2892 WILSON, HEILBRON, AND SUTHERLAN D : CONTRIBUTIONSCCLXXT.-Cont~.i~utiorLs to Our Knowledge of Semi-carbaxorm. Part IV. Action of HydrogenChloride.By FORSYTH JAMES WILSO&, ISIDOR MORRIS REILBRON, andMAGGIE MILLEN JEFFS SUTHERLAND.IN the course of our investigations on tho preparation and proper-ties of some semicarbazones it was found that the presence of hydro-chloric acid produced colorations in solutions of some of thesesubstances. As the semicarbazones are, in part, basic compounds’it occurred to us that this development of colour might be dueto the formation of salts, and in fact experiments instituted toelucidate this point showed that some of these substances do formsalts with acids.The following experiments were carried out to determine underwhat conditions salts are formed, and to what extent their forma-tion is influenced by the constitution of the semicarbazone.Forthe most part the investigations have been made on the hydro-chlorides oE the semicarbazones. Various methods were tried forthe preparation of these salts, and it was found that special pre-cautions had t o be taken against the presence of moisture, as thistended, in the presence of hydrochloric acid, to hydrolyse the semi-carbazone and give only the aldehyde o r ketone and semicarbazidehydrochloride.I n many cases the salt may be prepared by dissolving the semi-carbazone in dry chloroform and passing dry hydrogen chlorideinto the solution. The difficulty in this case is that, if the salt isunstable, exposure t o air while filtering brings about decomposi-tion, so that correct results are not obtained.The most satisfactoryresults were obtained by passing dry hydrogen chloride over tmhedry substance contained in a U-tube and estimating the quantityof acid addedTO OUR KSOWLEDOE OF SEMICARB.\ZONES. PART 1V. 2893Two ~iperoitylidenencetolzesemic~rbazolzes were prepared, an a-and a P-modification. These isomerides have different meltingpoints and different properties. a-Piperonylideneacetonesemi-carbazone was exposed to the action of dry hydrogen chloride, andan unstable, crystalline, vermilion salt containing 2.5 molecularproportions of hydrogen chloride was obtained. This salt onexposure to air loses hydrogen chloride, and finally gives a stable,orange mono hydrochloride.kl - Piperonylideneacetonesemicarbaaone gives with hydrogenchloride a stable, yellow mo~Lohydrochloride, and no further addi-tion can be made to this compound even on continued passage ofhydrogen chloride over the dry salt.A slight change in colour isobserved, but no addition of acid.This semi-carbazone exhibits interesting phototropic properties after exposureto bright light. On treating this substance with hydrogen chlorideit coinbiiies with 2 molecular proportions of hydrogen chloride, andgives an exceedingly unstable, deep orange compound. A sulphateof this semicarbazons was also prepared, which contained onemolecular proportion of sulphuric acid. The sulphate is brightyellow, and stable in ordinary air.Cinnamaldehydesemicarbazone, an unsaturated compound, might,be expected to combine with hydrogen chloride a t the double bond,or, at least, that the unsaturated nature of the substance wouldinfluence the formation of an additive compound.The presence of a phenyl group in the semicarbazide radicle evi-dently influences the absorption of hydrogen chloride, for it wasfound that cinna~aldehydepheitylsemicarbazo~~e unites with onlyone -nolecular proportion of hydrogen chloride, the monohydro-chloride thus obtained being yellow.On saturating cinnamalde-hydeplienylsemicarbazone with bromine a dibromide, @16H150N3Br2,is formed, and this substance does not combine with hydrogenchloride. The addition of bromine therefore prevents salt-forma-tion.A n~onobromo-derivative was prepared from this dibromide byboiling with alcohol, when hydrogen bromide was evolved and mot2 0-h Torti ocin 7tn nialdehydephen ylsemicarbazo n e , C16H,,0N3Br, obtained.This compound combines rapidly with hydrogen chloride, giving abright yellow salt containing one molecular proportion of hydrogenchloride.On preparing monobromocinnamaldehyde, and then for m-ing the phenylsemicarbazone and passing hydrogen chloride overthe compound, a d i h ydrochlwide is obtained, which is exceedinglyunstable, all