SYNTHESES WITH PHENOL UEKlVdTIVES, E'I'C. 977

XC I I I. --Syntheses writ h Phenol Deu-ivcct ives C w t C C ~ P L i? ~y cc Mobile Nityo-group. P a ~ t VI . Substituted ALkyl- and A yyl-phenylumines ; Colour in Relation to Tautomerisrn.

By RAPHAEL MELDOLA and WILLIAM FRANCIS HOLLELY.

IN former communications relating to the above series of syntheses, the last of which was published in 1911 (Meldola and Euntzen, T., 99, 2034), attention has been cancentrated mainly on the formation of iminazoles and iminazolium compounds and their isomeric carbinols by the action of amines on trinitroacetylamino- phenol.* Throughout this series of researches the latter compound

The effective trinitro-compound employed in all our former researches was the 2 : 3 : 6-trinitro-~-niiiinopheiiol (formerly regarded as the 2 : 3 : 5-trinitro-co1ii~ou1i~l). Attempts havr been made froin tinie to time to obtain trinitro-derivatives of o- aiid nt-aminophenol, but hitherto without simess. The nitration products of diacetyl- maminophenol have recently been re-investigated by Reverdin and Widmrr (Ber., 1914, 46, 4066), who have also failed to obtain trinitro-derivatives. These authors state tha t they have been unable to prepare 6-nitro-~n-acetylaminophcnol as onc of the products of nitration of diacety1.m-aminophenol by the method described by one of the authors and F. C. G. Stephens in 1908 (T., 89, 925). This conipouiid is more soluble, and separates more slowly, than the isomeric 4-nitro-compound which is simultaneously formed. If the mother liquor is too dilute or allowed t9 remain for an insufficient time, the 6-nitro-componnd may easily be overlooked. That we actually had the 6-nitro-compound in hand is proved by oiir having obtained froin it the 6-nitro-?n-aminophenol, of m. p. 158", identical with that obtained by Reverdiii iltid Widmer by the hydrolysis of the acctyl derivative prepared by their method of nitration (loc. cit., p. 4069). We have repeated the preparation of the t u o isomerides by the original method, and have obtained the same results as before, both as regards products and melting points. The discrepancy in the melting points of the mono- acetyl derivatives requires clearing up, but the discrepancy of results, is possibly due to the nitration being carried out by our process a t a higher temr erature, name?y, in an ice-bath illstead of in a fuxzing mixture of ice and salt. Under the latter condi- lious both acetyl groults are retained, aud the sole product (according to the descriptiou

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978 MELDOLA AXL) HOLLELY : SYNTHESES WITH PHENOL

has been cousidered to be the 2 : 3 : 5-trinitro-derivative, but later evidence (Meldola and Reverdin, T., 1913, 103, 1484) has been adduced which has rendered necessary a revision of this formula so far as concerns the third nitro-group, which has now been shown to be in position 6. We may take the present opportunity, there- fore, of pointing out that this revision necasitates a corresponding revision of the formulze of the various derivatives as shown below:

KO2 N*X NO, X*X NO, N - X

v \/ \/ \/ N N N

/\ /\ /\ /\ HO< 7 )' 1

No,,: 1 /\ 3 / 'C<&

H() &<'\ HO' ' Y >c,y NO,< 4 /\ I 3/ 2c*Y NO"\"///\</ 1:

/\ H O Z

I z 5 : 7-l)iiiitro-iniiiiaxolcs 5 : 7-Dinitro-irniiiazoliuiii 5 : i-l>initro-carbinoIs in- instead of 4 : t-dinitro- compouuds instead of stead cif 4 : 7-dinitro-deriv-

These formulze 5ecome of special interest in connexion with the colour of certain iminazolium bases (see T., 1911, 99, 1286, 1293), of which the hydrated forms are red. The colour of t h a e com- pounds is thus seen to be connected with the " quinole " structure assigned to the coloured hydrates of the quinone-ammonium com- pounds (T., 1912, 101, 918), the parallelism between the two wries being now complete :

derivatives. 4 : 7-dinitro-derivatives. atives.

HO OH \/

HO OH \ /

given in tho Bcrichle) is the 6-nitro-cornpound. If, as seems probahle, a t a somewhat higher temperature the nitration is accompauied by the renioval of the 0-ncetyl group, as so frequently happens in such cases, both isomerides may be formed, as in our original process. We are able to confirm the statement of Reverdin and Widmer that the nitro-derivatives of manisidine cannot by any ordinary process he carried to a trinitro-stage. The research in this field is, lio\Yever, i u the hands of 31. Reverdin cind his colleagues.

