摘要:

86 MORGAN : INFLUENCE OF SUBSTITUTION ON THE XI.-Injluence of Substitution on the E’ornza t ion o f il)iazocc.naines and Aminoaxo-compounds. By GILBERT THOMAS MORGAN, D.Sc. THE action of a diazonium salt on an aromatic amine gives rise to a diazoamine or an aminoazo-compound, according as the diazonium residue RON,* remains attached to the aminic nitrogen or takes up its position in the aromatic nucleus. The former mode of combination occurs with the primary mono- amines of the benzene series, these bases yielding diazoamines. The mono-alkylated monoamines of the benzene series, on the other hand, exhibit a tendency to form azo-compounds ; methylaniline, for example, when treated with diazobenzenesulphonic acid, yields a mixture of the diazoamino-compound, SO,H*C,H,*N,*NMePh, and the isomeric aminoazo-acid, SO,H*C,H,*N,*C,H,*NHMe (Bernthsen and Goske, Beis,, 1887, 20, 925, Bamberger and Wulz, Ber., 1891, 24, 2082).A somewhat heterogeneous class of bases including the following substances :-diphenylamine, the naphthylamines and their mono-alkyl derivatives, m-phenylenediamine and certain of its homologues and substitution products, gives rise to aminoazo-compounds without the intermediate formation of stable diazoamines. Dimethylaniline and a few other tertiary amines also yield aminoazo-derivatives, but with these bases the1production of diazoamines is obviously impossible, There is some reason for believing that the difference between the behaviour of aniline and that of m-phenylenediamine towards diazonium salts is due to the greater reactivity of the disubstituted ring, so that substituent radicles find their way more readily into the aromatic nucleus of the diamine than into that of the monoamine.The introduction of chlorine and bromine by the action of hypo- chlorous and hypobromous acids respectively is a case in point ; the latter halogen enters the nncleus of the diamine so easily that m-phenylenediacetyldibromoamine, C,H,(NBrAc),, could not be isolated (Morgan, Trans., 1900, 77, 1209 ; Chattaway and Orton, Bey., 1901,34, 160), whereas phenylacetylbromoamine, Ph*NErA.c, is a comparatively stable substance (Chsttaway and Orton, Trans., 1899, 75, 1046 ; 1900, 77, 800). Reasoning by analogy, it seems probable that the initial phase of the interaction between m-phenylenediamine and a diazonium salt involves the formation of an unstable diazoamine, this substance immediately changing into the isomeric aminoazo-derivative.This assumption is, however, not supported at present by any direct experi- mental evidence. With the view of gaining additional information asFORMATION OF DIAZOAMINES ARD AMINOAZO-COMYOU NDS. 8’7 to the course of this reaction, the formation of azo-derivatives of the homologues and substitution products of m-phenylenediamine has been studied. 2 : 4-Tolylenediamine has long been known to be as reactive towards diazocompounds as m-phenylenediamine itself, and more re- cently this was also shown to be true of 1-chloro-2 : 4-phenylenediamine and its bromine analogue. These bases readily yield azo-compounds, which, except for some slight differences in shade of colour, closely resemble those derived from the parent base, The hydrochlorides of chloro- and bromo-chrysoidines, for example, are obtained in crystals very similar in shape and colour to those of the ordinary chrysoidine of commerce.The disubstituted m-diamines may be divided into two series with reference to their behaviour towards diazonium salts. The first series consists of the bases having the general formula Y whilst the second comprises all those disubstituted m-diamines which contain one free para-ortho-position with respect to the amino-groups. The bases of the second series can be grouped together, because, pro- viding this condition is fulfilled, the nature and position of the two substituent radicles exercise very little influence either on the course of the reaction or on the colour of the resulting azo-compound. An amine of this series may possess any one of the following formulae : X Y Y Y 11.111. I v. Diamines corresponding with formulz I1 and I11 have been investi- gated and the results compared with those obtained in the case of their isomerides belonging to series I. The first diamines t o be examined from this standpoint were the two diamino-m-xylenes described by Greviogk (Bey., 1884, 17, 2426), these bases having tho following constitutions : Me NK, The former is produced by the reduction of 3 : 6-dinitro-nz-xylene, the chief product of the nitration of m-xylone; whilst the latter is88 MORGAN: INFLUENCE OF SUBSTITUTION ON THE obtained from 2 : 4-dinitro-m-xylene, this nitro-compound being a bye- product in the same operation.Grevingk (Zoc. cit.) states that both these bases, when treated with benzenediazonium chloride, give colouring matters of the chrysoidine type, but he does not seem to have isolated any definite products. Witt, however, after an unsuccessful attempt to prepare an azo-compound by the action of diazobenzenesulphonic acid on the symmetrical base, main- tains that this diamine does not yield chrysoidine derivatives (Ber., 1888, 21, 2419). As a matter of fact, the two isomerides behave very differently towards diazonium compounds. The consecutive base reacts just like 2 : 4-tolylenediamine, readily yielding a red azo-compound when treated with benzenediazonium chloride in the presence of sodium acetate ; the symmetrical diamine, on the other hand, gives rise t o a volumin- ous, brownish-yellow precipitate, which froths considerably, evolving nitrogen, and finally becomes resinous, even while in contact with the ice-cold mother liquor.This unpromising result was experienced with other symmetrically disubstituted m-diamines and seemed to confirm Witt’s conclusion. These failures could not, however, be accepted as conclusive evidence that the diamines of the type indicated by formula I cannot yield azo-compounds, inasmuch as the firm of Oehler & Go. has patented the production of colourirg matters derived from 2 : 4-tolylenediamine- 5-sulphonic acid (D.R.-P. 40905), Me a substance having a constitution similar to that of the bases in question.Accordingly, further experiments were made with different diazo-compoundP, until, finally, it was found that these bases would combine with primulin dyed and diazotised on the cotton fibre. Under these conditions, the symmetrically disubstituted diamines yielded azo-colouring matters possessing a yellowish-brown colour, and differing altogether from the reddish-brown compounds produced by similar means from the diamines belonging to the second series. These results show unmistakably that the relative position of the azo- and amino-groups is the most important factor in determining the shade of colour produced. With the experience gained in these experiments on diazotised primulin, another attempt was made to prepare azo-compounds from 4 : 6-diamino-m-xylene and the simpler diazonium salts.The product of reaction mas allowed to remain in the ice-cold solution forFORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 89 one or two hours and the tarry precipitate then washed, dried, and carefully extracted with alcohol or benzene, In this way, a small yield of aminoazo-compound was produced and the reaction was shown to occur both with benzene- and p-toluene-diazonium salts. The investigation was now extended to the symmetrical base, 5-chloro-2 : 4-tolylenediamine, simultaneously described by Reverdin and Crdpieux (Bey., 1900, 33, 2507) and by Morgan (Trans., 1900,77, 1209), and also to its isorneride, 2-chloro-3 : 5-tolylenediamine, prepared by Nietzki and Rebe (BRT., 1892, 25, 3005). The latter compound contains one free para-ortho-position with respezt to the amino-groups and might be expected t o resemble 2 : 4-tolylenediamine and 2 : 4- diamino-m-xylene in its behaviour towards diazonium salts.This anticipation was completely confirmed ; the interaction resulted in the immediate Formation of an azo-compound, the yield being practically quantitative. The symmetyical isomeride behaved like the similarly constituted 4 : 6-diamino Ira-xylene ; a brownish-yellow, voluminous precipitate was again produced, which evolved nitrogen and speedily became resinous. I n this case, also, an xzo-compound was extracted from the tarry product, but the yield was even poorer than that obtained in the experiment with the xylene base. Since 4 : 6-dichloro-m-phenylenediamine (Trans., 1900, 77, 1206) combines with diazotised primulin, an attempt was made to condense it with benzenediazonium chloride and its p-toluene homologue.i n these experiments, there was a considerable amount of frothing and formation OF resinous product, but the precipitate, on extraction, yielded a large amount of unaltered base and did not furnish any azo- compound. Although this result does not establish beyond doubt the fact that an azo-derivative is not produced, yet, in conjunction with the evidence obtained from the preceding experiments, i t seems to indicate that, with these symmetrically disubstituted m-diamines, the tendency to form an azo-compound diminishes as the acidity of the molecule increases. This increase in acidic character results from the gradual replacement of methyl by chlorine, the pairs of substituent radicles in the three diamines being respectively 2Me, ClMe, and 2C1.The brownish-yellow precipitates, which evolve nitrogen and become tarry, are probably unstable diazoamines. This conjecture receives additional support from the fact that under comparable conditions diaminomesitylene yields a similar, readily decomposable product, and in this instance the unstable substance cannot possibly be an azo- derivative. Meldola has also noticed the formation of a labile inter- mediate diazoamino-compound in the preparation of p-nitrobenzene- 5-azo-4-m-xylidine (Trans., 1883, 43, 428). The aminoazo- bases derived from 4 : 6-diamino-nt-xylene and 5-chloro-90 MORGAN: INFLUENCE OF SUBSTITUTION ON THE 2 : 4-tolylenediamine contain the azo-groups in the position contiguous to the two amino-radicles, their constitution being indicated by the general formula Y NH, The azo-compound derived froin 2 : 4-diamino-m-xylene has the constitution Me NH, /--\ since the position ocoupied by the azo-group is the only reactive position available in the original diamine.In the case of 2-chloro-3 : 5-tolylenedinmine, the azo-group may enter the ring in either the di-ortho-position or in one of the two para-ortho- positions with respect to the amino-radicles. The ease with which the azo-compound is produced in almost theoretical yield renders it in the highest degree probable that the entrant radicle takes up the para-ortho- psition forming a colour base having the following configuration, C1 Me Noreover, the azo-compound produced on the cotton fibre from this diamine and diazotised primulin has the reddish-brown colour charac- teristic of the colouring matters having this constitution.The naphthglamines and their derivatives containing hetero- nmleal substituents belong to the class of amines yielding azo- compounds without the intermediate formation of stable diazoamines, and are thus distinguished from aniline and its homologues, the o d y exception on record being P-naphthylamine-8-sulphonic acid, which, unlike its isomerides, gives a stable diazoamino-compound with benzenediazonium chloride (Witt, Ber., 1888, 21, 3483). A similar difference has been noticed in the behaviour of' the two series of amines towards formaldehyde, P-napb thylamine yielding derivatives containing the methglene carbon atom attached to the aro- matic nuclei (Trans., 1898, 73, 536), whereas aniline and its homo- logues give rise to intermediate compounds of the methylenenniline and methylenedianiline types, containing methylene united with the nitrogen of one or two amino-groups, The investigation of these methylene cornpounds (Morgan, Trans., 12100, 77, S14) also showedFORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS.91 that the presence of a substituent radicle in the a-position contiguous t o the amino-radicle of P-naphthylamine prevented the transference of methylene into the ring. Inasmuch as in their reactions with aromatic amines, formaldehyde and diazonium salts attack similar positions in the basic molecule i t might be expected that a /3-naphthylamine derivative substituted in the manner indicated mould yield a diazoamine but not an azo- compound.One compound of this type, namely, 2-diazoamino-1-chloro-4-bromo- naphthalene, has already been obtained by Meldola and Streatfeild (Trans., 1895, 6’7, 911) by the action of nitrous acid on 1-chloro-4- bromo-P-naphthylamine. If the production of this diazoamine is deter- mined by the presence of the chlorine atom in the a-position conti- guous t o the amino-radicle, then it should be possible to obtain similar compounds from 1-chloro-P-naphthylamine. The experimental results amply confirmed this assumption. The action of nitrous acid (I mol.) on this amine (2 mols.) gave rise to 2-diazoamino-l-chIoronaphthalene, C1 a, well defined diazoamine resembling the compound described by Meldola and Streatfeild.Mixed diazomines also were produced by the interaction of various diazonium salts and 1-chloro-/I-naphthylamine. p-Nitrobenzene-2- diazoamino-1-chloronaphthalene, prepared by the action of p-nitro- benzenediazonium chloride on this base, was also produced by the con- densation of 1 -chloro-2-naphthalenediazon~um chloride on p-nitroaniline ; this result indicates that Kekulh’s rule relating to the €ormation of mixed diazoamines is applicable to those containing both naphthalene and benzene nuclei. These diazoamines do not show any tendency to change into amino- azo-compounds containing the azo-group attached to the naphthalene nucleus. Here also, as in the case of the methylene derivatives, the directing influence of the amino-radicle in P-naphthylamine seems to be exerted only in one direction, and accordingly the substituent radicles readily shift into the contiguous a-position, but do not replace the hydrogen attached to the adjacent &carbon atom.92 MORGAN: INFLUENCE OF SUBSTITUTION ON THE XX PE R I M E N T AL.A c ~ i o n oj' Dinxo~iiuri~ Xcdts on the m-Diamino-m-qlenes. Prcpccration of the Diaenines.-m-Xylene is nitrated in quantities of 250 grams by slowly adding a well-cooled mixture of concentrated nitric and sulphuric acids (2-3 parts HNO, of sp. gr. 1-52 to 2 parts H,SO,) to the hydrocarbon surrounded by ice and salt. When the hydrocarbon is added to the acid, a considerable amount of trinitro- xylene is formed a t the commencement of the operation.The mixture, after remaining for several hours a t the ordinary temperature, is warmed for two hours at 40-50' and then poured on t o ice. The crude, viscid nitro-compounds are drained .from oily products and the solid residue is crystallised from alcohol, the last operation being repeated two or three times. The crystals obtained in this manner consist of 4 : 6-dinitro-m-xylene melting a t 91-92' (Grevingk, Zoc. cit., gives m. p. 93'). The alcoholic mother liquors, when united and allowed to evaporate spontaneously, deposit an oily substance which is withdrawn as soon as the separation of crystalline product commences. This second crop of solid nitro-compound is crystallised repeatedly from alcohol, and the final product consists, very largely, OF 2 : 4-dinitro- m-xylene, crystallising in rosettes of hard, well-defined, flattened needles which melt somewhat indefinitely at 58-61'.Grevingk gives 80' as the melting point of the pure compound. As repeated crystallisation does not raise the melting point, the substance is reduced without further purification, The alcoholic mother liquors obtained by working up 1250 grams of m-xylene yield about 120 grams of the partially purified nitro-compound. The final mother liquors furnish a further quantity of oily nitro-compound. These oily products, obtained at various stages of the operation, when united and reduced give rise to impure 4 : 6 -diamino-wz-xylene. The diamines are obtained by reducing the respective dinitro- xylenes with iron, 100 grams of the nitro-compound being treated with 130 grams of iron filings, 800 C.C.of water, and 12 C.C. of con- centrated hydrochloric acid. The whole of the water is not added at the commencement of the operation, but about 300 C.C. are introduced gradually during the reduction in order to moderate the reaction, which sometimes becomes very violent, The product, rendered alkaline with 8 grams of sodium hydrogen carbonate, is filtered from iron oxide; the filtrate acidified with acetic acid is treated with excess of acetic anhydride (about 60 grams). The precipitated diacetyl derivative is collected after 12 hours ; the filtrate, when concentrated and treated with a further quantity of the anhydride, yields a second crop of diacetyldiaminoxylene. After crystallisation from glacial acetic acid,FORMATION OF DTAZOAMINES AND AMINOAZO-COMPOUNDS, 93 the diacetyl compound is hydrolysed with concentrated hydrochloric acid and the resulting diuminoxylene hydrochloride crystallised from water and then decomposed with the calculated amount of concentrated po tassi um hydroxide solution, The 4 : 6-diamino-m-xylene separates in the solid form and is finally purified by crystallisation from water; it then melts at 104O, the melting point being identical with that given by Grevingk.The isomeric 2 : 4-diamino-m-xylene separates as an oil ; this, after separa- tion from the potassium chloride solution by means of ether, is dis- tilled under diminished pressure. After three distillations, a viscid oil is obtained boiling a t 170-174" under 13 mm. pressure ; this sub- stance, when cooled to - lo", gradually solidifies to a mass of crystals melting indefinitely at about 17".The yield from 1250 grams of xylene is about 25 grams. These bases have been characterised by means of their acyl deriva- tives, as these latter are well defined substances easily prepared by the ordinary processes. Diformyl-4 : 6-diarnino-m-xylene crystallises from water in colour- less, slender, flattened, silky needles and melts at 182-183". 0.2122 gave 27.1 C.C. moist nitrogen at 18"and 758mm. N=14.71. C,,H120,N2 requires N = 14.58 per cent. The diacetyl derivative is very sparingly soluble in alcohol, but dissolves more readily in glacial acetic acid ; it crystallises in lustrous, silky needles and melts above 260'. The dibenzoyl derivative, C,H,Me,(NH*CO*C6H,),, crystallises from alcohol or ethyl acetate in small, lustrous plates and melts at 25 2-25 3".0.1570 gave 11.5 C.C. moist nitrogen a t 18" and 758 mm. N = 8-43. C22H,,02N, requires N = 8-13 per cent. Diformyl-2 : 4-diamino-m-xylene crystallises from water, alcohol, or ethyl acetate in rosettes of colourless needles and melts a t 219-220°. 0.1148 gave 14.4 C.C. moist nitrogen a t 19" and 759 mm. N = 14.29. Cl,,H1202N2 requires N = 14.58 per cent. The diacetyl derivative is sparingly soluble in alcohol and crys- tallises from glacial acetic acid in colourless, felted needles; it melts above 260'. The dibenxoyl derivative crystallises from alcohol in felted needles and melts a t 232". 0.1458 gave 10.8 C.C. moist nitrogen a t 18" and 759 mm.N = 8-56, C2,H2002N, requires N = 8.13 per cent.94 MORGAN: INFLUENCE OF SUBSTITUTION ON THE Action of Benzenediaxoizium Chloride o n 2 : 4-Diumino-m-xylene. -A solution of benzenediazonium chloride, prepared from 5.4 grams of aniline hydrochloride, is added to a dilute ice-cold solution of 5 grams of the diamine acidified with 3 C.C. of concentrated hydrochloric acid. The solution remains clear until excess of crystallised sodium acetate (10 grams) is added and then a gelatinous red precipitate is produced which after remaining for a few hours is collected. The substance is purified by crystallisation from methyl alcohol. Benzene-5-azo 2 : 4-diamino-m-xylene crystallises in yellowish-brown needles and melts a t 208-209O. 0.0308 gave 6-2 C.C. moist nitrogen a t 1 8 O and 769 mm.N = 23-54, C14H16N4 requires N = 23.33 per cent. The azo-compound is distinctly basic and dissolves in dilute hydro- chloric acid ; the hydrochloride, however, is amorphous and separates in masses of red filaments. The platinichloride is a brick-red, amor- phous, insoluble salt. Benxene-5-azo-2 : 4-d~acet&?iccmino-m-xylene, C6H,*N2*C,HMe,(NH*CO*CH3)2, prepared by warming the crude azo-base for a few minutes with a mixture of glacial acetic acid and acetic anhydride, crystallises from alcohol in orange plates melting above 260O. N = 17.16. 0.1952 gave 28.8 C.C. moist nitrogen a t 19' and 769 mm. C,,H2,0,N4 requires N = 17.28 per cent. A comparative experiment made with 2 : 4-tolylenediamine shows that the two bases behave in a precisely similar manner towards diazonium salts.Benzene-5-azo-2 : 4-tolylenediamine (compare Stebbins, Bey., 1880, 13, 717) crystallises in orange-brown needles or leaflets and melts at 161'. Benzene-5-axo-2 : 4-diacetyltolylenediami./~e, C,H,*N,*C,H,Me(NH* CO-CH,),, crystallises in flattened, orange prisms and melts at 216-2179 0.1756 gave 27.4 C.C. moist nitrogen a t 20Oand 769 mm. N= 18-06. C17H,,0,N, requires N = 18.06 per cent. Action of Dicc;zonium Xalts on 4 ; 6-Diarnino-m-xyZene.--The same proportions of diamine and benzenediazonium chloride are employed as in the preceding experiment, On adding the sodium acetate to the clear solution containing the other reagents, a bulky, brotvnish- yellow precipitate is formed which rapidly darkens and becomes resinous. After 2 hours, the product is collected, washed, dried, and extracted with alcohol.From this extract, benxens-5.ccxo-4 : 6-diamino-m-FORMATION OF DIAZOAMIXES AND AMINOAZO-COMPOIJNDS. 95 xylene, C,H,*N,*C,RMe,( NH,),, separates in deep red, rhombic plates which after two crystallisations melt a t 182-183'. The compound is not decomposed on long boiling with alcoholic hydrochloric acid. It develops a deep orange coloration with concentrated sulphuric acid, and readily yields acyl derivatives by the ordinary processes. 0.0832 gave 0.2140 GO, and 0.0503 H,O. 0.1030 C = 70.14; H= 6.70. ,, 20-3 C.C. moist nitrogen a t 1 8 O and 767 mm. N=22*98. C14H,,N, requires C = 70-0 ; H = 6.66 ; N = 23.30 per cent. The diacetyl derivative, C,H,*N,*C,HMe,( NH*CO*CH,),, obtained from the preceding base by the action of acetic anhydride, crystallises from alcohol in brownish-red needles and melts above 260".0,1390 gave 20.8 C.C. moist nitrogen a t 18' and 759 mm. N = 17.10. C,,H,,O,N, requires N = 17.28 per cent. p-Toluene-5-axo-4 : 6-diamino-m-xylene, C,H,Me*N,*C,H~e,(N H,),, obtained by substituting an equivalent amount of p-toluidine for the aniline employed in the preparation of the preceding azo-diamine, crystallises from alcohol or benzene in deep red, rhombic plates and melts at 165-166'. I t closely resembles its homologue in chemical and physical properties. 0.1517 gave 34-5 C.C. moist nitrogen a t 2 1 O and 754 mm. N = 21.43. C15HlsN4 requires N = 22.04 per cent. Action of Diaxonizcm # a h on 5-Chloro-2 : 4tolyylenediccmine and 2-Chloro-3 : 5-tolylenediarnine.5-Chloro-2 : 4-tolylenediamine can be readily obtained in large quan- tities by the author's method (Trans., 1900, 77, l209), and i t has been further characterised by the prepzration of a series of its diacyl derivatives. pre- pared by heating the base for 3 hours with 2-3 parts of concentrated formic acid, is obtained as a dark brown precipitate on treating the product with dilute ammonia ; it is purified by three crystallisations from water in the presence of animal charcoal, and finally separates from this solvent in colourless, silky needles melting at 166". Diformyl-5-chloro-2 : 4-tolylenediamine, C,H,UeCl(NH* CHO),, 0.1218 gave 0.2370 CO, and 0,0520 H,O. 0.2076 ,, 24 C.C. moist nitrogen a t 18" and 768 mm. N = 13.49. 0,1318 ,, 0.0869 AgC1.C1= 16.31. C9H,0N,Cl requiresC = 50.82; H = 4.23; N = 13.18; C1= 16.70 per cent. The diacetyl derivative melts above 260", and not at 240' as pre- viously indicated j it is obtained free from the moooacetyl compound C=51*72 ; H=4*74.96 MORGAN : INFLUENCE OF SUBSTITUTION ON THE by heating the base with excess of acetic anhydride, and crystallising the product from glacial acetic acid; it is sparingly soluble in methyl, ethyl, or amyl alcohol, separating irom any of these solvents as a microcrystalline powder ; it crystallises from pyridine or acetic acid in small prisms. C1= 14.83. Cl,H1,ON,C1 requires C1= 14.76 per cent. 0.1405 gave 0.0842 AgC1. The dibenxoyl derivative, prepared by the Schot ten-Baumnnn method, crystallises from alcohol in colourless, acicular lamell 8 and melts a t 205'.0.2209 gave 0.0890 AgC1. C1= 9.96. 0.1576 ,, 10.5 C.C. moist nitrogen a t 19" and 761 mm. N=7*70. C,,,H170N2CI requires C1= 9.74 ; N = 7.68 per cent. Benzene-3-axo-5-ch2os.o-2 : 4-tolylenediamine, C,H5*N2* C,HClMe(NH,),. -The brownish-yellow precipitate produced by adding an excess of sodium acetate to a dilute hydrochloric acid solution containing equi- valent quantities of benzenediazonium chloride and 5 -chloro-2 : 4-tolyl- enediamine, is allowed to remain in contact with the mother liquor for 2 hours and then collected, dried, and extracted with alcohol. The filtered extract slowly deposits a crop of dark brown crystals con- taminated with tar ; the crude benzene-3-axo-5-chloro-2 : 4-tolylenedi- artzine is repeatedly crystallised from alcohol and finally obtained in dark brownish-red plates melting a t 147O.The compound is not de- composed by prolonged boiling with alcoholic hydrochloric acid and develops a deep yellowish-brown coloration with concentrated snlphuric acid; it readily yields acyl derivatives when treated with the appro- priate reagents. The dibenxoyl derivative, C,H;N,* C,KMeCI(NH* CO*CGH5)2, pro- duced by the Schotten-Baumann method, crystallises from alcohol in transparent, brownish-yellow plates and me1 ts at 236-237'. 0.1692 gave 17.3 C.C. moist nitrogen a t 19" and 765 mm. N = 11.83. C2,H,,0,N,C1 requires N = 11 *95 per cent. The acetyl derivative crystallises from alcohol in brownish-red, p-Toluene-3 -axo-5-ch~oro-2 : 4-tolylenediamine, flattened prisms, and melts at 225'.C,H,Me* N, C,HClMe( NH,),. -This azo-compound closely resembles its lower homologue and is pre- pared in a precisely similar manner. In this case also there a considerable evolution of nitrogen accompanied by the formation of much tarry product, and the yield of crystalline base is small. The substance crystallises from alcohol in dark brown plates and melts at 152".FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 97 0.1196 gave 0.0600 AgCl. C1= 12.41. 0.1971 ,, 35.2 C.C. moist nitrogen a t 21' and 754 mm. N = 20.16. C,,H,,N,CI requires C1= 12.93 ; N = 20.00 per cent. A dilute hydrochloric acid solution of 4 : 6-dichloro-m-phenylene- diamine and benzenediazonium chloride, when treated with sodium acetate, yields a yellow precipitate, which, when crystallised from alcohol, separates in brown leaflets melting a t 137'.The product contains from 37 to 39.6 per cent. of chlorine and seems to consist chiefly of unchanged diamine; this base melts at 137' and contains 40.11 per cent. of chlorine, whereas the percentage of this element in the required azo-compound would be 25.26. A negative result was also obtained with ptoluenediazonium chloride ; in this experiment, 14-7 grams of the diamine were employed, and 8.7 grams of the unchanged base were recovered after recrystallisation, the other products of reaction being tarry and indefinite. On the other hand, the dichlorodiamine combines with diazotised primulin, for a piece of cotton cloth impregnated with this diazo- compound and placed in an aqueous solution of the base gradually acquires a brownish-orange colour, similar in shade to the azo-colouring matters produced under these conditions from 5-chloro-2 : 4-tolylene- diamine and 4 : 6-diamino-m-xylene.Benzene-6-axo-2-chZoro-3 : 5-toZyZenediamine.-2-Chloro-3 : 5-tolylenedi- amine (Bw., 1892,25,3005), is readily obtained from 3 : 5-dinitro-2-chloro- toluene, the nitration product of o-chlorotoluene, by the iron-filings method of reduction. The iron oxide is freed from the diamine by washing with alcohol; the alcoholic and aqueous extracts are mixeci together, acidified with acetic acid, and treated with excess of acetic anhydride. The acetyl derivative, crystallised from glacial acetic acid, is hydrolysed with hydrochloric acid, and the free base purified by crystallisation from water, in which solvent it is more soluble than its symmetrical isomeride ; it separates in long needles melting a t 74'.The azo-compound, prepared in the ordinary way, separates im- mediately as a flocculent, yellow precipitate on the addition of sodium acetate to the hydrochloric acid solution of its generators ; it crystallises from a mixture of benzene and petroleum in tufts of long, orange-red, acicular prisms, these crystals being sometimes more than an inch in length. The substance melts at 134O, yields a deep brownish-red coloration with concentrated sulphuric acid, and is not decomposed by prolonged boiling with alcoholic hydrochloric acid. N = 21-00. 0.1448 gave 26.2 C.C. moist nitrogen a t 1 8 O and 766 mm. 0,1643 ,, 0.0928 AgC1.C1= 13.97. VOL. LXXXI. H C,,H,,N,CI requires 01 = 13.62 ; N = 21-49 per cent.98 MORGAN : INFLUENCE OF SUBSTITUTION ON THE Benzene-6-axo- 2- chloro-3 : 5-diacet y Ztol ytenediamine, C,H,*N2*C,HMeCl( NH*CO *CH,),, produced by gently heating the azo-base with acetic anhydride, is readily soluble in acetic acid or benzene, but dissolves only sparingly in alcohol or ethyl acetate; it crystallises in silky, orange needles and melts a t 251O. 001074 gave 14.6 C.C. moist nitrogen a t 17Oand 762 mm. N= 15.68. 0.1631 ,, 0.0663 AgC1. C1= 10.06. C17H170,N,CI requires C1= 10.30 ; N = 16.25 per cent. The dibenxoyl derivative obtained by the Schotten-Baumann method crystallises from benzene in orange needles and melts at 233O. 0,1162 gave 11.7 C.C. moist nitrogen at 1 8 O and 758 mm. N = 11.69, 0.0717 ,, 0.0213 AgCl.C1=7*35. C,7H,,0,N,C1 requires C1= 7.58 ; N = 11 *95 per cent. Action, of Bircxonium XaZts on 1-Chloro-P-naphthyzamine. 2-Diazoamino- 1 -chZoronaphthaleme, CloH,CI- N, NH* CloH,Cl, separates as a light yellow precipitate on adding excess of sodium acetate to the mixture formed by slowly dropping a glacial acetic acid solution of I-chloro-/I-naphthylamine (1 mol.) into a hydrochloric acid solution of 1 -chloro-2-naphthalenediazonium chloride (1 mol.) ; it crystallises from benzene or chloroform in golden-yellow needles and melts at 1 5 2 O . The diazoamine may also be produced by adding sodium nitrite (1 mol). to an ice-cold alcoholic solution of 1 -chloro-P-napht hylamine (2 mols.) acidified with hydrochloric acid, the precipitation of the compound being completed by the addition of a saturated aqueous solution of sodium acetate.The product obtained in this way is, however, often contaminated with an amorphous,-red substance, which is not readily removed in the subsequent crystallisations. 0.1711 gave 17.1 C.C. moist nitrogenat 215Oand 769 mm. N=11.49. 0.2358 ,, 0.1817 AgCl. C1=19.19. C20€113N3C12 requires C1= 19.39 ; N = 11.47 per cent. Although insoluble in alcohol, i t readily dissolves in alcoholic potassium hydroxide, yielding a deep orange-coloured solution, this result pointing to the existence of a potassium derivative. The com- pound is remarkably sensitive to light, and after a few weeks' exposure its crystals, although retaining their shape, acquire a dark chocolate colour ; it is decomposed on warming with hydrochloric acid, evolving nitrogen and yielding 1 -chlor o-P-napht hylamine and resinous pro- ducts.FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS.9 9 p-Nitrobenzene-2-diazoarnino- 1 -chZoi.onaiu~~tl~alene, NO,* C,H,*N, *NH C,,H,Cl, is obtained by adding a hydrochloric acid solution of p-nitrodiazonium chloride (prepared from 3 grams of p-nitroaniline) to a cooled alcoholic solution of 1-chloro-/3-naphthylamine (4 grams), the precipitation of the diazoamine being completed by the addition of sodium acetate. It may also be prepared by mixing together solutions containing equivalent quantities of 1-chloro-2-naphthalenediazonium chloride and p-nitro- aniline. The diazoamine produced by either of these processes is obtained as a voluminous, yellow precipitate ; it is almost insoluble in alcohol and only sparingly soluble in benzene, separating from the latter solvent in brownish-yellow leaflets melting and decomposing at 197-198'.0,1342 gave 19.8 C.C. moist nitrogenat 21' and 759 mm. N = 17.08. 0.1614 ,, 0.0692 AgC1. C1= 10.65. C,,H,,O,N,Cl requires C1= 10.87 ; N = 17.15 per cent. The diazoamine is fairly soluble in hot chloroform, but when boiled for some time with this solvent it partly decomposes. It is acidic in character and its potassium derivative, produced by dissolving the compound in an alcoholic solution of potassium hydroxide, yields a a deep purple solution. Ethyl Derivative of p-Nitrobenxene-3-diaxoami.fLo-l-chlorornap~t~aZene, ~0,*C6H,*N,*NEt*CloH6~~.-An alcoholic solution of the potassium derivative of the preceding diazoamine is boiled with a slight excess of ethyl iodide until the deep purple coloration of the mixture changes to orange. The crystalline product obtained on cooling the alcoholic solution is purified by crystallisation from benzene, and separates from this solvent in hard, orange-yellow, prismatic crystals melting at 193-194'. This compound does not develop a purple coloration with alcoholic potassium hydroxide and on analysis gives numbers corre- sponding with those required for an ethyl derivative of the mixed diazoamine. 0,2382 gave 32.1 C.C. moist nitrogen at 19' and 769 mm. N = 15.68. 0.1452 ,, 0.0584 AgCl. C1= 9.96. C,,H,,O,N,Cl requires C1= 10.01 ; N = 15.80 per cent. A diazoamine resembling the preceding ethyl compound, but melting at 182-1 83", is produced by adcling a solution of I-chloro-2-naphthalene- diazonium chloride to an alcoholic solution of ethyl-p-nitroaniline. The study of these alkyl derivatives of naphthalenoid diazoamines is, however, still incomplete owing to the difficulty experienced in a1 ky lating 1 -chloro-P-naph t hy lamine and its analogues. H 2100 MOIR : CYANOHYDROXYPYRIDTNE DERIVATIVES My best thanks are due to Miss F. M. G. Micklethwait for assisting in the preparation and analysis of several of the compounds described in this communication, and to Mr. E. Lodge for examining the tinctorial properties of the two series of nminolzzo-derivatives, ROYAL COLLEGE OF SCIENCE, LONDON. SOUTH KENSINGTON, S. W.