the hydrogen chloride being liberated on exposureto air.Cinnamaldehydesemicarbazone was next prepared.VOL. cv. 9 2894 WILSON, HEILERON: AND SUTHERT,AND : CONTRIBUTIONSSimple semicarbazones, such as acetonesemicarbazone and acetone-phenylsemicarbazone, also absorb hydrogen chloride, but no colouris developed ; the substances remain white, but lose their crystallinestructure and fall to powder.Acetonesemicarbazone forms a com-parat'ively sts~ blo monohydrochloride, whereas the addition ofhydrogen chloride to acetonephenylsemicarbazone reaches a maxi-mum when one and a-half molecular proportions have been takenup. This salt loses hydrogen chioride very rapidly, becoming mcrestable when half a molecular proportion of hydrogen chloride hasbeen lost, that is, the monohydrochloride is comparatively stable.Acetophenonesemicarbazone and acetophenonephenylsemicarbazonewere also examined, as these contain more phenyl groups in themolecule, and might be expected to react differently.These sub-stances combined very readily with hydrogen chloride, giving, ineach case, a yellow dihydrochzoride, which is exceedingly unstable.A simple aromatic aldehydesemicarbazone, such as benzaldehyde-semicarbazcne, reacts also with hydrogen chloride, giving a mono-hydrochloride, which is comparatively stable and only slightlycoloured. Benzaldehydephenylsemicarbazone gives a yellow di-hydrochloride, which is very unst'able.From the results obtained it would seem, first, that the mono-hydrochlorides are f o r the most part more stable than the dihydro-chlorides, and, secondly, that the introduction of a phenyl groupinto tho basic partl of the molecule of unsaturated semicarbazonesdiminishes their capacity for addition of hydrogen chloride, whereasin the case of the saturated semicarbazones it increases this capacity.This is shown by a comparison of cinnamaldehydesemicarbazonedihydrochloride and cinnamaldehydephenylsemicarbazone mono-hydrochloride with benzaldehydesemicarbazone monohydrochlorideand benzaldehydephenylsemicarbazone dihydrochloride.We intend t o extend these investigations to a larger number ofsemicarbazones before giving our views on the possible change ofstructure during addition of acids t o semicarbazones, but as cir-cumstances have arisen which render the continuation of the workimpossible for the present and as i t is uncertain when it can becompleted i t was thought advisable to record these results.E XPE R I MEN T AL.Piperoi&den eacetonesemicarbazones.Yellow piperonylidereacetone was prepared according t o Haber'smethod (Ber., 1891, 24, 618).Haber recrystallised his productfrom alcohol, in which the substance is sparingly soluble, but itwas found more convenient, to use benzene as the solvent. ThTO OUR KNOWLEDGE OF SEMICARBAZOKES. PART IV. 2895white, stereoisomeric piperoiiylideneacetone was also prepared byHaber’s method.A semicarbazone was prepared from each ketone in the usualmanner, and crystallised first from alcohol and finally from chloro-form. It was found that the two stereoisomeric ketones gave oneand the same semicarbazone, melting a t 217O, and a mixture ofthe products showed no depression of the melting point:0,2020 gave 29-15 C.C.N, a t 16O and 766.5 mm. N=16*85.The semicarbazone forms white crystals, which are insoluble inWe designate this semicarbazone as the a-modification.On hydrolysis with hydrochloric o r acetic acid the semicarbazoneyielded the yellow modification of piperonylideneacetone.A solution of this a-semicarbazone in alcohol was exposed t oultra-violet light for thirty hours. The alcohol was then evaporatedand the residue fractionally crystallised, first from water andfinally from benzene and Gglit petroleum. Besides unaltered sub-stance there was obtained a fairly large quantity of a crystallinesubstance melting a t 168O. The substance crystallises in creamyneedles, which are more readily soluble in chloroform or alcoholthan the a-semicarbazone. We designate this product the P-modi-fication, since analysis showed it t o have the same composition asthe a-modification :C1,H&,N, requires N,= 17.0 per cent.water, and fairly soluble in hot alcohol or chloroform.0.1400 gave 20.5 C.C.N, a t 12O and 746 mm. N=1-6.94.C,,H,,O,N, requires N = 17.0 per cent.Addition of Hydrogen Chloride t o t