlhat the mixture in equal volumes is not the most sensitivetQ a spark. The addition of oxygen still further increases thesensibility.Consider the explosion-wave traversing the mixture H, + 0,674 DlXON : THE UNION OF HYDROGEN AND OXYGEN I N FLAME.111. But a stronger argument has been drawn by K. G. Falk*from his experiments on the ignition point of gaseous mixturesheated by adiabatic compression.Acting on the very ingenioussuggestion of Professor Nernst, he has compressed different mixturesof hydrogen and oxygen in a steel cylinder by means of a weightfalling on a piston, and has determined the volume of the compressedgas by measuring the lowest point reached by the piston. Heconsiders the whole mass of gas is heated equally throughout untilit reaches the ignition point, and then that the whole detonatespractically instantaneously, when the explosion stops the descent ofthe piston. On the assumption that the piston had no time tomove downwards appreciably after the ignition point was reached,he calculates the temperatures of ignition of different mixtures :Ignition point.605”540514530571The last four figures are plotted out, and the dotted curve drawnthrough them on page 676.Falk says: “The fact that themaximum affinity is shown by the mixture H,+O,, proves thatH,O, must be the first product of the reaction between hydrogenand oxygen.”Falk gives as his reasons for the assumption that the gas detonatesinstantaneously throughout its whole mass, once the ignition tem-perature is reached, the fact that the explosions are of greatviolence, and that the compression was very nearly the same in thecase of electrolytic gas whether the weight fell from a lower or ithigher altitude. What he found to be nearly true of the rapidly-firing mixtures, 2H,+ 0, and H, + O,, he has assumed to be alsotrue of the less rapidly-firing mixtures with excess of oxygen, andof mixtures of hydrogen and air.When I read Falk’s first paper, it occurred to nie that thedescending piston must send in front of it sound-waves, which wouldbe reflected from the bottom of the cylinder back to the pistonagain, and so bn, producing by their collisions zones of higher tem-perature, a t one of which the flame would eventually start.Falkstates in his second paper that Professor Jouguet has made thesame criticism. By photographing the explosion produced by theadiabatic compression on a rapidly-moving film, I have shown thatthe flame does start from a point, and in the more slowly burningmixtures the spread of the flame throughout the gas takes anappreciable time.Moreover, the point of ignition can be made to* K. G. Falk, J. Amer. Chm. Xoc., 1906, 28, 1517 ; 1907, 29, 1536DIXON : THE UPU’ION OF HYDROGEN AND OXYGEN IN FLAME. 675vary by altering the velocity of the piston. With electrolytic gasthe photographs show that the explosion-wave is very quickly setup, but the flame always starts f r o m one point. The mass of thegas i s n o t fired instnntaneousZy, although the time required in thiscase for the flame to reach the piston is negligible. With such amixture as H, + ZO,, the time required t o set up the explosion-waveis not negligible.I f we accept Nernst’s definition of the ignition point of amixture of gases as that temperature at which a mass of the gasrapidly self-heats itself by combination until it bursts into flame,and if this flame starts at some point in the mixture and spreadsfrom that point, there will be two periods during which the pistonmay continue to move after the “ ignition point ” has been reached :(i) the period from the beginning of rapid self-heating until theflame appears; and (ii) the period required for the flame to spreadthrough the gas and stop the descent of the moving piston.Just as the time required f o r the flame to set up the explosion-wave differs in different mixtures, so does the time required for theself-heating from Nernst’s ‘‘ ignition point ” to the actualappearance of the flame.When a mixture of air and hydrogen (5 vols.to 2) was com-pressed in the cylinder, and the descent of the piston was arrestedby means of a steel collar, I found the ignition temperature a fewdegrees only above that of electrolytic gas.This was in agreementwith our previous determinations at atmospheric pressure. Butwhen the piston was allowed to descend until it was stopped bythe explosion of gases, as in Falk’s experiments, I could obtainignition points, not only as high as Falk’s (649O), but, by increasingthe velocity of the piston, I got temperatures of 700°, 800°, or 900°at pleasure. A similar variation was found for the mixtureIt was evident that the error due to the movement of the pistonduring the ‘‘ pre-flame ” period of self-heating might be far greaterthan the error due to the movement of the piston a f t e r the flamehad started.I n determining the temperatures of ignition of mixtures ofhydrogen and oxygen, it was necessary, therefore, to stop the descentof the piston artificially the moment the gases were brought to theself-heating temperature.This was effected by having on the endof the piston a steel head, which was caught by a steel collar at acertain point in its descent. By varying the thickness of the collar,the piston could be stopped a t any point. By a series of trials acompression was found which fired the mixture, and a slightly lesscompression, which did not. The mean between the two was takenH, + 40,676 DIXON : THE UNION O F HYDROGEN AND OXYGEN IN FLAME.as the ignition point,. On repeating each experiment several times,nearly concordant ignition points were obtained.For the sake of comparison with Falk’s numbers, I have calculatedthe mean ignition points from my compression-volumes, using thesame ratio of the specific heats (y=1’40) as Falk has done. Thetemperatures so calculated are plotted in Fig. 2 with the continuouscurve drawn through them:Ignition pointsMixture. (y=1*40).H5 + 0 2 542H4 + 0, 536H, + 0, 53013, -t 0, 525H6+ 0, 557”Ignition pointsMixture. (y = 1 *40).H, + 0 4 520”H, + 0 5 516HZ + O6 512H,+O, 509 ir, + 0, 507570”56556055555054554053553052552051551050525 50 100 150 200 250 300 350 400Vols. of 0, t o 100 vols. of HO_.My ignition point for electrolytic gas agrees closely with thatfound by Falk, an agreement which shows that this mixture musthave a very short period of flameless combustion, and the spread ofthe flame must be very rapid. I find the mixture in equal volumeshas a lower ignition point than electrolytic gas, but it is not themixture of “maximum affinity.” The further addition of oxygenregularly lowers the ignibion point. I would submit, therefore, thaOBITUARY NOTICES. 677the ignition points of hydrogen and oxygen mixtures do not provethat hydrogen peroxide is the first product of the reaction.I began this address with a note of warning, and would wishtbo end on the same note. I have spoken of the use of hypothesesand hinted a t their abuse. I n criticism it has been my desire-atleast since the fierce invectives of youth lost their sweetness-to begentle with my adversary’s and stern with my friend’s hypothesis.If ever any of my old research students look back on my criticismsof their work with feelings from which time has removed thebitterness, I think they will admit that a t least I saved them fromtlie publication of hypotheses, useful perhaps at the time, butcertainly untenable in the light of fuller knowledge