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DERIVATIVES CONTAINING A MOBILE NITRO-GROUP. 979

Further researches on the quinone-ammonium compounds, which are now in progress, will enable us to deal with this part of the subject more fully in a future communication.

In the formation of iminazoles from 2 : 3 : 6-trinitroacetylamino- phenol and aniines the intermediate products are substituted alkyl- or aryl-phenylamines (T., 1906, 89, 1940; 1908, 93, 1660). I n some cases these intermediate products have been isolated, but since with all primary amines the final product is invariably a n iminazole, the mobile nitro-group is, as shown in former communi- cations, in position 3:

OH OH NO,/\NO, -+ ,,)NH*R

NO,/\NO, ($NO,

NH* CO*CH, NH*CO%H,

O*CH, O*CH, I n tcrmedia te corn pound.

/\NO2 --+ /\NH-R NO,j/NO, W,,N*2

NH*CO*CH, NH*CO*CH,

It has also been shown (Meldola and Reverdin, T., 1913, 103, 1490) that in 2 : 3 : 5-trinitroanisidine the 2-nitregroup is mobile under the influence of amines, and the acetyl derivative of this compound might accordingly be expected to give rise to a seriea of substituted alkyl- or aryl-phenylamines under similar conditions (see above formule). I f in the acetyl derivative it is also the fl-nitro-group which is mobile, no iminazole formation would he possible, and the results made known in the present paper prove conclusively that this inference is correct. It will be observed from the above formula that in both isomerides the mobile nitro- group (marked *) is in the position of maximum instability, namely, ortho with respect to one nitro-group, and para with respect to the other, thus conforming with the general rule which regulates mobility (T., 1906, 89, 923; 1907, 91, 1474).

Colour in Relation to Tautomerirrm.

The chief interest attaching to the present seriea of compounds is the evidence of tautomerism associated with change of colour, which is distinctly shown by the substance resulting from the reaction between 2 : 3 : 5-trinitroaceto-p-anisidide and aniline. The evidence in $his case appears to us to point to the conclusion that the groups concerned in this tautomerism are the 3-nitro-group and

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980 MELDOLA AND HOLLELY: SYNTHESES WLTH PHEKOL

the 2-phenylamino-group. this view are given below:

The reasons which have led us to adopt

(11.) (111.)

The compound in question is phenolic in character, as, in fact, are all the compounds resulting from the replacement of the 2-nitro-group by amine residuea. This property might be attri- buted t o the replaceability of the H atom (marked *) in the acetylamino-group (formula I). The original trinitroacetoanisidide is, however, also phenolic, dissolving in alkaline solutions with a deep yellow colour, and being precipitated unchanged by acids.* As the original trinitro-compound is colourless and its salts are yellow, a structural change on salt-formation probably takes place, the configuration shown in formula I1 being assumed in presence of alkali, and the configuration I resumed on acidification (see paper by one of the authors and J. T. Hewitt, T., 1913, 103, 881). Since the substitution of the phenylamino-group for the 2-nitro- group does not interfere with the phenolic character, it is evident that the nitro-group in question is not concerned in the production of this property of the substance, and formula I1 may therefore be assigned to the compound in alkaline solution, which solution is of a deep orange colcmr. The presence of the phenylamino-group in position 2, however, brings in a new character, namely, the capability of existence in two distinct coloured forms in the solid, crystalline state. As will be seen from the experimental data, the free compound can be obtained in ochreous needles or deep red scales, the two forms being interconvertible. In accordance with all analogies, we consider the highly-coloured red form to possess the inner salt structure (111), and the light ochreous form in the free stete the constitution shown in formula I, both forms probably assuming configuration I1 in alkaline solution.

Experimental evidence in f a v o w of this interpretation of the observed tautomerism is given in the subsequent part of this paper; thus the disappearance of colour when the hydrogen of the phenylamino-group is replaced by acid radicles may be ascribed to the destruction of the salt-forming capacity of this group by

* M. Keverdin, to whom we art: greatly iiidebted for tho supply of trinitroaoeto-p- aiiisidide used in this research, informs us that the phenolic character of this compound has also been observed by himself and Rf. Bosshard in their laboratory.