h e a-Modification.The reaction was first carried out by passing dry hydrogenchloride into a solution of the substance in dry chloroform. Areddish-orange precipitate’ separated, which was collected and driedon a porous tile, This substance was very unstable, and easilydecomposed by moisture. To determine the amount of hydrogenchloride with which the semicarbazone had combined the substancewas warmed with excess of standard alkali, and the residual alkalititrated with standard acid.The results varied with each prepara-tion, but approximated to a compound of the formulaC,,H,,03N3,2HCl.Owing to the unsatisfactory nature of the results obtained by thismethod the following procedure was finally adopted.ThisU-tube was specially constructed so that the substance can beexposed to the action of the gas in thin layers. For this purposeinstead of the ordinary tube of long limb and narrow bend theA U-tube closed by means of glass stop-cocks was used.VOL. cv. 9 2896 WILSON, HEILBRON, AND SUTHERLAND : CONTRIBUTIONSlimbs of the U-tubel were 8 cm. apart and the limbs only 5 cm. inlength.The tube was first filled with dry air and weighed (weight=a).Dry hydrogen chloride was then led into the tube until the weightwas constant (weight=b).The hydrogen chloride was then dis-placed by a current of dry air, and a quantity of the a-semi-carbazone introduced into the tube (weight of tube + semicarbazone+air=c). Dry hydrogen chloride was then passed through thetube until the weight was constant; this was obtained only afterseveral days. As therewas a possibility that the hydrochloride might be unstable in airthe atmosphere of hydrogen chloride was not displaced, but* a cor-rection was made for weighing in such an atmosphere.The tube was then closed and weighed.Thus : Weight of tube + hydrochloride +hydrogen chloride = d.- Weight of semicarbazone ---a.Weight of hydrogen chloride1 added = d - { c + (71 - a ) }.Weight of hydrochloride = d - b .0.3040 semicarbazone gave 0.4198 ‘hydrochloride.HCl added =27.58.C12H,303N3,2$HCl requires HCl = 26-93 per cent.This salt forms bright, vermilion-coloured crystals. The meltingpoint was indefinite, since decomposition takes place on heating ;this occurs a t about 125-140O.I f this salt is exposed to light for some days in the tube in whichit was weighed the colour changes from vermilion t o deep orangewithout change in weight. In order to prove that the change ofcolour was not due to slight loss of hydrogen chloride, hydrogenchloride was again passed over the substance, but the orange colourremained unchanged, and the weight was not altered. On pro-longed exposure to light the orange-coloured salt acquired a greentint without change in weight.The vermilion colour was notrestored either on warming or cooling the substance, or on keepingi t in the dark. The experiment was repeated, the semicarbazonethis time being subjected to the action of hydrogen chloride in thedark. The same absorption took place, and the vermilion-colouredsalt was again obtained :HCI added = 0.2254 semicarbazone gave 0.3114 hydrochloride.27.61.C,2H,30,N,,2$HC1 requires HC1= 26.93 per cent.This salt on exposure to air a t the ordinary temperature rapidlyevolves hydrogen chloride. A sample of the salt was exposed t othe air a t room temperature until, after drying in a desiccator,the weight was constant. For this several weeks were requiredTO OUR KNOWLEDGE OF SEMICARBAZONES.PART IV. 2897The substance so obtained was orange, but not so deep in colouras the orange salt, Cl,H130,N,,2~HCl, just mentioned. Analysisshowed the product to be a monohydrochloride.The substance was warmed gently with excess of N/20-alkali, andthe residual alkali, after filtration, titrated with N / 20-sulphuricacid :0.1534 required 11.4 C.C. NI20-NaOH. HC1= 13.52.This orange monohydrochloride is only partly decomposed bywater, but is completely decomposed by dilute alkalis. It is appa-rently quite stable in ordinary air, and in a closed tube it meltsand decomposes at 173-175O.The residue obtained by treatment of the monohydrochloridewith alkali was recrystallised from alcohol, and proved to be thea-semicarbazone.C12H130,N,,HC1 requires HC1= 12.83 per cent.Addition of Hydrogen ChZoride to the P-Semicarbazone.A solution of the #3-semicarbazone in dry