ISSN:0368-1645    

DOI:10.1039/CT9109700661

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

OBITUARY NOTICES. 677OBITUARY NOTICES.CHARLES GRAHAM.BoltN SEPTEMBER 4TH, 1836 ; DIED NOVEMBER I ~ T H , 1909.THIRTY years ago, few names were more prominently identifiedwith the science and technology of brewing and malting in thiscountry than that of the subject of this memoir, and there are notninny men to whom those industries owe a heavier debt ofgratitude. Many greater investigators in this department ofapplied science there have been : men whose researches have earnedfor them almost world-wide renown, but it is t o the everlastingcredit of Graham that he was one of the earliest to recognise howgreatly science could aid in the development of the great industriesto which he devoted the best part of his life, and that he succeededin bringing home that all-important fact to large numbers of menwho were steeped in empiricism, and suffering from the paralysinginfluence of an unjustified complacency. From an early age,Graham manifested an intense love of natural science, and havingas a very young man decided to adopt chemistry as a profession,he entered the Chemical and Agricultural College a t Kennington,where he worked under Mr.Nesbit, devoting his attention toanalytical chemistry in general, and to agricultural chemistry inparticular. With a view to graduating a t the University ofLondon, he a few years later entered University College as astudent, and in 1864 took the degree of Bachelor of Science.About this time he was appointed an assistant t o Dr. A. W678 OBITUARY NOTICES.Williamson, then Professor of Chemistry a t that College, and in1866 he received the degree of Doctor of Science a t the Universityof London.Early in 1867, while still engaged a t UniversityCollege, he was invited by Baron H. von Rath, a Member of theReichsrath and President of the Rhenish Agricultural Society,to act as resident chemical adviser at his mining works in Nassau.Graham accepted that position, and was a little later appointedarbitrator in chemical matters between the German mine ownersand the English contractors. During this period Graham’sattention was largely devoted to a study of the Nassau phosphatedeposits, and t o questions connected with the chemistry of soiland to the rationale of artificial manuring. During the years1868-1870 he published, in German agricultural journals, a numberof papers on those subjects, all of which recorded painstakingand sound work, and several of which afforded evidence of thatscientific “ prevision ” which was so noticeable a characteristic inlater years.These papers attracted a good deal of attention a tthe time, and on the expiration, in 1870, of his German engage-ment, he was invited to proceed to Spain to examine and reporton some extensive mining properties in that country. On hisreturn to England a few months later, Graham resumed histutorial work at University College, and at the same timesupplemented his income by carrying on an analytical and con-sulting practice, and it was then that he seriously turned hisattention to the science of brewing and t o the technology of thefermentation industries generally.On December 8th, 1873, hedelivered the first of his well-known Cantor lectures, “On theChemistry of Brewing,” and the remaining four of the series weregiven on December 15th, and in the following February. Thesewere delivered before large audiences at the Society of Arts, werewidely reproduced in the trade and other journals, and produceda great impression. It was not that they contained much that wasstrikingly novel, and certainly nothing that was epoch-making,but they were well modelled, and admirably calculated t o effecttheir main object,, namely, to make the practical man think forhimself. At the end of the concluding lecture, Graham said :“After all, it (that is, this course) has only been suggestive.I t smain object has been to raise discussion, and excite inquiry. . . .My criticisms, however, have been solely actuated by a desire tomake you look a t the matter from a new standpoint, so that youmight see the rationale of the processes employed.” In a verydirect and personal sense, these lectures certainly did “ exciteinquiry,” and, as a result, Graham speedily built up a largeconsulting practice among brewers, maltsters, vinegar makers, anOBITUARY NOTICES. 679others; but they had a far more widely reaching effect, for hheytended in no small degree to accelerate the decline of empiricismand quackery, and to stimulate the spirit of inquiry and research.That they contained many views which are not altogether inaccord with our modern knowledge is not to be wondered at, butthey were models of clear subject arrangement, were characterisedby lucidity of treatment, and were occasionally illuminated byflashes of what, for want of a better term, must be called scientificforesight or prevision.I n fact, not a few processes which are ofcomparatively recent introduction into brewing and maltingpractice will be found to have been suggested, or at leastadumbrated, in those lectures. Six years later, that is, in 1879,Graham attempted to do for bakers what he had already donefor brewers and maltsters, and delivered before the Society ofArts a second series of Cantor lectures, “On the Chemistry ofBread Making.” These were modelled somewhat on the lines ofhis brewing lectures, and, in the words of the presiding chairman,were “not unworthy to take a place by the side of his formercourse.” Graham was always keenly interested in the work ofthe Society of Chemical Industry, and a t the first general meetingof that Society in June, 1881, communicated a paper on LagerBeer, which was a serious attempt to make the English publicacquainted with the virtues and properties of the low-fermentationbeers as made and consumed on the Continent.For a com-paratively short communication, this paper contains a vast amountof information, and can even now be studied with advantage.In 1878 Graham was appointed Professor of Chemical Technologyat University College, London, and in that capacity had t o dealwith the application of chemistry to a number of industries.Courses of study were laid down for metallurgists, alkali, soap andmanure manufacturers, manufacturers of glass, cement, artificialstone, etc., bleachers, dyers and calico printers, brewers, distillers,and vinegar manufacturers, agriculturalists, and consultingchemists and public analysts.Special courses of lectures weregiven on the chemistry of the alkali trade, on the chemistry ofbrewing, and on agricultural chemistry, of which by far the mostimportant and most numerously attended were those devoted to thechemistry of