ISSN:0368-1645    

DOI:10.1039/CT9028100086

出版商:RSC    

年代:1902

数据来源: RSC

摘要:

100 MOIR : CYANOHYDROXYPYRIDTNE DERIVATIVES XI I.-Cyanohydq-ozypyridine Derivatives fyom Diuceto- nitrile. New Derivatives of q-lutidostyril. By JAMES MOIR, M.A., B.Sc., 1851 Exhibition Scholar of Aberdeen University . DIACETONITRILE was first prepared in 1889 by R. Holtzwart, in E. von Meyer's laboratory, by the action of sodium on acetonitrile in the presence of a diluent such as ether, which serves to keep the tempera- ture below that required to form the terrnolecular polymeride cyan- methine (J. p . Chem., 1889,39, [ii], 329). While attempting to make the latter compound for another purpose, I found that even if acetonitrile alone be used, diacetonitrile is almost the sole organic product (instead of cyanmethine) if the sodium be present in excess. During these experiments, in attempting to crystal- lise the diacetonitrile from hot water, I noticed that ammonia was evolved during the digestion of the solution on the water-bath, and that subsequently a different substance crystallised from the liquid.The formation of this substance, which is sparingly soluble in all the ordinary solvents and beautifully crystalline, had already been observed by Holtzwart, who made an extensive study of diacetonitrile. Although he analysed the compound and assigned to i t the formula C,H,ON,, unfortunately he did not succeed in elucidating its constitu- tion. The mechanism of the process by which it arises is, however, not difficult to imagine, if it be remembered that, as Holtzwart has shown, diacetonitrile has the constitution CH;C(NH,):CH.CN, and that it is easily converted by hydrolysis into the isodynamic form of cyanacetone, CH,.C(OH):cH.CN. If two molecules of the latter compound lose one of water, a compound of the formula C,H,ON,will be produced. This formula is that of an anhydride of cyanacetone; CH,* C:CH* CN CH,*C:CH* CN Holtzwart therefore proposed to write the formula >o ' von Meyer subsequently suggested the alternative formiila CH; E*GH,* CN NC*C*CO*CH,FROM DIACETONITRILE. 101 My experiments have led me to conclude that such formule afford no adequate explanation of the extreme stability and inactivity of the substance, and they seem to me to justify the conclusion that the compound is in reality 3-cyano-~-l~tidostyl.il: 7% or, more probably, a polymeride of that substance formed by a process analogous to that by which benzonitrile is converted into cyanphenine. Attempts to determine the molecular weight were frustrated by the insolubility of the substance, I n preparing diacetonitrile and the compound under discussion, the methods described by Holtzwart and by von Meyer mere in the main followed. As diluents of the acetonitrile, dry ether, benzene, and toluene were tried without much benefit.I n all cases, the yield of diacetonitrile leaves much to be desired. The best results are obtained as follows. Forty grams of acetonitrile (distilled over phos- phoric oxide or solid potash) having been covered with a layer of dry light petroleum (to exclude air), 10 grams of sodium in thickish slices are introduced gradually through the condenser.The action is very violent until the surface of the metal becomes coated; finally, the flask is heated during four hours on the water-bath. The mixture, having been transferred to a Buchner funnel, is thoroughly stirred, to separate the product from the sodium, which can then be mechanically removed. The solid-a mixture of sodium diacetonitrile with sodium cyanide-is mixed with just enough water to dissolve it ; diacetonitrile separates as an oil and may be completely recovered by extracting with benzene and then evaporating off the solvent. To prepare Holtzwart’s compound, the benzene extracts are digested with about 20 parts of water : as the benzene evaporates, ammonia is given off and the liquid becomes brown ; eventually it deposits needles of the condensation compound.The mother liquor, on digestion with water, yields a further quantity together with a red gum. The product is obtained practically pure by one crystallisation from glacial acetic acid. The loss caused by the formation of bye-products in this double condensation is so great that the yield of the final product is seldom over 8 per cent. of the acetonitrile used. The substance so obtained agrees on the whole with Holtzwart’s description, forming bundles of small, short needles ; it has an intensely bitter taste. It is equally soluble in boiling water and alcohol to the extent of about 1 per cent.; it is more soluble in boiling glacial acetic acid, but in boiling benzene only to the extent of 1102 MOIB : CYA NOHYDKOXYPYHIDPNE DERIVATIVES part in 600.I have to add the correction that the purified substance melts sharply at 293' (305' corr.), although it darkens somewhat above 280'. It can be sublimed without much loss a t a higher temperature. Holtzwart states that his compound melted '( oberhalb 230' "-a serious underestimate, as I have never observed a lower melting point than 260'' even in the case of the crude preparation. Holtzwart's formula was confirmed by the following analysis : It crystallises out easily on cooling these solutions. 0.1513 gave 0.35 96 CO, and 0.0752 H,O. C = 64.82 ; H = 5.52. 0.0855 ,, 13.7 C.C. moist nitrogen a t 13.5' and 750 mm. N = 18.63. C,H,ON, requires C = 64.79 ; H = 5.45 ; N = 18.95 per cent. Despite the presence of two nitrogen atoms, the compound is not basic and may be crystallised from aqueous acids; it does not combine with platinic chloride.It is easily soluble in alkali hydroxides, metallic derivatives being formed ; these can be isolated by adding excess of alkali, and crystallise well from a mixture of absolute alcohol and ether, although very soluble in spirit or acetone, The potassium derivative forms long, lustrous needles ; the sodium derivative, short,, opaque needles. That they are phenolic in character is shown by the fact that the addition of carbon dioxide or of ammonium salts to their solutions causes a precipitate of the original substance. Attempts were made to analyse these, but the results were vitiated by the rapid absorption of carbon dioxide during the drying; the figures are too low in consequence.0.2472 potassium derivative gave 0.1100 K,SO,. 0.4923 sodium derivative gave 0.1804 Na,SO,. 0.1329 ,, ,, dried in a vacuum, gave 19.7 C.C. moist K = 19.97. C,H70N,K requires K = 21.01 per cent. Na = 11-88. nitrogen at 13' and 746 mm. N = 17.2. C,H70N,Na requires N = 16.47 ; Na = 13.54 per cent. Holtzwart's compound is a substance of unusual stability, and is not (1) Prolonged boiling with a 10 per cent. aqueous or alcoholic solu- (2) Prolonged boiling with methyl iodide and sodium hydroxide. (3) Prolonged heating a t 120° with 70 per cent. sulphuric acid. (4) Heating at 80' with fuming sulphuric acid. ( 5 ) Prolonged boiling with acetic anhydride. It had previously been shown by workers in von Meyer's laboratory that it is not affected by acetyl chloride, hydroxylamine, nitrous acid, &c.It gives no coloration with nitrososulphuric acid. It is only slightly attacked by boiling dilute nitric acid and by permanganate, affected by tion of sodium hydroxide.FROM DIACETONITRlLE. 103 and although it at once reduces a solution of chromium trioxide in acetic acid, nothing definite can be isolated. It is also scarcely affected by boiling its solution in absolute alcohol with a large excess of sodium. The first clue to the nature of the substance was obtained by heating it with zinc dust; a distillate smelling like pyridina was obtained, but in too small a quantity for investigation. The only attempt to hydrolyse the compound which has succeeded was performed by heating it with concentrated hydrobromic acid (d 1.47) in a sealed tube during 6 hours a t 170'.A large yield of a substance was obtained, which proved t o be $-lutidostyril, or 2 : 4-di- methyl-6-hydroxypyridine, a substance first described by Hantzsch (Bey., 1884, 17, 2904), derivatives of which have frequently been ob- tained by the interaction of ethyl acetoacetate or its derivatives and ammonia (Gaxxetta, 1886, 16, 449 ; Annulen, 1890, 259, 169 ; Trans., 1895, 67, 220; 1897, 71, 299, &c,). It will be seen that the formula of +-lutidostyril, C7H,0N, may be derived from that of the original substance, C,H,ON,, by displacing CN by H, and that the latter may be regarded as a cyano-$-lutidostyril. This was confirmed by the detection of carbon dioxide and ammonia as bye-products of the interaction, which may be expressed as follows: C,HN(CH,),(OH)*CN + 3H,O + HBr = C,H,N(CH,),*OH + NH,Br + CO,.The slightly charred contents of the tube were extracted with water, filtered, and concentrated on the water-bath until the excess of acid was removed. On redissolving in a little water and adding soda until neutral, ammonia was freely evolved and the solution nearly solidified owing to the separation of a mass of long needles. These were filtered off and were found to be free from sodium and to melt a t 171-173". When heated in a test-tube, this product sublimed un- changed, the sublimate melting a t 176', and after recrystallisation a t 177-178' (179-180" corr.). It boiled at 303' (uncorr.). On adding excess of sodium hydroxide to its concentrated solution, a sodium derivative crystallised out in thin, lustrous plates.The substance is therefore Hantzsch's $-lutidostyril. This was further established by directly comparing the product with a specimen made by Collie's method (Trans., 1897, 71, 299). On bromination, it gave a product agreeing with Kerp's 3 : 5-dibromo-$- lutidostyril, but melting and decomposing at 253' (corr.) (Kerp gives 235'). 0.1058 gave 0.1405 AgBr. Br = 56.49. CH, C,H,ONBr, requires Br = 56.89 per cent. This substance is therefore Br/\;r CH,!N)OH104 MOIB : CYANOHYDROXYPYRIDINE DERIVATIVES On nitrating the $-lutidostyril, two compounds were obtained, one of which was Collie's 5-nitro-derivative melting at 254" (corr.) ; the other which crystallised in rosettes of short needles melting constantly at 196' (corr.), also gave numbers on analysis agreeing with those required for a mononitro compound, and was apparently a, mixture of Collie's 5-nitro- compound with the 3-nitro-compound (m.p. 260' corr.), which I have obtained in a different way (see p. 116). The sodium derivative of the product melting at 196' (corr.) was made, washed with ether, and analysed : 0.0650 gave 0.0234 Na,SO,. The free substance is therefore a nitro-$ -1utidostyril. I n the preliminary note (Proc., 1901, 17, 235), I described this incorrectly as 3-nitro-$-lutidostyril itself. Both compounds give, on reduction, the colour-reactions characteristic of 5-amino-$-lutidostyril (Collie, Trans., 1898, '73, 233). I f Holtzwart's compound be regarded as a cyano-$-lutidostyril, it must be represented by one or other of the two following formuh: Na = 11.68.C7H703N,Na requires Na = 12.1 2 per cent. and, curiously enough, its formation from 2 mols. of "isocgan- acetone " can be explained on either supposition, according as it is assumed that either methyl or hydroxyl wanders in the process. The following scheme will make this clear : H 7% QH3 C NC.Q+3 NC*FH \cH or CH~-C@*OH HO*C\N/C*CH,. (4. (B. 1 The compound represented by the formula (B) is already known, and has been prepared in a manner which loaves no doubt as to its constitution, namely, by condensing acetylacetone, ammonia, and cyanacetic ester (that is, acetylacetonamine and cyanacetamide),FROM DIACETONITRILE. 105 N C . C I ~ . 2 ' . ........... p 3 i I OiC CO \NHiH ............. W", ......................+ ,>cH -+ NH,! ..................... (Guaeschi, Atti R. Accad. Torino, 1892, 28, Centr., 1893, ii, 648; 1899, i, 289). As Guareschi's compound was stated to mine melted a t 293' (uncorr.), I found it *C*C@C\CH I I I HO*C\ /C*CH,. N 330; 1898, 34, 27; C%m. melt at 288-289', whilst necessary to prepare the former substance for comparison with my product. The two com- pounds exhibited a remarkably close resemblance, both physically and chemically, and careful comparison was necessary to determine that the tw.0 were in reality different ; indeed, it is only in their derivatives that the difference is a t all decided. Guareschi's compound forms longer and more lustrous needles than mine, although possessing similar sparing solubility in the usual sdvents and the same alkaloidal bitter taste.The melting point given in the literature is a cowected one ; hence the difference between the isomerides in this respect is twelve or thirteen degrees instead of four. [I found Guareschi's compound t o melt at 291' (corr.), whilst Holtzwart's melts at 305' (corr.). A mixture of the two melts between 270' and 275', but if this mixture be recrystallised, the product is quite different in appearance from either constituent, consisting of long, hair-like needles, which me I t a t 235--242O.I The only other physical property in which the crystals differ is their action on polarised light-Holtzwart's compound (m. p. 305') causing a uniform extinction at about 50' to the axis, whilst the crystals of Guareschi's isomeride (m. p. 291') frequently produce no effect, and when an extinction is observed it is confined to half the breadth of the needles and is nearly parallel to their axis.Chemically, too, Guareschi's compound resembles mine (1) in being non-basic ; (2) in affording metallic derivatives (which are, however, less soluble than those of my compound) ; (3) in giving +-lutidostyril, carbon dioxide, and ammonia when hydrolysed by fuming hydrobrornic acid, the cyanogen group being directly displaced by hydrogen just as in the case of the isomeride (p. 103) ; (4) in resisting the action of sodium hydroxide, sulphuric acid, methyl iodide, &c. This complete analogy between the two compounds leaves no doubt that both are cyano-J/-lutidostyrils, and as Holtzwart's compound is dzjTeTent from Guareschi's-which is 5-cyano-$-lutidostyril [formula (B)]-it can only have the constitution represented by formula (A),106 MOIR : CYANOHYDROXYPYRIDINE DERIVATIVES Such a compound should yield only mono-derivatives; this was actually found to be the case.Brornination of Holtxwart's Compound.-A nearly saturated solution of the substance in glacial acetic acid was mixed at 40' with a similar solution of an amount OF bromine just in excess of one molecular proportion. Action soon set in, crystals separating from the solution. The liquid was diluted to separate the part remaining in solution and the product was digested first with a warm dilute solution of potass- ium carbonate and then with a cold very dilute solution of sodium hydroxide. The slight residue insoluble in alkalis was recrystallised from boiling glacial acetic acid, from which it separated in minute prisms, nearly insoluble in other solvents, melting at about 270" (280' corr.), but decomposing, This substance contained 33.0 per cent.of bromine. The amount obtained was very small and insufficient t o determine its nature, On precipitating the alkaline solutions with acid, substances were obtained which ultimately proved to be identical, The major product was that extracted by sodium hydroxide ; this was purified by dis- solving it in the least possible quantity of a solution of sodium hydr- oxide and concentrating the liquid to the point of crystallisation. Long, white needles of a sodium derivative were thus obtained, easily soluble in water, and having a soapy feel.Before analysiug this substance, it was recrystallised. 0.2291 gave 0.1760 AgBr. C8H60N2BrNa requires Br = 32.08 per cent. To separate the parent substance, the solution was precipitated with acid ; the precipitate was well washed with boiling water, dried, and analysed, as it could not be recrystallised. It consisted of minute, white needles, which melted at 313' (327O corr.), but underwent decomposition. Br = 32-69. 0.1929 gave 0.160 AgBr. Br = 35.3. C8H70N2Br requires Br = 35.21 per cent. The amount of bromine found in the portion extracted by alkali There can be no doubt that the substance produced was the carbonate was 35.79 per cent. CH3 o-bromo-compound 7 CH,(~)OH~ CN"Br isomeric with the p-bromo-compound (m. p. 261') obtained by Guareschi.Nitration of EIbltawart's Compound.-This may be effected either with fuming nitric acid and with a mixture of this acid with strong sul-FROM DIACETONITRILE. 107 phuric acid. No change occurs below 50°, and a t a higher temperature the action tends to be violent. To complete the nitration, the solution was warmed on the water-bath during a few minutes, cooled, diluted with ice, and then supersaturated with sodium hydroxide. On stand- ing, a sparingly soluble sodium derivative of the nitro-compound crys- tallised out in orange rosettes. On recrystallisation, these formed long, yellow, lustrous needles, sparingly soluble in water, and quite distinct, therefore, from the salt of Collie's 5-nitro-+-lutidostyril- carboxylic acid (Trans., 1898, 73, 234). 0,2591 gave 0.0865 Na,SO,.The colour is doubtless due to isomerisation to the quinonoid nitroate Na= 10.80. C,H,03N3Na requires Na = 10.71 per cent. CH3 CH~\,):O NC":No*oNa, of which the white, nearly insoluble, free CH, substance is the $-acid, that is, On acidifying the solution of the salt, the nitro-compound was pre- cipitiated as a nearly white mass of needles, which melted at about 240°, but decomposed. After several recrystallisations from boiling water, it was obtained in long, opaque prisms which melted a t 253' (260' corr.). As the product resembled Collie's nitro-acid, I determined nitrogen in it ; although the nature of the substance prevented slow combus- tion, the result shows that the cyanogen group is intact. 0,1985 gave 37-2 C.C. moist nitrogen at 85' and 753 mm.N=22.59. C,H70,N, requires N = 2 1 *80 per cent. The potassium salt of this substance closely resembles the sodium salt, whereas the ammonium salt is deeper in shade, forming reddish- brown prisms melting a t 251' (corr.). A further quantity of the nitro-compound was obtained by evapor- ating the alkaline liquid, then acidifying, and extracting with alcohol. No other product could be isolated. An attempt to remove the cyanogen group with fuming hydro- bromic acid led only to the destruction of the substance. Nitration of Guamschi's Con&pound, C,H,ON,.-This was carried out as in the preceding experiment. The nitro-compound separates on diluting the acid in pale green, lance-shaped crystals. These melt at 261-263' and dissolve in a solution of potassium carbonate, forming108 MOIR : CYANOH YDROXYPYRIDINE DERIVATIVES an intensely yellow liquid, which, however, on evaporation, gives a white solid.To remove traces of a coloured impurity, the solid was washed with a little water; the white potassium salt was then redis- solved and the nitro-compound precipitated from the orange-yellow solu- tion by acid. After recrystallisation, it formed spear-like, oblique plates melting a t 263-264’ (272O corr.). The sodium and ammonium salts were also white in the solid state, but gave yellow solutions. The colour phenomena manifested by the two isomeric nitro-deriva- tives are obviously analogous to those given by 0- and p-nitrophenol respectively, to which they correspond in the relative arrangement of the nitro- and hydroxy-groups. On hydrolysing the nitro-compound by warming i t with fuming sulphuric acid a t looo, diluting, and boiling with a nitrite (Bouveault’s process), a new compound was obtained giving salts which were orange in the solid state.Its ammonium salt dissociates on drying. The best direct evidence of the position of the cyanogen group in Holtzwart’s componnd is afforded by the behaviour of the amino- compound formed on reducing its nitro-derivative. A solution of this substance gave very characteristic colour reactions, namely, (a) a cherry- red colour on aerial oxidation in presence of ammonia; (b) with ferric chloride, a green colour, darkening to a n intense indigo shade (very sensitive). Precisely similar changes were observed by Collie t o take place in the case of his 5-amino-$-lutidostyril and its carboxy-acid (Trans,, 1898, 73, 232).There can therefore be little doubt that Holtzwart’s compound is, as previously argued, the nitrile of Collie’s acid. To complete the series of reduction products, the nitro-derivative of The free substance melts a t 282” (corr.). CH, Guareschi’s compound-presumably &N -wasboiled withzinc CH,!~)OH and acid as before. The solution gave merely a dull brown shade with ferric chloride, and on adding ammonia an intense blue fluor- escence was developed, but no colour appeared in the liquid. Much time was unsuccessfully devoted to attempts to establish a direct connection between Holtzwart’s compound and Collie’s +-lutido- styril-3-carboxylic acid. The ester of this acid is obtained by condens- ing ethyl p-aminocrotonate under special conditions, an interaction in every way anaIogous to mine (Trans., 1897, 71, 299) ; I am greatly indebted to Dr.Collie for a specimen of this ester with which he provided me when, a,t first, I had some difficulty in preparing it. Attempts were made both to hydrolyse Holtzwart’s compound to Collie’s acid, and also to transform the latter into the former. AlthoughFROM DIACETONITRILE. 109 neither series gave positive resnlts, the experiments are of interest as exemplifying the stability of this class of compound. I n the first instance, a solution of the substance, in 80 per cent. alcohol, was boiled during fifteen hours with potassium hydroxide in large excess. The alcohol was then boiled off and a solution of ammonium carbonate added ; a copious cry stallisation of the unchanged substance took place.It was to be expected that if any carboxylic salt were formed i t would remain in solution; but on acidifying the filtrate only a faint turbidity was produced, and, as the expected acid (Trans., 1897, 71, 304) is practically insoluble in water, i t may safely be asserted that no hydrolysis whatever had occurred. This peculiar procedure mas neces- sitated by the fact that both the expected acid and its nitrile have the same melting point and general properties. I n addition to the methods already mentioned, heating with soda under pressure and also fusion with potash were tried; both pro- cesses, however, destroy Holtzwart’s compound completely, although it is attacked only a t a high temperature. Again, the action of warm fuming sulphuric acid (which hydrolyses Guareschi’s isomeride) was tried in vain, the substance being either unattacked, or sulphonated t o a minute extent.The inverse experiments are of greater interest, as throwing light on the probable cause of the resistance to hydrolysis of the nitrile group in Holtzwart’s compound ; for the same inertness is shown, in a lower degree, by the carbethoxyl group in Collie’s ester (m. p. 137’), and this is doubtless the cause of the failure of my efforts to synthesise the corresponding nitrile. I n the first experiment, the ester was heated with excess of strong ammonia during five hours at 155-160’; prac- tically no action occurred, the only new product being a very small quan- t i t y of the ammonium salt of Collie’s acid.This is very soluble in water. No trace of an amide was observed. Similarly, the ester was quite unaffected when heated with excess of zinc-chloride-ammonia. This agent also did not act on the corresponding ethyl 6-chlorolutidinecarb- oxylate obtained by Collie by the action of phosphorus pentachloride on his ester (Trans., 1898, 73, 589). I n the remaining experiments, I started with the acid (melting at 300° corr.). I n preparing it, time can be saved by fusing the ester with potash; quite a high temperature is necessary, but the yield of acid is good, as it completely precipitated on acidifying the solution of the product. The dry ammonium salt of the acid was first heated with excess of phosphoric oxide a t 300’, but on extraction with water, no trace of Holtzwart’s compound was left.On heating the ammonium salt alone, it decomposed smoothly a t its melting point (about 270O) into +-lutidostyril, carbon dioxide, and ammonia. In a final experiment, the acid was heated with 2 mols. of phosphorus pent.achloride, and after110 MOIR : CYANOHY DROXY PYRI DINE DERIVATIVE8 removing the oxychloride the residue was heated with excess of solid ammonium carbonate. On working up the product, a small quantity of sparingly soluble needles mas separated ; these, however, contained chlorine and were not investigated. These experiments exemplify the ‘( protective influence ” of the two o-methyl groups on every group which becomes imprisoned between them in the ring. Several cases in which this kind of protection is Br observed in benzene compounds, for example, /\CN, have been I IBr v 0% investigated by Sudborough and others.The cyanoxylene, /\CN j?OH, (Noyes, Amer. Chem. J., 1898, 20, 792), is a particularly close analogue of Holtzwart’s compound. There remain to be mentioned two points in which my experience has differed from Holtzwart’s; the first has reference to the bye- products formed in preparing the substance C,H,ON, from diaceto- nitrile, and the second to the action of phosphorus pentachloride on this compound. By treating the distillate obtained in preparing his compound with phenylhydrazine acetate, Holtzwart claims to have obtained cyanacetonephenylhydrazone. I was unable to confirm this observation, but as the liquid in the flask gives the hydrazone copiously, it is possible that in Holtzwart’s case some of this liquid may have come over mechanically with the ammonia.I n any case, the litera- ture on cyanacetone is in a state of confusion, there being no less than four claimants for the name. Of these, (I) that described by Glutz (J. pr. Chem., 1870, [ii], 1, 141) seems to be crude$-lutidostyril; (2) Bender’s sparingly soluble, beautifully crystalline compound, may be Holtzwart’s C,H,ON, (Ber., 1871,4, 518), whilst the oils and syrups obtained by Matthews and Hodgkinson (Ber., 1882, 15, 2679), and by James (Annulen, 1885, 231, 245), seem to be polymerides of the true cyanacetone of Holtzwart, a substance whicb, however, seems to have hut a momentary existence. As to the action of phosphorus pentachloride on Holtxwart’s com- pound, the author states (Zoc.cit., 329) that the product is gummy, but that he isolated from it a substance melting a t 175’ and giving figures agreeing with those required for the formula C,H6N, [which Beilstein enters wrongly as C,H,N, (Handbuch, 3, 1455)l. I n an experiment with a pure preparation of the substance, I found it very difficult to cause any action to take place, but finally obtained a small quantity of glistening needles melting at 165-166”, but con- taining chlovine not removable by alkalis. This substance is probablyFROM DIACETONITRILE. 111 the corresponding 2-chlorolutidine derivative, ‘’ or CH,(N)Cl ’ C8H7N,C1, but the quantity obtained did not permit of an aaalysis being made, I tried to synthesise it by the Sandmeyer method from the corresponding amino-compound (see next part), but only obtained Holtzwart’s compound instead ; such abnormalities in the behaviour of 2-aminopyridines have been frequently observed. It is evident from Holtzwart’s description of this experiment that he must have used a crude material, and I think that his compound C,H,N, owes its formation to some impurity.I found, for example, that on boiling the crude compound with acetic anhydride, a small quantity of a new compound crystallising in plates melting at 155’ was obtainable, whereas the pure substance gave no trace of this product. 11. The non-existence of vm Meyer’s Isomeric C,H,ON,.” By acting on diacetonitrile in ethereal solution with acetyl chloride and then adding water, Holtzwart obtained a base of the formula C,H,N,, melting a t 222’ (J.pr. Chem., 1889, [ii], 39, 236). The same compound was obtained by several other workers in von Meyer’s laboratory by acting on diacetonitrile with a variety of reagents, such as ethyl chlorocarbonate, ethylene dibromide, alcoholic hydrogen chloride, &c., all of which act merely by removing ammonia from two mols. of diacetonitrile and inducing condensation ; thus, 2C,H,N, = C,H,N, + NH,. I have found that the best yield of this compound is obtained by simply heating diacetonitrile with zinc-chloride-ammonia unfil the mass solidifies; on dissolving in acid and supersaturating with soda, the new compound is precipitated and may be filtered off. By acting on this substance with nitrous acid, von Meyer obtained a product of the formula C,H,ON,, which may evidently be regarded as the corresponding hydroxy-compound ; thus, C,H7N,-NH, + HNO, = C,H7N,*OH + N, + H,O (J.pr. Chem., 1895, [ii], 52, 89). This compound is described by von Meyer as melting a t about 260’, and he pronounced it to be different from the compound of the same formula made by Holtzwart in his laboratory in 1889, the evidence for this statement being the apparent difference in their melting points and certain differences in solubility. I have repeated this work, and find that the two compounds are in reality identical. The solution of the compound C,H9N, in dilute sulphuric acid was treated with a slight excess of nitrite and digested for some time at 30-40°, as it diaaotises with some difficulty.On112 MOIR : CYANOHYDROXYPYRIDINE DERIVATIVES boiling the solution, nitrogen was evolved ; the compound C,H,ON,, being non-basic, crystallised out on cooling, and after one crystallisa- tion from water, melted at 278-282O ; on recrystallising, the melting point was raised to 291-29Z0, and under the microscope the crystals were indistinguishable from those of Holtzwart’s compound. The melting point was not depressed by mixing the two. To confirm this result, the product was nitrated by the method described on page 107, and gave the golden needles of the sodium ‘ salt ’ of 5-nitro-3-cyano-$-lutidostyril there described. On reduction with zinc dust and sulphuric acid, the two colour reactions with ammonia and with ferric chloride were obtained.I n all these particulars, von Meyer’s product agrees with Holtzwart’s compound and no doubt can remain as to their identity. It is curious that von Meyer, having both substances at his disposal, should have been led to consider them different ; yet if is evident, judging from their melting points, that his specimens must have been very impure, and hence misleading data as to solubility, &c., were given by them. isomeric C,H,ON, I’ (Beilstein, Handbuch, 4, 1151) is thus 3-cyano-$-lutidostyril, and as it is obtained by the diazo-reaction from the compound C,H,N,, the latter must be 3-cyano-6-amino-2 : 4-lut- idine and its formation by the direct condensation of diacetonitrile may be expressed as follows : Von Meyer’s 3-Cyano-2 : 4-dimethyl-6-aminopyridine, From these data, probable constitutions can be assigned to the obscure compounds obtained by von Meyer’s students from diaceto- nitrile with various agents.Thus, the compound C,H,,ON, (m. p. 1 4 5 O ) , from cyanamide, which on boiling loses carbon dioxide and C,H,N3 (m. p. 222”). CHQ NC/\” ammonia, leaving Holtzwart’s C,H,ON,, must be UH,( )NH.CO.NH,, N and one of the compounds C,H,,N,, from hydrazine, must be CH, NC/\ CH,! JNH.NH; N113 FROM DIACETONITRTLE. 111. ~-Lutidostyril-5-car~ox~~~c Acid und some of its Derivatives. As already mentioned, every attempt to hydrolyse Holtzwart’s C,H,ON, (3-~yano-+-lutidostyril) to the corresponding acid has failed. On the other hand, I have succeeded in obtaining from Guareschi’s isomeride (5-cyano-q-lutidostyril) the corresponding amide and acid, I may, however, first describe a number of experiments instituted to ascertain the mechanism of Guareschi’s interaction, which is character- ised by the ease with which it takes place without a condensing agent.The interacting substances are ethyl cyanacetate and P-diketones, in the presence of a primary amine, and the reaction has been realised by its discoverer in a large number of cases (Atti R. Accud. Torino, 1893, 28, 330, 836; 1898, 34, 24; see also 1900, 36, 645). Of these, the simplest is that leading to the compound C,H,ON, (m. p. 2 8 9 O corr.) from acetylacetone, ethyl cyanacetate, and ammonia ; but since the first two substances are both acted on by ammonia, forming respectively acetylacetonamine, CH,*C(NH,):CH*CO*CH,, and cyan- acetamide, NC*CH,*CO*NH,, these must be considered the true inter- acting compounds.I found, in fact, that when the ammonia acts beforehand on only one of the substances, the condensation does not occur ; that is, mixtures respectively of acetylacetone with cyanacet- amide, or of acetylacetonamine with ethyl cyanacetate, do not con- dense ; whereas, if acetylacetonamine and cyanacetamide are pre- viously prepared free from ammonia, then the condensation occurs on mixing their aqueous solutions and gently warming. Now there are two possible explanations of this interaction, CH,.C~;o .................... c.3.c.. ....................... ........................ , .......................... / I H,N! \ H,’C*CN CH + co or CH + C * OH, \ \\ ,........................ // \\ i ........................ // CH,*C*INH * ......... 2 ............... H*jNH CH,*C* iNH, I. H/C*CN ....................... of which only the former is a Lc methylene condensation.” To decide between them, the experiment of heating acetylacetonamine with cyan- acetmethylamide was performed. The sole product was the N-methyl- derivative of Guareschi’s compound, C,H,ON,, and it appear sto me that its formation is not explicable by the second of the two schemes, as in this case there is no amino-group free from which water can be formed with the adjacent carboxyl group. This condensation, therefore, occurs as follows : .......................... CH,*C:O H,;C*CN CH3 . /\CX / .......................... \\ ...................... / I C H,*C* i ‘N ........H 2 ............ HiN __: \ + CH,(”J:O CH + co *CH, CH3 VOL. LXXXI.114 MOIR : CYANOHYDROXYPYRIDINE DERIVATIVES On the other hand, when the methyl group is introduced into the other constituent of the reaction, that is, when acetylacetone-methyl- amine is heated with cyanacetamide, the sole product is Guareschi's compound C,H,ON,, and not its N-methyl derivative. In this case, methylamine, and not ammonia, is eliminated, and in both cases the amine originally attached to the acetylacetone is the one which is expelled when the condensation takes place, the present reaction being expressed as follows : CH,, ~ . ~ . ............................ CH3 ............... H,IC*CN /\CN / ,.................. \\ ,. ................................ / CHQIH \ CH + co -+- CH,*C*iNHCH, HiNH .................................8 Another experiment had the object of ascertaining whether the acid- ifying influence of the cyanogen group is the determining factor in such condensations, and this was found to be the case, for when malonamide was substituted for cyanacetamide, no condensation with acetyl- acetonamine could be induced, although the only variation is the sub- stitution for the active CN group of the CO*NH, group. The methods of hydrolysis which proved successful with Guareschi's compound were: (1) fusion with potash; (2) treatment with warm fuming sulphuric acid. As both processes gave the same products, I shall confine myself to the latter one, which gives a good yield. I f the solution of Guareschi's compound in the acid (10 per cent, SO,) be diluted after standing for some time at the ordinary temperature, only unchanged substance separates ; if, however, the solution has been warmed a t 100' for a short time, nothing separates on dilution, but after several days a copious crystallisation of rosettes of needles is obtained. These are sparingly soluble in water, melt at 2 0 9 O OH9 (215'corr.), and consist of the sulphate of the amide, cE),N)OH &Om€, , .they are not affected by acetic anhydride, and when treated with ammonia or boiled with solution of potassium carbonate give the amide which melts a t 220-221' (22'7' corr.), is quite easily soluble in water, and appears to be dimorphous, forming at first hard granules, which on recrystallisation give small, flat needles with square ends.Like the other substances of this class, i t is easily soluble in caustic alkalis, forming a phenolic ' salt' crystallising in plates ; even on boiling with potassium hydroxide, hydrolysis of the amide to the acid is slow, as is also shown by its occurrence in the potash fusion. Unlike the original product, the amide acetylates readily, and, curiously enough,FROM DIACETONITRILE. 115 the product after recrystallisation is so like Guareschi's compound, C,H,ON,, that at first I thought it had been regenerated by the de- hydrating nction of the reagent. It forms long, white needles melting without darkening at 279-280° (290O corr.). That this substance is different from the two compounds of the formula C,H,ON, was proved by the method of mixed melting points and also by an analysis which CHQ /\CO *NH* CO*CH3 gave results agreeing with the formula CH) IOH \" 0.1075 gave 13.0 C.C.moist nitrogen at 1 8 O and 756 mm. N = 13-89. C,,H,,0,N2 requires N = 13.49 per cent. It is remarkable that the amide should be so basic as to form stable salts and an acetyl derivative, and for this that it might be an amino-acid, namely, /\ CH,! ,OH IcooNH2, and to decide this point N reason I at one time thought CH, CHAN,NH2 'xco2H, instead of tried a number of experi- ments, such as the isonitrile test and the action of nitrous acid followed by alkaline P-naphthol. The results were negative and the second formula was then definitely proved by conversion of the substance, by means of bromine and soda, into Collie's 5-amino-~-lutidostyril, CH, / ) N R 2 , which gives extremely characteristic colour reactions CH3(N,OH (see page 108, and Trans., 1898, 73, 232).The substance (m. p. 227') is therefore really the amide of $-Zutido- styriZ-5-carboxytic acid. As the hydrolysis of the amide is effected only slowly by acids or alkalis, I tried the action of nitrous acid. On boiling the solution, nitrogen was evolved and the carboxylic acid-which is very sparingly soluble- was precipitated. This acid forms needles closely resembling its iso- meride (Collie's +-lutidostyril-3-carboxylic acid, m. p. 300-304°), but melts at 244O (252' corr.), and, like its isomeride, decomposes into +lutidostyril and carbon dioxide when heated above its melting point. Potassium Sak of +--LutidostyriZ-5-carboxylic Acid, m.p. 252O (corr).-This was prepared by adding a solution of potassium carbonate to the acid, evaporating to dryness, and crystalIising from boiling alcohol. The next step was to obtain this acid. It forms long, flat needles and was dried at 120'. I 2116 CYANOHYDHOXYPYRIDIN E DERIVATIVES. 0.1564 gave 0.0668 K,SO,. C,H,O,NK requires K = 19.06 per cent. 3-Nitro-~-Iutidost~ri~.-In preparing this compound, T followed Collie's description of the processes used in producing 5-nitr+$-lutidostyril (Trans., 1898,73,231). On nitrating the acid melting at 244') I obtained 3-~itro-~~lutidostyril-5-cur~oxylic acid in the form of white, sparingly soluble needles melting at 225-227' (corr,), and giving intensely orange salts. On reduction in acid solution, the solution gave the same brown coloration with ferric chloride as its nitrile (the amino- derivative of Guareschi's compound, see p.108) gives. On heating the above nitro-acid at 260' until the evolution of carbon dioxide ceases, it is transformed into 3-nitro-$-Iutidostyr~l, which on recrystallisation forms pale, shining leaflets moderately soluble in water and melting at 260' (corr.), and on reduction gives a reddish- brown coloration with ferric chloride. The analogy with Collie's work in this field is brought out by the following scheme : K= 19.18. CH, CH3 OH3 CO,H/\ CO,H/\ NO, /\NO, cH,!~)oH -+ cH,!N!oH -+ CH,!~)OH Collie's acid, 5-Nitro-~-lutidostyril- 5-Nitro-+-lutido- m. p. 300-304" (corr.). 3-carboxylic acid. styril. CH3 CH, CH3 /\CO,H NO,f)CO,H CH,!~)OH CH3\N,0H New acid, 3-Nitro-+-lutidostyril- 3-Nitro-+-lutido. m. p. 252" (corr.). 5-carboxylic acid. styril. The Fwmation of $-Lutidost ril from Ethyl Acetoacetate. Duisberg (Annalen, 1882, 213, 174)) by heating ethyl acetoacetate with excess of ammonia, evaporating, and heating the resulting gum at 80°, obtained a compound decomposing a t about 280' and event- ually giving figures approximating to those required for the formula C,H,ON,. Thinking that this might be Holtzwart's compound, I tried to obtain it by heating ethyl acetoacetate with an equal bulk of strong ammonia in a sealed tube during 2 hours at 150'. The product was an oil con- taining crystals, but the latter were merely ammonium carbonate. On evaporating the thick filtrate from these, a brown gum was left which was kept on the water-bath for some time and then boiled with water and excess of animal charcoal. On concentrating the pale filtrate, ITHE DETERMINATION OF AVAILABLE PLANT FOOD IN SOILS. 117 obtained crystals which, after purification by repeated crystallieation from water, melted at 173-175O (177-179° corr.), and behaved in all respects as +-ZutidostyriZ. This had evidently been formed from isodehydracetic acid, the first stage in the condensation of ethyl acetoacetate. CH,. ~'joH---.-Etio-c-o;~~K CH,*C-CH ) .............................. CH,* 8-p QH , + Y*CH,+ QH Y-CH, --t VH !*OH, ........................... CO*[OEt H\C' GO-0 GO--N ,...... .................... , Ethyl acetoacetate. -+ " isoDeliydracetic acid." 3 +-Lutidostyril. CHEMICAL DEPARTMENT, CENTRAL TECHNICAL COLLEGE, LONDON, S. W.