chloroform was satur-ated with dry hydrogen chloride.A yellow, crystalline precipitateseparated almost immediately, which was collected, washed withchloroform and light petroleum, dried on a porous tile, and finallyin a desiccator. This substance was analysed in the way alreadydescribed, and proved to be a moimhydrochtoride :0.3249 required 10.8 C.C. iV/ 10-NaOH. HC1= 13.3.The monohydrochloride is canary-yellow, melts and decomposesa t 169O, is stable in air, and fairly stable towards water. Ondecomposition with alkali a white substance was obtained, whichon crystallisation from alcohol yielded the a-modification only, andnot the #3-modification.Hence in this way transformation from theP- into the a-modification can be effected. Thus:Piperonylideneacetone (white) \,Piperonylideneacetone (yellow) /Cl,Hl,O,N,,HC1 requires HC1= 12.9 per cent.4 a-Piperonylideneacetone-7( semicarbazoneI.t.1J.&Piperon ylideneace t o ne-semicarbazoneP-Piperonylideneacetone-semicarbazone + 1HCla-Piperonylideneacetone-semicarbazone..143.a-piper on ylideneacetonesemicarbazone+ 24HCla-Piper onylideneacetoneseniicarbazone+ lHCla-Piperonylideneacetonesemicarbazone.9 ~ 2898 WILSON, HEILBRON, AND SUTHERLAND : CONTRIBUTIONSI n order to determine whether this moiiohydroclrloride couldcombine with more hydrogen chloride a weighed quantity wasplaced in a U-tube and dry hydrogen chloride passed over it.Noincrease in weight took place, but the substance acquired a greentinge.C'in n a rn n lde h ydes e rn ica r b az o n e.This compound was prepared according t o Young and Witliam'smethod (T., 1900, 77, 230). It is white, and, if freshly prepared,undergoes no change of colour in the dark. I f , however, it is firstexposed to bright light', which produces no visible effect, and thenplaced in the dark, a yellow colour is developed. This yellowcolour disappears on reexposure of the substance t o light. Evi-dently the freshly prepared substance' must first be made active byexposure to intense light before phototropic properties are deve-veloped.Further, if either of the active! forms is recrysta~lised, theactivity disappears, and exposure t o bright light is again necessaryto develop phototropic properties. These three modifications allpossess the same melting point, namely, 217O, which is slightlyliiglier than that recorded in the literature. An alcoholic solutionof the semicarbazone was exposed to ultra-violet light for thirtyhours. The solution was then concentrated, and the residue frac-tionally crystallised, but unaltered substance only was obtained.Addition of Hydrogeta Chloride to the Semicarbazone.Owing t o the sparing solubility of the substance in all coldsolvents the reaction could not be carried out in solution. Accord-ingly a weighed quantity was placed in a stoppered U-tube of theform already described, and dry hydrogen chloride passed over thesemicarbazone until the weight became constant.The same pre-cautions were taken as in the previous experiments, the substancebeing weighed in an atmosphere of dry hydrogen chloride and acorrection made for the difference in weight of hydrochlorideweighed in hydrogen chloride and hydrochloride weighed in air :HCl added = 0.4148 semicar bazone gave 0.5820 hydrochloride.28.11.C,,H,,ON,,BRCl requires HCl = 27.86 per cent.This salt of cinnamaldehydesemicarbazone, which is evidently adihydrochloride, is deep orange, and very unstable. Moist airimmediately decomposes it, with the formation of a viscid com-pound. During the preparation of the salt the semicarbazone, onfirst passing hydrogen chloride over it, partly fuses, changes colourto yellowish-orange, and finally the substance becomes powderysnd assumes a deep orange colourTO OUR KNOWLEDGE OF SEMICARBAZONES.PART IV. 2899As the dihydrochloride is unstable in ordinary moist air i t wastransferred from the U-tuba to a weighing bottle in dry air inwhich the salt is comparatively stable. A melting-point' tube wasfilled a t the same time, sealed, and the melting point found t o be80--83O, decomposition also occurring. The apparatus used was asimple but very efficient arrangement, which enabled us t o work indry air with comparative ease.Addition of Szclphuuric Acid to CiPznumalcFeh,?/dcsemicarbcrzo?