brewing and malting. That Graham’s life at thistime was a busy one may easily be imagined, for in addition tohis exacting professorial duties at University College, including,of course, both lectures and laboratory instruction, he carried ona large consulting practice, and was, moreover, for more thanthirteen years County Analyst under the Sale of Food and DrugsActs for the three divisions of Lincolnshire.In 1889 Graha680 OBITUARY NOTICES.resigned his Chair with the title of Emeritus Professor, and carriedon, in association with the writer of this memoir, a private con-sulting practice, chiefly in relation to the fermentation industries.A t the end of about ten years he retired to Hastings, where helived very quietly, and where he died on November 13th last, a tthe age of seventy-four.He wits an old Member of the Chemical Society, having beenelected in 1862, and served on the Council during the years1880-1881.He was also an original Fellow of the Institute ofChemistry, and had been a Vice-president and an Examiner ofthat body. Graham was a man of iron will and of immense forceof character, and, like many such men, was apt to conceive violentlikes and dislikes, which, so far as an outside observer could judge,were frequently without justification. I n scientific matters cautiousto a fault, and never sparing any pains himself in endeavouringto arrive a t the truth, he was angrily impatient of all who,through defective powers of observation, intellectual laziness, orcarelessness, communicated to him statements which he knew tobe incorrect. He was a man of wide scientific attainments, andpossessed a large fund of hard common sense, qualities whichrendered his advice (not always confined to purely technicalmatters) of the greatest value to his numerous clients.Easilymoved to anger by opposition, direct in his speech, and oftenbrusque in his manner, he was, nevertheless, capable of formingreal attachments, and was the author of many acts of unostenta-tious kindness. Throughout his life, however, his main affectioncentred in his old College, and those who knew him at all wellwill hardly have been surprised that at his death he should havebequeathed to it the bulk of his estate. Apparently strong andvigorous, he yet knew much of physical suffering, and one cannothelp feeling that there is some connexion between that fact andthe terms of his bequest, namely, that it should be devoted to theencouragement of research, having for its object “ the prevention,cure, or alleviation of human disease and suffering.”A.CHASTON CHAPMAN.THEOPHILUS HORNE REDWOOD.BORN JULY 3 1 s ~ , 1849; DIED MARCH 3 1 s ~ , 1909.THEOPHILUS HORNE REDWOOD, the second son of Dr. TheophilusRedwood, was born on July 31st, 1849. He was educated a tUniversity College School, and received his instruction in chemistryin the laboratory of his father, who was Professor of Chemistry a OBITUARY NOTICES. 681the Pharinaceutical Society. For many years he acted as assistantto his father, and then turned his attention to industrial chemistry,accepting an appointment as chemist on the lime plantations ofMessrs. Sturge on the island of Montserrat, West Indies.Sub-sequently he became associated with the important undertakingnow known as Borax Consolidated.He possessed unusual artistic taste, which he turned to goodaccount in cultivating the a r t of landscape photography longbefore the days of films and dry plates. H e was elected a Fellowof the Royal Photographic Society in 1896.He suffered from a congenital malformation of the spine, whichin his later years caused partial loss of power in the lowerextremities, and otherwise prejudicially affected his health, buthis affliction was borne uncomplainingly, his hopefulness, cheerful-ness, and sense of humour being maintained to the last.Although of remarkable keenness of intellect, he was an excep-tionally modest and unselfish man, always taking a kindly andactive interest in the welfare of others, and a t all times readywith encouragement and sympathy.He had, indeed, a charmingdisposition, was loved by all who knew him intimately, and nevermade an enemy.Although for the last two or three years of his life he waspractically confined to his house, he was contemplating anothervisit to the islands of the West Indies, when he had an attackof pneumonia, to which he succumbed on March 31st, 1909.He leaves a widow, two sons and two daughters.B. D.SIR THOMAS WARDLE.*BORN JANUARY ~ ~ T I I , 1831; DIED JANUARY 3RD, 1909.SIR THOMAS WARDLE was born at Macclesfield on January 26th,1831. He was the eldest son of Mr. Joshua, Wardle, of CheddletonHeath, near Leek, who founded the silk dye works of Joshua Wardleand Son, at Leek Brook, when Sir Thomas was scarcely a year old.Educated at Macclesfield and Leek, he entered his father’s business,and his early energies soon bore fruit in the well-being of the firm.His efforts in life were not destined to be restricted to one particularchannel, for soon after the death of his father he brought intobeing the silk and cotton printing business of Wardle and Co., a tHencroft, Leek. Sir Thomas Wardle was a, keen student ofchemistry, geology, and archzeology, and later on of sericiculture,and his tastes ranged over an even wider field.* Abridged, by permission, from the JlmriaaZ of Tndia,t Art and Ividmtr682 OBITUARY NOTICES.The first dealing Sir Thomas had witJi Indian products was thetrial he made, at the instigation of Sir George Birdwood, to utiliseTasar silk, the wild silk of India, and to make it a marketablecommodity. As a result of his experiments he succeeded inbleaching the brown fibre and in dyeing it with such perfection asto make it serviceable in the manufacture of fabrics.For severalyears a Wardle collection of bleached and dyed Tasar silks was onexhibition at Lyons, and this was shown in the British sectionof the 1878 Paris Exhibition. Sir Thomas became a juror at thisInternational Exhibition, and had the honour to be appointed aChevalier of the Legion of Honour.A t the instigation of Sir George Birdwood, the Secretary of Statein the year 1885 sent Sir Thomas Wardle out to India in orderto make a typical collection of silk textiles and native embroideriesfor the Silk Culture Court of the Colonial and Indian Exhibition,and he was also requested to visit the Bengal silk districts and tomake a report on sericiculture.As an outcome of the inquiry, itwits brought to light that 60 per cent. of the silkworms died ofpreventible diseases, and that the reeling from the cocoons in thefilatures was very imperfect.I n the year 1887 he accepted the position sf Chairman to theSilk Section of the Manchester Jubilee Exhibition, and, chieflythrough his energies, a display of silk manufacturing processes fromthe reeling of cocoons onwards was exhibited. It was from thisexhibition that the Silk Association of Great Britain and Irelandcame into existence, witth Sir Thomas Wardle as its president, andto this honourable post he was elected, without intermission, yearafter year, until his death in 1909.During the year 1896 Lieut.