ISSN:0368-1645    

DOI:10.1039/CT9028100100

出版商:RSC    

年代:1902

数据来源: RSC

摘要:

THE DETERMINATION OF AVAILABLE FLANT FOOD IN SOILS. 117 XIII.-The Detepmination o f Ava.ilable Plant Food in Soils by the use of Weak Acid Solvents. By ALFRED DANIEL HALL, and PRANCIS JOSEPH PLYMEN. IN the analysis of soils, it has been customary of late years to employ a weak acid solvent in order to extract those mineral constituents, phosphoric acid and potash in particular, which are present in the soil in such a state of combination as to be readily taken up by the crop. The phosphoric acid and potash thus extracted have been termed the available,” as distinct from the total, amounts of the same substances which can be extracted by hot, strong hydrochloric acid, or other solvent, which completely breaks up the soil. It is claimed that better indications of the comparative richness or poverty of the soil and of the need or otherwise for special mineral manures can be obtained by determinations of the available rather than of the total constituents, the information supplied by the latter being often not in accord with the results of cropping.Although chemists are agreed generally about the value of weak solvents in the analysis of soils, considerable diversity of opinion exists as to the acid to use and the theoretical basis on which its action depends. Dilute acetic acid, originally suggested by H. von Liebig, was used by Dehhrain (Ann. Agron., 1891, 17, 445). An aqueous solution of carbon dioxide has been worked with in America, by Gerlach ( h n d w . Versuchs.-XtcLt., 1896, 46, 201) and by T. Schloesing (Compt. vend., 1900, 131, 149).Its adoption is obviously based upon the fact that the natural soil water, by which much of the nutrient matter of118 HALL AND PLYMEN : THE DETERMINATION OF the soil is conveyed to plants, largely owes it solvent power to carbonic acid. Petermann, in his examinations of Belgian soils (Rechedes de Chirnie et Physiologic, 1898, 3, 50), employs an ammoniacal solution of ammonium citrate for the determination of available phosphoric acid ; he regards it as 44 veritable reactif de groupe,” distinguishing between the mineral phosphate of lime and the precipitated phosphates of lime, iron, and alumina which will rapidly come into action in the soil, Hydrochloric acid of various strengths has been used ; the American Association of Official Agricultural Chemists has recommended a solution of fifth-normal strength; trials have also been made in America with hundredth-normal hydrochloric acid.Emmerling (Bied. Centy., 1900, 29, 7 5 ) has recommended a solution of oxalic acid of 1 per cent. strength for the purpose of distinguishing between phosphoric acid combined with the alkaline earths and that combined with the sesquioxides. HoEmeister (Landw. Ve~*suchs.-Xtat., 1898, 50, 363) suggests an amrnoniacal solution of humic acid for estimating the relative values of different forms of phosphoric acid, and Maxwell (J. Amer. Chem Xoc., 1899, 21, 415), in his examination of Hawaiian soils, used a 1 per cent. solution of aspartic acid, which was found to dissolve “phosphoric acid, lime, potash, and other bases out of the soil in almost the exact proportions that these elements have been found in the waters of discharge and in which they are removed by cropping.” T.Schloesing, jun, (Compt. rend., 1899, 128, 1004), working with dilute nitric acid of various strengths, found that as the strength of the acid was increased, the amonnt of phosphoric acid dissolved first increased, then remained stationary during a certain range, and then began to increase again; a t which point, and not before, iron began t o appear in the solution. He concludes that this stationary pro- portion of phosphoric acid indicates the amount of readily available calcium phosphates and that the beginning of the attack upon the ferric phosphate marks the point at which all the available phosphoric acid has passed into solution.But of all the dilute acids, none has been more widely applied to the determination of “available” plant food than a 1 per cent. solution of citric acid, as described by Dyer in a communication to this Society (Trans., 1894, 65, 115), the 1 per cent. citric acid solution being taken as approximating both to the nature and average strength of the natural solvent, the root sap. It is, however, doubtful if sufficient data exist upon which to base any a pri0s.i decision as to the best acid and strength to employ; theAVAILABLE PLANT FOOD IN SOILS. 119 state of combination of the phosphoric acid and potash in the soil, the nature of the root sap, and the part i t plays in obtaining mineral matter from the soil as compared with that which enters the plant by osmosis from the natural soil water, are all too imperfectly known to provide a theoretical basis for a method of analysis.I n the present state of our knowledge, these processes can only be tested by com- paring the conclusions to which they lead with the results obtained by cropping the soil ; indeed, the crop alone can measure the material avaiIable in the soil. It was in the hope of obtaining some critical results with regard to the various acids suggested for determining the available constituents in the soil that the authors have obtained a number of soils which have been the subject of field experiments, and submitted them to the action of certain of the acids indicated above. As a rule, abnormal soils have been chosen, that is, soil which are markedly deficient in available phosphoric acids or potash, as indicated by the large returns which could be obtained by the application of one or other of these substances in the shape of manure.By the kindness of Sir J. Henry Gilbert, the authors further were enabled to examine seven samples from the Broadbalk Field at Rothamsted, which had been under wheat and continually manured in the same way for forty-two years. Sir Henry Gilbert was good enough to furnish the authors with material drawn from seven sharply contrasted plots on this classic field, sufficient for duplicate determina- tions of both the phosphoric acid and potash dissolved by all the solvents to be described later. Determinations were made of both phosphoric acid and potash in the Eroadbalk soils and in four other cases ; the nine remaining soils were only analysed for one constituent.Arising out of the work, determinations were also made of the calcium carbonate and the organic matter in each soil, and a few other determinations were made t o ascertain what degree of variation might be introduced by the strength of the acid employed an3 thequantity of calcium car- bonate present. The Xoils Examined. The soil samples from the Broadbalk Field, Rothamsted, were taken in October, 1893; the plots had then grown wheat continuously for fifty years and the same manures had been applied to each plot year by year, with one exception, for forty-two years (J. Bo3. Agric. Xoc. Eng., 1884, 20, 391). The following table shows the numbers under which the plots are described in the Rothamsted Memoirs, the manures per acre per rtnnum, and the average yield of grain and straw :120 HALL AND PLYMEN: THE DETERMINATION OF Grain.Straw. No. of plot. Manure per acre per annum. Bushels. Cwt. 2b Farmyard manure, 14 tons .................. 34-8 321 5 Minerals only ................................ 14; l2i 7 Minerals + 400 pounds ammonium salts 32% 32% Ch Minerals + 275 pounds sodium nitrate.. 34f 384 3 Unmanured continuously ................. 122 108 6 Minerals + 200 pounds ammonium salts 24 21+ 16 Minerals + 800 pounds ammonium salts, 13 years - Unruanured, 19 years.., ..................... 274 28$ 10 years - - .................................... - Minerals + 550 pounds sodium nitrate, .................................... I n the above table, ‘‘ minerals ” stands for 200 pounds of potassium sulphate, 100 pounds of sodium sulphate, 200 pounds of magnesium sul- phate, and 3; cwt.of superphosphate (37 per cent. soluble phosphate) ; ammonium salts means equal parts of sulphate and chloride of ammon- ium containing about 43 pounds of nitrogen, which is also that con- tained in 275 pounds of sodium nitrate. If the quantities given above are translated into pounds of phosphoric acid and potash supplied and removed per acre per annum, the follow- ing approximate figures are obtained. They are partially taken from a recently published paper by Dyer on the phosphoric acid and potash in wheat soils of Broadbalk Field, Rothanisted (PM. Ty*ans., 1901, B. 194, 235-290), and are based on the manures supplied and the analyses of the grain and straw removed : Plot. 2b 3 5 6 7 16 9 C6 Phosphoric: acid.Supplied. Removed. 78 26 0 9.3 65 14 64 17 62 22 64 26 35 20 Potash. Siipplied. Removed. 235 50 0 15 104 23 108 33 107 51 108 50 50 43 Of the other soils, No. 1 is a clay soil from Essex furnished by Nr. T. S. Dymond. Some of the results obtained on this field in 1899 may be quoted as showing the response of the soil to dressings of phosphates : Sodium nitrate, 2 cwt. ............................. 3.3 8-2 9 ) ,, 4 cmt. superphosphate 17.8 25.4 Manure. Without lime. With lime. Other results with phosphatic manures, both in this year and 1900,AVAILABLE PLANT FOOD IN SOILS. 121 confirm the need for phosphates (see The Essex Field Experintents, 1901, I, 28).Soil No. 2 is a Welsh soil from Cardigan, selected by MI-. T. Parry as typical of the soils in that district which respond freely to dressings OF basic slag. The experimental plots in the same field showed ‘‘ astonishing results ” for a dressing OF 10 cwt. of basic slag, but, being in pasture, no weights can be given. Soils Nos. 3,6, and 10, were indicated by experiments carried out under the Bath and West of England Agricultural Society, in 1891, as likely to be deficient in available phosphoric acid, and were kindly procured for us by the occupiers, Mr. J. B. Till, of Park Farm, Thornbury, Gloucester- shire ; Mr. E. W. Drew, of Crichel, Wimborne, and Mr. W. H. Tremaine, of Trerice Manor, Grampound Road, Cornwall, from the fields which had been under experiment. The following extract from the report on the trials (J.Bath and West of Englccnd Agric. Soc., 1891-1892, [iv], 2, 264) shows the effect of phosphatic dressings on the mangold crop : 4 cwt. nitrate. Plot. Character of soil. With 4 cwt. nitrate. ’, superphosphate. 3 Gravelly loam ............... 6 32.3 6 Deep loam on chalk ...... 12.7 26 10 Stone rush .................. 8.7 19.7 Soil No. 4 is from strong land on the Weald Clay, near Marden, Kent ; the sample was taken from an arable field immediately adjoin- a hop garden which has been under experiment since 1895 by the South Eastern Agricultural College. The plots have always given large returns for the application of phosphates, as will be seen from the following table, giving the mean results 1895-1899 : Mean of 5 years’ crop, Plot.Manure per acre per annum. cwt. 1 Nitrogen, potash, 6 cwt. phosphates ......... 12.5 2 7 7 9 , 8 7, ......... 15.1 3 9 , 77 10 .......... 15.7 4 9 7 ,7 15 9 7 9, ......... 16.6 On the same soil, the omission of potash gave no consistent returns ; on three occasions, the plot receiving nitrogen, phosphates, and potash was superior by 9 per cent., 6 per cent., and 1 per cent. respectively; on two occasions, it was inferior by 15 per cent. and 11 per cent. ; hence we may fairly conclude that the soil can supply the potash re- quirements of an ordinary crop (see J. Soutit, Eastern, Agric. Coll., 1900, No. 5 is a sandy soil, resting on the Tunbridge Wells beds, near Frant, and is also taken from a field adjoining a hop garden which has been under experiment. In this case, phosphates above a certain No.10, 33).I22 HALL AND PLYMEN: THE DETERMINATION OF point give little return, but potash salts prodiice a great increase in the crop. Plot. Manure per acre per annuin. Mean crop. The table sets out three years’ results : 1 Rape dust 15 cwt. ( = 7 0 lbs. nitrogen)+O ................. 15.2 2 > 7 +basic slag 5 cwt. 15.1 3 ....................... 16.1 I ) 9 , 9 , 10 ,, 4 9 9 9 ) 9 9 15 ,, ........................ 15.4 5 7 7 9 , ,, 5 +potassium sulphate 5 cwt. 17.7 ........................ The only consistent increase in crop each year has been on the plot receiving potash, where the effect has also been noticeable in the character of the foliage (see J. South Eastern Agric. Coll., Zoc. cit.). by Mr.J. Alan Murray of the University College, Aberystwyth, and was taken from grass land on a light, alluvial loam a t Falcondale, which has been under experiment for 8 years, and has given marked returns for dressings of phosphatic manure. Taking the mean figures for 4 years, when phosphatic manures were applied, the excess of hay produced as compared with the plots receiving no phosphate was as follows (see Univ. Coll. A6erystwyth, Annual Report on Pield Experiments, 1900) : 336 lbs. per acre. J , 224 ,, ............ 518 ,, !, 336 7 > ............ 552 ,, ,, 85 ,, basic slag .................. 364 ,, .................. 713 7 7 9 9 170 77 .................. 777 ,, 7 7 255 ? Y Soil No. 7 was supplie For 112 lbs. superphosphate ............ > 7 77 77 ,, Soils 8 and 9 were from the garden at Hamel’s Park, Buntingford, Essex, belonging to Mr.H. Shepherd Cross, M.P., a soil notable for causing chlorosis in many species of plants grown there, especially in laurels, fruit trees, and chrysanthemums. Applications of superphos- phate had mitigated the onset- of the disease, but it is by no means certain that a deficiency in available phosphoric acid is the cause. Soils 11 and 12 were from the experimental plots of the South Eastern Agricultural College, at Wye ; the soil is a light loam resting on the chalk and as a rule shows no particular need for mineral manures. Soil 11 was from a plot which had for five consecutive years grown barley without manure. Soil 12 had also grown barley, but had received a general dressing of artificial manures, including 4 cwt.of superphosphate containing 26 per cent. of soluble phosphate and I+ cwt. of potassium sulphate. The following mean figures obtained with barley, oats, and grass in 1896 and 1897 serve to show the response the crop makes to mineral manures ; the various crops are reduced to a common standardAVAILABLE PLANT FOOD IN SOILS. 123 by calculating them on a basis of 100 for the plot with the complete manure. Plot. Maiiiires per acre. Relative crop. A. No manure ........................................................... ’73 B. Nitrogen + 2 cwt. superphosphate, no potash ................. 93 87 E. Nitrogen + 2 cwt. superphosphate, 2 cwt. pol,assium sulphate 100 Soil No. 13 was supplied to the authors by Mr. J. L. Duncan, B.Sc., from his farm at Birgidale Knock, Rothesay, N.B. It is a deep, alluvial loam, in good heart, but gave extraordinary returns for potash in some experiments with turnips carried out by Professor J.Patrick Wright in 1895. Nitrogen, potash, + 1 cwt. D. Nitrogen + 2 cwt. potassium sulphate, no phosphoric acid ... Nitroge n and Manure, nil. Phosphate only. phosphate. sulphate of potash. Crop, nil. 5.9 8.9 19.8 tons. (See Repovts on Mcmuring, &c., Glusgow and West of Scotland I’echnical College, 1 89 6 .) The Dilute Acids Used. Since the 1 per cent. solution of citric acid is so widely used, es- pecially among chemists in this country, for the determination of available phosphoric acid and potash, it was taken as the basis of comparison, and the other acids, as far as possible, were reduced to the same strength.This seemed preferable to using the other arbitrary strengths which have been suggested, such as 1 per cent. acetic acid, 1 per cent. and one-fifth normal hydrochloric acid, especially as pre- liminary experiments showed that the strength of the acid is a factor in the amounts of phosphoric acid and potash dissolved. Citric acid solution containing 10 grams of the pure crystallised acid per litre is approximately one-seventh normal and is equivalent to a solution of acetic acid containing 8-57 grams per litre and one of hydrochloric acid containing 5.2 grams per litre. The ammonium citrate solution cannot be compared in strength with the other solvents; it is made up according to Petermann’s formula, and used for the estimation oE phosphoric acid only : 1 litre contains 87.1 grams of ammonium citrate, rendered alkaline by 9.2 C.C.of strong ammonia (sp. gr. O*SSO); 500 C.C. are digested with 50 grams of the soil for 1 hour a t a temperature of 35-40’, with constant shaking. As a source of water charged with carbonic acid, recourse was had t o the ‘6 sparklet ’’ bottles of commerce ; one of the larger sized bottles holds conveniently 50 grams of soil and 500 C.C. of water. Into this a sparklet charged with liquid carbon dioxide was broken in the usual124 rIALL AND PLYMEN: THE DETERMINATION OF way, the c w % . " the bottle were allowed to stand for a week and shaken from time to time as with the other weak acids. The larger spsrklets mere found by trial to contain about 4.5 grams of carbon dioxide, so that the solution within the bottle would contain a little less than 9 grams per litre, and be approximately 0.4 normal.After opening the bottle, as soon as the first effervescence has subsided, the solution must be rapidly filtered and the filtering completed before all the free carbon dioxide has diffused out of the liquid. When chalk is present in the soil, a strong solution of calcium bi- carbonate is produced in the sparklet bottle, and precipitation of cal- cium carbonate begins when the solution is brought into contact with the atmosphere. Preliminary tests showed that solutions of acid cal- cium phosphate and calcium bicarbonate can exist together until the excess of carbon dioxide is expelled, when calcium phosphate is pre- cipitated.However, the first portions of calcium carbonate precipi- tated during filtering, although mixed with a little fine clay, showed no appreciable amount of phosphoric acid. The three acids, citric, acetic, and hydrochloric, of the same titre, together with carbonic acid water, were used on the soils for the estimation of both the phosphoric acid and potash. itlethods of Analysis. The soil samples were all air-dried, gently broken in a mortar with a wooden pestle, and passed through a sieve having round holes 3 mm. in diameter. The stones retained by the sieve were rejected, the fine earth that passed the sieve was used for analysis without any further preparation. I n the case of the soils from the Broadbalk Field, the samples had already been put through a wire sieve with meshes -;P inch apart.The 3 mm. round sieve took out a few more stones, amounting to about 24 grams from each sample of 3 pounds, or, approximately, 1.8 per cent. Except in the case of the ammonium citrate and the carbonic acid solutions, 200 grams of the air-dried soil were put into a Winchester quart bottle with two litres of the dilute acid, the bottle was kept stoppered and shaken whenever convenient during 7 days at the ordi- nary temperature of the room. At the end of this period, the solution was filtered and an aliquot part of the extract (generally 500 c.c.) was evaporated to dryness and ignited. For the determination of phosphoric acid, the residue was attacked with hydrochloric acid, evaporated to dryness, and ignited very gently to render the silica insoluble.It was then taken up with dilute nitric acid, a few grams of ammonium nitrate were added,AVAILABLE PLANT FOOD IN SOILS. 125 with 50 C.C. of a solution of ammonium mcl?bdate, containing 60 grams of molybdic acid per litre. The volume of the nitric acid solution was always brought to 50 C.C. before adding the ammonium molybdate, in order that the work should always be carried out under uniform conditions. The mixture was well stirred and allowed to stand in a warm place, not exceeding 40°, for 24 hours. The phosphomoly bdic acid, after washing with ammonium nitrate solution, was dissolved by ammonia into a tared basin, evaporated to dryness, ignited gently over an Argand burner, and weighed. The resulting material was assumed to contain 3.794 per cent.of phosphoric acid. In potash determinations, the ignited residue from the evaporated solution was taken up with weak hydrochloric acid and the potash determined by Tatlock’s method as described by Dyer (loc. cit., p. lal), the potassium platinichloride being sometimes weighed as such, and sometimes converted into metallic platinum. The so-called ‘‘ total ” potash and phosphoric acid were determined on portions of the same soils that were ground until they would pass through a woven sieve of 1 mm. mesh. Twenty grams of such soil were extracted with 70 C.C. of strong hydrochloric acid containing 20.2 per cent. of pure acid (that is, the acid which results on boiling the con- centrated acid under ordinary atmospheric pressure) for 48 hours on a water-bath in a loosely stoppered flask.The amount of calcium carbonate is calculated from the amount of carbon dioxide evolved on treating the soil with dilute acid by a method described in another communication (this vol., p. 81). Some of the carbon dioxide may be derived from magnesium car- bonate, but as the factor that is wanted is the amount of “base” available in the soil, it is not necessary to attempt to differentiate between calcium and magnesium carbonates. All the figurea given are calculated as percentages on the soil in an air-dry condition; the amount of water each soil loses a t 100’ is also given. I. PHOSPHORIC ACID RESULTS. Soils from the Byoadbalk Piela?. I n the table on p. 126, the results obtained by the action of the various acids employed on the soils from tbe seven plots of the Broadbalk wheat field are set out.(1). A first inspection of the figures shows that in general citric acid dissolves the most, ammonium citrate a little less, hydrochloric acid comes next in order, then acetic acid, the carbonic acid charged water dissolving least of all. This order of solvent power is preserved in each plot. Taking the means of the quantities dissolved from the six manured plots, 2b, 5, 6, 7, 9a, and 16, it will be seen that the citricHALL AND PLYMEN: THE DETERMINATION OF Dung ........................... Unmanurccl .................. Minerals + 200 lb. ammon- ium salts. ................... Minerals + 400 lb. ammon- ium salts.. ................... Minerals + 275 lb. sodium nitrate.. ......................Minerals+ 800 lb. am-> Minerals only ............... 126 - Plot. ___ 2b 3 5 6 7 9a 0.0477 0 *0080 0.0510 0.0446 0'0402 0.0295 TABLE I. BI ail nri 11 g. Citric. I I--- ... ...... monium salts 13 years Unmanured Minerals+ 550 1b.sodinm nitrate ........ .10 years ITCI. Acetic. 0'0224 0.0021 0.0360 C-0264 0.0243 0.0070 0.0051 0'0166 0'0011 0.0098 0'0086 0.0067 0.0032 0'0016 0'0095 0'0005 0.0058 O-OU31 0*0030 0'0021 0.0011 0.0433 0.0069 0.0388 0.0283 0.0266 0.0197 0*0141 0.209 0.114 0'228 0.195 0'191 0.164 0.157 acid dissolves about ten times as much as the carbonic acid, about five times as much as the acetic acid, and twice as much as the hydrochloric acid (Table 11). I n the case of the unmanured plot, the ratios are of the same order. TABLE Ir.I P206 dissolved from I I Solvent. 1 Six manured plots. 1 Unmanured plot. Citric acid ..................................... Ammonium citrate ....... - .................... Hydrochloric acid ............................. Acetic acid ..................................... Carbonic acid ................................... 0.0390 0.0080 0'0202 0.0021 0 0077 0'0011 0*0005 0.0042 0.0285 i 0.0069 i (2). The ratios in which the various acids dissolve phosphoric acid are not the same for each plot, as will be seen from a consideration of the following table (111), where the results are recalculated as per- centages of the '' total " phosphoric acid, that is, the amount dissolved by strong hydrochloric acid from each soil. It is now seen that as the total phosphoric acid in the soil diminishes, so does the fraction which is soluble in any of the acids, Citric acid disaolvesmore than 20 percent, of the total phosphoricacid in the soil from the dunged plot and from the plots receiving minerals alone or minerals and ammonium salts; the percentage drops to 13.3 in the soil from plot 16, which had been for some time unmanured and at other timesAVAILABLE PLANT FOOD IN SOILS.Ammonium citrate ..,I 90.8 Hydrochloric acid ...... 46'9 Acetic acid ............... 34.8 Carbonic acid ............ 19.9 I27 86.2 76.1 26'2 70.6 13.7 ~ 19'2 6'2 I 11.4 TABLE 111. Plot. I 2b. I 3. 7. 9a. 16. 5. i 6. I 0.228 1 0.195 I I ___ I Oe209 Total 1)hosphoric acid. 1- -~ Perceiitages of total dis-; solved by :- I Citric acid .............. ,j 22.8 Ammonium citrate ...30'7 Acetic acid ............... 7-92 Carbonic acid ...... .....,I 4.53 Hydrochloric acid ...... , 10.f 0.114 0.191 0'164 _. .- 0.157 I 7-02 6.05 1.84 0.965 0'439 , 22.4 ~ 22.9 17.0 ' 14.5 15'1 13.5 4.30 ~ 4-41 2-54 ~ 1.64 21 '1 13'9 12 *7 3.51 1-57 18.0 12'0 4'28 1 -95 1 -28 13 '3 8.98 3'25 1 -02 0.701 drained OF minerals by the use of heavy dressings of nitrogenous manures, and still further drops to 7 per cent. in the soil from the unmanured plot. With the other acids, the same progression is observed. The crops first remove the more soluble portion of the phosphoric acid within the soil, and on those plots where the phos- phoric acid has been reduced by cropping, the residue is in a com- paratively insoluble form, attacked with increasing difficulty by the dilute acids employed.(3). 1 n order to compare the relative powers of attack possessed by the acids on the different plots, it is convenient to take as a standard for each plot the amount dissolved by the citric acid and reduce the results given by the other acids to this basis. The following table is thus obtained : TABLE IV. Amount dissolved by 1 Plot 2b .I 3. 1 5. 6. 7. 9%. I-l-l----- 100 Citric acid .............. .I 100 1 100 1 100 100 I100 --I- /- I-/-- _~ 63 -5 59'2 19.3 7.0 66.2 60 '4 16.7 7.5 66.8 23 *7 10.8 7 *1 of the It is clear that some difference exists between the actions various acids; if a given acid has twice the solvent power of another in dealing with one soil, i t does not follow that the same ratio mill be preserved on passing to a soil of a different type.The solution of hydrochloric acid has about two-thirds the solvent power of the citric acid in dealing with soil from the group of plots 5, 6, and 7, which receive minerals alone or with ammonium salts ; one-128 HALL AND PLYMEN: THE DETERMINATION OF half with the soil from 2b, which contains much organic matter ; and less than one-fourth with the soils from plots 9a and 16, where the minerals have been accompanied by nitrate. When compared with citric acid, acetic acid also dissolves a smaller proportion of the phosphates in the soils from the nitrated plots 9a and 16, but a higher proportion than usual when dealing with the dunged plot 5. Carbonic acid dissolves a fairly constant proportion of the phosphates dissolved by the citric acid except in dealing with the dunged plot, when its solvent powers are comparatively high.The attack of ammonium citrate is relatively speaking at its best in dealing with the dunged plot and with the continuously un- manured plot. (4). Turning now to the practical question, which acid yields results most in accord with the past history of the plots, it will be convenient to arrange the results in a fresh form. I n the following table (V), the amount of phosphoric acid dissolved from plot 5 (minerals only) will be taken as the standard of comparison, thus showing the varia- tion caused by the plots in the case of each acid. Plot 5 is chosen for the standard, as it has been continually manured with minerals, and but scantily cropped owing to the absence of nitrogen; it should therefore contain the greatest amount of '' available " phosphoric acid.TABLE V. Plot 5 . . . . a , ,, 2b ... , , 6 ...... , , 7 .. I . . . ,, 9a ... ,, 16 ...... , , 3 ...... Total. 100 91 *9 85.5 83.8 71.9 68.9 50.0 Citric. 100 93.5 73 '0 68-8 57'8 40'8 15'7 Ammonium citrate. 100 112 a7 '4 78.8 50 '8 36.4 17 -8 HCI. 100 62 *2 73.3 67.5 19'4 14'2 5 - 8 Acetic. 100 169 87.8 68'4 32 *7 16'3 11.2 c** 100 164 53.5 51.7 36.2 19'0 8'6 It is seen that all the weak solvents give more trustworthy information about the soil than the strong hydrochloric acid does. With the strong hydrochloric acid, the variation in passing from the richest plot, 5, continuously manured with superphosphate and very scantily cropped, to the poorest plot, 3, which has been cropped without manure for 50 years, is only 100 : 60, whereas with other acids the ratio varies from 00 : 1 7 4 to 100 : 5.8.With a few exceptions, each of the cids would set the plots in the same order of fertility ; the ratios ofAVAlLABLE PLANT FOOD IN SOILS. 129 -~ 1275 1193 1115 1005 738 520 165 attack shown by citric acid and ammonium citrate are fairly similar, those of acetic and carbonic acids are still more alike. Acetic and carbonic acids and ammonium citrate rate 2b, the dunged plot, as richer than 5, the plot which receives minerals only. Hydrochloric acid rates the dunged plot very low, below 6 and 7, receiving mineral manures with ammonium salts ; hydrochloric acid also rates 9a, the nitrated plot, very lorn, extracting less than one- third as much from this plot as from plots 6 and 7, whereas citric acid would make this plot almost as rich as 6 and 7.With the variable factors introduced by the long-continued use of dung, ammonium salts, and nitrate respectively, it would be difficult to say which of these plots would be shown by crop- ping as relatively the richest in phosphoric acid; the surplus of the phosphoric acid supplied as manure over that removed in the crop during the last 42 years gives some figures wherewith to form an opinion, but one that does not take into account the different states of combination into which the phosphoric acid has entered in the soil. The following table compares the surplus of phosphoric acid added to the soil during the last 50 years with the amounts removed from each plot by the various acids, assuming for the fine earth down to the depth of 9 inches, an average weight of 2,500,000 lbs.per acre. The figures are in pounds per acre. - _ ~ - ~ 970 1082 707 665 492 TABLE VI. 900 560 660 607 175 127 52 Plot 5.. . . . I ,, 2 b . . , , , 6 ...... , , 7 ..... I ,, 9a ,. ,, 16 ....., , , 3 ..... - _ _ _ 245 415 215 167 80 40 27 *5 Surplus P,O, retained by soil. 2582 2619 2355 1985 1885 765 - 467 P,05 dissolved by I 1 HC1. I Acctic. CO,. Citric. ' Amnionium citrate. __.~_ 145 237 77 -5 75 52.5 27 *5 12.5 The following table shows the calcium carbonate and the loss on The loss on ignition includes ignition of the soils under consideration. both organic matter and water of hydration, but as the latter is likely t o be constant in dealing with soils from the same field, the variations in the loss on ignition represent pretty nearly the varia- tions in the amount of organic matter present.VOL. LXXXI K130 HALL AND PLYMEN: THE DETERMINATION OF 6 . 