~e.A quantity of the semicarbazone was rubbed into a paste withconcentrated sulphuric acid, when the mixture became oily andyellow.Dry ether was added, the mixture being kept cool, thenjust sufficient absolute alcohol to bring the whole into solution, andthe mixture placed in ice. On keeping for some time yellow needlescrystallised from the solution, which were collected, washed withdry light petroleum, and dried first on a porous tile and finallyin a desiccator. Analysis showed the compound t o be a salt ofsulphuric acid. The analysis was conducted in the same way asin the case of the hydrochlorides, namely, the salt was warmedwith excess of N/10-alkali and the residual alkali titrated withN / 10-acid :0.109 required 7.325 C.C. N/lO-alkali. H,SO, = 32-92.C,,H,,ON,,H,SO,~ requires H,SO, = 34.1 per cent.P r e p r a tion of Cinicamalde hydephe nylsemicurbazo tz e.Molecular quantities of cinnamaldehyde in alcohol and of phenyl-semicarbazide hydrochloride in water were mixed.The solutionbecame deep orange, and a precipitate immediately formed, whichwas collecte'd, washed with water, and crystallised first from alcoholand finally from a mixture of chloroform and light petroleum.The pheiL~lsemicarbazoIzc: crystallises in white, felted needles,melting a t 205O. It is readily soluble in chloroform or hot alcohol,and practically insoluble in light petroleum :0.200 gave 27.2 C.C. N, a t 1 2 O and 751 mm. N=15*93.The behaviour of the phenylsemicarbazone towards light isexactly the same a s that of cinnamaldehydesemicarbazone. Thefreshly prepared subst,snce is not affected by light or darkness, but,if i t is exposed t o bright light and then placed in the dark a deepyellow colou=.is developed, which disappears on again exposing t olight. Rise of temperature accelerates the conversion of the whiteinto the yellow^ modification. Thus on exposing a sample of thecolourless, inactive modification to light and then placing in aCI6H,,ON, requirc3s N = 15.84 per cent2900 WILSON, HEILURON, AND SUTHERLAND : CONTRIBTJTIONSclosed steam-oven the yellow colour becomes apparent almost imme-diately. I f , however, the preliminary exposure to light is omittedno change of colour is developed by heating the substance in thedark. The melting points of the three modifications were thesame, namely, 205O.A chloroform solution of the phenylsemicarbazone was exposedfor thirty hours t o ultra-violet light.The solution was carefullyexamined, but only unchanged substance was obt'ained.Addition of Hydrogen Chloride to Cinnamaldehydephenyl-semicar b azone.A concentrated solution of the phenylsemicarbazone in drychloroform was saturated with dry hydrogen chloride. A yellow,crystalline precipitate soon separated, which was collected, washedwith chloroform, and dried on a porous tile. It was analysed inthe usual way, and found t o be a monohydrochloride:0.6465 required 20-9 C.C. N / 10-NaOH. HC1= 11.8.C16H150N3,HCl requires HCl = 12.11 per cent.The hydrochloride is canary-yellow, stable in air, and fairlystable towards water.It melts and decomposes a t 161-162O. Asthe semicarbazone of cinnamaldehyde formed a dihydrochloride onpassing dry hydrogen chloride over the dry substance it wasthought that the phenylsemicarbazone might react with anothermolecule of hydrogen chloride if exposed to the1 action of dryhydrogen chloride in the dry state. Accordingly, a quantity of themonohydrochloride was placed in a U-tube and treated as alreadydescribed in the preparation of other hydrochlorides. After thegas had been passed over the monohydrochloride for several daysit was found that no increase in weight had taken place, thesubstance remaining a monohydrochloride. No change in colourwas observed. Starting, however, with cinnamaldehydephenylsemi-carbazone (white variety) and passing hydrogen chloride over thedry substance, the gas is rapidly taken up, and the colour becomesdeep yellow.After passage of the gas for one week the percentageof hydrogen chloride absorbed was found to be 19.72; thereafterweighing a t intervals the hydrogen chloride content appeared t odiminish, and after passage of the gas for thirty-eight days thepercentage was found to be 17.4. After this the compound con-tinued t o lose hydrogen chloride, but a t a very slow rate, and withcontinued passage of the gas would probably approximate