-Colonel Sir Adelbert Talbot,K.C.I.E., was appointed Resident in Kashmir, and, as a result ofhis study of Sir Thomas’s encouraging reports on the possibilitiesof Kashmir silks, he recoinmended H.H.the Maharajah of Kashmirto commence the industry on a commercial basis and in a scientificand extensive manner. I n 1897 Sir Thomas was requested toconsult with Sir George Birdwood a t the India Office on the subject,and subsequently he was sent to France and Italy to select thebest races of silkworm eggs, and to acquire the very best reelingmachinery, as well as to find a suitable person to direct operationsin Kashmir.In the year 1897, a t the instance of Lord Salisbury, he receivedfrom her Majesty the Queen the honour of knighthood for thework he had given to India and the silk industry generally.From the year 1897 the sericiculture in Kashmir progressed andwent ahead by leaps and bounds, and in 1900 the output of raw silOBITUARY NOTICES.683was 57,921 lbs.; in 1901 it increased to 90,648 lbs.; and in 1902it reached the very creditable figure of 135,221 lbs.A t a later date Sir Thomas Wardle strongly advocated thecommencement of silk weaving in the State, and he was instructed,with the Maharajah’s sanction, to send out from England theplant necessary for an initial factory, and the first instalment was200 looms, together with a young and capable weaver fromMacclesfield to superintend the preliminary stages.Success provedto be in the wake of this venture, and at the present time scientificweaving takes place daily at Srinagar.One of the most important honours, and certainly the one thatgave Sir Thomas Wardle one of his greatest pleasures in life, washis admission by the Worshipful Company of Weavers to thehonorary freedom of the Weavers’ Company on February 3rd, 1903.He was then able to acquire the Freedom of the City of London.Sir Thomas Wardle wrote many monographs on scientific andtechnical subjects. He added a learned chapter in the geology ofLeek and district to the first edition of the “History of Leek,”by John Sleigh, published in the year 1862.His splendid collectionof carboniferous limestone fossils he gave to the Nicholson Instituteat Leek. Other works on geology were: (( Geology of the Roches,”“ Geology of Shuttlingslowe,” (( Geology of Mid-England.” He alsowrote on the technical aspects of artistic weaving, and his mono-graph on “ The Present Development of Silk Power-loom Weavingin France” was the outcome of a visit to Lyons in 1893 toinvestigate the subject. His works on silk and the silk industrywere most numerous, the most important being (I Report on theEnglish Silk Industry,” “ Silk : its Entomology, History, andManufacture,” “ History and Growing Utilisations of Tasar Silk,”(‘ The Wild Silks of India,” ‘( The Dyes and Tans of India,” (( TheAdulteration of Silk by Chemical Weighting,” Kashmir : its NewSilk Industry,” etc., and his last work was a monograph on the‘‘ Divisibility of Silk Fibre,” published in 1908.Sir Thomas Wardle died peacefully at his Leek residence onJanuary 3rd last year, in his seventy-eighth year, surviving his wifeby seven years.He always lived a life of high pressure, he workedwell, and played well, and it was doubtless in consequence of thisjudicious combination of the two that he was enabled to live a lifeof almost youthful activity. It was only six months from hisdeath that the strain perceptibly told on him, and from that periodhe gradually sank and passed away.VOL. XCVII. z 684 OBITUARY NOTICES.ALEXANDER FORBES WATSON.BORN JANUARY IGTH, 1872; DIED AUGUST 4TH, 1909.ALEXANDER FORBES WATSON, Chief Chemist in the Brewery ofMessrs.Arthur Guinness, Son and Co., Ltd., died on August 4th,1909, in his thirty-eighth year, as the result of an accident atFerbane, King’s Co., Ireland.He was born in Edinburgh on January 16th, 1872, and receivedhis early education at George Watson’s College in that city. I n1889 he began t o study chemistry a t Surgeon’s Hall, Edinburgh,and the Heriot-Watt College, where Prof. W. H. Perkin, jun.,occupied the chair of chemistry. He then entered the Universityto become a student under Frof. Crum Brown, and graduatedB.Sc. in 1893, in which year he was also appointed a UniversityAssistant. During his career as a student he gained the HopeScholarship, and in 1894 the George Heriot Fellowship.I n pursuit of an intention to devote himself to some branch oftechnical chemistry, Mr.Watson turned his attention to bio-chemical problems in connexion with brewing, and in order t oacquire a special knowledge of mycological work, he spent sometime in the laboratory of Alfred Jorgensen in Copenhagen, andalso in that of Dr. Mach, of the Scientific Institute of San MichBle,where a study of wine ypsts could be made. +On his return toEdinburgh, Mr. Watson was appointed Lecturer on Fermentationin the University, but his tenure of this post ceased in 1896, whenhe took up his appointment as Chemist to Messrs. Guinness.Although Mr. Watson as a chemist was probably not widelyknown, those who had any acquaintance with the extent andvariety of his professional work knew him for a man of distinctionin all that he did. The problems of a great brewery call for anapplication of almost every branch of chemistry, and Mr. Watson,encouraged by a sympathetic directorate, was not slow to demon-strate the interpretative powers of laboratory experiments in theirbearing on practice. His success was largely due to his facultyof adhering to strictly scientific methods, while never failing tosteer his investigations according to the practical object in view.In the biochemical industries this is, perhaps, a much more difficultproposition than it is generally known to be; a t any rate, thechemist who would be a success in an essentially conservativeindustry like brewing must be ever ready to justify his science bywhat it can add to practical experience, instead of producingresults which may be only interesting and suggestive. From sucha point of view, R4r. Watson was one of the most able technica1 : 4-DICHLOROANTHRAQUINONE AND ITS DERIVATIVES. 685chemists of his day, and although his work as an investigatorwas compressed into a few short years, its soundness and thorough-ness have probably not been surpassed, even in an industry whichis justly celebrated for the high standard of its scientific work.J. H. M