2-50 3.75 2-03 TABLE VII. 7. 9a. ~ - _ _ _ _ 2'62 4'17 4'44 4'49 1.92 2.06 1 2b. 1 3. 1 5. --I---- I---/- Calcium carbonate . . , . . . 3 -86 3-55 3'67 Loss on ignition .........I 6'21 I 3'32 1 3'65 Hygroscopic water lost at 100" ..................... 2'26 1'92 1'85 16. 3.03 4 -34 2'33 The amounts of either calcium carbonate or organic matter present in the soils do not shed any consistent light on the different rates of attack shown by the solvents employed. The amount of calcium carbonate present is in no case sufficient to neutralise the acids, for which purpose about 15 grams of the carbonate would be required.Much of the calcium carbonate in the soil of plots 6 and 7 has been removed by the continual use of ammonium salts, and this may ex- plain why the hydrochloric acid dissolves far more from these plots than from the nitrated plot 9a, which is richest in calcium carbonate. Phosphoric mid-Broadbnlk Field. I_ 00.5 r C m c p HCl 1 Acelic I Carbonrc 1 Ammon Cirrate T G l c> I0AVAILABLE PLANT FOOD IN SOILS. 131 Carbonic. But the acetic acid, the solvent action of which is little affected by variation in the calcium carbonate present, also dissolves less from 9a than from plots 6 and 7. On the other hand, the dunged plot is rich in calcium carbonate and is comparatively resisted to hydrochloric acid, yet it is the plot which yields the most to acetic acid.It is noticeable that the citric acid and ammonium citrate solutions contain considerable quantities of organic matter, silica and salts of iron and aluminium. The same mineral materials are attacked by the hydrochloric acid, but are not present to any appreciable extent in the solutions in acetic and carbonic acids. The comparative action of the various acids may be most clearly seen in the diagram on p. 130, where the heights of the vertical columns are proportionate to the amounts of phosphoric acid dissolved in each case. For purposes of comparison, the total phosphoric acid soluble in strong hydrochloric acid is added, Gut plotted to the smaller scale of one-tenth. Phosphok Acid Results on other Soils.The following table shows the percentages of phosphoric acid dis- solved by each of the acids from the soils 1 to 12 previously described, arranged according to the total amount of phosphoric acid they contain : Amlnoniulr citrate. TABLE VIII. Soil. 1 2 3 4 5 6 7 8 9 10 11 12 Citric. _~.___^_ 0-0055 0.0085 0'0100 0'0029 0'0082 0.0033 0.0233 0-0210 0'0085 0.0071 0'0240 0.6420 HC1. 0 -0024 0'0013 0'0035 0'0021 0'0031 0'0003 0-00435 Acetic. 0'0007 0.0007 0'0016 0.0007 0'0011 0'0003 0 *0006 0.0067 0 0016 0.0033 0'0013 0.0030 0.0017 0.0023 0-0008 0*0011 0'0019 0'0080 0.0295 0.0128 i 0'0104 I 0.0099 ' 0'0122 1 0,0182 i 0.0210 0'0040 0'0016 0-0022 ' 0-0081 0-0022 0.0019 i 0.0022 I 0.0089 0'0360 0.0120 0.0089 ~ 0.0540 0'0167 1 0'0056 0*0014 ' 0.0166 Strong HC1.Total. 0.073 0.089 0.089 0.104 0'110 0.112 0.118 0'121 0.142 0.145 0.152 0.163 (5). It is at once seen that the order in which the soils are arranged according to the total phosphoric acid is not the order of their relative richness in 'I available " phosphoric acid as judged by any one of the dilute solvents. This is only to be expected, considering the very differ- ent types of soil here brought together. The results generally afford K 2132 HALL AND PLYMEN: THE DETERMINATION OF strong confirmation of the practical value of dilute solvents in judging of the need of a given soil for a phosphaticmanure. With three excep- tions, all the soils contain more than 0.1 per cent. of total phosphoric acid, which has Seen regarded as sufficient for fertility ; yet the cropping tests of these soils show that; onIy two, 11 and 12, are at all properly furnished with phosphoric acid.If, on the contrary, Dyer’s limit of 0.01 per cent. of phosphoric acid soluble in 1 per cent. citric acid be taken as a criterion, the two latter soils are sharply dis- tinguished from the rest, as containing 0.024 and 0.042 per cent. re- spectively, and the others with two exceptions would be rated as in need of phosphoric acid. With acetic acid as a solvent and a limit of 0.0025 per cent. of phos- phoric acid soluble, all the soils except the two, 11 and 12, known to be provided with phosphoric acid, would be rated as in need of a phos- phatic manuring. (6). The action of the different acids can be best reviewed by plot- ting them as before, and also by recalculating the results in terms of the amounts dissolved by citric acid from each soil, compare Table IX (p.133) with Table IV (p. 127). Table X. (p. 133) shows the calcium carbonate, the hygroscopic moisture, and the loss on ignition for each soil. I n Table XI (p. 133) the soils 1 to 12 are arranged as the Broadbalk soils in Table V (p. 128) ; that is, one soil is taken as a standard of comparison (in this table, No 5, which is known to be very slightly if a t all in need of phosphatic manuring); the phos- phoric acid dissolved by each acid from this plot is called 100, and the amounts dissolved by the same acid from the other plots are reduced to this standard. An inspection of the diagram (p. 134) shows that citric, acetic, hydro- chloric and carbonic acids agree, with one or two exceptions, as to the comparative richness in available phosphoric acid of any plot.The vertical columns representing the acids rise and fall together in pass- ing from plot to plot, as was the case with the Broadbalk soils. The ammonium citrate, however, gives results essentially different ; i t rates soil 2 as better than 3, the other acids make 3 distinctly richer than 2 ; again, i t rates 4 below 5, contrary to the relative position assigned to these two soils by the other acids and by cropping experiments. From all the soils 1-8, 10, and 12, ammonium citrate extracts more than citric acid, a result never obtained with any of the Broad- balk soils. The high and irregular results given by ammonium citrate as compared with the other acids may probably be attributed to the comparative richness of these soils in organic matter and their poverty in calcium carbonate.The soils, 2, 4, 6, 7, and 8, which are ratedSoil. 1. I 2. 1 3. i 4. ~ i 5. i 6. I 7. 1 1 9. i l O . l l 1 . TABLE IX.-Percentages of P,O, dissolved by other solvents calculated on that taken up by citric acid. 12. Citric acid ....................... Amnionium citrate ............ Acetic acid ........................ Carbonic acid,. .................... Hydrochloric acid.. ............. 100 144 58-9 100 1 100 100 347 138 362 1;:; 1 35.0 73.2 15'9 24'4 15-3 29'6 60.6 \ 100 100 121 ~ 370 37'8 ' 9.1 13'9 ' 9'1 27'9 24.0 Calcium carbonate ............... 0.03 trace 0'04 1 0.01 0'08 Loss on ignition ...............5.93 10.43 3.68 4'74 3.09 Hygroscopic water.. ............. 4'26 6'34 3*13 2'34 2'73 I ! 100 137 32.7 4.5 8 -3 0.21 0.03 6.01 9'10 4.87 2.75 7. ____- 162 184 140 52% 48-0 107 . - Citric acid ........................ Ammonium citrate ............ Hydrochloric acid.. ............. Acetic acid.. ..................... Carbonic acid.. ................... Total ............................. 8. 256 212 216 138 110 83-0 100 100 31 -9 7-5 9'1 the loss 0.01 9 '19 4'74 100 94 *8 47 *1 18.9 25.6 TABLE XI.-Percentages of dissolved P,O, calculated on plot 5. on ignition. 3.00 0.03 1 4'59 5.09 ~ 7.11 4'08 3'98 j 2.76 1 2-06 5. 1 1. --I-- 100 67 *3 100 61.4 100 66.1 2. 104 298 42.3 57'0 56 '8 80'6 3. 122 129 113 139 129 81.3 4. 35.0 67 -7 61 '4 76.0 ' 94'2 105 6. 40.2 9.7 26.3 34'9 123 102 I 100 100 126 69.2 31.1 1 69'6 9.104 129 141 129 81'4 95.2 100 129 85.7 28% $ 21.2 t? M cd t? P 3'32 3 4.01 q 1.87 8 tJ L m I I 0 86.0 90 *o 70 *6 96 '1 170 132 293 168 539 491 138 62 '0 512 545 1161 1053 390 148 +134 HALTA AND PLYMEN: THE DETERMINATION OF u3 0 0 t- I I 1 m l-l 0 0 0 0 0 Phosphoric oxide, P,Os, per cent.AVAILABLE PLANT FOOD IN SOILS. 135 comparati+ely high by ammonium citrate, are rich in organic matter, 2 and 7 being the only pasture soils in the group, and 8 an artificially made soil. No. 5, which is rated low by ammonium citrate, is excep- tionally deficient in organic matter. The quantities dissolved by acetic and carbonic acids are very similar; it is to be noticed that acetic acid dissolved slightly less than carbonic acid from the soils 1-10, which are, with the exception of 9, short in calcium carbonate, but that it obtained the larger amount of phosphoric mid from soils 11 and 12 and from the Broadbalk soils which contain more than I per cent.of calcium carbonate. On close inspection of the figures many differences are evident in the mode of attack of the various acids, which when followed up on a number of soils will provide information as to the forms i n which the phosphoric acid of the soils is combined. The authors, however, wish in this communication to confine themselves to the question of which dilute acid yields results most in accord with the known history of the soils, and is therefore most likely to be useful in judging an unknown soil. (7). A few figures may be here inserted showing the effect of varia- tion in the strength of the acid used, and of additions of calcium carbonate to the soil.Dyer (Zoc. cit.) has already given figures showing that an increase in the strength of the acid results in more phosphoric acid going into solution ; the authors' results are in the same sense : TABLE XII. Solvent. Citric acid 0.2 normal ....................... ,, 1 per cent. ........................ ,, 0.1 normal ........................ Percentage of P,05 dissolved. Soil 7. Soil A. 0.0198 0'0133 0.0084 0.0424 0'0349 0.0206 Soil A does not appear elsewhere in this paper, but was chosen as one rich in phosphoric acid and calcium carbonate, but poor in organic matter, and thus a complete contrast to soil 7. Soil 7 was further mixed with varying amounts of calcium carbonate, obtained by grinding Iceland spar to a fine powder, and subjected to the action of citric, acetic, and carbonic acids, with the following results :136 HALL AND PLYMEN: THE DETERMINATION OF Soil only ._......... , ... .. ... . ........ ... + 2 per cent. calciiini carbonate , , 3 7 + 5 9 J ,, ,, 9 9 + I 0 9 , 9 , ,, TABLE XIII. 0.0133 0’0006 0 ‘0090 0 -0009 0.0056 0.0006 0*0007 0.0007 i Phosphoric acid. I 1 - - I Soil 7. I Citric. I Acetic. I- I- co,. __ 0*0011 0.0007 0 *0009 0.0009 Potash. _____ Citric. - 0.0148 0.0092 0.0092 - Acetic. - 0’00714 0.00706 0.00710 These trials were not pushed further; the citric acid as it was neutralised by the calcium carbonate dissolved less and less phosphoric acid, until with 10 per cent.of calcium carbonate (more than is requisite for complete neutrality), the amount of phosphoric acid dissolved approximated to that dissolved by carbonic acid only. The solution effected by carbonic acid is independent of the calcium carbonate present, and that effected by acetic acid approximately so, because the liberated carbonic acid is an equally efficient solvent. Review of Results. (8). On reviewing the whole of the results, it seems very improbable that any distinction of kind can be drawn between (‘ available ” and ‘6 non-available ” compounds of phosphoric acid in the soil ; that is, there is not a compound or group of compounds available,” which can be wholly removed by the plant or dissolved by Rnn acid before the remaining compounds are attacked.Were this the case, those soils which contain only n limited amount of ‘‘ available ” phosphoric acid would yield all of it or none to a given solvent, and the strength of the solvent would be without influence on the result when the time limit is large. On the contrary, the amount of phosphoric acid dissolved varies with both the nature and strength of the acid. There is no reason for regarding the phosphoric acid dissolved by the citric acid solvent as the available ” phosphoric acid in the soil rather than that which is dissolved by the acetic acid. A soil which contains much or little ‘ I available ” phosphoric acid according to one acid would be rated in the same way by another acid, even when the absoluteamounts dissolvedare ten times as great in one case as in another.The individual acids possess a certain selective power for different combinations of phosphoric acid and attack the different types of soils with more or less vigour, but in the main the relative action of all the acids on all the soils is alike,AVAILABLE PLANT FOOD IN SOILS. 137 The phosphoric acid of a soil must not be looked on as existing in certain compounds A, B, C, D, &c., of which A and B are insoluble and unavailable, C and D as “available ” ; rather A, B, C, D, &c., repre- sent compounds possessing in each soil a coefficient of solubility, vary- ing with the acid and with their own physical condition. The latter factor affects all the acids alike, and combined with the absolute quantity of the phosphoric acid in the soil determines the “ available ” phosphoric acid.The available phosphoric acid measured by a given acid depends on the coefficient of solubility possessed by the acid and the relative proportions of A, B, C, D, &c., in the soil. As soils of the same type contain A, B, C, D, &c., in roughly the same proportion, the latter factor is eliminated and the amounts of available phosphoric acid from different soils as measured by any one of the acids will be proportional to the phosphoric acid which is really (‘ available,” so that all the acids will show roughly the same relations between the soils. Again, a soil may contain di- and tri-calcium phosphates, ferric and aluminium phosphates, and organic compounds of phosphorus like nuclein and lecithin; it would be no gain to discover a reagent which would dissolve the di- and tri-calcium phosphates only and leave the rest, for the physical conditions of these phosphates may render them less ‘‘ available ” to the plant than the other com- pounds of phosphorus present which happen to be in a favourable physical or mechanical condition for solution.On this view the hope must be abandoned of finding any particular acid which will dissolve out the ‘‘ available ” phosphoric acid and leave the rest ; in the results obtained by any acid, the factors are too numerous and variable to admit OF exact discussion; because of its complexity, the method becomes empirical and the best acid is that which most accords with experience. (9). I n forming a conclusion as to the most suitable solvent, three things should be taken into account : (a) The amount of phosphoric acid dissolved should show a wide variation in passing from soil to soil, so as t o discriminate sharply between rich and poor soils.The largest quantity of phosphoric acid dissolved by strong hydrochloric acid from any one of the soils examined is 0.228 and the smallest 0.0727 per cent. ; other things being equal, variations of this order would not discriminate so well between the soils as the variations exhibited by citric acid, which lie between 0.051 and 0.0029, or of acetic acid, which lie between 0.012 and 0*0003 per cent. ( b ) The amount of phosphoric acid dissolved from normal soils should be sufficient for exact estimation, so that the variations ex- hibited may be of a different order of magnitude from the experimental error, which is inevitably large.138 HALL AND PLYMEN: THE DETERMINATION OF (c) The variations in the amount of phosphoric acid dissolved should so follow the known history of the soils that the reaction of an un- known soil to phosphatic manures can be predicted from its analysis.For this reason, the action of the acid should not be markedly affected by other variable constituents in the soil, such as calcium carbonate and organic matter. Ammonium citrate fails to meet the last requirement ; although when dealing with soils of one type, like the Broadbalk soils, its results fall into line with those given by the other solvents, yet with the other soils the indications provided by tlie analysis do not agree with experience.Soils 2, 7, and 8 yield comparatively large quantities of phosphoric acid to ammonium citrate solution and would be rated as sufficiently supplied with phosphoric acid, but 2 and 7 respond freely to phosphatic manures. Soils 4 and 6 yield more phosphoric acid than 5, which is quite contrary to the crop results. These discrepancies are due to the solubility of the humus containing phosphorus compounds in the alkaline ammonium citrate solution, thus introducing material of a different order of solubility, and as the ammonium citrate solution offers no compensating advantages it may be dismissed as uneuitable. Hydrochloric acid presents many anomalies of attack; it has very little solvent power for phosphoric acid when dealing with soils 1-10 which are poor in calcium carbonate; for example, it can only dissolve 0.0031 per cent.from soil 5, which is fairly provided with phosphoric acid as judged by the crop, whereas it can get 0.0021 per cent. from the unmanured plot at Rothamsted, and as much as 0.0167 per cent. from soil 11, the poorish chalky Wye soil which had been unmanured for 5 years. The Broadbalk plot 9a, which receives minerals and sodium nitrate, is rated very low ; it yields only three times as much phosphoric acid as the continuously unmanured plot, and less than one-third as much as the corresponding plot 6, which receives ammonium sulphate instead of sodium nitrate. The duuged plot is also rated as inferior to the plots receiving minerals and ammonium salts. On the whole, the results obtained with hydrochloric acid are difficult to reconcile with experience, and present no features which would justify its recommendation in place of citric acid.Wccter chcwged with curbonic acid is so similar in its action to acetic acid, both in the relative and absolute amounts dissolved from the various soils, that the greater convenience of using the latter acid would cause it to be preferred. The choice thus becomes narrowed down to acetic and citric acids. Of these two, acetic acid better satisfies the first condition laid down With the above, the variations in the amounts dissolved are larger.AVAILABLE PLANT FOOD IN SOILS, 139 Broadbalk soils they range from 169 to 11.2, against 100 to 15.7 for citric acid (Table V). On the other soils they range from 1053 t o 26.3, against 512 to 35 for citric acid (Table XI).AS regards the second criterion, the quantities of phosphoric acid dissolved by the acetic acid are very small, one-tenth t o one-fifth of the amount dissolved by citric acid. The limit to be taken as indicating the need for phosphatic manuring would be about 0.002 per cent., which means the determination of only 0.001 gram of phosphoric acid in the 500 C.C. of solution commonly employed. On the other hand, the acetic acid solution is the easier t o manipulate, owing to the absence of iron, alumina, silica, and dissolved organic matter ; SO that the experimental error is not likely t o be greater than with citric acid, less indeed in unskilled hands. AS regards the interpretation of the results, it is clear that all soils deficient in calcium carbonate,as 1-8, are rated very low by acetic acid.I n such soils, much of the phosphoric acid is present as precipitated ferric and aluminium phosphates, which are left practically untouched by the acetic acid, yet there is no evidence that such phosphates are quite “ non-available ” for the crop. Soil 5 is a case in point ; acetic acid dissolves only 0.001 per cent. of phosphoric acid, yet the crops on this soil find no great need of phosphates. The Broadbalk soils are very clearly differentiated by acetic acid, the doubtful point being the comparatively low position attached to 9a and 16, the nitrate plots. The position assigned to these two plots and to 5 in the other group makes it difficult to accept acetic acid as the most ‘( critical ” solvent.Considering the results yielded by citric acid, some difficulty of interpretation attaches to soils 2, 3, 7, and 8. Taking the limit of 0.01 per cent. of phosphoric acid suggested by Dyer, soils 7 and 8 are above the limit with 0,0133 and 0.021 per cent. respectively ; soil 3 is on the limit, and soil 2 is a little below with 0-0087 per cent. ; yet the field trials indicate a need of phosphates on soils 2, 3, and 7, probably on 8 also, although as an exceptional soil it is hardly comparable with the rest. Of all the soils examined, soils 2, 7, and 8 show the greatest loss on ignition ; 2 and 7 are old pastures, 8 is a made soil containing leaf mould, and as citric acid dissolves some of the organic matter of soils, i t is to this source that the high proportion of phosphoric acid yielded by these soils may be attributed.Probably the superior limit of 0.01 per cent. of phosphoric acid, as indicative of the need of phosphatic manuring, requires revision when dealing with pastures and other soils rich in organic matter. The results yielded by soil 5 also require a little explanation ; the citric acid solution only dissolves 0.0082 per cent., yet the crops show no exceptional response to phosphatic manuring. The soil is a very140 HALL AND PLYMEN: THE DETERMINATION OF light sandy loam, typical of many of the soils derived from coarse, ferruginous sandstones of secondary age. It contains very little calcium carbonate (0.08 per cent.) and little organic matter (loss on ignition 3-08 per cent,).The phosphoric acid must be largely present in this soil as ferric phosphate, and although citric acid is a better solvent than acetic acid in such cases, even the citric acid does not indicate all the phosphoric acid that seems to be ‘L available ” for crops. Gerlach (loc. cit.) has already indicated that typically sandy soils from which citric acid dissolves less than 0.01 per cent, of phosphoric acid may give little response to phosphatic manures. As regards the Broadbalk soils, the results yielded by citric acid are more in accord with our knowledge of the plots than those furnished by acetic and the other acids; in particular the plots receiving nitrate 9a and 16, though below all the others except the unmanured plot, are shown as still high above the limit which may be taken to indicate the need of phosphatic manuring.Reviewing the whole body of results, the authors consider the 1 per cent. solution of citric acid gives results which are most in accord with the known history of the soils. On soils well provided with cal- cium carbonate all the acids tried give very similar relative results, but this type of soil is rarely in need of phosphatic manuring, and the practical question for which the analysis is performed, whether the soil is in need of phosphatic manuring or not, usually arises in the case of soils poor in calcium carbonate. From these soils, acetic acid can extract so little that it reduces them all to practically the same level, whilst citric acid is able to dissolve the natural phosphates of iron and alumina in a manuer more in accord with the natural attack of crops.11. POTASH RESULTS. Methods of analysis based upon the solvent action of weak acids must be even more empirical, when dealing with the potash in soils than with the phosphoric acid, Certain definite compounds of phos- phorus, such as the organic residues, the phosphates of the sesqni- oxides, the neutral and acid phosphates of calcium and magnesium, exist in the soil, and are, to some extent, differentially attacked by the various solvents, but the potash compounds are far more com- plex and indefinite. I n addition to more or less weathered silicates, like felspar and glauconite, there are indefinite compounds formed when humus and clay withdraw potash from the solution produced by the weathering of potash minerals or the application of manures, Even the amount of potash dissolved by strong hydrochloric acid from a soil is a purely conventional figure, dependent ou the strengthAVAILABLE PLANT FOOD IN SOILS.141 of the acid and the length of attack; the Broadbalk soils, for example, yield about 0.5 per cent. of potash to strong hydrochloric acid, but the total potash contained in the soil from plot 5 , as determined after breaking up the soil completely with ammonium fluoride, amounted to 2-26 per cent. The tables below show the results yielded by the soils from the same seven plots of the Broadbalk Field at Rothamsted, and by five other soils previously described ; the results are also set out graphically on p. 143 in the same manner (compare p.131) as were the phosphoric acid results. TABLE XIV. Potash-soils from Broadbalk Field. - 13iot. 2b 3 5 6 7 Da, Manuring. Dung .......................... Unmanured. .................... Minerals only.. ................ Minerals 200 Ib. ammouiuni salts ........................... Minerals 400 lb. ammoniuin salts ........................... Minerals 275 lb. sodium nitrate ........................ Minerals 800 lb. ammon- ium salts .13 years Unmanured .19 years Minerals 550 lb. sodium nitrate.. ......... .10 years I ........ ..... Citric. 0'0400 OmO043 0.0458 0.0322 0-0233 0 *0272 0.0203 HCI. 0'0684 0'0147 0.0522 0.0487 0.0464 0'0414 0'0421 Acetic. 0'0451 0'0082 0.0307 0.0271 0-0240 0-0237 0'0184 arbonic 0.0380 0'0111 0.0215 0.0151 0.0091 0.0238 0.0145 - Strong HCI.0-453 0.380 0 '463 0.530 0.500 0'440 0.504 On examining the results yielded by the Broadbalk soils, it is noticeable that the amounts of potash dissolved by the different acids are very similar, much more so than with phosphoric acid. Citric acid dissolves ten times as much phosphoric acid as the water charged with carbonic acid, whereas hydrochloric acid, the most energetic solvent for potash, dissolves only about three times as muchas the weak- est, which is again carbonic acid. On the whole, each acid leads to the same conclusions with regard to the relative richness of the plots in '' available " potash, but citric acid shows the widest variation in passing from plot to plot; the ratio of 2b, the dunged plot, t o 3, the un- manured plot, is 9.3 : 1 for citric acid against 4.65 : 1 , 5 5 : 1, and 3.4 : 1 for hydrochloric, acetic, and carbonic acids respectively. The results with the Broadbalk soils would indicate that the citric acid is the most "critical'' solvent for '' available " potash in the soil.HALL AND PLYMEN : THE DETERMINATION OF - (0 L 0 C 0 5 ]e r( 0 0 e 0 0 0 0 Potash, K,O, per cent.AVAILABLE PLANT FOOD IN sons.Loss 011 ignition. TABLE XV. Potash dissohed by wet& acids from other soils. Water lost a t 100". Soil. -1- Citric. 0.0104 0.0156 0.0053 HCI. -- 0.0480 0'0580 0.0113 0.0154 0'0178 0*01'76 1 0.390 4.59 0'0241 0.378 3'32 0.0057 1 0.313 0'01 j Acetic. Carbonic/ 'EZg 1 CaCO,. 0-0059 j 0'0062 j 0.439 0'0053 , 0.0079 ' 0'592 1 I 0'08 0'02 143 4.08 4'01 4'74 3.09 12.53 2-06 1.87 3-13 2 3 4 13.04 11 12 4 s 13 Of the other soils examined, 11 and 12 should be compared together as soils freely supplied with calcium carbonate, whereas soils 4, 5, and 13 are notably deficient in this constituent.Soils 11 and 12 are from the plots, side by side, on the same field, shown by experi- ment not to be particularly in need of potash manuring. No. 11 had been cropped without manure for 5 years, during which time 12 had received each year a general manure containing 1; cwt. per acre of potassium sulphate. All the weak solvents show 12 as richer than 11 in ' I available " potash, whereas the strong hydrochloric acid would make them practically alike. The difference between them is most sharply drawn by citric acid; it is also noticeable that citric acid shows both plots as comparatively poor in '' available " potash, the other three acids would rate them as comparatively rich. Of the other three soils, field experiments have shown that 4, a strong clay, is in no need of potash manuring, but 5 and 13 gave very marked returns for potash dressings.Strong hydrochloric acid would make both 5 and 13 much richer in potash than 4 ; it dissolves 0.593 and 0.439 per cent. respectively from 13 and 5, against 0.313 per cent. from soil 4. Dilute hydrochloric acid would also set soil 4 below 5 and 13 in (' available " potash, acetic and carbonic acids would rate them alike, the differences between the various results being of the same order as the experimental error. Citric acid alone draws a sharp distinction between the soils ; it dissolves 0.025 per cent. from 4, and only 0.011 and 0.0085 per cent. respectively from the other two soils. The results with these five soils afford most striking evidence of the practical value of weak solvents as against extraction with a strong acid in judging of the requirements of n soil for a potash manure ; a t the same time, they indicate if may be necessary in the light of extended experience to adopt different limits for soils of different types, for example, soils rich or poor in calcium carbonate. 0*0050 0'0093 0'0250 0'0110 0'0085144 THE DETERMINATION OF AVAILABLE PLANT FOOD IN SOILS. Of the four weak acids employed, the authors regard citric acid as furnishing results most in accord with the history of the soils exam- ined. Xummar y. The authors have compared the amounts of phosphoric acid that could be extracted from nineteen different soils by a 1 per cent. solution of citric acid, by equivalent solutions of hydrochloric acid and acetic acid, by a saturated solution of carbonic acid, and by an ammoniacal solution of ammonium citrate respectively. Seven of these soils were from plots on the Broadbalk Field, Rothamsted, which had been continuously manured in the same manner for forty-two years previously; the re- maining twelve were soils of very varied origin, which had been the subject of crop experiments and whose reaction to phosphatic manuring was well marked. I n the same seven soils from the Broadbalk Field, the authors deter- mined the potash extracted by the same dilute solvents, with the exception of ammonium citrate ; five other soils of different origin, whose response or otherwise to potash manuring had been tested by experiment, were also examined in the same way. Determinations were also made of the phosphoric acid and potash dissolved after long digestion with strong hydrochloric acid, of the loss on ignition, and of the earthy carbonates present in each soil. The authors conclude :-(1). That no sharp line of distinction can be drawn between ‘‘ available ” and non-available phosphoric acid and potash in the soil, and that any process of determining the ‘ I available ” constituents is an empirical one, dependent on the strength and nature of the acid used. (2). That the weak solvents give information as to the requirements of a given soil for mineral manures of a far more trustworthy nature than that which is afforded by such a solvent as strong hydrochloric acid. (3). That of the acids examined, the 1 per cent. solution of citric acid gives results most in agreement with the recorded history of the soil, although there is evidence that the same interpretation cannot be put on results obtained from all types of soil. Soum EASTERN BGRICULTUKAL COLLEGE, WYE.