t o 12.11per cent. or 1 molecular proportion of hydrogen chloride.On exposure to air this hydrochloride again gives the stablemonohydrochloride TO OUR KNOWLEDGE OF SEMICARBAZOKES. PART IV. 29010.2014 required 6.5 C.C.N / 10-alkali. HCl= 11.79.C,,H150N3,HCI requires HC1= 12.11 per cent.I n the same way tjhe yellow modification of cinnamaldehyde-phenylsemicarbazone was exposed to the action of dry hydrogenchloride in the dark. The yellow compound formed was slightlydar;ker in shade than that from the white modification, and it alsoreached a maximum addition of hydrogen chloride. The maximumafter ten days in this case was 19-46 per cent.. The hydrogenchloride content diminished much more rapidly, and in thirty-eight days fell to 15.15 per cent., again an approximation t o1 molecular proportion. On exposure to air this hydrochloridegives, like that of the white modification, a stable monohydro-chloride :0'232 required 7.4 C.C. N / 10-NaOH.HC1= 11.59.C16H,,0N3,HCI requires HC1= 12.11 per cent.Addition of Sulphuric Acid to Cinnamddehydephenyl-semicarbazone.The phenylsemicarbazone was mixed with a small quantity ofconcentrated sulphuric acid, alcohol added until the substance dis-solved, and the mixture cooled in ice. After a time yellow crystalsseparated, which were collected and recrystallised from glacialacetic acid. The sulphate was analysed in the usual way by heat-ing gently with excess of standard alkali and titrating the residualalkali :0*100 required 11.1 C.C. rV/ 10-NaOH.C,,H,,ON,,H,SO, requires H,SO, = 26.99 per cent.The sulphate is a brilliant, yellow-coloured powder, stable in air,but easily decomposed by COT& water and dilute alkali with theformation of the phenylsemicarbazone and sulphuric acid.H,SO, = 27.2.Yreparatiom of a Dibiornide of CiiznamalclPI~ydepherzyl-semicarbazoize.The theoretical quantity of dry bromine in dry chloroform wasadded to the phenylsemicai-bazone dissolved in dry chloroform,and the mixture was allowed to remain for half-an-hour, whenyellow crystals began t o appear. When all t,he substance hadcrystallised out the crystals were collected, dried, and recrystallisedfrom chloroform.The substance crystallises in canary-yellowneedles, which are very sparingly soluble in chloroform, and melta t 187O. Analysis showed it t o be the &bromide of cinnamalde-hydephenylsemicnrbazone :0.200 gave 17.1 C.C. N, at 10" and 754 mm. N=10*14.C,6H,,0N3Br, requires N = 9.91 per cent2902 WILSON, HEILBRON, AND SUTHERLAND : CONTBIRUTIONSThis dibromide was subject,ed to the action of dry hydrogenchloride, but no addition took place.Evidently the dibromidedoes not form a hydrochloride. Also on treating cinnamaldehyde-phenylsemicarbazone monohydrochloride with bromine in chloro-form solution and adding light petroleum a yellow precipitate isobtained, which consists of the dibromide of cinnamaldehydephenyl-semicarbazone.Prepmatioil. of a Mo?zobrorno-derivative of Ciimamaldehyde-p h enyl se micar b azo n e from the U i b roinid e.It was found that on recrystallisation from alcohol the dibromidewas decomposed, hydrogen bromide being liberated and a whitesubstance melting a t 1 6 8 O crystallising out. Some of the cinnam-aldehydeplienylsemicarbazone dibromide was theref ore boiled inalcohol until dissolved, then diluted with water, and the productallowed t o crystallise :0'200 gava 21.05 C.C.N, a t 1 2 O and 739 mm. N=12*15.C,,H,,ON,Br requires N = 12.20 per cent.The substance obtained is therefore a monobromo-derivative ofcinnamaldehydephenylsemicarbazone. It crystallises in small,colourless, glistening needles, which after several crystallisationsmelt a t 195O. It is readily soluble in chloroform, benzene, or boil-ing alcohol, but practically insoluble in light petroleum.Additioih of Hydroget8 Chloride to the Monobromo-derivntive ofCimzanzalde hydephe?zylsemicarbazone.A weighed quantity of the monobromo-derivative was placed ina U-tube and subjected t o the action of hydrogen chloride in t.hemanner already described. Reaction took place immediately, anda yellow salt was produced.Passage of the gas was continued untilthe weightj became constant:HCl 0.6624 monobromo-derivative gave 0.7458 hydrochloride.added = 11.18.C,,H&N,Br,HCl requires HC1= 9-59 per cent.The hydrochloride is bright canary-yellow, and