ISSN:0368-1645    

DOI:10.1039/CT9109700677

出版商:RSC    

年代:1910

数据来源: RSC

摘要:

1 : 4-DICHLOROANTHRAQUINONE AND ITS DERIVATIVES. 685XLV.-1 : 4-Dichloroanthraquinone and Its Derivatives.By GERTRUDE MAUD WALSH and CHARLES WEIZMANN.NAPHTHACENEQUINONES prepared by the condensation of 3 : 6-dichloro-phthalic anhydride and a-naphthol, and the elimination of water fromnaphthoylbenzoic acid, have been previously described (Harrop, Norris,and Weizmann, Trans., 1909, 95, 279), and also the anthraquinonesfrom 3 : 6-dichlorophthalic anhydride and the three xylenes (Harrop,Norris, * and Weizrnann, ibid., 1312). The present communicationdeals with the parent quinone and 1 : 4-dichlorohydroxymethylanthra-quinones derived from o-, m-, and y-cresols. The condensation of3 : 6-dichlorophthalic anhydride and benzene was carried out byLe Royer (Anncclen, 1887, 238, 356), but he did not prepare thecorresponding quinone.1 : 4-Dichloroanthraquinone has been isolatedby Hammerschlag (Ber., 1886, 19, 1109), and was also obtained byGraebe (Ber., 1900, 33, 2019). In order further to characterise thisquinone, several of its derivatives have been prepared.The condensation of dichlorobenzoylbenzoic acid (I) to the quinone(TI) is easily effected by warming with fuming sulphuric acid.C1 CI(I. 1 (11.)When warmed with concentrated nitric acid in presence of a littlefuming sulphuric acid, 1 : 4-dichloroanthraquinone yields a mononitro-derivative, which is easily reduced to the corresponding amino-com-pound by tin and acetic acid. When heated with fuming sulphuric acid,1 : 4-dichloroanthraquinone forms a monosulphonic acid.The twochlorine atoms are readily displaced by phenoxy-groups when heatedwith excess of sodium phenoxide, furnishing the corresponding I : 4-diphenoxyanthraquinone (111) :OPh/\-GO-/)1 I-co I\/ -\/OPh(111.)2 2 686 WALSH AND WEIZMANN :The condensation of 3 : 6-dichlorophthalic anhydride with 0-, rn-,and p-tolyl methyl etherd by means of aluminium chloride, and thesubsequent closing of the ring by fuming sulphuric acid to producethe desired quinones, does not proceed so smoothly and satisfactorilyas in the case of the formation of 1 : 4-dichloroanthraquinone.3 : 6-DichZoro-5'(or 6'-)-hydvoxy-2-0(0r m-)-toluoylbenxoic acid (IV)c1 Me(or OH) c1 Me( I n w. 1is prepared from 3 : 6-dichlorophthalic anhydride and p-tolyl methylether in presence of aluminium chloride.Most of the acid ishydrolysed during the reaction, and part of it is converted into thecorresponding quinone. When treated with a molecular proportionof bromine in warm acetic acid solution, this acid forms a monobromo-derivative, which, on dissolving in warm fuming sulphuric acid, givesprobably the corresponding bromo-quinone, but the yield is poor, andi t was not found possible to obtain this quinone in sufficientquantitiesfor analysis. By the removal of water from the above 3 : G-dichloro-hydroxy-2-toluoylbenzoic acid, 1 : 4-dichloro 8-hydroxy-5-methylanthra-puinone (V) is obtained in small yield.The replacement of the- two chlorine atoms by phenoxy-groups doesnot take place so easily as in the case of the parent quinone (11).The presence of copper powder is necessary, and even then only one ofthe chlorine atoms is attacked.With phenyl mercaptan, even in thepresence of copper powder, no substitution occurs.3 : 6-Dichlorophthalic anhydride condenses with o-tolyl methylether and also with m-tolyl methyl ether to form 3 : 6-dichZoro-3'(or 2'-)-hydroxy-2-o(or m-)-toluoylbenxok acid (VI) and 3 : 6-dichloro-4'(or 2'-)-methoxy-Z-o(or p-)-toluoylbenzoic acid (VII) respectively :/\-CO--f)OH(or Me) /\-CO--/(pw \/c1 Me(or OH) c1 Me(or OMe)\/ I b0,H \/ )OMe(orMe)c1 c1V I . 