ISSN:0368-1645    

DOI:10.1039/CT9028100117

出版商:RSC    

年代:1902

数据来源: RSC

摘要:

DOBBIE AND LAUDER: CORYDALINE. PART VII, 145 XIK-Corydaline. Pwt vrz The Constitution of Cory daline. By JAMES J. DOBBIE, M.A., D.Sc., and ALEXANDER LAUDER, B.Sc. THE results obtained by oxidising corydaline with potassium perman- ganate and nitric acid have been described in previous communications I n the present paper, some additional experimental details are given, and the whole of the results are discussed in their bearing on the con- stitution of the alkaloid. Attention has already been drawn to the resemblance which cory- daline bears to berberine (Trans., 1899,75, 670). This resemblance is not merely superficial; the two alkaloids probably differ only in some of the details of their structure, The comparison, however, must be drawn, not between corydaline and berberine, but between corydaline and tetrahydroberberine, or between dehydrocorydaline (which differs from corydaline by 4 atoms of hydrogen) and berberine. The con- clusion, based on the chemical investigation, that the two alkaloids are closely related, has been confirmed by an examination of their absorp- tion spectra, which we have found to be almost identical.The spectro- scopic results will form the subject of a separate communication. Corydaline has been analysed in recent years by various chemists, with results practically identical with those which we published in 1892 (Trans., 61, 244; Freund and Josephi, Annalen, 1893, 277, 1 ; Ziegenbein, Arch. Phrm., 1896, 234, 492 ; Martindale, ibid., 1898, 236, 214). From the analytical results, we deduced t-he formula C22H2904N, and Preund and Josephi the formula C22H2704N.The latter is probably the correct formula. By the action of mild oxidising agents such as dilute nitric acid or iodine in alcoholic solution, 4 atoms of hydrogen are removed from the corydaline molecule and an intensely yellow base, dehydrocorydaline, C22H230,N, is produced, from which, by reduction, an optically in- active modification of the alkaloid may be obtained (Ziegenbein, Zoc. cit. ; E. Schmidt, Arch. Phurm., 1896, 234, 489 ; Dobbie and Marsden, Trans., 1897,71, 657). The ease with which corydaline can be oxi- dised to dehydrocorydaline, and dehydrocorydaline reduced to cory- daline, shows that these two substances are very closely related to one another. It will be remembered that berberine, which is a yellow base like dehydrocorydaline, and tetrahydroberberine, which resembles cory- daline in being colourless, can also be readily converted the one into the other.When corydaline is heated with a concentrated solution of hydrogen iodide, it is converted into a phenolic derivative containing four hydr- VOL. LXXXI. L146 DOBBIE AND J,AUDER: CORYDALINE. PART VII. oxgl groups, each molecule of corydaline yielding 4 molecules of methyl iodide. The alkaloid has therefore all its four oxygen atoms present in methoxyl groups (Trans., 1892, 61, 605). By oxidising corydaline with potassium permanganate a t the boiling point, the chief products of oxidation are hemipinic and m-hemipinic acids : 0Me OMe/\CO,H !,)CO,H Hemipinic acid. OMe/\C02H OMe()CO,H ?it- Hemipinic acid.The presence of two benzene nuclei in the molecule is thus established (Trans,, 1894, 65, 57; 1897,71, 657; 1899, 75, 670). Along with the hemipinic acids, a small quantity of corydaldine is also obtained, the yield of which is considerably increased by conducting the oxida- tion a t the ordinary temperature. Corydaldine has been shown to CH,* 0 GO-IfH have the following constitution, CH,. O>C6HH"<G&.CH; which proves the presence of an isoquinoline nucleus in the alkaloid (Trans., 1899, 75, 670). When nitric acid is used as the oxidising agent in place of perman- ganate, dehydrocorydaline is first produced ; oce of the benzene nuclei is next destroyed, and the beautiful, yellow, dibasic corydic acid, C,,HI7O,N + iH,O, formed. When corydic acid is in turn oxidised with perrnanganate at the boiling point, i t is resolved into an in- soluble, colourless, tribasic acid, C,7H,,0,N, which we propose to term corydilic acid, a methylpyridinetricarboxylic acid, and m-hemipinic acid (Dobbie and Marsden, Trans., 1897, 71, 657).I n the present paper, it is shown that the methylpyridinetricarboxylic acid has either the formula CO,H CO,H or Corydilic acid, on continued boiling with potassium permanganate, is gradually split up into a mixture of the methylpyridinetricarboxylic acid and m-hemipinic acid. These results afford a basis for the discussion of the constitution of corydic acid. This acid is derived from dehydrocorydaline by the destruction of one of the benzene nucIei, and since it yields m-hemipinic acid as one of its oxidation products, the nucleus which is destroyed must be that from which hemipinic acid is derived.The 2-methyl- pyridinetricarboxylic acid, which is also one of the oxidation pro- ducts of corydic acid, contains 6 atoms of carbon, exclusive of theOxidation products of corydaline. Cory daline, C22H27OdN. M. p. 135". I I -~ I I I Oxidation with KMnO,. 4 Oxidation wit; dilute HN03. 4, Dehydsocorydaline, I I C _ H 0 N. Hemipinic acid, m-Hempinic acid, I 23~ I M. p. 175". I J. Corydaldine, CI, a1303N- C6H2(CO2H),(O'CHJ,* C6H,(CO&)2(O 'CH& Methylpyridinetri- carboxylic acid, [l : 2 : 3 : 41. [l : 2 : 4 : 51. I Corydic I acid, Oxalic acid. CU?H1706N. CSHvOGN. Oxidation with KMn04. m-Hemipinic acid. &I. p. 218". I M. p. 208". &idat.ian with KMnO,.I I I I I Corydilic acid, m-Hemipinic Methy1p;ridinetri- acid. carbdxylic acid. Oxidation with KMnO,. Pyridine-2 : 3 : 4 : 6 - te tracarboxy lic 4?H,,O,N. I I M. p. 228". Oscidation with KMnO,. I I I Methylpyridinetri- I nt-Hemipinic acid. carboxylic acid, acid. C,H50BN.148 DOEBIE AND LAUDER: CORYDALINE. PART VII. carbon atoms of the carboxyl groups. It cannot, therefore, be derived from the pyridine ring of the isoquinoline nucleus, since the investiga- tion of corydaldine has shown that this pyridine ring has no sidechain attached to it. The 2-methylpyridinetricarboxylic acid represents, therefore, a second berberine, must be for corydic acid : ring to which the nitrogen atom, common. We thus arrive a t the C0,H as in the following case of formula FIG.1. -Cor ydic acid. This formula accounts for the relation of the molecular formula of corydic acid to that of dehydrocorydaline; for the presence of the two carboxyl groups, and for the formation, on oxidation, of corydilic acid, the 2 -methylpyridinetricarboxylic acid, and m-hemipinic acid. The formation of the last-named acid establishes the position of the methoxyl groups, There is no direct experimental evidence to prove that the positions of the carboxyl groups are those which we have assigned to them, rather than the positions 4 : 5, but we shall presently state our reasons for introducing a direct link between the carbon atoms 2 and 5, which limits the carboxyl groups to the positions shown in the formula. The formula (Z), which me have assigned to dehydrocorydaline follows from that of corydic acid.Perkin's formula for berberine is placed side by side for comparison (Perkin, Trans., 1889, 55, 63) : FIG. 3. -Berberine. FIG. 4. -Co&ydaline. FIG. 5. -Tetrahfdroberberine.THE CONSTITUTION OF CORYDALINE. 149 Corydaline differs from dehydrocorydaline in containing four more atoms of hydrogen. Having regard to the great ease with which corydaline can be oxidised to dehydrocorydaline and tho latter substance reduced t o corydaline, it may be assumed that we have to do here with a group similar to that which exists in certain anthracene and acridine derivatives, and such as Perkin has assumed to be pre- sent in berberine. The existence of a double bond between the carbon atoms 5 and 6 and of a direct bond between the carbon atoms 2 and 5 in ring I1 of the formula for dehydrocorydaline (Fig.2) would explain the ease with which the one substance passes into the other. The formula proposed for corydaline, (Fig. 4), explains the reac- tions and accounts for the formation of all the derivatives of the alkaloid which have been examined. By oxidation, the rings, which for convenience of reference we have numbered I and IV on the diagram, would yield hemipinic and m-hernipinic acids respectively, and ring I1 methylpyridinetricarboxylic acid. Corydaldine, CllH,,O,N (Fig. 6), containing rings I11 and IV, would result from the oxidation of corydaline in the same way as o-aminoethylpiperonylcarboxylic anhydride (Fig. '7) results from the oxidation of berberine : CO,H FIG.6. -Corydaldine. FIG. 7.--w-AminoethyJ- FIG. 8.-Corydilic acid, piperonyl carboxylic anhydride, Corydic acid (Fig. 1) would be formed by the destruction of ring I, and corydilic acid (Fig. 8) from corydic acid by the oxidation of ring 111. If our formulae are correct, they incidentally prove that Perkin's formula, which we have quoted, is to be preferred to the alternative formula suggested by him for berberine, in which the carbon atoms 2 and 5 are conrected by a double bond, because, on account of the presence of the methyl group in dehydrocorydaline, no double bond is possible between the carbon atoms 2 and 5, and i f a double bond existed in berberine in this position the very close resemblance between the two substances would not be satisfactorily explained.When the decomposition products of berberine are compared with those of corydaline, a close parallelism is observed between them. Both alkaloids yield hemipinic acid as a derivative of ring I. From rings I11 and IV, a-aminoethylpiperonylcarboxylic anhydride is obtained in the case of berberine, just as corydaldine is obtained from the corre-150 DOBBIE AND LAUDER: CORYDALINE. PART VII. sponding rings of corydaline, acid : Ring IV of berberine yields hydrastic the corresponding decomposition product of corydaline being m-hemi- pinic acid. The oxidation product obtained from ring I1 is of special interest in the case of both alkaloids. Weidel (Bev., 1879, 12, 410), by oxidising berberine with strong nitric acid, obtained as chief oxida- tion product berberonic acid : CO,H We have also obtained the same acid from a new derivative of ber- berine, which is desaribed in another communication.I n discussing the constitution of berberine, Perkin does not take into account the occurrence of berberonic acid amongst its decomposition products. It, is clear, however, that its occurrence affords important confirmation of the correctness of his formda, since it would result from ring I1 by the oxidation of the attached rings I and 111, but could not result from ring 111, which mould yield cinchomeronic acid. There is thus direct evidence in the case of berberine, as well as in the case of corydaline, of the existence of a fourth closed chain in the molecule of the alkaloid, It is remarkable that both in the case of berberine and of corydaline, ring I1 is the more stable of the rings to which the nitrogen atom is common, From neither alkaloid has any acid corre- sponding to ring I11 been obtained.A further instance of the com- parative ease with which ring I11 in corydaline is broken up is afforded by the formation of corydilic acid from oorydic acid. Whilst our formula for corydaline satisfactorily accounts for the similarity between this alkaloid and berberine, it also explains the absence from amongst the decomposition products of corydaline of derivatives corresponding t o berberal, C201Xl,07N, berberilic acid, C20H1909N, oxyberberine, C,,H170,N, &c., all of which have an atom of oxygen attached to the carbon atom 2 of ring 11. On account of the presence of the methyl group in combination with the correspond- ing carbon atom in corydaline, it would be impossible for an oxygen atom to occupy this position in similar derivatives of corydaline. On the other hand, the formation of corydic acid from corydaline suggested that it might be possible to obtain a similar acid from berberine.We show in a separate communication that by the oxidation of berberine with dilute nitric acid such an acid is readily produced. One further point remains to be dealt with, the stability of theTHE CONSTITUTION OF CORYDALINE. 151 methyl group in ring 11. With the exception of the pyridinetetra- carboxylicacid (see below), all the oxidation products in which ring 11 is present, so far examined by us, contain this group. This is not remarkable when it; is recalled that prolonged treatment with potassium permanganate in alkaline solution is required for the preparation of 2 : 3 : 4 : 6-pyridinetetracarboxylic acid, either from 2 : 4 : 6-trimethylquinolinecarboxylic acid (Michael, Annulen, 1884, 225,121) or from flavinol (Fischer and TLiuber, Ber., 1884, 17, 2925).When, however, large quantities of corydaline are oxidised it might be expected that small quantities of a monocarboxylic acid should be obtained. We believe that we have had such an acid in our hands. I n our earlier experiments, in which several hundred grams of cory- daline were oxidised with potassium permanganate at the boiling point, a small quantity (about 1.5 grams) of a colourless nitro- genous acid which crystallised in tufts of delicate, silky needles and melted sharply a t 156' (Trans., 1895, 67, 17) was obtained.We were only able to make a slight examination of this substance. A nitrogen determination gave a result agreeing with that required by the formula C,lH2,0,N*C02H (nitrogen, found, 3.55 ; calculated, 3.50 per cent.). A determination of the methoxyl groups by Zeisel's method showed that the four methoxyl groups present in corydaline were also present in this acid, and the analysis of a silver salt showed that the acid possessed a high molecular weight. We leave over for the present the full discussion of the relation be- tween the constitution and the colour of some of the corydaline deriva- tives. The further investigation of the products obtained by the oxidation of corydic acid with potassium permanganate at the ordinary temperature, described below, promises to throw further light on this question.It may, however, be mentioned now that the colour seems to depend on the presence of rings I1 and 111, since only the derivatives which contain these rings are coloured. EXPFRIMENTAL. The oxidation of corydic acid with potassium permanganate (Dobbie and Marsden, Trans., 1897, 71, 657) has been repeated on a larger scale, and the results already published have been confirmed; the pro- ducts of oxidation are corydilic acid, C12H6N(O*CH3)2(C02H)3, a methyl- pyridinetricarboxylic acid, C,HpO,N, and m-hemipinic acid. Examination, of t?Le ~ethylpyridinetrica?.boxylic Acid. This acid can be obtained, not only by the oxidation of corydic acid with permanganate, but also by the oxidation of corydaline with strong nitric acid in the manner followed by Weidel in the preparation of152 DOBBIE AND LAUDER: CORYDALINE.PART VII, berberonic acid from berberine (Beg*., 1879, 12, 410). The yield by this method is, however, unsatisfactory. The analysis and general properties of this acid have already been given (Trans., 1897, 71,657). The copper salt, obtained by adding copper acetate to a neutral solution of the acid is blue in colour, and not yellow, a8 previously stated. This acid is undoubtedly a methylpyridinetricarboxylic acid, as is shown by its analysis and the analysis of its salts, but it is not identical with any of the known acids of this constitution. Freund and Josephi (AnmaZen, 1893, 277, lo), from the simiIarity in behaviour of methyl- corydaline and hydrohydrastinine, inferred that corydaline, like hydrastine, contains a methyl group attached to the nitrogen atom.By heating the acid with sodium amalgam, we failed to obtain any evidence of the formation of methylamine, and concluded from this that the methyl group was not attached to the nitrogen atom, as Freund and Josephi suggested. This conclusion was confirmed by the investigation of corydaldine which has no methyl group attached to its nitrogen atom. Further, Herzig and Meyer (Monatsh., 1897, 18, 385) showed that there are only four methyl groups altogether in corydaline which can be split off by the action of hydrogen iodide, and since we have shown that there are four methoxyl groups, there can be no methyl in union with the nitrogen atom.The methylpyridinetricarboxylic acid is an exceedingly stable sub- stance and can be boiled for some time with a dilute solution of potassium permanganate without undergoing any appreciable amount of oxidation. When, however, it is dissolved in excess of potassium hydroxide and a solution of potassium permanganate added, it slowly undergoes oxidation, the operation requiring from eight to nine days at the temperature of the water-bath for completion. Two experiments were made, one with 3 grams and the other with 2 grams of the acid. The excess of permangsnate was reduced, the alkaline solution filtered, neutralised with nitric acid and treated with calcium nitrate t o remove a small quantity of oxalic acid which had been formed.After filtering from the precipitated calcium oxalate, the solution was treated with lead acetate and the precipitate filtered off and washed. On decomposing this precipitate with hydrogen sulphide, a strongly acid solution was obtained, which on evaporation yielded a residue very soluble in water and insoluble in alcohol, This residue contained inorganic matter, Its solution was found to give an insoluble salt with copper acetate which remained undissolved even when heated with acetic acid. It was therefore precipitated with copper acetate with the object of removing the inorganic matter, the blue copper preci- pitate filtered, well washed first with strong acetic acid and then with water, and decomposed with hydrogen sulphide. The acid obtained from the filtrate was still found, however, to be contaminated with aTHE CONSTITUTION OF CORYDALINE.153 small quantity of inorganic matter, from which by reprecipitation we were unable completely to purify it. We mere thus unable to get an accurate determination of the melting point or a specimen of the acid in a sufficiently pure state for analysis. So far as the qualitative examination was concerned, the acid showed all the properties and gave all the reactions of 2 :3: 4:6- pyridinetetracarboxylic acid obtained by Michael (Annalen, 1884, 225, 121) from 2 : 4 : 6-trimethylquinolinecarboxylic acid, and by Fischer and Tauber (Ber., 1884, 17, 2925) from flavinol. I t agreed with this acid in being very easily soluble in water and very sparingly so in alcohol; in giving with ferrous sulphate a dark cherry-red colour, and with ferric chloride a yellow precipitate.With calcium chloride, the free acid gave no precipitate, but with barium chloride a copious white precipitate. The copper salt, as already mentioned, was insoluble even in boiling acetic acid. The silver salt on ignition decomposed suddenly, swelling up and filling the crucible with reduced silver which resembled a mass of tea leaves, exactly as described both by Michael and by Fischer and Tauber. Further information a3 to the identity of the oxidation product of the methylpyridinetricarboxylic acid was obtained by boiling it with strong acetic acid. When 2 : 3 : 4 : 5-pyridin'etetracarboxylic acid is heated at 160°, 3 : 4 : 5-pyridinetricarboxylic acid is obtained, and 2 : 3 : 5 : 6-pyridinetetracarboxylic acid decomposes at 150' into 3 : 5- pyridinedicarboxylic acid.I n both cases, the carboxyl groups which are eliminated are adjacent to the nitrogen atom. It was therefore to be anticipated that, under similar treatment, the tetracarboxylic acid obtained by the oxidation of the methylpyridinetricarboxylic acid would yield cinchomeronic acid by tho elimination of the carboxyl groups 2 and 6, if we had rightly identified it. As a matter of fact, we found that cinchomeronic acid was produced by boiling with acetic acid, and identified without difficulty. The tetracarboxylic acid was boiled for some time with strong acetic acid and tho solution evaporated to dryness, The residue was insoluble in cold and only dissolved with difficulty in hot water.The aqueous solution deposited the acid on cooling in colourless, prismatic crystals, which after purification by recrystallisation melted a t 260". The acid was insoluble in chloroform, almost insoluble in ether, and only very slightly soluble in alcohol, It gave no reaction with ferrous sulphate or with ferric chloride. Silver nitrate and lead acetate gave white precipitates when added to its aqueous solution, Calcium and barium chlorides gave no precipitate even on the addition of ammonia. The copper salt was more soluble in cold than in hot water and was precipitated by warming a cold aqueous solution ; the precipitate redissolved again on cooling. The last reaction which is characteristic of cinchomeronic (pyridine-3 : 4-154 DOBBIE AND LAUDER: CORYDALINE.PART VII. dicarboxylic) acid, taken in conjunction with the melting point, solu- bility, and the reactions above described, left no doubt as to the identity of the acid which we had obtained. Cinchomeronic acid might be formed either from pyridine-2 : 3 : 4 : 5-tetracarboxylic acid or -2 : 3 : 4 : 6- tetracarboxylic acid, by the elimination of the carboxyl groups 2 and 5 or 2 and 6 respectively. It could not be derived from the 2 : 3 : 5 : 6- acid. The tetracarboxylic acid which we obtained not only agreed in every respect with the 2 : 3 : 4 : 6-acid, but differed from the 2 : 3 : 4 : 5 - isomeride in giving no precipitate with zinc sulphate in neutral solu- tion. The difficulty of removing inorganic matter from the tetra- carboxylic acid which we obtained is characteristic of the 2 : 3 : 4 : 6 - acid.The methylpyridinetricarboxylic acid from corydalioe must there- fore have one or other of the following formulae (Figs. 9 and 10) : CO,H FIG. 9. The position of one of the CO,H FIG. 10. carboxyl groups must be adjacent to the nitrogen atom, since i t follows that, when the isoquinoline nucleus is destroyed in the formation of methylpyridinetricarboxylic acid, the carbon atom 1, next to the nitrogen atom, must have a carb- oxyl group attached to it representing carbon atom 9, which is common to the benzene and pyridine rings of the isoquinoline nucleus (see Fig. 2). The two remaining carboxyl groups must represent one of the rings of the corydaline molecule which has been destroyed by oxidation and must therefore occupy positions adjacent to one another.The position of the methyl group is fixed by the following consider- ations. It cannot occupy the position 4, because, in that case, the only arrangement possible would be [CH, : (CO,H), = 4 : 2 : 5 : 63. This acid is known, and is not identical with the acid under investigation. The position 3 is likewise excluded, since, in that case, the tetracarb- oxylic acid obtained on oxidation would be [ (C02H)4 = 2 : 3 : 4 : Fi or 2 : 3 : 5 : 61, having regard to the fact that two of the carboxyl radicles represent a ring destroyed by oxidation, and must therefore be adjacent to one another. By similar reasoning, position 5 is excluded; the methyl group must therefore occupy the position which is assigned to it in the formula.It is shown earlier in this paper that the methyl- tricarboxylic acid is probably [ CH, : (CO,H), = 2 : 3 : 4 : 61, but we have no direct experimental evidence which enables us to decide between this formnla and [CH, : (CO,H), = 2 ; 4 : 5 : 61.THE CONSTITUTION OF CORYDALTNE. 155 Examination of Corydilic Acid, C,,H,N( O*CH,),(CO,H),. The analysis and description of this acid have already been published (Dobbie and Marsden, Trans., 1897, '71, 657). Corydilic acid is obtained along with m-hemipinic and 2-methylpyridinetricarboxylic acids when corydic acid is oxidised with potassium permanganate at the boiling point. From the former it is easily separated, but it is more difficult than we at first supposed to free it entirely from the latter.Repeated recrystallisations are necessary to effect complete purification. This explains why the specimens which we analysed gave results slightly lower than the theoretical numbers. I n addition t o the reactions already described for this acid, we have made the following observations. I t s aqueous solution gives no reaction with ferrous sulphate or ferric chloride, and no precipitate with barium chloride, calcium chloride, cadmium chloride, or copper acetate, even in presence of ammonia. From alkaline solution, corydilic acid is precipitated by the addition of excess of strong hydrochloric acid. If, however, the alkaline solution is exactly neutralised with dilute hydrochloric acid, no precipitation takes place, and a slight excess of hydrochloric acid may be added with- ozt causing the acid to separate.The solution so obtained has a faint green colour, and on standing, sometimes deposits pale, greenish- yellow crystals, which apparently consist of a hydrochloride of the acid. The crystals are very unstable, and decompose on the addition of water, leaving a residue of corydilic acid. Owing to its instability, we were unable to get this substance in a fit condition for analysis. Oxidation of Corydilic Acid with Potassium Permanganate. Corydilic acid is very stable, but on heating for several hours with potassium permanganate in alkaline solution it gradually undergoes oxidation. The acid employed was carefully purified from every trace of the methylpyridinetricarboxylic acid. About 6 grams of the pure acid were oxidised in quantities of 2 grams a t a time.After removal of the manganese oxides, the alkaline solution was concentrated and precipitated with lead acetate. This precipitate, on decomposition with sulphuretted hydrogen, yielded a mixture of acids, which, on separ- ation by fractional crystallisation, was found to consist of undecom- posed corydilic acid, m-hemipinic acid, and the 2-methylpyridinetri- carboxylic acid. The two latter acids were compared with specimens prepared directly from corydaline and found t o agree in every respect, It has already been shown that corydilic acid is tribasic, and that i t contains two methoxyl groups. The following formula expIains its156 DOBBIE AND LAUDER : CORYDALINE. PART VIT. formation from corydic acid as well as all the facts connected with its decomposition products: CO,H FIG.11. Oxidcbtion of Corgdic Acid with Potassium Permccnganate at the Ord incw y Temperature. Corydic acid was suspended in cold water and about twice its weight of potassium permanganate added in aqueous solution in small quanti- ties a t a time. The alkaline solution was precipitated with silver nitrate and the precipitate decomposed with sulphuretted hydrogen in the usual way. The filtrate, on evaporation, deposited a bright yellow acid which, after purification by repeated recrystallisation from water, melted at 212-21 5". This acid is anhydrous, and diifers from corydic acid in being more soluble in cold water and in giving a precipitate with silver nitrate in neutral solution. It was dried at 100' and analysed, with the following results : 0.2503 gave 0,5506 GO, and 0.1207 H,O. C=59*99; H=5.36. 0.2086 ,, 0,4621 CO, ,, 0.0990 H,O. C = 60.42 ; H=5*27. 0.2748 ,, 10.6 C.C. nitrogen at 16' and 758 mm. N = 4.55. Cl,H170,N requires C = 60.18 ; H = 5.33 ; X = 4.39 per cent. This acid is dibasic and forms both a normal and an acid silver salt. Its precise relation to corydic acid is still under investigation. We have limited our investigation of corydaline derivatives and de- composition products to those substances which seemed most important for the determination of the constitution of the alkaloid, as the ex- pense entailed has been very heavy. For the same reason, our account of some of the substances actually described is less complete than we could have wished. We hope in a future paper to supplement the information on some of the more important points which require fuller elucidation. We have to express our best thanks to the Society for the liberal assistance granted to us from the Research Fund, and to Prof. W. H. Perkin, jun., for kindly giving us specimens of the decomposition pro- ducts of berberine for comparison with those of corydaline. UNIVERSITY COLLEGE OF NORTH WALES, BANGOR.