fairly stable inIt is part'ly decomposed air, gradually losing hydrogen chloride.by water and completely by dilute alkaIi.Yre para t io i b of Mo ILO b ro m o cin na muld e h yde p h e tcy 1 s e NL icar b a z o ii, e .Cinnamaldehyde was first brominated according to the methoddescribed by Zinckel and Hagen (Ber., 1884, 17, 1815). Thebrominated product separated at once, and was crystallised froTO OUR KNOWLEDGE OF SEMICARIUZONES.PART IV. 2903alcohol. It was mixed with the necessary quantity of phenylsemi-carbazide in alcoholic solution, when the phenylsemicarrbazo,ze sepa-rated immediately and was crystallised from alcohol :0.250 gave 26.2 C.C. N, a t 12O and 745 mm. N=12*13.The substance crystallises in flat', colourless prisms, melting a t197O. It is soluble in alcohol or chloroform, but more readilysoluble in the latter than is the monobronio-compound derived fromthe dibromide. It is not identical with the latter substance, as isshown by crystalline structure, solubility, and melting point.C,,13,,0N3Br requires N = 12-22 per cent.d dditiotb of HydrogeTL Chloride to t h e above n-ioizobrornocititiar6r)i-alde hydephenylsemicarbaso ne.Hydrogen chloride was passed over a weighed quantity of thesubstance until the weight became constant.The addition ofhydrogen chloride took place a t once, but several days elapsedbefore the weight became constant :0.5922 phenylsemicarbazone gave 0.713 hydrochloride. HCladded = 16-94.C,,H,,0N3Br,2HCl requires HC1= 17.50 per cent.This di/Lydrochloride of monobromocinnamaldehydephenylsemi-carbazone is bright yellow, of a slightly deeper shade than themono hydrochloride of the monobromo-compound obtained fromcinnamaldehydephenylsemicarbazone dibromide. It is, however,much more unstable, and on keeping even in a stoppered weighingbottle loses hydrogen chloride, the colour at the same time dis-appearing. A portion of the salt was exposed t o the air for sometime, then dried in a desiccator, and weighed. This treatmentwas repeated until the weight was constant, which condition wasreached a t the end of three weeks, and the yellow colour hadentirely disappeared.On titrating a weighed quantity of thesubstance with standard alkali it was found that the hydrochloridehad lost the whole of tho hydrogen chloride on exposure to the air.Addition of Hydrogen Chloride to Acetonesemicarbazotie.Dry hydrogen chloride was passed over a weighed quantity ofacetonesemicarbazone (m. p. 187O) in the manner previouslyadopted. Hydrogen chloride was absorbed a t once, and the sub-stance fused slightly, although no change in colour occurred. Aftersome time the substance became powdery, the U-tube was weighed,and increase in weight found t'o have taken place.Hydrogenchloride was then passed over the substance until the weightbecame constant 2904 WILSON, HEILBRON, BND SUTHERLAND : CONTRIBUTIONS1.1 984 acetonesemicarbazone gave 1.5820 hydrochloride. HC1added = 24.24.C,H,ON,,HCl requires HCl = 24.09 per cent.The hydrochloride is evidently a monohydrochloride, and isobtained as a white powder, melting in a closed tube a t 150-151O.It is unstable in ordinary air, and hydrogen chloride is graduallyevolved from it. I n dry air i t is comparatively stable.Addition of Hydrogen C hl om'de to A c e t oneph enylsemicar bazoize.Dry hydrogen chloride was passed over a weighed quantity ofacetonephenylsemicarbazone (m.p. 1 5 7 O ) as before until the weightwas constant. The substance caked slightly on the first addition ofhydrogen chloride, but ultimately became powdery. No colour wasproduced, but an addition in weight occurred, showing the forma-tion of a salt:HCl 1.1088 phenylsemicarbazone gave 1.4180 hydrochloride.added = 21.80.Cl,H130N3,HC1 requires HCl -- 16-05 per cent.Cl~H130N3,1~HCl ,, HC1= 22.26 , , ,,On exposure t o air it rapidly loses hydrogen chloride.Addition of Hydrogen Chloride to Acetophenonesemicarbazone.Dry hydrogen chloride was passed over a weighed quantity ofthe semicarbazone (m. p. 202O) as before. The substance fusedalmost immediately and a yellow colour was developed. The weightincreased gradually, but did not become constant, and the substanceremained semi-solid, and appeared to decompose.The amount ofhydrogen chloride taken up approximated to two molecular propor-tions, but the results