1 (VII.)These two acids when treated under the conditions described in theexperimental part of this paper lose water and form the correspondingmethylanthrnquinones ('VIII and IX) :c1 Me(or OH) c1 Me(or OMe)/\-GO- /\1 --CO-(,!OMe(or Me)'(IX* 1I /\-CO-/)OH(or Me)(V 111.)p 0 - 1 \/ \ c1C1 : 4-DICHLOROANTHRAQUINONE AND ITS DERIVATIVES.687The latter (IX) is, however, produced in such very minute quantitiesthat sufficient has not yet been obtained for analysis.EX PER I MENTAL.1 : 4- Dichloroanthraqzl~ione, C,H,C12<CO>C6H,. coThe quinone is obtained by heating 50 grams of 3 : 6-dichlorobenzoyl-benzoic acid with 50 grams of boric acid, together with an excesg offuming sulphuric acid (containing 10 per cent. of sulphur trioxide), tolooo for a few minutes. After cooling, the mass is poured on ice andfiltered. Traces of unchanged acid are removed by boiling dilutesodium hydroxide, and the quinone is finally purified by crystallisa-tion from glacial acetic acid, from which it separates in yellow needles,melting a t 186' :0.1493 gave 0-3291 CO, and 0.0293 H,O.C=60*12 ; H=2*18.C,,H,O,Cl, requires C = 60.64 ; H = 2.16 ; C1= 25.63 per cent.0.1513 ,, 0.1539 AgC1. Cl=35*18.1 : 4-Dichloroanthraquinone is soluble in benzene, alcohol, or aceticacid.1 : 4- Dichloro-5-nnit~*oc~nthrapuinone, * C,H,CI,<CO>C,H,*NO,. GO1 : 4-Dichloroanthraquinone is dissolved in concentrated nitric acidcontaining a little fuming sulphuric acid, and gently warmed for fiveminutes, The deep yellow solution is poured into water, when thenitro-compound crystallises out. On recrystallisation from glacialacetic acid it melts at 238'.It is readily soluble in benzene, butinsoluble in methyl alcohol. From acetic acid it separates in minute,yellow needles :0.1343 gave 0.2559 C 0 2 and 0.0165 H,O.0-1587 ,, 6.7 C.C. N, (moist) a t 18" and 740 mm. N = 4-70.C,,H,O,NCl, requires C = 52.17 ; H = 1.55 ; N = 4.35 ; C1= 22-05per cent.C=51*98 ; H = 1-37,0.1221 ,, 0.2068 AgCl. Cl=21*65.This is prepared by reducing the nitro-quinone just described withtin in acid solution. The nitro-compound is dissolved in acetic mid,tin added, and the mixture heated, when the liquid assumes Rcrimson colour. The product is poured into water and neutralised* From analogy to anthraquinone the nitro-group probably occupies the 5-positio11688 WALSH AND WEIZMANN :with sodium hydroxide, when the base separates in red needles, melt-ing at 199' :081440 gave 6 C.C.N, (moist) at 17' and 748 mm.The acetyl derivative is obtained by heating the base with excess ofacetic anhydride in presence of pulverised zinc chloride. The productis poured into water, and the resulting precipitate is collected and purifiedby crystallisation from xylene, from which it separates in yellowneedles, delting at 178'. With concentrated sulphuric acid it gives ared coloration :N = 4.75.C,,H70,NCI, requires N = 4.79 per cent.0.1584 gave 6.4 C.C. N, (moist) at 15' and 746 mm.C,,H90,NCI, requires N = 4.18 per cent.The acetate of 1 : 4-dichloro-5-aminoanthraquinone melts at 185' :0.1834 gave 0.3678 CO, and 0-0580 H20. C=54*69 ; H=3*53.C16H,,0,NC1, requires C = 54-54 ; H = 3.12 per cent,N= 4.61.1 ; 4-DichZoroanthrapuinone-6-suZphonic Acid,This acid was isolated in the form of its sodium salt in the followingmanner : One part of 1 : 4-dicbloroanthraquinone was mixed withtwo parts of fuming sulphuric acid (containing 10 per cent.of sulphurtrioxide), and heated in an oil-bath (150-180°) until a drop of themixture gave a clear solution in water. The product was then cooledand poured into water, neutralisod with sodium carbonate, andevaporated, when yellowish-brown crystals of tzhe sodium saltappeared :0.1528 gave 0.0288 Na,SO,.When fused with potassium hydroxide and the product poured intoNa= 6.12.C,,H,O,Cl,SNa requires Na = 6.07 per cent.water, a brilliant purple coloration is obtained.1 : 4-Dip?henoxyanthracpuirnone, C6H,(OPh),<co>C,H,.coTen grams of 1 : 4-dichloroanthraquinone were mixed with 15 gramsof sodium hydroxide and a large excess of phenol, and the mixtureheated in an oil-bath to lS0' for two hours. The red liquid productwas acidified, and the excess of phenol removed by distillation in acurrent of steam, when the diphenoxy-compound remained behind as adark oily mass, which solidified on cooling. It crystallises frommethyl alcohol in reddish-yellow needles, melting at 238O :0.1676 gave 0.4875 CO, and 0,0621 H,O. C=79.33; H=4.1.C26H1604 requires C = 79.59 j H = 4.05 per cent1 4-DICHLOROANTHRAQUINOXE AND ITS DERIVATIVES. 