ISSN:0368-1645    

DOI:10.1039/CT9028100145

出版商:RSC    

年代:1902

数据来源: RSC

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THE RELATIONSHIP OF CORYDALINE TO BERBERINE. 157 XV.-TJle Relationship of Corydaline to Berberine. Bei*beridic Acid. By JANES J. DOBBIE, M.A., D.Sc., and ALEXANDER LAUDER, B.Sc. PERKIN (Trans., 1890, 57, 992) has proposed the following alternative formulae for berberine, expressing the opinion that (I) is the more probable of the two : L I. 11. In the preceding paper, we have shown that the constitution of corydaline can be represented by a formula similar to I, and assum- ing the correctness of this formula for corydaline, that the absence of compounds corresponding to berberal, C,,HI7O7N, berberilic acid, C,,H,,O,N, &c., from amongst the decomposition products of cory- daline is explained.* Whilst the absence of certain decomposition products is satisfactorily accounted for, the similarity of the formulae assigned to the two alkaloids suggested the possibility of obtaining from berberine an acid corresponding to corydic acid, and, as a matter of fact, we found no difficulty in preparing the expected acid by a method similar to that used in the preparation of corydic acid. For convenience of reference, we shall provisionally term the substance so obtained berberidic acid.Ten grams of berberine nitrate were suspended in two Iitres of dilute nitric acid (1 in 20) and heated a t the temperature of the water-bath until completely dissolved. When the solution cooled, a small quantity of the new acid was deposited as a yellow, crystalline precipitate. This was filtered off, the solution neutralised with ammonia, concentrated, and precipitated with silver nitrate.The silver precipitate was decom- posed with sulphuretted hydrogen and the acid separated by fractional crystallisation from a more soluble substance not yet examined, which was formed along with it. I n crystallising the acid, a considerable amount of t a r q matter separated out. The acid was finally freed from this and obtained in a pure state by dissolving in sodium hydr- oxide and precipitating with hydrochloric acid. I n later preparations, * For further comparison of berberin with corydaline, see preceding paper,158 DOBBIE AND LAUDER: THE RELATIONSHIP OF the purification was greatly facilitated by fractional precipitation with silver nitrate, the first fraction carrying down most of the tar. The subsequent fractions were light in colour and practically pure.The yield of purified acid amounted to about 20 per cent. of the berberine nitrate used. Berberidic acid crystallises from water in radiating tufts of yellowish-brown, prismatic crystals, which have a pure yellow colour when powdered. It contains no water of crystallisation. When heated in a capillary tabe, it darkens at about 235' and remains without further change, so far as can be seen, until 285', when it melts with decomposition. It was dried at 100' and analysed, with the following results : 0,2637 gave 0,5925 CO, and 0-0866 H,O. C=61*28; H=3.61. 0.3243 ,, 13.0 C.C. nitrogen at 16' and 761.5 mm. N=4.75. 0.2808 ,, 11.0 C.C. ,, 13' ,, 751 mm. N=4.63. Cl,H,,O,N requires C = 61-34 ; H= 3-51 ; N = 4.47 per cent. 0.2831 ,, 0.6344 CO, ,, 0.0917 H,O.C=61*12 j H=3.59. Berberidic acid is insoluble in cold and only sparingly soluble in boiling water. It is very sparingly soluble in boiling alcohol and in- soluble in ether or chloroform. It dissolves easily in sodium hydroxide to a dark blood-red solution, from which it is precipitated by hydro- chloric acid, All its salts, with the exception of the two silver salts, appear to be soluble. The normal silver salt is obtained by precipitating a solution of the acid, which has been neutralised with ammonia, with silver nitrate. A curdy, yellow pre- cipitate is obtained, which darkens on exposure to light. This salt was repeatedly prepared and analysed without exact results being obtained, owing, apparently, to admixture with the acid salt.The acid silver salt is prepared by precipitating an aqueous solution of the acid with silver nitrate. The curdy precipitate so obtained is filtered, washed, and purified by repeated recrystallisation from water. It is finally obtained in stellate clusters of beautiful, yellowish-brown needles. On heating, it decomposes suddenly with evolution of thick, brown vapours. After being dried at loo', it was analysed with the following results : Berberidic acid is dibasic. 0.2470 gave 0.0828 AgCl. Ag = 25 *23. 0,2616 ,, 0.0655 AgCl. Ag = 25.04. C,,H,,O,NAg requires Ag = 25.71 per cent. When berberidic acid is heated with concentrated hydrogen iodide solution, no methyl iodide is evolved, a fact which proves that in the formation of this acid the ring of the berberine molecule containing the methoxyl groups is destroyed.CORYDA1,INE TO BERBER.INE, BERBERIDIC ACID.159 Oxidation of Berberidic Acid with Potassium Permanganata-Five grams of berberidjc acid were boiled with a dilute solution of per- manganate until the permanganate was no longer reduced. The solution was filtered from the manganese oxide, concentrated, and pre- cipi tated with silver nitrate. The silver precipitate was decomposed with sulphuretted hydrogen and the filtrate from the silver sulphide evaporated to dryness. The residue was repeatedly exhausted with hot absolute alcohol, in which a considerable part of it dissolved. The portion of the residue insoluble in hot alcohol dissolved readily in boiling water, from which it separated on cooling in prismatic crystals.The acid so obtained was decolorised by boiling with charcoal and purified by repeated recrystallisation from water. I t melted at 235' or 242', according to the rate of heating. It dissolved with difficulty in cold, but was readily soluble in boiling, water ; it was insolubb in ether or chloroform. Its aqueous solution gave an orange-red colora- tion with ferrous sulphate. The acid agrees in every particular with C0,H /\CO,H \N berberonic acid, co HI ) , which was obtained by Weidel (Ber., 1879, 12, 410) by the direct oxidation of berberine with concentrated nitric acid. The melting point of berberonic acid is variously given a t The normal silver salt, which is almost insoluble in water, was pre- pared by precipitating a solution of the acid, previously neutralised with ammonia, with silver nitrate.After bemg dried at looo, it was analysed with the following result : 238--.242'. 0.2978 gave 0.1798 Ag. Ag=60.38. C,H20,NAg, requires Ag = 60.88 per cent. The presence of hydrastic acid amongst the decomposition products of berberidic acid has not yet been proved. By dissolving berberidic acid in potassium carbonate and oxidising it with potassium perman- ganate a t the ordinary temperature, a small quantity of a substance was obtained as a scum on the surface of the strongly alkaIine solu- tion. From its insolubility in potash, we suspected that this sub- stance might be w-aminoethylpiperonylcarboxylic anhydride, which is insoluble in alkaline solutions. On examination, we found that it agreed in every particular with the anhydride in its neutral reaction, solubility, peculiar mode of crystallisation, and behaviour with mercuric chloride. As the amount of substance obtained was too small to admit of complete purification, the melting point observed was slightly lower than that given by Perkin. Berberidic acid clearly bears the same relation to berberine that;160 FORSTER AND MICKLETHWAIT : STUDIES IN THE corydic acid bears to dehydrocorydaline. Since it contains no methoxyl groups, it follows that the ring of the berberine molecule which yields hemipinic acid is destroyed in its formation. The occurrence of o-aminoethylpiperonylcarboxylic anhydride and berberonic acid amongst its oxidation products proves that it contains the three remaining rings and that its constitution may therefore be expressed by the formula : UO,H By oxidising berberidic acid with potassium permanganate at the ordiiiary temperature, a yellow derivative is obtained like that obtained from corydic acid by similar treatment.As berberine, unlike corydaline, can be obtained at comparatively low cost, we have undertaken a more thorough investigation of ber- beridic acid, which we hope will throw further light on the constitu- tion of both alkaloids, and especially on the relation between the constitution and colour of some of their derivatives. UNIVERSITY COLLEGE OF NORI-H WALES, BANGOR.

ISSN:0368-1645    

DOI:10.1039/CT9028100157

出版商:RSC    

年代:1902

数据来源: RSC

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160 FORSTER AND MICKLETHWAIT : STUDIES IN THE XV1.-Studies an the Camphane Series. Part VI. Stereoisomeric Halogen- Derivatives of a-Benxoyl- camphor. By MARTIN ONSLOW FORSTER and F~ANCES M. CC. MICKLETHWAIT. IN accordance with its unsaturated character, 1-hydroxy-2-benzoyl- camphene, the enolic form of a-benzoylcamphor, immediately decolorises a solution of bromine in an indifferent solvent. At the same time hydrogen bromide is eliminated, and if om molecular proportion of the halogen is employed, the crystalline residue obtained on evaporating the liquid has the empirical formula of benaoylbromocamphor. There is no difficulty, however, in resolving this product into two distinct substances which, although isomeric and nearly alike in chemical behaviour, are widely different in physical properties.The more soluble constituent of the mixture crgstallises from alcohol in six- sided prisms, melts at 114O, has [a],, -lO*Oo in benzene, and [a],CAMPHANE SERIES. PART VI. 161 + 10.3' in chloroform; the isomeride is deposited from alcohol in rectangular plates, melts at 214', has [.ID - 53.2' in benzene, and [aID - 19*3O in chloroform. The method of preparation, the fact that neither substance dissolves in alkalis, and the transformation of both isomerides into l-hydroxy-2- benzoylcamphene by the action of alcoholic potash, are circumstances which point to the conclusion that the compounds in questionare a-bromo- derivatives of a-benzoylcamphor, and that their physical differences are the result of a difference in configuration.Theoretical considerations, moreover, led us to expect the formation of two derivatives displaying isomerism of the cistrans-type, as indicated by the following formulae (compare Lowry, Trans., 1898, 73, 572) : 3 + It is evident that a similar explanation would account also for the production of two isomerides from enolic benxoylcamphor in the event of that substance being shown to have the alternative formula, namely, C:C(OH)*C6~, that of phenylhydroxymethylenecamphor, C,HI4<bo 7 8 possibility which is not yet excluded. Several instances of this form of isomerism in the camphor series have now been established. Leaving aside the somewhat uncertain cases of the monohalogen derivatives of camphor, there remain the isomeric chlorobromocamphors, chloronitrocamphors, and bromonitro- camphors investigated by Lowry (Trans., 1898, 73, 569 and 986), and the benzylbromocamphors described by Haller and Minguin (Compb.rend., 1901, 133, 79). Up to a certain point, the case of the benzoylbromocamphors resembles those of the four derivatives men- tioned, the difference between the two forms being, however, greater than has been observed hitherto ; but an important feature distinguishes it from those already described. In dealing with the isomeric chlorobromocamphors, Lowry records unsuccessful attempts to convert a'-chloro-a-bromocamphor into a-chloro-a'-bromocamphor by the action of heat and of acids (Trans., 1898, 73, 581). Neither in his subsequent communication nor in the paper of Haller and Minguin (Zoc. cit.) is it stated that the chloronitro- camphor, bromonitrocamphor, or benzylbromocamphor of lower melting point can be transformed into the corresponding isomeride, and it is VOL.LXXXI. &I162 FORSTER AND MICKLETEWAIT: STUDIES IN THE probable therefore that the change cannot be effected or it would have been observed. It is in this respect that the benzoylbromo- camphors differ from the foregoing disubstituted a-derivatives, for the compound having the lower melting point is readily converted into the isomeride by the action of hydrogen bromide. This transformation is the fmst recorded instance of stereoisomeric change on the part of a disubstituted derivative of camphor in which both substituents occupy the a-position. It has therefore a direct bearing on the explanation given by Marsh in accounting for the unstable character of a specimen of bromqcamphor which is described as melting at 61' (Trans., 1890, 57, 832 ; compare also Lowry, Trans., 1898, '73, 572).The validity of the explanation in question depends on the formation of an intermediate isomeride, which represents the enoIic modification of the material transformed, and, in the case discussed by Marsh, would have the formula The experiments described in this paper have led us to consider this explanation improbable. I n the fist place, it cannot be applied to derivatives of camphor of the class to which benzoylbromocamphor belongs, and secondly, there seems to be no need for my explanation so complex, several cases of stereochemical transformation being known in which there is no room for any structural change to occur.In general features, the benzoylchlorocamphors resemble the corresponding bromoderivatives very closely, the two modifications which melt at 88' and 2 1 9 O displaying similarity as regards solubility and crystalline form when compared respectively with the bromo- derivatives melting at 114O and 2149 It is noteworthy, however, that we have been hitherto unable to convert one isomeride into the other. Moreover, the action of sodium hypochlorite on enolic benzpylcamphor gives rise to a preponderating quantity of the benzoglchlorocamphor of the lower melting point, whilst the benzoylbromocamphor of the higher melting point is the almost exclusive product when potassium hypobromite is employed ; bromine dissolved in chloroform yields a mixture of the isomerides in nearly equal parts, whilst bromine and glacial acetic acid containing sodium acetate afford chiefly the benzoyl- bromocamphor of lower melting point. In describing the stereoisomeric halogen derivatives of a-benzoyl- camphor, we have adopted the convention suggested by Lowry (Zoc.cit.), so that the nomenclature of the new derivatives may be uniform with that of the unsymmetrical di-derivatives already prepared. Assuming that benzoylcamphor, with [ aID + 13'7-5O in alcohol, is an a-derivative, it will be noticed that the optical influence of the benzoyl radicle exceeds that of the chlorine atom, since a-chlorocamphor has [aID + 9 6 O in the same solvent; it may be concluded therefore that tho di-CAMPHANE SERIES.PART VI. 163 derivative which has a specific rotatory power least removed from that of camphor itself, is that which contains the benzoyl radicle in the a-position. This modification is the one which melts at 219’, having [a], + 26*2O in chloroform, and is accordingly termed a-benzoyl-a’- chlorocamphor. In the case of the bromo-derivatives, it is not so easy to decide which isomeride contains the benzoyl radicle in the a-position, because the recorded values for the specific rotatory power of benzoyl- camphor and of bromocamphor in alcohol are practically identical. There is reason to believe, however, that the specific rotatory power of benzoylcamphor a t the moment of dissolution in alcohol is lower than ID + 1 3 7 5 O , because the substance, dissolving somewhat slowly in the cold solvent, suffers partial conversion into the enolic modifi- cation, with [a], + 2 6 2 O , before it can be examined in the polarimeter ; chloroform, however, which dissolves the substance very readily, yields a solution having [ + 125O, and it is therefore probable that the optical influence of the benzoyl radicle is less powerful than that of the bromine atom, because a-bromocamphor has [.ID + 135O.I f this is the case, the modification which melts at 114O and has [aID + 1 0 ~ 3 ~ in chloroform must be called a’-benzoyl-a-bromocamphor, whilst the isomeride melting at 214O, having a specific rotatory power more remote from that OF camphor, must be regarded as having the bromine atom in the a’-position ; m. p. Camphor ........................+ 42’ ( alcohol ) - a-Chlorocampbor ............... + 96 ( ,, ) - a-Bromocamphor ............... + 135 ( ,, ) - a-Benzoylcamphor ............ + 125 (chloroform) - a‘-Benzoyl-a-chlorocamphor ... - 28 ( ,, ) 8 8 O a-Benzoyl-a’-chlorocamphor ... + 26 ( ,, ) 219 a‘-Benzoyl-a-bromocamphor ... + 10 ( ,, ) 114 a-Benzoyl-a’-bromocamphor ... - 19 ( ,, ) 214 From this table, it will be noticed that the benzoylchlorocamphor and benzoylbromocamphor supposed to contain the halogen in the a-position both melt a t the lower temperature, whilst the less readily fusible modifications are assumed to have the halogen substituted in the a’-position. EXPERIXENTAL. aa-BenxoyZ6romocamphors, C,H,,< CBr*CO*C6H, I co Twenty grams of 1 -hydroxy-2-benzoylcamphene were dissolved in chloroform and cooled in melting ice.A cold solution of 12.4 grams of bromine in chloroform was then added in small quantities at a time, &r 2164 FORSTER AND MICKLETHWAIT: STUDIES IN THE and the pale red liquid, from which hydrogen bromide was being evolved, transferred to basin and allowed to evaporate spontaneously. A previous experiment having shown that two compounds are produced by this means, the crystalline residue was divided into four fractions by extracting it successively with quantities of hot alcohol amounting to 100 C.C. (twice), 200 c.c., and 300 c.c., and allowing the solutions to cool. Fraction I, weighing 6 grams, consisted of thin, transparent needles melting somewhat indefinitely at 108-110'; a 2 per cent. solution in benzene gave [ a ] D - 15.4'; and in chloroform [aID 3.7.9'.A large proportion being readily soluble in warm, light petroleum (b. p. 50-goo), the whole fraction was extracted with this solvent ; the solution de- posited large, thin, six-sided prisms melting at 114' and giving [ a ] D - 10*Oo in benzene and [ a ] , + 10.3' in chloroform. Recrystallisation from light petroleum did not change the specific rotatory power. Fraction 11, weighing 8 grams, consisted chiefly of needles, and melted somewhat indefinitely at 109-11 1' ; a 2 per cent. solution in benzene gave [ a ] , - 19-5', and in chloroform [ a]D + 2.9'. Fraction 111, weighing 2 grams, consisted of thin, rectangular plates, beginning to shrink and to change colour a t about 185' and melting a t 210' ; a 2 per cent. solution in benzene gave [ a ] D - 52*3', and in chloroform [ aID - 18.5'.Fraction IV, weighing 3 grams, consisted of thin, rectangular plates, beginning to shrink and to change colour a t about 190°, and melting a t 214' ; a 2 per cent. solution in benzene gave [a], - 53-52', and in chloro- form [ a ] D - 19.3'. The properties of this fraction were not altered by recrystallisation from boiling alcohol. d-Benxoyl-a-brmocamphor is most conveniently prepared by dissolving 1 -hydroxy-2-benzoylcamphene in glacial acetic acid containing 14 mols. of sodium acetate and adding 1 mol. of bromine dissolved in glacial acetic acid; the white precipitate obtained on pouring this liquid into water is then collected, washed, dried, and crystallised from light petroleum. It is readily soluble in chloroform, benzene, alcohol, or light petroleum, crystallising from the last-named in large, transparent, six-sided prisms, and from alcohol in slender needles having the same crystalline form : 0.1992 gave 0*1101 AgBr.Br= 23.52. C17Hl,0,Br requires Br = 23.88 per cent. The subdjance melts at 114', but fusion is not complete until the temperature is raised to about 180'. A solution containing 0.5 gram in 25 C.C. of benzene a t 21' gave aD -24' in a 2 dcm. tube, whence the specific rotatory power [ a ] D - 10.0' ; 0.5029 dissolved in 25 C.C. of chloroform at 21' gave aD + 25', corresponding to [aID + 10.3'.CAMPHANE SERIES. PART VI. 165 a-Benzoyl-a'-bromocamphor was obtained in the following manner. One hundred grams of bromine were dissolved in an ice-cold aqueous solution containing 150 grams of potassium hydroxide, and slowly added to 20 grams of 1-hydroxy-2-benzoylcamphene dissolved in dilute potash.The sticky solid which immediately separated soon hardened, and after an interval of 12 hours was collected, washed, and recrystal- lised from boiling alcohol. The yield of aa-benzoyl bromocamphor obtained by this method is quantitative, and the product consists chiefly of the variety of high melting point. It dissolves very readily in chloroform, but only sparingly in cold alcohol or benzene, and is almost insoluble in boiling light petroleum ; it crystallises from hot alcohol in transparent, rectangular plates, begins to shrink and to change colour at about 190°, and melts at 214' t o a pale brown liquid which evolves gas. The substance may be crystallised from concentrated nitric acid without undergoing change : 0.1353 gave 0.0756 AgBr.Br = 23.77. CI7H,,O,Br requires Br = 23.88 per cent. A solution containing 0-5015 gram in 25 C.C. of benzene at 21° gave aD - 2'8' in a 2 dcm. tube, whence the specific rotatory power [a], - 53.2'; 0.6451 gram dissolved in 25 C.C. of chloroform at 21' gave U, - loo', corresponding to [a],, - 19-3O. Action of Alcoholic Potassium H3droxide on aa-Bennoyl6romocamp~~. -A specimen of a-benzoyl-a'-bromocamphor which melted at 210' and gave [.ID - 18.5' in chloroform, was heated during 4 hours in a reflux apparatus with potassium hydroxide (2 mols.) dissolved in alcohol. The liquid soon became dark brown, and on evaporation yielded a residue which dissolved completely in water.A current of well washed carbon dioxide was then passed into the aqueous solution until no further pre- cipitation occurred, and the product, after crystallisation from alcohol, was obtained in the pink octahedra characteristic of 1-hydroxy-Bbenzoyl- camphene. The same compound was obtained by reducing a'-benzoyl-a-bromo- camphor with alcoholic potassium hydroxide. Action of Bromine on 1-Benxox~-2-benxoylcampherne.-When a solution of 1-benzoxy-2-benzoylcamphene in chloroform is treated with bromine, the colour of the halogen is not immediately destroyed, but after an interval, action is found to have taken place. Ten grams of the dibenzoyl derivative were dissolved in 100 C.C. of chloroform and enclosed in a stoppered bottle with 4.4 grams (1 mol.) of bromine, After 24 hours, the colour of the halogen had almost disappeared.On allowing the liquid to evaporate, a considerable quantity of hydrogen bromide was liberated, and a crystalline residue was obtained having the odour of ethyl benzoate. The solid product,166 FORSTER AND MICKLETHWAIT: STUDIES IN THE weighing 9 grams, was exhausted with 50 C.C. of hot alcohol, and the solution deposited crystals melting a t 110-1 15' and giving [a], + 4.1' in chloroform : 0.1598 gave 0.0884 AgBr. Br = 23.54. C17Hl,0,Br requires Br = 23-88 per cent, The substance was evidently a mixture of the two aa-benzoylbromo- camphors, and by repeated cry stallisation from alcohol, a specimen of the modification of higher melting point was obtained, giving [a]D - 19.5O in chloroform. Conversion of One Isomride into the .Other.-During the first at- tempt to separate the isomerides from one another by fractional crys- tallisation, a most unexpected change of the variety of lower melting point took place. A specimen of t h a t substance, which had been re- crystallised twice from alcohol without altering the melting point, melted a t 11 1-1 12' and gave [ a ] D - 29.0' in benzene ; it was dissolved in hot alcohol, which on cooling deposited lustrous plates melting at 201--204O, and giving [a], - 51.0' in benzene. Although we have not succeeded in reproducing the conditions of this experiment, the transformation of one modification into the other can be effected by the agency of hydrogen bromide. A specimen of a'-benzoyl-a-bromocam- phor melting at 109-1 1 1' and giving [ aID + 2.9" in chloroform was finely powdered and placed in a stoppered bottle with sufficient fuming hydrobromic acid to convert it into a thin paste.The following morn- ing, water was added and the solid product filtered and washed. The substance, when dried in the desiccator, melted at about 200' and gave [.ID - 18.6' in chloroform, and when recrystallised from alcohol yielded the lustrous plates characteristic of a-benzoyl-a'-bromocamphor. Action of Bromine on a-Benxoylcamphw. In describing the a-substituted halogen di-derivatives of camphor, Lowry (Trans., 1898,73, 572) suggests that '' the production of stereo- isomeric di-derivatives is most readily explained by supposing that the action of the halogen involves addition to the enolic form of the mono- derivative." This explanation is a very probable one, and the follow- ing experiment appears to give it direct support, A specimen of ketonic a-benzoylcamphor, giving only a faint colora- tion with ferric chloride, was dissolved in cold glacial acetic acid containing sodium acetate (18 mols.) ; to this liquid, a solution of bromine (1 mol.) in glacial acetic acid was added, when it was observed that the colour of the halogen was immediately destroyed.Although it must be remembered that a small proportion of the benzoylcamphor is enolised by the solvent, it is still fair to say that the behaviour of a-benzoylcamphor towards bromine exactly resembles that of theCAMPHANE SERIES. PART VI. 167 unsaturated enolic isomeride, and it is noteworthy that the identity extends to the product of the change, which gives rise to $-benzoyl-a- bromocamphor in both cases.Having found that potassium hypobromite converts 1-hy droxy-2- benzoylcamphene into a mixture of the benzoylbromocamphors, we employed the corresponding method in preparing the benzoylchloro- camphors in preference to treating the hydroxy-compound with the free halogen. Ten grams were dissolved in dilute aqueous potassium hydroxide, cooled with fragments of ice, and treated with 200 C.C. of a solution of sodium hypochlorite containing 30 grams of available chlorine per litre. A pink, dough-like solid separated and rapidly became hard. After an interval of several hours, the product was collected, washed, and extracted with 100 C.C. of boiling alcohol, thus dividing the substance into two portions, of which the more readily soluble melted somewhat indefinitely a t 85-87' and gave [.ID - 20.6' in chloroform, whilst the residual fraction melted at 219' and gave at-BenxoyEa-chZorocamphw, obtained by recrystallising the more soluble fraction from alcohol and then from light petroleum, crystal- lises from each solvent in prisms and melts at 88': C1= 12-08, C17H,,0,Cl requires C1= 12.22 per cent. [ u ] D + 26.0'. 0-1284 gave 0.062'7 AgC1. It is readily soluble in alcohol and very freely so in chloroform, but dissolves only sparingly in light petroleum. A solution containing 0.4185 gram in 25 C.C. of chloroform a t 21' gave uD -56' in a 2 dcm. tube, whence the specific rotatory power [ aID - 27.9'. a-Bsn~yGa'-chlorochor remains after the mixture of the two isomerides has been exhausted with a small quantity of hot alcohol ; it crystallises from that solvent in plates resembling the corresponding bromo-derivative and melts at 219': C1= 12.29. C17H1902Cl requires Cl = 12.22 per cent. 0*1324 gave 0.0658 AgC1. It is freely soluble in chloroform, but dissolves only sparingly in alcohol and is insoluble in light petroleum, A solution containing 0.3973 gram in 25 C.C. of chloroform at 21' gave aD +50' in a 2 dcm. tube, whence the specific rotatory power [aID + 26.29 ROYAL COLLEGE OF SCIENCE, LONDON. SOUTH KENSINGTON, S. W.

ISSN:0368-1645    

DOI:10.1039/CT9028100160

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年代:1902

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168 DIXON: THE ACTION OF PHOSPHORUS XVI I --The Action of Phosphoms Tyitlziocyanate on Alcohol. By AUGUSTUS EDWARD DIXON, M.D. IN a preliminary note (J. p. Chem., 1872, [ii], 7, 474), Lossner records that he has obtained (1) by the action of phosphorus tri- chloride on potassium thiocyanate in alcoholic solution, a substance crys- tallking in fine needles, whose analysis leads to the empirical formula CsHl,0N4S, ; and (2) from benzoyl chloride and alcoholic potassium thiocyanate, a compound, C,H90NS. No analytical results are given in this note, which is very brief; but the interaction in which benzoyl chloride takes part is dealt with by Lossner a t considerable length in a paper published a couple of years later (i6id., 1874, [ii], 10, 237) ; the compound C8H,0NS now appears as CloH,,02NS, that is, benzoyl thiocyanate plus a mol.of ethyl alcohol, and is regarded by him as ‘ benzoylethyloxysulphocarbamic acid,’ PhCO*NEt*CO*SH; a paper dealing with the constitution of this substance and of certain of its derivatives has lately been published (Dixon, Trans,, 1899, 75, No reference is made in Lassner’s second communication to the compound CSH,,ON4S, ; nor, in fact, so far as the author can ascertain, is any description of it to be found in chemical literature. It is not easy to understand how a substance of this composition could be formed out of the materials used, unless through the occurrence of some profound decomposition ; with the view of ascertaining whether such a change really took place, and more particularly since the interaction to be ex- pected of these substances appeared to belong to the class of interactions recently studied by the writer, in which phosphorus and phosphoryl thiocyanates’ take part (Trans., 1901, 70, 541), i t was decided to re- examine Lijssner’s reaction.Before doing so, and incidentally to the incipient study just mentioned, some experiments were carried out in order to learn whether “ phosphorus thiocyanate,” P(SCN), or P(NCS),, would unite directly with ethyl alcohol so as to afford a phosphoretted thio- urethane, thus : 375). P(NCS), + 3~,H5*OH = P(NH*CS*OC,HJ, ; although, in view of the great ease with which both this and the corresponding phosphoryl derivative undergo hydrolysis, it scarcely seemed probable. The phosphorus compound was prepared as already described (Zoc.cit., p. 545)’ about 13 grams of phosphdrus trichloride being used in each preparation : on treating the benzene solution with absoluteTRITHIOCYANATE ON ALCOHOL, 169 alcohol, there was marked evidence of chemical interaction, the temperature rising in three successive experiments in which it was measured, by 47", 46', and 59' respectively, whilst free thiocyanic acid was evolved. On concentrating the mixture at the ordinary temperature, a yellow, crystalline solid was deposited ; the mother liquor formed a clear brown syrup, intensely acid, reacting freely for thiocyanic acid and phosphorus, and soon beginning to decompose with evolution of mercaptan. The solid product occurred in limited quantity, not more than a gram, at most, being obtained for every 13 grams of trichloride used ; it was insoluble in benzene, sparingly soluble in boiling water, and moderately so in hot alcohol, but did not crystallise well from the latter solvent.When recrystallised from much boiling water, it was obtained in yellow, flexible, hair-like needles (on one occasion several inches long and closely resembling Spirogyrci in outward appearance) : they began to darken and change at about 2304 but were not melted at 2509 The substance contains no phosphorus, and hence is not the desired phosphorus trithiotriurethane. I t is desulphurised by heating in alcoholic solution with ammoniacal silver nitrate, or with alkaline lead tartrate; its aqueous solution is somewhat acid to litmus and gives with lead acetate a bright yellow precipitate.Ferric chloride yields practically no colour reaction, either when added to the aqueous Rolution or to the mixture produccd by first dissolving the solid in warm alkali hydroxide and then acidifying the solution with hydro- chloric acid. The substance dissolves readily in potassium cyanide solution, and the resultant liquid, if acidified and treated with ferric chloride, now gives the intense blood-red thiocyanic reaction. From the properties just described, there could be little doubt that the substance was nothing more than isopersulphocyanic acid, C,H,N,S,, and the results of analysis showed this to be the case : S found, 64.3; N found, 18.9; C,H,N,S, requires S == 64 ; N = 18-7 per cent. The mechanism whereby this substance comes to be formed is probably as follows : the '' phosphorus thiocganate " is decomposed in part by the alcohol, yielding free thiocyanic acid : P(SCN), + 3C2H,*0H = P(O*C,H,), + 3HSCN ; whilst another portion, in like manner, yields phosphorous acid : under the influence of this mineral acid, the former could afford &?opersulphocyanic acid, thus : 3HSCN = C,H2N2S3 + HCN.Save the isopersulphocyanic acid, no other solid product was found ;170 ACTION OF PHOSPHORUS TRITHIOCYANATE ON ALCOHOL. consequently, if the phosphorus trithiotriuretbane is formed, or, at all events, continues t o exist, under the above conditions, it must be as one of the constituents of the acid, syrupy mother liquor, but the foul smell of the latter rendered it so unpleasant to work with that it was not examined further, However, as phosphorus trithiotriurethane, if capable of existence under ordinary circumstances, would probably be a solid substance more or less easily decomposable by moisture, it is doubtful whether it could have been extracted from the liquor, even if present.As regards the interaction between alcoholic potassium thiocyanate and phosphorus trichloride, there was scarcely any reason to anticipate that it would run a course materially different from that between phos- phorus trithiocynnate and alcohol ; however, the experiment was tried, with the following result. On dropping phosphorus trichloride into a saturated solution of potassium thiocyanate in 99.5 per cent. alcohol, violent action occurred, and potassium chloride was precipitated ; on filtering this off and concen- trating the filtrate by slow evaporation, thiocyanic acid escaped, and yellow, crystalline material separated in an oily, very acid, liquid ; the former, when recrystallised from boiling water, proved to be identical with the solid obtained from phosphorus thiocyanate and alcohol, namely, isopersulphocyanic acid. I n this case, as the liberated thio- cyanic acid is in contact with much free hydrochloric acid proceeding from the interaction between the phosphorus haloid and the alcohol, it is a simple matter to account for the production of isopersulphocyanic acid.As in the preceding case, the quantity of this acid bears but a small proportion to the amount of phosphorus chloride used. So far, the miter has failed to identify any other substance in the solid pro- duct, yet Lossner, strange to say, does not mention the occurrence of isopersulphocyanic acid at all.It would seem, therefore, either that the interaction must have pro- ceeded on different lines when conducted by this chemist, or else that, through some accident, he must have attributed to isopersulphocyanic acid, C,H,N,S,, the formula C,H,,ON,S,. How this could happen it is not very easy to see, considering that the percentages of sulphur are 64 and 40.8, respectively. It is conceivable, however, that some un- suspected cause of error may have temporarily crept into his analytical practice, more especially bearing in mind that his benzoyl chloride product, above mentioned, which was stated in the preliminary note t o have, according to the results of analysis, the formula, C,H,ONS, turns out to be really CloH,,O2NS; here the theoretical results are by no means so widely divergent as in the preceding case, but still the figures differ by nearly 4 per cent.for the sulphur, 3 per cent. for the nitrogen, and so on.CONSTITUTION OF BENZENEAZO-a-NAPHTHOL. 171 In the hope of possibly obtaining phosphorus tribenzyltrithiocarb- amate, a cold, somewhat dilute solution of phosphorus thiocyanate ” in benzene was treated with benzyl alcohol. Interaction occurred at once, the temperature of the mixture rising by about 30’; but after driving off the solvent and allowing the residue t o stand, a mere trace of white, solid matter was deposited, the amount being too small to per- mit of identification. It crystallised well in white prisms from boiling water, volatilised completely, on heating, without preliminary fusion, gave no ammonia when heated with alkali, contained no phoephoras, gave no colour reaction with potassium cyanide, hydrochloric acid, and ferric chloride, and consequently was neither isopersulphocyanic acid nor phosphorus tribenzyltrithiocarbamate. The mother liquor was almost completely volatile in a current of steam; the distillate, a yellowish oil, consisted partly of unchanged benzyl alcohol, and partly of an unpleasant smelling oil which contained sulphur but no phos- phorus, the latter being wholly retained in the trifling residue of the steam distillation. CHEMICAL DEPARTMENT, QUEEN’S COLLEGE, CORK.