could not be trusted owing to the semi-fusedcondition of the substance.AdditioiL of Hydrogen Chloride to Acetop~~enoiEephenylsemi-carbaaone.This compound behaved in much the same way as the semi-carbazone. Addition of hydrogen chloride takes place with fusion,and a deep yellow colour is developed. The effect of strong coolingwas tried in this case, the tube being surrounded by carbondioxide snow. Even under these conditions the substance fusedalthough the colour developed was very much less. I n the caseof this phenylsemicarbazone the hydrochlorkle solidified t o a hardmass adhering t o the tube.Two experiments were tried: (1) Addition of dry hydrogenchloride a t room temperature TO OUR KNOWLEDGE OF SEMICARBAZONES.PART IV. 29050.5932 phenylsemicarbazone gave 0.7808 hydrochloride. HCladded = 24-02.C1,H,,0N3,2HC1 requires HCl = 22.36 per cent.(2) Addition of hydrogen chloride at the temperature of solid0.3272 phenylsemicarbazone gave 0.4094 hydrochloride. HClcarbon dioxide :added = 20.05.Addition of Hydrogen Chloride t o Benzaldehydesemicarbazone.Hydrogen chloride was passed over the semicarbazone (m. p.222O) in the manner already described. The colour changed fromwhite to greyish-white, and slight fusion took place on the firstformation of the nionohydrochloride :HC1 added = 0.8548 semicarbazone gave 1.061 3 hydrochloride.19-45.C8H,0N,,HCl requires HCI = 18-29 per cent.The hydrochloride is greyish-white, melts a t 199O, and is fairlystable in air.Addition of Hydrogen Chloride to Be?zzaldehydephee.nylsemi-carbazone.The phenylsemicarbazone was dissolved in dry chloroform, anddry hydrogen chloride passed through the solution.The solutionbecame yellow, and a white precipitate formed, which was collectedin an atmosphere of dry air, washed with chloroform, and driedon a porous tile. A quantity of this was placed in a dry, previ-ously weighed weighing-bottle, the bottle weighed, and the contentswere shaken into excess of standard alkali; the excess of alkaliafter warming the mixture was titrated with standard acid:0.2598 required 13.3 C.C.N/10-NaOH.The hydrochloride evidently loses hydrogen chloride too rapidlyeven in dry air to allow of accurate estimation.The substance was therefore exposed to the action of dry hydro-gen chloride until the weight became constant. The substancebecame yellow immediately on the passage of the gas, and a t thesame time partly liquefied. The final product was deep yellow andsemi-solid in appearance.Owing to fusion having taken place a satisfactory result was notobtained :0.3264 phenylsemicarbazone gave 0.4196 hydrochloride. HClCl4Hl30N3,2HC1 requires HCl = 23-4 per cent.HC1= 18.68.Gl,H,,ON3,2HC1 requires HC1= 23-4 per cent.added = 22.212906 CONTRIBUTIONS TO OUR KNOWLEDGE OF SEMICABBAZONES.This dihydrochloride is yellow and exceedingly unstable ; itAnnexed is a summary of the compounds examined.decomposes immediately on exposure t o air.Substances investigated,a-Piperonylideneacetone-semicarbazone8-Piperonylideneacetone-semicarbazoneCinna m a1 d e h y de s e m i -carbazoneChnamaldehydepheny 1 -semicarbazoneCinnamaldehydephen y 1 -semicarbezone di-bromideMonobromo-d e r i v a t i v efrom cinnamaldehyde-phenylsemicarbazonedibromideMonobromocinnamal de -hydesemicarbazoneAcetonesemicarbazoneAcetonephenylsemic r b-azoneAcetophenonese mi c a rb-Ace t op hen o n ep h e n y 1-Benzaldehydesemicarb-Henz a1 de h y d ep h en y 1-azonesemicarbazoneazonesemicarbazoneMols. HCladded.2121Noadditioii121221(indefinite)2Colour of ad-ditive product,VermilionCanary- yellowDeep orangeCanary -yellow-YellowEright ycllowNo colourNo colourYellowYellowGreyishYellowStability of additiveproduct.Very unstable, af-fected by light,stable a t 1 mol.HCl.Stable.Unstable.Stable.Fairly stable ; gradu-ally loses HCl.Unstable.C o m p a r a t i v e l ystable in dry air.HC1 evolvedslcmly in ordinaryair.Unstable. Tends tostability a t 1 mol.HC1.Unstable.[Jnstable.Fairly stable.Exceedingly un-stable.I n conclusion, we desire t o express our thanks to the CarnegieTrust for the Universities of Scotland for a grant which defrayedthe expenses of the work. We also desire to record our thanks t oProfessor G. G. Henderson for the interest he has taken in theseinvestigations.CIIEMISTRY DEPARL'MENT,ROYAL TECHNICAL COLLEGE, GLUGOW