6891 : 4- D~p?~enoxy~nt~raquinon~ dissolves in concentrated sulphuricacid with a red colour, which changes to a rich amethyst on theaddition of a little fuming sulphuric acid.When warmed on thewater- bath with concentrated nitric acid containing a little fumingnitric acid i t dissolves, forming a light red solution, from which, onpouring into water, a dinitro-derivative, melting a t 206O, is precipitated.C26H,,0,N, requires N = 5.81 per cent.0.1393 gave 7.1 C.C. N, a t 1'7" and 746 mm. N-5.80.3 : 6-Dichloro-5'(or 6'-)-hydroxy-2-o(or m-)-toluoyZbenzoic Acid,CO,H*C,H,C1,*CO*CGH,Me* OH.3 : 6-Dichlorophthalic anhydride (180 grams), purified by distillationin a vacuum, was mixed with p-tolyl methyl ether (100 grams) incarbon disulphide solution, and aluminium chloride (300 grams) wasgradually added. The mixture was heated on a water-bath for eighthours.The dark red semi-solid mass was then decornposod with iceand hydrochloric acid, and the carbon disulphide and the unchangedp-tolyl methyl ether were removed by distillation in a current oEsteam. The residual product was dissolved in sodium hydroxide, andagain distilled in a current of steam with animal charcoal. Thefiltered alkaline liquid was decomposed by ice and hydrochloric acid,when the acid separated as a bulky, cream-coloured precipitate. Itwas collected, dried, and purified by crystallisation from acetic acid.Most of the 3 : 6-dichloromethoxy-2-toluoylbenzoic acid sufferedhydrolysis, and some of the hydroxy-acid produced condenses t o thequinone. Ry repeated crystallisation of the product of the reactionfrom methyl alcohol, 3 : 6-dichlorohydroxy-2-toluoyl benzoic acid masobtained, but it was somewhat difficult to free it from all traces of themethoxy-acid :0.1428 gave 0.2914 CO, and 0.04524 H20.C = 95-65 ; H = 3.53.0,1635 ,, 0,1468 AgCI. C1= 22.21.C,,H,,O,Cl, requires C = 55.38 ; H = 3-08 ; Cl = 21 -84 per cent,3 : 6-Dichloro-5'(or 6'-)-hydroxy-2-o( or m-)-toluoyl6enxoic acid crystal-liaes from methyl alcohol in colourless needles, melting at 173'. Itssodium salt is yellow. When heated with one molecular proportion ofbromine in acetic acid solution on the water-bath, substitution readilyoccurs, and on pouring into water a monobromo-derivative is precipi-tated. It crystsllises from methyl alcohol in pale yellow, minuteneedles, melting at 188'.When warmed with sulphuric acid containing a little boric acid, itforms a quiiione melting at 242", but the yield is poor690 WALSH AND WEIZMANN :1 : 4 -DichZoro-8 -hydroxy - 5-met h y lanthruquinone,This was prepared by heating the above 3 : 6-dichlorohydroxy-2-toluoylbenzoic acid with an excess of fuming sulphuric acid (containing10 per cent.of sulphur trioxide) in presence of boric acid for a fewminutes at 130'. The mixture was cooled, poured on ice, andfiltered. It was freed from acid by boiling with sodium carbonate,washed with dilute hydrochloric acid, and crystallised from glacialacetic acid :0.1231 gave 0,2662 CO, and 0.0321 H,O. C = 58-97 ; H = 2-89.C,,H,0,C12 requires C = 58.63 ; H = 2.60 ; C1= 23.12 per cent.0.1392 ,, 0.1269 AgCl.C1=22.56.This quinone separates from acetic acid in minute, yellow needles,meltingat 259', and is sparingly soluble in benzene. I t dissolves inconcentrated sulphuric acid, giving a brilliant red solution with apurple fluorescence.When 3 : 6-dichloromethoxy-2-toluoylbenzoic acid was condensedin a similar way, it was hydrolysed and gave the above quinone.The acetyyl derivative of 1 : 4-dichloro-8-hydroxy-5-methylanthra-quinone is readily prepared in the usual way by means of aceticanhydride and zinc chloride. It crystallises from acetic acid in long,lemon-yellow needles, melting at 181' :0.1515 gave 0.3213 CO, and 0.0424 H,O. C = 57%5 ; H = 3.11.C,7HI,0,Cl, requires C = 58.45 ; H = 2.86 ; C1= 20.34 per cent.1 (or 4)-Chloro-S-hydroxy-4( or l)-pAenoxy-5-rnet?qlanthraquinone.