ISSN:0368-1645    

DOI:10.1039/CT9028100168

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年代:1902

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CONSTITUTION OF BENZENEAZO-a-NAPHTHOL. 171 XVIII.-The Relatio?zship between the Orientation of Sub- stituents in und the Constitution of Benxeneaxo-a- naphthol. JOHN THEODORE HEWITT and SAMUEL JAMES MANSON AULD. THE question of the constitution of the oxyazo-compounds has areused a considerable amount of discussion, and in order to obtain further information on this point, one of the authors of the present commun- ication has, in conjunction with several of his pupils, made experi- ments on the substitution derivatives of these substances. In all cases 60 far studied, the results have given an unqualified support t o the oxyazo-formula, the phenolic nucleus always being first attacked by dilute nitric acid or bromine i n presence of an excess of sodium acetate. The appearance of a communication by Mohlau and Kegel (Ber., 1900,33, 2858), in which they ascribed a tautomeric formula to benzeneazo-a-naphthol, rendered necessary the further investigation of the action of substituting agents on the benzsneazonaphthols. The results obtained in the case of the azo-derivatives of P-naphthol are reserved for a future communication.Mohlau and Kegel found that pquinones and their derivatives172 HEWlTT generally reacted with diaminobenzhydrol) to C,H,*N(CH,),I : AND AULD: CONSTITUTION OF benzhydrol and Michler’s hydrol (tetramethyl- form compounds of the type [R=C,H, or 0 and extending the reaction to the so-called benzeneazo-a-naphthol obtained substances in which the hydrol had behaved as if the azo-com- pound were quinonoid in type.Had a strong acid been present, such a reaction would not have been surprising ; the condensation was, how- ever, carried out in the absence of such a compound. Moreover, the complicated azo-derivatives so obtained behaved, on acetylation, as quinone-hydrazones, the acetyl group attaching itself to a nitrogen atom. By the complete reduction of the acetyl derivative of benzene- azotetramethyldiaminobenzhydryl-a-naphthol, Mahlau and Kegel ob- tained acetanilide but could detect no aniline ; from these results, they concluded that benzeneazo-a-naphthol, as well as the condensation product with Michler’s hydrol, had the constitution of quinone- hydrazones. The condensation was, however, not incompatible with the presence of both forms in equilibrium in solution, whilst the course of the acetylation OF the condensation product might be explained in a similar way in conjunction with the undoubted steric hindrance which might be experienced in the case of acetylating an ortho-substituted a-naphthol.We therefore resolved to re-examine the acetylation of benzeneazo-a-naphthol, and further to study the action of substituting agents on the azo-naphthol itself. It may be mentioned here that the results of all experiments made with nitric acid on benzeneazo-a- naphthol were thoroughly unsatisfactory ; either reaction did not take place or only tarry products were obtained. Reduction of Benxeneazo-a-naphthyl Acetate. Benzeneazo-a-naphthol was prepared by Witt and Dedichen’s method (Ber., 1897, 30, 2657), and acetylated by boiling in a reflux apparatus with excess of acetic anhydride and fused sodium acetate.The melt- ing point of the product (128’) agreed with that given by Zincke and Bindewald (Ber., 1884, 17, 3030). The complete reduction of this sub- stance was effected in cold alcoholic solution, so that any possibility of one or other product becoming acetylated during the process and thus leading to erroneous conclusions might be obviated. Two grams o€ the acetyl derivative were dissolved in 100 C.C. of absolute alcohol and treated with 5 C.C. of concentrated sulphuric acid mixed with 10 C.C. of alcohol. Zinc dust was now added and the solution wellBENZENEAZO-a-N APHTH OL. 173 shaken until entirely colourless. The excess of zinc dust was re- moved by filtration and the filtrate diluted with water, rendered alka- line with sodium carbonate, and then twice extracted with ether.The ethereal extracts were united, the excess of ether evaporated, and the residue distilled in a current of steam. The presence of aniline in the distillate was confirmed by its conversion into tribromoaniline. I n one experiment, the weight of tribromoaniline obtained was prac- tically equal t o that of the benzeneazonaphthyl acetate employed. After the steam distillation, the residue in the flask was examined in order to isolate the other product of fission ; the acetoxy-a-naphthylamine could not, however, be obtained in a crystalline form. By partial reduction of benzeneazo-a-naphthyl acetate, a hydrazo- compound is obtained, which, from its insolubility in dilute alkali, evidently does not contain a free hydroxyl group.To obtain this substance, 1 gram of benzeneazo-a-naph thy1 acetate was dissolved in alcohol, a small quantity of acetic acid added, and the solution shaken with zinc dust until colourless. The filtered solution deposited crystals on standing, which were collected, washed, and dried. The substance so obtained, although a t first colourless, turned faintly yellow on dry- ing; the melting point (160-165') was far from sharp and the sub stance reddened considerably on heating. 0.1685 gave 0.4580 CO, and 0.0866 H,O. 0.1445 ,, 11.9 C.C. nitrogen" at 15O and 754 mm. N == 9.51. These results absolutely confirm the constitution usually assigned to benzeneazo-a-naphthyl acetate, namely, that it is an oxygen ester.The possibility of the existence of an isomeric derivative was also examined. Benzeneazo-a-naphthol, on treatment with mineral acids, readily furnishes salts of a-naphthaquinone phenylhydrazone. Two grams of benzeneazo-a-naphthol were added to glacial acetic acid which had been saturated with hydrogen chloride and warmed in a flask provided with a reflux tube down which 8 grams of acetyl chloride were added in small quantities a t a time. After half-an-hour's heat- ing a t looo, the product was poured into water, the precipitate collected, and recrystallised from glacial acetic acid. The acetyl derivative so obtained melted at 127' and when mixed with the acetyl derivative prepared by acetylation with acetic anhydride and fused sodium acetate did not depress its melting point.Hence salts of a-naphtha- quinone phenylhydrazone furnished derivatives of benzeneazo-a- naphthol on acetylation. C = 74.13 ; H = 5-69, C,,H,60,N, requires C = 73.97 j H = 5-48 ; N = 9.52 per cent. * Measured over 50 per cent. potassium hydroxide solution.174 HEWITT AND AULD: CONSTITUTION OF Action of Bromine on Benxeneaxo-a-naphthol. In acting with bromine on an oxyazo-compound, a solution or sus- pension of the latter in acetic acid is best employed, and it is very necessary to take especial care that hydrogen bromide is removed as quickly as it is formed. I f this be not done, the hydrogen bromide converts oxyazo-compounds into salts of quinone-hydrazones and sub- stitution takes place in the nucleus free from oxygen (Hewitt and Aston, Trans., 1900, "7, 712, 810).The bromination of benzeneazo- a-naphthol has already been effected by Margary (Gazzetta, 1884, 14, 271), who took no precautions to avoid presence of a mineral acid. The substance so prepared he regarded as pbromobenzeneazo-a- naphthol, stating that he obtained p-bromoaniline on reduction. Such a result would not have been surprising were it not that the product is described as occurring in two forms melting at 185' and 197" respectively, whereas the substance obtained synthetically by Bamber- ger melted at 237-238O (Bey., 1895, 28, 1896). Bromination, if carried out in the following manner, furnishes a product, melting a t 196O which contains no bromine in the benzene nucleus. Benzeneazo-a-naphtho1, together with its own weight of fused sodium acetate, is dissolved in 10 times its weight of glacial acetic acid.The calculated quantity of bromine, diluted with t k c e its weight of acetic acid, is then added and the mixture allowed to stand at the ordinary temperature in a closed flask until the odour of the bromine has disappeared ; this frequently requires a meek. The solid matter is then filtered off, washed with water, and recrystallised from boiling glacial acetic acid, in which the substance is fairly soluble, although the cold solvent dissolves it but sparingly. Analysis showed that a monobrorno-derivative had been produced : 0-2040 gave 0.1132 AgBr. Br = 23-97. 0-2460 ,, 0.1404 AgBr. Br = 24.22. 0-2239 ,, 17-0 C.C. nitrogen at 20° and 737 mm. N = 8.61, C1,Hl,ON,Br requires Br = 24-42 ; N = 8.58 per cent.The substance dissolves very easily in acetone, it is also dissolved by alcohol, ether, carbon disulphide, or ethyl acetate, benzene dis- solves it only sparingly, whilst in light petroleum it is almost insoluble. The solution in strong sulphuric acid has a much bluer shade than that of the parent substance. The reduction was effected by solution in alcohol and boiling with an excess of tin and hydrochloric acid in a reflux apparatus for 1 hour. After cooling, sodium hydroxide was added in excess and the mixture distilled in a current of steam. The distillate was rendered alkaline with soda, shaken with a small quantity of benzogl chloride, and theBENZENEAZO-CZ-NAPHTHOL, 175 precipitate collected and recrystallised from benzene. Colourless plates separated, which proved to be free from halogen and melted at 158' (uncorr.).The substance was therefore benzanilide. It follows that when benzeneazo-a-naphthol is brominated in presence of sodium acetate, one atom of bromine enters the naphthol nucleus. The only benzeneazobromo-a-naphthol hitherto described is the 8-bromo-4- benz- eneazo-a-naphthol prepared by Meldola and Streatfeild (Trans., 1893, 63, 1058). It is probably not identical with our compound, although its melting point, 197O, lies very near to that of the substance obtained by direct bromination. To further characterise the latter, a number of derivatives have been prepared and analysed. The ethyl ethr was obtained by dissolving, successively, 0.1 gram of sodium and 1.0 gram of the azo-compound in 6 C.C.of ethyl alcohol and heating with an excess of ethyl bromide for 2 hours at 120-130'. The precipitate obtained on addition of water was recrystallised twice from a mixture of chloroform and alcohol; the product melted at 220° (uncorr .) : 0-1060 gave 0-0540 AgBr. The ethyl ether is a black powder, fairly soluble in acetic acid and somewhat readily so in chloroform. Most of the other usual organic solvents dissolve i t only sparingly in the cold. The acetyt derivative was obtained by boiling in a reflux apparatus for 2 hours a mixture of the azophenol with 14 times its weight of fused sodium acetate and 3 times its weight of acetic anhydride, The substance was isolated in the usual manner and recrystallised from glacial acetic acid; its melting point was found to be 146O (corr.) : Br = 22-51.C18Hl,0N,Br requires Br = 22.53 per cent,. 0.1441 gave 8.55 C.C. nitrogen a t 8' and 755 mm. C,,H,,O,N,Br requires N = 7*59 per cent. To compare the product obtained by substituting bromine in benzeneazo-a-naphthol with the three bromobenzeneazo-a-naphthols, the latter were prepared and converted into acetyl derivatives. N = 7-63, The Isorne~ic Brorno6enneneazo-a-nap~t~oZs. o-Bromobenzenenzo-a-naphthoZ.-Pure o-bromoaniline (prepared from o-nitraniline by Sandmeyer's reaction and subsequent reduction of the o-brornonitrobenzene so obtained) was diazotised, the solution of the diazonium salt added to the requisite quantity of a-naphthol dissolved in methylated spirit, and an aqueous solution of sodium acetate stirred into the mixture. The product was collected, washed with dilute alcohol, and recrystallised from glacialacetic acid, in which it is fairly176 CONSTITUTION OF BENZENEAZO-a-NAPHTHOL. soluble on boiling, but only sparingly so when cold.I t melted at 183' (corr.) : 0.2917 gave 21.0 C.C. nitrogen a t 14O and 754 mm. The ucetyl derivative, after recrystallisation from boiling glacial 0.1728 gave 10.3 C.C. nitrogen at 14' and 754 mm. m-Bromo6enxemccxo-a~aphtho1, after recrystallisation from benzene, 0-2298 gave 16.8 C.C. nitrogen a t 20' and 761 mm. The acetyl derivative was prepared in the usual manner ; it melted 0.1252 gave 9.0 C.C. nitrogen at 23' and 744 mm. p-Bromo6enxeneaxo-a-naphthol has already been described by Bam- berger (Ber., 1895, ZS, 1896). The melting point given by him is 237-238O ; our preparation melted at 226' (uncorr., the corrected melting point mould be about 233').These melting points do not differ materially, but are far removed from those given by Margary, namely, 185O and 197O (Zoc. cit.). 0.0572 gave 0.0328 AgBr. The ucetyl derivative was also prepared in order to characterise the Prepared in the usual manner and recrystallised N = 8-49. C16H,,0N2Br requires N = 8.58 per cent. acetic acid, melted at 123' : N= 7-03, C,sH180,N,Br requires N = 7-59 per cent. melted a t 21 1' (uncorr.) : N = 8-36, C,,H,,0N2Br requires N = 8.58 per cent. a t 112O : N = 7.80, C,,H,,O,N,Br requires N = 7.59 per cent. On analysis : Br = 24.36. C,,H,,ON,Br requires Br = 24-42 per cent. substance further. from glacial acetic acid, it melted at 141O (corr.) : 0.1484 gave 0.3195 CO, and 0.0499 H,O. C=58*72 ; H-3.68. The substance is easily soluble in benzene or chloroform, fairly so in acetone or ethyl acetate, but only sparingly so in alcohol. It is thus conclusively proved that in absence of strong acids, benzene- azo-a-naphthol furnishes a substance which does not contain bromine in the benzene nucleus. The position of the bromine atom in the %-naphthol nucleus has not been determined ; it probably enters position 2. So far, attempts at preparing the substance by the inter- action of phenylhydrazine and Zincke and Schmidt's 2-bromo-1 : 4- naphthaquinone (Ber., 1894, 27, 2757) have been unsuccessful, although from the production of benzeneazo-a-naphthol from a-naphtha- C18H1302N2Br requires C = 58.54 ; H = 3-52 per cent.MAGNETIC ROTATION OF SOME POLYHYDRIC AT~COHOLS. 17’7 quinone and phenylhydrazine observed by Zincke and Bindewald, the carrying out of such a reaction appears easy of accomplishment. Under the circumstances, we are compelled to leave the actual proof t h a t position 2 is occupied by the bromine atom to some future occasion. EAST LONDON TECHNICAL COLLEGE.

ISSN:0368-1645    

DOI:10.1039/CT9028100171

出版商:RSC    

年代:1902

数据来源: RSC

摘要:

MAGNETIC ROTATION OF SOME POLYHYDRIC AT~COHOLS. 17’7 XIX-The Magnetic Rotation of some Polyhydric By W, H. PERKIN, sen., Ph.D., F.R.S. THE remarkable changes in optical activity which many carbohydrates show when in solution in water have engaged the attention of several observers for a long period. To take an example, a freshly prepared solution of glucose has a rotation of [ u ] ~ + 105*16’, but this gradually diminishes and finally becomes constant after about six hours, the rotation being then [ a ] , + 52-49’ (Parcus and Tollens, Annalen, 1890, 257, 160). This phenomenon has been called bi-, multi-, or muta-rotation, and i t has been suggested by Tanret (Compt. rend., 1895, 120, 1060) that the first form of glucose should be called a-glucose and the second P-glucose ; this method of distinguishing the two modifications will be used in the present paper, not only in the case of glucose, but in all cases where birotation has been observed.A re‘surne‘ of the views which have been entertained in reference to birotation is given in a paper by Horace Brown and S, U, Pickering “On the thermal changes attending change of rotatory power of carbohydrates” (Trans., 1897, 71, 769). From this, it is seen that the earlier attempts to explain the phenomenon of bi- or multi-rotation were based on physical considerations. Subsequently, the probable chemical aspect of the matter came to be more fully discussed ; E. Fischer, for example, has suggested that the remarkable birotation shown by glucose may be due t o the gradual assimilation of water and conversion into the heptahydric alcohol, C6HI4O7, This view has latterly found considerable favour, and Brown and Pickering think that the results of the heat determinations made by them are con- sistent with it.As the study OP the magnetic rotations of the sugars might possibly throw some light on this difficult subject, it was thought desirable t o undertake the examination of some of the more important of these substances. Until lately, however, the measurements could not be Alcohols, Hexoses, and Saccharobioses. VOL. LXXXI. N178 PERKIN: THE MAGNETIC ROTATION OF SOME made with any degree of accuracy, because strong solutions of these sugars rotate the plane of polarisation through such large angles that, as is well known, the impurities in the sodium light seriously affect the appearance of the half-shadow disc of the polarimeter, causing the two sides to be very unequally tinted, so that useful numbers oannot be obtained.Thus, a 50 per cent, solution of fructose in a 100 mm. tube has an optical rotation of about 50°, and this is the point at which the magnetic rotation commences, Fortunately, after many attempts, I have succeeded in finding a simple spectroscopic arrange- ment by which this difficulty can be overcome, so that very large angles may now be measured with considerable accuracy, and with this new arrangement I have found it possible to determine accurately the magnetic rotations of a number of carbohydrates. I n a future com- munication, I hope t o give an account of this improvement and also of the new apparatus which I am at present using for the deter- mination of magnetic rotations, Besides the sugars themselves, two of the polyhydrio alcohols have been measured, so that the magnetic rotations of this class of com- pounds from the mono- to the hoxa-hydric are now known, with the exception of that of the pentahydric alcohol, C5H1,05, which, however, can be easily estimated, The examination of this series of alcohols was important in order that a basis might be obtained from which to calculate the probable rotation of the various sugars.The numbers obtained for the magnetic rotation of this group of alcohols may be briefly summarised as follows : Mol. mag. rot. Methyl alcohol,. ............. H,(CH*OH) 1.640 Glycol ........................ H,(CH*OH), 2.943 Glycerol ..................... H,(CH*OH), 4.1 11 Erythritol ..................H,(CH*OH), 5.230 Pentitol (missing) ......... H,(CH*OH), 6.300 est. Mannitol .................... H,(CH*OH), 7.351 If the magnetic rotations of the alcohols actually examined be plotted out, they form a regular curve, from which the rotation of the missing pentahydric compound may be calculated; also if the curve be carried further, the rotations of the heptahydric and other higher alcohols may be estimated, doubtless with considerable accuracy (see diagram), From this curve, it will be at once seen that the successive CH*OH groups have a smaller and smaller value as they are repeated; this, however, is not due to the group CH*OH as a whole, but to the hydroxyl group which it contains, since in the homologous series of paraffins, aliphatic acids, monohydric alcohols, and esters, it has been conclusively proved that the value of each CH,, even in com- pounds containing eighteen carbon atoms, is constant, namely, 1 *023.POLYHYDRIC ALCOHOLS, HEXOSES, AND SACCHAROBIOSES.1'19 Attention has previously been directed to the diminishing influence caused by successive displacements of hydrogen by hydroxyl (Trans., 1884, 45, 559); this diminishing influence is more clearly seen by subtracting from the value of the polyhydric alcohol that of the corre- sponding alcohol containing one hydroxyl less in its molecule. I n these cases, in which the magnetic rotation of the latter has not been 0.6 0.7 0.8 0-9 1 '0 1 '1 1-2 1.3 1.4 The m a p t i c rotations are found by adding the ordinates to the cudon num6ers of the abscGsoe.directly determined, it can be obtained by the addition of the value of CH, to that of the next lower alcohol, thus : Diff. for O H Mol. mag. rot. disp. H. ............ Glycol C?2H,tOH), 2'g43} 0.163 C,H,(OH), 4*111 ] 0.145 Glycerol Ethyl alcohol ... C,H,(OH) 2 9 3 0 ......... Less ......... CH, + C,H,(OH), 3.966 N 2180 PERKIN: THE MAGNETIC ROTATION OF SOME Diff. for OH Mol. mag. rot. disp. H. ......... CH, + C,H5(0H), 5.230 5.134 I O'Og6 7'351 } 0.028 Erythritol . . , . , . C,H,(O-H), Pentitol C5HZ (OH), 6'300} 0.047 Mannitol C,H,(OH), Less ......... Less ......... CH, + C,H6(OH), 6.253 Less ......... CH,+C,H,(OH), 7.323 ......... The influence of the hydroxyl group displacing hydrogen must, there- fore, evidently become practically nil when tbe substitution has been repeated seven or eight times.The results exhibited in the above tables will be found to be very important in the calculation of the probable rotations of glucose, fructose, &c. Glucose is known to be an aldehyde. Now the difference between the molecular magnetic rotations of an aldehyde and an alcohol, for example, between those of heptyl alcohol and heptyl aldehyde, is 0.438, so that the calculated rotation of glucose caii be obtained by subtract- ing this amount from that of mannitol." Mannitol .............................. '7.351 Less .............................. 0,438 Glucose ................................ 6.913 Fructose is known to be a ketone. The difference betweon the magnetic rotation of a ketone and an alcohol, for example, between that of sec.octy1 alcohol and of methyl hexyl ketone, is 0.495; this subtracted from the value for mannitol should give the rotation of fructose.Mannitol .............................. '7-351 Less .............................. 0.495 Fructose.. ............................... 6.856 - The actual determinations of the magnetic rotations of glucose and fructose in aqueous solution have given almost identical numbers in both cases, but the results are considerably lower than those calculated above. Glucose calc .......... 6.913 Fructose calc. ......... 6.855 Found ............ 6.723 Found ............... 6.729 Diff. .............. 0.190 Diff ................... 0-126 - - * The actual comparison should, of course, be between glucose and sorbitol, but the change of m e asymmetric carbon atom in passing from sorbitol to mannit01 would have, if any, so little effect on the magnetic rotation that it may be neglected.POLYHYDRIC ALCOHOLS, HEXOSXS~ AND SACCHAROBIOSES. 18 1 The question then arises : Why are the actual magnetic rotations of these sugars, debermined in solutions which have undergone the usual maximum change in optical rotation, lower than those calculated '2 IS this due to the assimilation of water and the formation of a heptahydric alcohol, C,H,(OH),, or must some other explanation be found '1 From the experimental part of the paper, it is seen that the magnetic rotation of glucose in aqueous solution, obtained by subtracting the value of 11H,O from that of a solution of the composition C,H,,O,,llH,O, is found to be 6.723, and the same number is found in a similar way from solutions of other concentrations.If, however, the glucose had assimilated 1 mol. of water from the solution to form the heptahydric alcohol C,H?(OH),, the rotation of this compound will be obtained by subtracting the value of only 10H,O from the result of the determin- ation, that is to say, it will be 7.723. From the examination of the curve (p. 179), it is clear that the rotation of the alcohol C,H,(OH)V will be 8-380 ; if from this we deduct the value for CH, (1.023), we obtain 7.347 as the value of the alcohol C,H,(OH)7, a number which is very different from that actually found, namely, 7.723. This evidence therefore seems to show that glucose in solution is the anhydrous substance C,HI2O,, and is not combined with water to form the hepta- hydric alcohol C,H,( OH),.Lowry (Trans., 1899, 75, 215), when referring t o the subject of birotation, suggests that the difference between glucose in the anhydrous condition and in solution, after all change has taken place and the optical rotation become constant, may be due simply to isomeric change, the aldehydic form I in the following table passing partly into one of the isomeric modifications I1 or 111, Of these expressions, formula I1 was first proposed by Tollens (Bey., 1883, 16, 923), and afterwards considered by E. Fischer as possibly, although not probably, repre- senting the constitution of anhydrous glucose. YHO $X€*OH $H*OH QH'OH ,+H~OH ?*OH YH*OH O\YH~OH VH*OH $?H*OH $?H*OH QH*OH ?€€*OH CH,*OH CH,*OH CH,*OH I.11. 111. If, however, formula 111 be examined, it will be seen that it re- presents an unsaturated compound, and this, according to the mag- netic rotation, cannot be correct. The introduction of an ethylene linking into the molecule of a saturated substance is known to raise FH-OH YH182 PERKIN: THE MAGNETIC ROTATION OF SOME the magnetic rotation by 1*620*, and the value of glucose (calculated from mannitol) would thus become 6.913 + 1.620 = 8.533, which is far higher than the value actually found (6.723). It has already been pointed out (p. 180) that the value for glucose in solution (6.723) is lower by Oa190 than it should be if the substance were an aldehyde, and the question then arises whether a compound of the formula I1 would have a lower rotation than one having the aldehydic formula I.That this will be the case can be shown from the following comparisons between the values found for glucose in solution, and those of ethylene oxide and the lactones, that is, of substances which are constituted somewhat similarly to formula 11. CH The value of ethylene oxide O<bHf, calculated from that of gly- Y col (2.943) by taking away 0.751 for the loss of the elements of water (see p. 184) is 2.192, the value found was 1.935, making a difference of 0.247 (Trans., 1893, 63, 490). I n the case of the lactones which have been examined, namely, butyrolactone and valerolactone, Butyrolactone. Valerolactone. the following are the differences between values found and calculated in a similar way: for butyrolactone - 0.230, and for valerolactone - 0.195, average, 0.212.Now the constitution represented by formula I1 agrees best with that of the lactones, inasmuch as it contains a chain of four carbon atoms closed by oxygen. If then glucose, when dissolved in water, assumes to a greater or less extent this constitution, there is good reason for believing that its rotation would be lower than that of the aldehydic form, 1, by about 0.2. This, it will be seen, agrees nearly exactly with the number actually found, and there is therefore strong support for the contention that, in solution, glucose has the constitu- tion represented by formula 11, or exists in some form analogous t o this.The solution would probably also contain a small quantity of glucose in its ordinary aldehydic condition ; it is therefore possible that the rotation of the /3-form in the pure state may be a little lower still than that found. The value for ordinary unsaturation with loss of H, is 1.112, but as no hydrogen is lost in this case, the value for unsaturation will be lq112+0*508, the value of H,.POLYHYDRIC ALCOHOLS, HEXOSES, AND SACCHAROBIOSES. 183 If now formula I1 be slightly modified, an expression for the POS- sible condition of fructose insolutionmay, in a similar way, be obtained which will be as follows : $.?H,*OH C*OH / I What has been rJaid about glucose applies equalIy well to fructose; the rotation is in bobh cases the same, and is lower than the calculated value, although not quite to the same extent ; it is therefore probable that fructose exists in solution, not as a ketone, but chiefly in a state represented by the above formula, or by some other formula similar to this, If we now consider the relationship between the calculated mag- netic rotation for glucose in its aldehydic form and that found for galactose in solution, we have the following numbers : GIUCOS~, calc........................... . 6 *9 13 Galactose, found ....................... .6'887 0.026 - I n considering these numbers, it should be noted that in optically active compounds, difference in configuration only does not appear to in- fluence magnetic rotation ; it is therefore probable that the magnetic rotation of galactose as an aldehyde is the same as that of glucose as an aldehyde, If, then, galactose in aqueous solution had been present entirely in its aldehydic form, the number found should have been 6*913, and the slight lowering observed in the value, namely, 0.026, appears to show that, whilst present for the most part in its aldehydic form, galac- tose has to some extent been converted into a modification similar to that represented by formula I1 in the case of glucose in solution.It is, however, remarkable that this small change appears to be accompanied by so large an alteration in the optical rotation, since galactose, which shows a rotation of approximately [a], + 134.5' in freshly prepared solutions, has a value of only [a]D + 84*2O, when the solution has been left to stand until the rotation has become constant, the formation of the small amount of the substance of formula I1 being accompanied by a fall in the optical rotation of no less than 50.3'.Thereis, however, no evidence to show what the optical rotation of substances of the type represented by formula I1 would be in the case of glucose,184 PERKIN: THE MAGNETIC ROTATION OF SOME fructose, or galactose. It is quite possible that such forms of the sugars, although similar in general character, might have very widely different optical rotations, and this is evidently the case, since fructose is lsvorotatory in solution, whilst glucose and galactose are dextro- rotatory in different degrees. Quite possibly a dextrorotatory alde- hydic sugar might yield a laevorotatory substance of the type repre- sented by formula I1 on going into solution, and this might be so in the case of galactose when it is entirely converted into its isomeric form.We have in nitrocamphor a remarkable instance of this kind of change, only of the reverse order; a-nitrocamphor, which is lsvo- rotatory, when changed into the isomeric $-nitrocamphor, becoming enormously dextrorotatory. Again, r-bromonitrocamphor in its normal condition has a rotation of [ a ] , -3S0, but in its pseudo-form has [a*]D + 188' (Lowry, Trans., 1899, '75, 223). The birotation of galactose is also much increased in amount by the addition of lead acetate to its solution, the rotation falling by 53 per cent. (Hanno Svoboda, Zeit. Ver. Rubenxucker.-Ind. Deut. Reichs, 1896, 46, A!t$t. 481, 29 pages; also Abstr., 1896, i, 406) I find also that a cold solution of caustic alkali reduces the rotation very considerably, As sucrose represents glucose and fructose less 1 mol.of water, its magnetic rotation can be easily calculated. The decrease in magnetic rotation caused by the loss of the elements of water when alcohol is converted into ethyl ether, acetic and propionic acids into their anhydrides, &c., averages about 0.752 (Trans., 1886, 40, 787), being in some cases a little less, and in others a little more than this ; therefore when this value is subtracted from those of the two sugars, the difference should approximately give the magnetic rotation of sucrose thus : a-Glucose + a-fructose, calc.. ....... .13*768 less H,O.. ............... .0.752 Sucrose calc............... .13416 found ..................... 12.586 - 0.430 From this it is seen that the experimental number is very much lower than the calculated. If, however, the experimental numbers of glucose and fructose in solution as @modifications be taken instead of those calculated for the magnetic rotation of the anhydrous or a-sugars, the following result is obtained :POLYHYDRIC ALCOHOLS, HEXOSES, AND SACCHAROBIOSES. 185 @Glucose + /I-fructose found ..... .13*452 less H,O ............... 0.752 Sucrose ..................... 12.700 found .................. 12.586 - 0.114 As the difference between the numbers actually found and those calculated in the above way is so small," it would seem that sucrose is apparently built up of the isomeric or /?-forms of glucose and fructose, and not of the aldehydic and ketonic forms. If, then, sucrose is built up of the isomeric forms of glucose and fructose, it will probably have the formula : $?H*OH 'VH CH,*OH CH,*OH and its constitution in the dry state and in solution will most likely be the same, since it does not exhibit the phenomenon of birotation.The above formula for sucrose has already been proposed by E. Fischer (Bey., 1893, 26, 2405); it is a modification of that suggested by Tollens (Ber., 1883,16,923), and clearly shows that when sucrose is hydrolysed it should at first be resolved into the isomeric or /I-modifi- cations of glucose and fructose : THOOH YH,*OH /?El *OH C*OH o<,YH*oH + o( ~ H - O H I FH*OH Q" FH \FH*OH CH,-OH CH,*OH &Glucose. B-Fructose. Naltose and Lactose.These sugars differ i n a marked manner from sucrose in that they possess birotatory and cupric reducing powers ; there can therefore be no doubt that they must have a structure essentially different from that of sucrose. * If, as supposed, the numbers found for these &compounds are a trifle high, on account of the solution containing a little of the a-compounds (see p. 182), this difference would be still smaller.186 PERKIN: THE MAGNETIC ROTATION OF SOME I n order to account for this difference, E. Fischer (Zoc. cit.) suggests TH,*OH YHO QH*OH FH*OH THOOH $?H*OH 0Q:::: $?H*OH CH--O----CH, Galactose radicle. Glucose radicle. I n this, the galactose radicle is represented as in the p- and the glucose radicle in the a-condition, whilst if this formula be applied t o maltose, one glucose radicle will be in the p- and the other in the a-condition.On investigating this matter, i t was a t first thought that the view of the difference in constitution between maltose and lactose on the one hand, and of sucrose on the other, received some immediate confirmation from the results of the magnetic rotations of the former, which are rather higher than the value obtained for sucrose; no doubt this has a bearing on the subject, but it is doubtful whether any great importance can be attached to this difference, From the fact, however, that these carbohydrates contain a glucose instead of a fructose radicle, their magnetic rotations should be about 0.05'7 higher than that of sucrose, the following formula for lactose : QH The rotations are as follows : Maltose, found ..................... ...12a690 Sucrose ,, ........................12.586 Lactose, found ...................... ..12.714 Sucrose ,, ....................... ,12586 L- + 0.104 - + 0.128 I f maltose be first considered, its magnetic rotation, on the assump- tion that its constitution is represented by the above formula, may be calculated thus : p-Glucose, found .......................... .6.723 a-Glucose, calc. ......................... .6*913 Less H,O.. .............................. .04'52 -- 13.636 Calculated mol. mag. rot. of maltose., .12*884 Found ................................... .12*690 Diff.. ................................... 0.1 94POLYHYDRIC ALCOHOLS, HEXOSES, AND SACCHAROBIOSES.187 This difference is almost exactly the same as that observed between a-glucose and P-glucose, 0.190 (p. 180), and points t o the probability that the second or a-glucose radicle in maltose also undergoes con- version, either entirely or in part, into the P-modification when the sugar is dissolved in water, and that the constitution of dissolved maltose is : QH,*OH CH*OH QH*OH /#?H*OH CH O < \ p * O H /CH~OH FH YH*OH '< CH*OH \b€€ 0 CH, The rotation, assuming that in a solution of maltose both glucose radicles are in the P-modification, may be calculated as follows : Mag. rot. of 2 mols. P-glucose ........... ,13.446 Less H,O .............................. 0.752 12.694 Found ................................ ,12*690 Diff. .................................0.004 The magnetic rotation of hcto8e~ as already stated, was found to be 12.714, and if this value be examined, it will be seen it aIso indicates that lactose in solution contains both the galactose and glucose radicles in the P-condition. It has been seen that galactose when in solution is chiefly in the a-condition ; if, however, it were principally in the P-condition,its rotation, no doubt, would be similar to that of @-glucose, so that the rotation of lactose should be the same, or nearly so, as that of maltose, and this is found to be the case, the difference being only + 0.020. In the dry state, it probably has the formula proposed by E. Fischer, and this is, of course, equally true of maltose. Very prob- ably these two carbohydrates, when in solution, always contain a little Qf the glucose radicle in the a- or aldehydic condition.EX PER IME NT AL. Erythritol, C4Hlo0,. The solution examined was supersaturated, containing 32.62 per cent. of erythritol, it being found possible to measure its rotation before crystallisation set in ; the composition of the solution was C4HIoO, + 1 4H20. This substance was purified by recrystallisation from water. Density, d 1So/lS0, 1.1043; d 20"/20°, 1.1033.188 PERKIN: THE MAGNETIC ROTATION OF SOME The average of three sets of determinations of the magnetic rotation made a t different times was : t. Sp. rot. Mol. rot. of sol. Mol. rot. of C4HI0O1' 15' 1.0220 19.230 5.230 Mannitol, C6H1,06. As in the case of erythritol, a supersaturated solution was employed ; it contained 18.176 per cent.of mannitol, its composition being C6H140, + 40H,O. This was recrystallised from water before use. Density, d 15'/15', 1.0752 ; d 2Oo/2O0, 1.0746. The average of four sets of measurements of the magnetic rotation made at different times gave : t. Sp. rot. Mol. rot. of sol. Mol. rot. of C,H,,O,. 17 -5' 1.0154 47.351 7.351 Ghcose, C6H1206. Two specimens of this substance were examined, one obtained from Kahlbaum, and the other, a very pure preparation, for which I am indebted to Dr. Horace Brown. With the former, four sets of measurements were made on different occasions and with solutions of various strengths, the most dilute being represented by C61E1206 + 20H,O, and with that from Dr. Horace Brown also four measurements were made, but with only one strength, represented by C6H120, + 11H20 and containing 47,619 per cent.of C6HI2O,. The products used were the monohydrate dried over sulphuric acid in a vacuum : The density of the solution C6H1206 + 11H20 was d 15'/15', 1.2147 ; d 2Oo/2O0, 1.2135. Magnetic rotation : t. Sp. rot. Mol. rot. of sol. Mol. rot. of C,HI,O,. 15' 1.0261 17.723 6.723 The average of the measurements made with Kahlbaum's specimen was 6.715, which is very close to the above. The permanent optical rotation of the solution containing 47.61 9 per cent, of C6H1,06 was [.ID 66-22' at 16.9'. This is a little higher than that given for weak solutions. If the magnetic rotations be calculated on the assumption that the glucose has assimilated a mol. of water and thus become a heptahydric alcohol, the solution will then have the composition C6H1407 + 10H,O.The calculation will be the same as the above, only the value of 10 instead of 11 mols. of water will have to be subtracted from the mole-POLYHYDRIC ALCOHOLS, HEXOSES, AND SACCHAROBIOSES. 189 cular rotation of the solution, and the rotation of the alcohol will thus become 7.723. Fmxose, C6Hl2OS. It was dried over sulphuric acid and its composition checked by a combustion ; it gave C, 39.8, and H, 6.8, the formula C,H1,O, requiring C, 40.0, and H, 6.7 per cent. Its solution was examined in one strength only, containing 50 per cent, of fructose and represented by C,Hl2O6 + 1 OH,O. This was prepared from inulin and obtai-ned from Kahlbaum. Density, d 15'/15O, 1-2226 ; d 2Oo/2O0, 1.2211. The average of five sets of measurements of the magnetic rotation, made on different occasions, gave : t.sp. rot. MOl. rot. Of Sol. MOl. rot. Of C,3H,&,3. 15' 1.0227 16*729 6.729 Optical rotation [.ID 96.19' a t 15'. Galactose, C,H1,06. This substance was examined in a very supersaturated solution, from which it does not crystallise very quickly. It contained 50 per cent. of the sugar, its composition being represented by C,H,,O, + 1 OH,O. Density, d 15"/15", 1.2311 ; d 20°/200, 1.2299. The average of four sets of measurements of the magnetic rotation, made on different occasions, gave t. Sp. rot. Mol. rot. of sol. Mol. rot. of C6H120B. 15' 1.0396 16.887 6.887 Optical rotation [a], 84.23' at 14.6". Sucrose, CI,H22011. The specimen used was ordinary sugar recrystallised from alcohol The composition of the solution used was represented (75 per cent.).by C12H,,011 + 19H,O, and contained 50 per cent. sucrose. Density, d 15'/15', 1.2327 ; d 2Oo/2O0, 1-2316. The magnetic rotation, determined on four different occasions, was : t. Sp. rot. MoI. rot. of sol. Mol. rot. of C12HaOll. 15' 1 *0247 31.586 12.586 Optical rotation [a ID 66.51' at) 17". VOL. LSXXI. 0190 MAGNETIC ROTATION OF SOME POLYHYDRTC ALCOHOLS. Maltose, C1,H,,O1l. For a very pure specimen of this compound, I am indebted to Dr. The solution employed contained 47% per cent. of the Horace Brown. sugar, its composition being represented by Cl2H2,OI1 + 20H,O. Density, d 15"/15', 1.2214 ; d 20°/200, 1.2205. The average of three sets of measurements of the magnetic rotation, made on different occasions, gave : t.Sp. rot. Mol. rot. of sol. Mol. rot. of CI2HnOl1. 15' 1.0288 33*690 12,690 Optical rotation [a]= 137.0' a t 16.7'. Lactose, C,, H,,O,,. This was obtained from Kahlbaum and was purified by fractional crystallisation, the crop deposited during the first 12 hours being rejected. The solution used was a supersaturated one containing 33,333 per cent. of the sugar, and had the composition C,,H,,O,, + 41H,O. Density, d 15"/i5O, 1.1413 ; d 20°/200, 1.1406. The magnetic rotation, as determined four times on different occa- It was dried in a vacuum over sulphuric acid. sions, was : t. Sp. rot. Mol. rot. of sol. Mol. rot. of Cl2H2?OI1. 18.4' 1.0213 53.714 12.714 Optical rotation [a]D 52.6' at 18'. Summary. The chief results obtained in this investigation go to show : (1) That the influence of successive hydroxyl groups in polyhydric alcohols on the magnetic rotations diminishes as they increase in number, until about the seventh is reached, when it becomes almost nil. (2) That solutions of glucose and fructose, after all change has taken place, give magnetic rotations which indicate that birotation is not due to hydration, but that it is caused by a change in the constitution of these substances. (3) That galactose, when in solution, does not undergo isomeric change to so large an extent as glucose. (4) That sucrose is built up of the isomeric or @forms of glucose and fructose by the elimination of the elements of a mol, of water.HYDROCYANIC, CYANIC, AND CYANURIC ACIDS. 191 ( 5 ) That maltose is formed from 1 molecule of glucose in the aldehydic or a-condition and 1 molecule in the isomeric or @-condition by the elimination of the elements of a mol. of water and that lactose is similarly derived from 1 molecule of a-glucose and 1 of @galactose, both being constituted in a similar manner t o that proposed by E, Fischer for lactose, also that when in solution these sugars undergo isomeric change, the a-portion becoming transformed, more or less, into the @-condition. This change accounts for the birotation and cupric reducing power of the two sugars.

ISSN:0368-1645    

DOI:10.1039/CT9028100177

出版商:RSC    

年代:1902

数据来源: RSC

摘要:

HYDROCYANIC, CYANIC, AND CYANURIC ACIDS. 191 XX.--The Constitution OJ Hydrocyanic, Cyanic, und Cyulzuric Acids. By F. D. CHATTAWAY and J. MELLO WADYORE. ALTROUUH the simplest cyanogen derivatives have been for more than a century among the most familiar of carbon compounds, there is no general agreement as to their constitution. They all contain a carbon and a nitrogen atom associated together, and different opinions are held as to the manner in which hydrogen or halogen atoms are at- tached t o this group. As a rule, well-defined classes of alkyl derivatives corresponding with each possible structure are known, the behaviour of which leaves no doubt concerning their molecular arrangement, but the reactions of the cyanogen acids, their salts and halogen derivatives, are contradic- tory, and apparently equally well-established facts lead to opposite conclusions.Hydrocyanic acid, cyanogen chloride, cyanic and cyanuric acids, for example, may have the following structures : C-OH co / \ \/ or HT TH oc co NH / \ R T \/ H*CiN or H*N:C Cl-CIN or Cl*N:C H*O*CiN or 0:C.N-H HO4C C-OH N The formulze generally adopted are those given first, the hydrogen, halogen, and hydroxyl being regarded as attached to the carbon atom, The knowledge which we have recently acquired of the strikingly different behaviour of halogen when attached t o carbon or to nitrogen made it probable that a study of the action of halogens on the 0 2192 CHATTAWAY AND WADMORE: THE CONSTITUTION OF cyanogen acids, and of the derivatives thereby produced, would afford direct evidence as to their constitution.Speaking generally, imino- hydrogen is more readily replaced by halogen than hydrogen attached to carbon, and the imino-halogen compounds are characteristically reactive, while the carbon halogen linkage is comparatively stable. Cyanogen chloride, bromide, and iodide were among the earliest discovered compounds of cyanogen, as they are formed with the greatest ease by the action of the halogens on aqueous solu- tions of hydrocyanic acid or its salts. A careful study of the be- haviour of these compounds shows that they possess all the typical and characteristic properties of compounds having halogen attached to nitrogen. They react, for example, quantitatively with solutions of hydriodic acid, sulphurous acid, and b ydrogen sulphide, hydrocyanic acid being in each case reformed, while iodine, sulphuric acid, and sulphur are respectively produced.Taking cyanogen bromide, for example, the reactions are repre- sented by the equations : C:N*Br + 2HI = C:N*H + HBr + I,. C:N*Br + H,SO, + H20 = C:N*H + HBr + H2S0,. C:N*Br + H2S = C:N*€€ + HBr + S. This behaviour shows that the halogen is attached to nitrogen and not to carbon in these compounds, and that, consequently, they must be represented by the formuke : C:N*CI ; C:N*Br and C:N*I. The carbon is conventionally represented as divalent, and the nitrogen as trivalent ; no very different conception, however, would be ex- pressed if the carbon were represented as tetravalent and the nitrogen as pentavalent, since what is implied is that the carbon is attached to the nitrogen by the resultant affinity which, under the circum- stances, the atoms are capable of exerting.The ease with which the cyanogen halogen compounds can be formed from prussic acid and its salts, and again transformed into them, makes it in the highest degree probable that these have the imino- constitution, and hence should be represented by the formuIae : C:N*H C:N*K C:N*Ag. This conclusion, moreover, is the only one which will satisfactorily explain their whole chemical behaviour." The relations of the cyanides and cyanogen chloride to cyanic acid * We have not thought it necessary to go into explanatory details as these can be easily supplied,HYDROCYANIC, CYANIC, AND CYANURIC ACIDS. 193 and its salts have been among the chief reasons which led to the adoption of the hydroxy-formulae : N:C.OH N:C*O*K(.for these compounds. Since, as we have just shown, the former are imino-compounds these relations become reasons for adopting the alternative imino- structure : O:C*NH and 0:C:N.K. For example, the production of potassium cyanate, when cyanogen chloride is treated with aqueous potash, has been used as an argument for the hydroxy-constitution, since if the chlorine in cyanogen chloride is attached to carbon, it could be regarded as a normal case of hydrolysis : NiC.01 + 2KOH = KCI + NIC*O*K + H,O. Cyanogen chloride, however, has the imino-structure, and the reaction becomes an argument in the other direction, for a comparison of this behaviour with that of the analogous cyanogen iodide shows that it must be regarded as a normal hydrolysis of a nitrogen chloride followed by oxidation of the potassium cyanide first formed : C:N*Cl + 2KOH = C:N*K + KOCl + H,O.= G.C.Y.*K t K!!l f K@. Analogy with cyanurio acid also is in favour of the imino-structure. The action of chlorine on a solution of potassium cyanurate is precisely similar to its action on potassium cyanide, the potassium atoms are replaced by chlorine, and a well-defined crystalline corn- pound is produced, thus : C3K3N303 + 3C1, = C3C13N303 + 3KCl. The entire chemical behaviour of this substance shows that the whole of its halogen is attached to nitrogen. It liberates chlorine when treated with hydrochloric acid, iodine with hydriodic acid, and oxidises sulphurous to sulphuric acid.Cyanuric acid is, in each case, reformed, and the reactions are quantitative ; the action with hydro- chloric acid, for example, takes place according to the equation : C3C13N303 + 3HC1 = C,H3N303 + 301,. It is hydrolysed by water or alkalis, yielding hypochlorous acid or hypochlorites. It reacts explosively with a strong ammonia solution, nitrogen being liberated, and also with a solution of hydrogen sulphide, setting free sulphur. Cyanuric acid is in each case reformed. The compound must therefore be trichloriminocyanuric acid.194 CIIATTAWAY AND WADMORE: THE CONSTITUTION OF Since cyanurates are so readily and completely converted into this trichlorimino-derivative, and the latter in many reactions equally readily and completely again into cyanuric acid, we are justified in concluding that Hofmann was in error in assigning a hydroxy- constitution to the acid and its salts, and that, on the contrary, they have the imino-constitution, and assuming the correctness of the cyclic structure that they must be expressed by the formulz co co co / \ Hr;J SJH oc GO \/ NH / \ K y TK oc co \ / NK \ / NCI Cynnuric acid. Potassium cyanurate.Trichlorimino- cyaiiuric acid. A similar study of the behaviour of cyanuric chloride and bromide confirms Hofmann’s conclusion that in them the halogen is attached t o the carbon and not to the nitrogen. They do not liberate iodine from hydriodic acid or sulphur from hydrogen sulphide, nor do they oxidise sulphurous acid, even when heated to looo with these reagents. This constitution, however, was to be expected from the structure of the cyanogen halogen compounds, from which they are produced by polymerisation under the influence oE halogen acids.Cganogen chloride and bromide, as we have shown, are chlorimino- derivatives in which the carbon being unsaturated is able to combine with two monad atoms. In the polymerisation, the halogen acid in all probability first adds itself on forming molecules having the constitution : H>C :N*Br, i>C:N*Cl or Br which, on coming into contact, unite into ring systems of normal structure with elimination of halogen acid, thus : \ / N + 3 HCI. As Hofmann has pointed out, all the relations of the cyanogen group can only be explained by assuming isomeric change to occur in certain reactions ; the issue is as to where this takes place.HYDROCYANIC, CYANIC, AND CYANURIC ACIDS.195 Cyanuric chloride, as is well known, yields cyanuric acid and hydrochloric acid on prolonged heating with water, the reaction being more rapid if alkalis are present. This and the corresponding con- version of cyanuric acid into cyanuric chloride by phosphorus pentachloride are the chief grounds on which Hofmann assigned the hydroxy-structure t o the acid. If, however, the views now put forward as to its constitution are correct, these are the reactions where isomeric change occurs, and analogous behaviour in other well-established cases renders this probable. We must assume that in the hydrolysis of cyanuric chloride normal cyanuric acid is first formed, but as in many cases where we have the grouping -b=cz, o*H the configuration is unstable and passes into the stable arrangement -8-zz , so here we have an intramolecular change, the stable imino-form of ordinary cyanuric acid being the result : CCl C*OH co \/ NH \/ N \ / NH The action of phosphorus pentachloride on cyanuric acid is probably analogous to its action on amides, the replacement of an oxygen atom by two chlorine atoms being followed by tho elimination of hydrogen chloride : GI c1 \ / ? / \ / \ M Y Gl\tj &/C1 c 1 c cc1 Cl’\ / ‘GI \ / c C 0 C HN N H -+ /\ \/ HT TH --+ oc GO NH N NH EXPERIMENTAL.Cganogm Chloride, C:N*CI. This compound shows the characteristic behaviour of a nitrogen chloride, although it reacts less readily than is usual with such substances. When hydriodic acid is added to an aqueous solution of cyanogen chloride at the ordinary temperature, very little iodine is liberated j the amount, however, increases slowly on standing, rapidly196 CHATTAWAY AND WADMORE: THE CONSTITUTION OF on heating t o near looo, until it reaches about 80 per cent.of that required by the equation : C:N*Cl + 2HI = C:N*H + HC1 + I,. If the heating be prolonged, the free iodine slowly disappears, probably owing to hydrolysis of the hydrocyanic acid, and oxidation of the formic acid or ammonia produced, When aqueous solutions of cyanogen chloride and hydrogen sulphide are heated together to looo, sulphur is set free in considerable quan- t i t y ; the hydrocyanic acid formed is mainly hydrolysed, but a small amount escapes decomposition and combines with some of the liberated sulphur to produce thiocyanic acid.Similarly, when solutions of cyanogen chloride and sulphurous acid or sulphites are heated to looo, the latter are oxidised while the hydro- cyanic acid is destroyed, probably hydrolysed. No liberation of chlorine can be detected when a soliition of cyanogen chloride is heated with hydrochloric acid to 100' ; the cyanogen chloride, however, is completely decomposed at this temperature. The production of potassium cyanate and chloride by heating cyano- gen chloride with caustic potash is probably due to the normal hydro- lysis which all chlorimino-compounds undergo, followed by a subse- quent oxidation of the cyanide by the hypochlorite formed. C:N*Cl+ 2KOH = C:N*K + KOC1 + H,O = 0:C:N.K + KC1 + H,O.Cyanogen Bromide, C:N*Br. Cyanogen bromide is much more reactive than cyanogen chloride. A t the ordinary temperature, it liberates iodine from hydriodic acid, sulphur from hydrogen sulphide, and oxidises sulphurous acid or sodium sulphite. All these reactions are quantitative, hydrocyanic and hydro- bromic acids being formed in equivalent amount, A weighed quantity o€ cyanogen bromide was added to an excess of a solution of hydriodic acid made by dissolving 10 grams of potassium iodide in 100 C.C. of a 5 per cent. solution of acetic acid ; hgdrocyanic acid and iodine were at once liberated, the latter being then estimated by sodium thiosulphate : 0.2439 liberated I = 46 C.C. N/lO iodine. C:N*Br requires 75.43 per cent. A weighed quantity of cyanogen bromide was added to an excess of an approximately decinormal solution of hydrogen sulphide ; sulphur * Throughout this paper the results are calculated on the assumption that the substances under consideration react as typical nitrogen halogen compounds, the numbers are then compared with the percentages calculated from the formula Br as :N-Br = 76.4.'HYDROCYANIC, CYANIC, AND CYANURIC ACIDS.197 was at once deposited and hydrobromic and hydrocyanic acids formed, together with a little thiocyanic acid, produced by the action of the sulphur on the latter ; the excess of hydrogen sulphide was then esti- mated by a solution of iodine : 0.4791 reacted with 90.7 C.C. N/10 H,S/2. A similar procedure was adopted in studying the reaction with sulphurous acid. A weighed quantity of cyanogen bromide dissolved in dilute acetic acid was added to an excess of a decinormal solution OF sodium sulphite, and then the excess of the latter estimated by a solu- tion of iodine : 05050 reacted with 95.25 C.C.N/10 Na,S0,/2. Br as :N*Br = '75.41. C:N*Br requires 75.43 per cent. No bromine is liberated when cyanogen bromide is heated with a solution of potassium bromide made acid with acetic acid, or when it is heated with strong hydrochloric acid to looo, although in the latter case it is decomposed just as cyanogen chloride is when similarly treated. Br as :N*Br = 75.68. C:N*Br requires 75.43 per cent. Cyanogen Iodide. Cyanogen iodide is more reactive than cyanogen chloride or cyanogen bromide, and behaves as a typical nitrogen iodide. It reacts with hydriodic acid, liberating iodine, with hydrobromic acid liberating bromine and iodine, with hydrochloric acid forming iodine monochloride ; it oxidises sulphurous acid and sodium sulphite, forming sulphates and sets free sulphur from hydrogen sulphide. Its behaviour towards several of these substances was very carefully studied by E.von Meyer ( Z p r . Chem., 1887, [ii], 35, 292). He showed that the reaction between hydrocyanic acid and iodine is a reversible one, and that two molecules of sulphur dioxide completely reduce two molecules of cyanogen iodide to hydrocyanic and hydriodic acids. He, however, writes the formula ICN, and concludes his paper by stating that it is the only oxygen-free iodide soluble in water which shows the surprising behaviour of liberating iodine under the action of reducing agents, but of remaining unattacked by reagents which set iodine free from other iodides.We have quantitatively studied the behaviour of cyanogen iodide in order to compare it with that of the bromide and the chloride. A weighed quantity of cyanogen iodide mas added to an excess of a solu- tion of 10 grams of potassium iodide in 5 per cent. acetic acid; hydro- cyanic acid and iodine were at once liberated, the amount of the latter being then estimated by sodium thiosulphate : 0.2964 liberated I= 38.8 C.C. N/10 iodine. I as :N*I=83*02. C:N*I requires 82.97 per cent.198 CHATTAWAP AND WADMORE: THE CONSTITUTION OF This result is exactly that required by the equation : C:N*I + HI = C:M*H + 12, When cyanogen iodide is dissolved in an excess of strong hydrochloric acid at the ordinary temperature, very little action takes place, but on warming to 20-30' the liquid becomes orange-coloured, owing to the formation of iodine monochloride, and the colour deepens as the tem- perature rises. There is no liberation of free iodine even on boiling the solution.Hydrocyanic acid is also produced. I n one experiment, the iodine monochloride was distilled off into a solution of potassium iodide, and the liberated iodine estimated, The amount of iodine monochloride obtained was about 2 per cent. below that required by the equation CN.1 + He1 = 0:N.H + ICl. The loss is prabably due to the hydrolysis of a small amount of the hydrocyanic acid and partial oxidation by the iodine monochloride of the products.When cyanogen iodide is similarly treated with hydrobromic acid, both iodine and bromine are evolved, but, as with hydrochloric acid, the amount falls somewhat short of that required by the equation CN.1 + HBr = C1N.H + BrI, probably from a similar cause. When a solution of sulphurous acid is slowly added to cyanogen iodide, iodine is liberated, hydrocyanic acid and sulphuric acid being simultaneously formed ; if, however, the iodide be added to an excess of sulphurous acid, no liberation of halogen occurs (compare Strecker, Annalen, 1868, 148, 90). A weighed quantity of cyanogen iodide was added to an excess of a decinormal solution of sodium sulphite so that no iodine was set free, and the excess of sulphite estimated by a dilute solution of iodine : 0.2960 oxidised 38.7 C.C.of N/10 Na,S0,/2. C:N*I requires 82.97 per cent. The action takes place according to the equation I as :No1 = 82.92. 2C:N.I + H,SO, + H,O = 2C:N.H + H,SO,. Sulphur is set free and hydrocyanic and hydriodic acids are formed when cyanogen iodide is added to an excess of a solution of hydrogen sulphide. I f the latter is slowly added to the iodide, iodine is also liberated, owing to the action of the hydriodic acid first formed on the unchanged cyanogen iodide. A little thiocyanic acid also is always formed from the interaction of some of the hydrocyanic acid with the sulphur.HYDROCYANIC, CYANIC, AND CYANURIC ACIDS. 199 I n the following experiment, cyanogen iodide was added to an ex- cess of hydrogen sulphide, the amount of the latter remaining unacted on being estimated by a solution of iodine : 0.2896 reacted with 37.9 C.C.N/lO H2S/2. The result is expressed by the equation I as :No1 = 83. C:N*I requires 82.97 per cent. 2C:N.I + H,S = 2C:N.H + 2HI + S. Its behaviour towards a solution of potassium hydrate also shows that in it the halogen is attached to nitrogen, and affords an explana- tion of the apparently different action of the similarly constituted cyanogen chloride and bromide. When it is added to a boiling solution of caustic potash, it is a t once decomposed ; among other products, a small quantity of potassium iodate is formed. Cyanogen chloride and bromide, when similarly treated, form no chlorate or bromate. All the cyanogen halogen com- pounds, however, are readily decomposed by caustic a1 kalis, yielding cyanates.The nitrogen halogen linkage, as is well known, behaves in a char- acteristic way on hydrolysis, the halogen being invariably replaced by hydrogen and becoming itself attached to the residual hydroxyl, thus : *N*X + H*O*H = *NOH + X.0.H. It is thus sharply distinguished from the carbon halogen linkage, where the opposite happens, thus : *COX + H*O*H = *C*O*H + XH. The formation of iodate in the reaction between cyanogen iodide and potash shows that, a t first, nitrogen halogen hydrolysis undoubtedly takes place, thus : C:N*I + 2KOH = C:N*K + K*O*I + H20. A certain amount of the hypoiodite, on account of the ease with which it is transformed into iodide and iodate, escapes reduction by the cyanide simultaneously formed, a reaction which results in the production of cyanate: C:N*K + K*O*I = O:C*N*K + KI, I n the cases of cyanogen chloride and bromide, the hypochlorite and hypobromite, which must first be formed, do not transform so readily, and consequently are wholly reduced.200 CHATTAWAY AND WADMORE: THE CONSTITUTION OF Cyanuric ChEoride and Bs*omide.These compounds show none of the reactions characteristic of the halogen nitrogen linkage. Small quantities of each were taken and heated for 30 minutes at 100’ in stoppered bottles, air being excluded, with solutions of hydr- iodic acid, hydrogen sulphicle, and sodium sulphite. No iodine or sul- phur was liberated, nor was the sulphite oxidised. This behaviour is in agreement with Hofmann’s view of their constitution, deduced from altogether different reactions, and with the formula assigned t o them by him and generally adopted : c c 1 / \ R Y c1c c c 1 CBr / \ Mr BrC CBr co / \ Cly- yc1 \ / co Trichloriminocyanui.ic Acid, NCl This compound is prepared with the greatest ease by dissolving cyanuric acid in the theoretical quantity of a 5 per cent.solution of caustic potash and passing a rapid stream of chlorine through the liquid cooled to 0’. Trichloriminocganuric acid separates as a heavy, white, crystalline powder which is obtained perfectly pure by washing a fern times with water and drying rapidly on a water-bath : 0,C3N3K3 + 3C1, = 03C3N,C13 + 3KC1. Using about 3 grams of acid, a yield of more than 90 per cent. of the theoretical is obtained. If a larger quantity than this be used or the temperature be allowed to rise, the yield is much diminished and the product is more or less impure.Trichloriminocyanuric acid is a white, crystalline powder which, under the microscope, is seen to consist of short prisms. It has a characteristic odour resembling that of hypochlorous acid. I t dis- solves to some extent in water and glacial acetic acid on heating, but, the greater part undergoes hydrolysis; it is very slightly soluble in chloroform, but insoluble in light petroleum. J t melts at aboutHYDROCYANIC, CYANIC, AND CYANURIC ACIDS. 201 245'. Its behaviour is in every way that of a typical nitrogen chloride. When added to strong hydrochloric acid, chlorine is liberated, the halogen escaping rapidly with effervescence ; it liberates bromine from hydrobromic acid, iodine from hydriodic acid; it oxidises sulphites to sulphates and sets free sulphur from hydrogen sulphide, cyanuric acid in all cases being reformed.When added to ammonia a violent action which may become explosive takes place, nitrogen is evolved, and cyanuric acid reformed. When boiled with water, dilute acids or alkaline hydroxides, it is hydrolysed, cyanuric acid and hypochlorites or the products of their transformation chlorides and chlorates, being produced. The percentage of chlorine was estimated by Carius' method, and several of the reactions referred to above have been quantitatively studied : 0.3280 gave 0,6052 AgCI. C1= 45.62. 0,C3N3C13 requires C1= 45-75 per cent. A weighed quantity was added to a solution of potassium iodide, made acid with acetic acid, and the iodine liberated estimated by thiosulphate : 0-4177 liberated I = 107.9 C.C.N/10 iodine. C1 as :N*Cl= 45.78. (j?, ) requires 45-75 per cent. r;J*Cl A weighed quantity was dissolved in acetic acid, an excess of an approximately decinormal solution of sodium Eulphite was added, and the excess afterwards estimated by a standard solution of iodine. C1 as :N*C1=45*79. 0.2'783 oxidised 71.9 C.C. N/10 Na,S03/2. o?, ) requires 45.75 per cent. ycl 8 A weighed quantity was heated with an excess of strong hydro- chloric acid, in a current of carbon dioxide, in an apparatus with ground glass joints (C'hem. Kews, 1899, 85) and the evolved chlorine passed into a solution of potassium iodide. 0.4689 evolved C1= 120.9 c.c. N/lO iodine.CI as :N*CI = 45.7. (.": ) requires 45.75 per cent, IyCl 3 These actions are represented by the equations :202 IIYDROCYANIC, CYANIC, AND CYAKURIC ACIDS. The reaction with hydrogen siilphide cannot be used to estimate the amount of chlorine attached to nitrogen, as this substance, like all nitrogen chlorides, oxidises a variable amount of the liberated sulphur to srilphuric acid. Action OT &ornine on Potassium Cyanurate. When bromine is added to a solution of cyanuric acid in the theor- etical amount of a 5 per cent. solution of caustic potash, a pale yellow substance separates from the liquid. This on exposure to air rapidly decomposes, bromine being evolved ; it cannot therefore be freed from water and analysed. It liberates iodine from hydriodic acid and violently decomposes ammonia with evolution of nitrogen, cyanuric acid being reformed in each case.When dried over sulphuric acid in an atmosphere of bromine, a pale orange-coloured powder is obtained which gives off bromine slowly at the ordinary temperature, rapidly at 1 OOO, leaving an orange powder having properties similar to those of the original substance. We have not yet been able to obtain a product which we could regard as a pure substance, the com- position varying considerably with slight differences of procedure, A very large number of analyses of different specimens seems to show that the body first formed is a bromine additive product of a bromimino- derivative of cyanuric acid, in which, however, all the imino-hydrogen of the cyanuric acid is not replaced.Action, of Chlorine and Bromine on Potassium Cyanate. Attempts to prepare a chlorimino-derivative of cyanic acid have hitherto been unsuccessful. When chlorine is passed into a cold solu- tion of potassium cyanate, it is absorbed, gas is evolved, and a white, crystalline powder separates, a very pungent odour, somewhat resem- bling that of cyanogen chloride, being noticed during the reaction.PERKIN : MYRICETIN. PART IT. 203 The white solid thus obtained is, however, cyanuric acid containing a little (5 to 6 per cent.) trichloriminocyanuric acid; on treating with hydrochloric acid o r ammonia to decompose the latter and recrystal- lising from water, pure cyannric acid is obtained. The action of bromine on a solution of potassium cyanate is similar and results in the production either of cyanuric acid or of the pro- duct already described as resulting from the action of bromine on a solution of potassium cyanurate. If bromine be added to a 25 per cent. solution of potassium cyanate, rapid evolution of nitrogen and carbon dioxide (approximately in the proportion N, : ZCO,) takes place, and the temperature rises to about 80°, if the addition be con- tinued until an excess has been added and this be then removed by boiling; cyanuric acid crystallises out on cooling. If the solution of cyanate be cooled in a freezing mixture and the bromine be added cautiously, similar effervescence takes place and a yellow solid separ- ates which in its composition and reactions resembles closely that obtained by the action OC bromine on potassium cyanurate; for example, it liberates iodine from hydriodic acid and nitrogen from ammonia, cyanuric acid being in each case produced. We are at present engaged in a study of various other reactions of tho cyanogen halogen derivatives which appears likely to throw additioual light on their structure. ST. BARTHOLOMEW’S HOSPITAL AND COLLEGE. LONDON, E,C.

ISSN:0368-1645    

DOI:10.1039/CT9028100191

出版商:RSC    

年代:1902

数据来源: RSC