-Unlike 1 : 4-dichloroanthraquinone, the chlorine atoms i n the quinonederived from p-tolyl methyl ether are not replaced by heating withsodium phenoxide.I n presence of copper powder, however, ouechlorine atom is displaced by the phenoxy-group. 1 : 4-Dichloro-S-hydroxy-5-methylanthraquinone (1 0 grams), phenol (50 grams), sodiumhydroxide (20 grams), and copper powder (2 grams) are heated in anoil-bath at lS0" for three hours. The brownish-red solution is acidified,distilled in a current of steam, and the residual oil left to solidify,any adhering oil being removed by porous porcelain. The quinoneseparates from methyl alcohol as a reddish-brown powder, meltingat 268':0.1297 ,, 0*1080 AgCl. C1= 20.68.0.1559 gave 0.3938 CO, and 0.0565 H,O.C = 68.90 ; H = 4.02.0.1003 ,, 0.0410 AgCl. C1- 10.01.C2~H1304Cl requires C = 69.14 ; H = 3.56 ; C1= 9.74 per cent.The compound is readily soluble in warin benzene or acetic acid,and dissolves in fuming sulphuric acid, forming a violet solutionI : 4-DICHLOROANTKRAQUINONE AND ITS DERIVATIVES. 69 1Attempts to prepare the corresponding phenylthiol derivative wereunsuccessful.3 : 6-DichZoro-3'(or 2'-)-hydroxy-%o(or m-)-tokoylbenzoic Acid,COzH*CGHzClz*CO* C,H,Me*OH.This acid was prepared by condensing 3 : 6-dichlorophthalic anhydridewith o-tolyl methyl ether in presence of aluminium chloride, as describedon p. 689. A reddish-purple product was obtained. After purificationand recrystallisation from acetic acid, white needles, melting a t 1 8 3 O ,separated :0.1473 gave 0.2977 CO, and 0.0475 H,O.C = 55-13 ; H = 3.59.C15Hlo0,CI, requires C = 55.38 ; H = 3.08 ; C1= 21.84 per cent.0.1453 ,, 0.1258 AgC1. C1= 21-87.The properties of this acid are similar to those of 3 : 6-dichloro-1 : 4-DichZoro-6(or 5-)-hydroxy-5(or 6-)-methyZanthl~aqzcinolzs,5'(or 6'-)-hydroxy-%o(or m-) -toluoylbenzoic acid.C,H,Cl,<~~>C,H,M e*OH,was prepared in the same way as described on p. 690. The yield isslightly better than in the case of the corresponding 1 : 4-dichloro-8- h y droxy-5 methylant hraquinone. The compound separates fromacetic acid as a flocculent, yellow powder, which decomposes at 249O :0.1063 gave 0,2313 CO, and 0.0313 H,O. C = 59.32 ; H = 3-27.C15H80zC12 requires C = 58.63 ; H = 2.60 ; C1= 23.12 per cent.0.1516 ,, 0.1378 AgCI. C1= 22.49.3 : 6-D ich lor 0- 4 '( o r 2 ' ) -met h ox y- 2- o( or p ) - to Zuoylbenxoic Acid,CO,H C,H,CI ,*CO*C,H,Me*OMe.This acid mas prepared as described on p. 689, but m-tolyl methylether was substituted for the para-compound. It separates from etherin colourlese needles, melting at 312O, which are readily soluble inalcohol or acetic acid :0.1694 gave 0.3531 CO, and 0.0596 H,O. C = 56.84 j H = 3.85.0.1316 ,, 0.1096AgC1. C1= 20.60.C]&~]@~c12 requires C = 56.63 ; H = 3-54 ; C1= 20.94 per cent.On fractionally crystallising from acetic acid, colourless, needle-shaped crystals separated, which decompose at 242'. This substanceappears to be formed by the condensation of two molecules of rn-tolylmethyl ether with one of 3 : 6-dichlorophthalic anhydride, but as onlya small amount was isolated, it was impossible to obtain well-agreeinganalyses692 PURVIS: THE ABSORPTION SPECTRA OF THE1 : 4-DichZoro-7'(or 5'-)-methoxy-5'(or 7'-)-methyZanthraquinone,C,H,Cl~<~~>C,H,Me*oM~.This compound was obtained by condensing the acid describedabove in the usual way, but nearly all of it was sulphonated duringthe process, and a very small yield of the quinone was obtained. I tis yellow, and, after crystallisation from acetic acid, decomposesat 236'.THE UNIVERSITY,M ANCHESTER

ISSN:0368-1645    

DOI:10.1039/CT9109700685

出版商:RSC    

年代:1910

数据来源: RSC