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DERIVATIVES CONTAINNG A MOBILE NITRO-GROUP. 981

the suppression of its basic character. The acetyl and nitroso- derivatives, which are colourless and respectively identical from whichever of the two forms they are prepared, have no doubt the normal structures :

O*CH, WCH,

/ A N h c c,; H /) N( NO) C, H K021,/iV02 NO,\,NO,

NH-CO-CH, N H*CO*CH, (I\'.) (V. 1

O*CH,

/ \ N ( A ~ or NO)*C,H, X02v: I NO,H

N-CO-CH, ( V I . )

Since these compounds are also phenolic and dissolve in dilute alkaline solutions with a yellow colour, i t is most probable that under these conditions salt formatlion takes place with the assump- tion of configuration VI, as in the cam of the unsubstituted phenyl- amino-derivatives.

Another observation recorded in this paper may perhaps be regarded as giving additional support to the inner nitrolic salt constitution of the red form. It has been found that the trinitro- anisidine condenses with monomethylaniline with the elimination of the methyl group and the formation of the same compound (plienylamiuo-derivative) as that resulting from the direct action of aniline. The details are given in the experimental part, but the interpretation is attempted here.

Supposing the reaction to take a noriiial course, the product would be as shown in formula VII, which represents the compound

OeCK, /\N (CH,) C,H, I I

N*2\,NO2 I 1 NH*CO*CH,

(VII . )

as a derivative of methyldiphenylamine. The demethylation takes place under the ordinary conditions of formation of the condensa- tion product, namely, on heating the trinitroanisidine with excess of monomethylaniline at looo, the reaction being :

Substituted-phenyl-nucleus-N( CH,)-C,H, + C,H,*NH*CH, =

Since the removal of methyl from rnethyldiphenylamine derip- substituted-phenyl-nucleus-NH*C,H, + C,H,*N( CH,),.

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982 MELDOLA AND HOLLELY: SYNTHESES WITH PHENOL

atives coiitainiiig the group *N*CR,*C,H, cannot, under ordinary conditions, be effected by simply heating with bases to looo, i t seems probable that tho nitro-group exerts a loosening influence by forming an inner salt, the intermediate compound having the formula (VIII) above. The compound would then contain the

group :h*C,B,, from which methyl might be expected to be more

readily eliminated. I f this interpretation of the reaction betweeii the trinitroanisidiiie aiid monomethylaniline is correct, the inner salt structure suggested receives further confirmation.

I n connexion with the foregoing suggested interpretation of the tautomerism observed, we may point out that the methoxy-group appears to play an essential part in the production of the pheno- menon, since the corresponding compound containing hydroxyl in place of the methoxy-group shows no indication of tautumerism. It appears also that the phenyl radicle (by virtue of its weight or other character 1) is specifically concerned in favouring the tauto- merism, all the compounds of similar constitution containing radicles other than phenyl existing, a t least visibly, in one form only. Whether tautomerism is possible in these other cases might be decided by a study of the absorption spectra.

CH,

i>*

EXPERIMENTAL. A 1 ctiou, o f ,1 triliiLe 011 2 : 3 : 5-l’~~i~titroaceto-p-n,lisiclidu.

The replacement of the 2-nitregroup takes place on boiling the trinitrc-compound for three to four hours in alcoholic solution with three molecular proportions of aniline. The same product is obtained by dissolving the trinitro-compound in excess of aniline and keeping the solution a t looo for an hour. The reaction takes place also at the ordinary temperature of the air, the transforma- tion under this condition requiring several days for completion. Whichever process is adopted, the excem of aniline is removed by extraction with hydrochloric acid, and the residue washed with water until the washings are no longer coloured by aminoaze benzene, the latter coinpound being formed by the action of the eliminated nitro-group on the aniline. The compound crystallises from glacial acetic acid in ochreous needles, and from alcohol in the same form, or, from more dilute solutions, as a mixture of ochreous needlee and red prisms. It was this last observation which led us a€ first to suspect that two distinct compounds were formed. and each form was examined separately, with the result that they were found t-o be identical in composition and intercon-

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DERIVATIVES CONTAINING A MOBILE NITRO-GROUP. 983

vertible, and could accordingly be regarded as tautomerides. The compound is phenolic, dissolving in aqueous alkali with an orange colour, and being precipitated unchanged by acids. The phenolic character is best shown by dissolving the compound in a little dilute alcoholic sodium hydroxide and then diluting with a large quantity of water. The substance remains in solution under these conditions, and on acidifying (preferably with acetic acid) separates slowly as the red modification, consisting of crystalline scales, which remain unchanged on drying. The red form is converted into the ochreous modification by rapid crystallisation from a concentrated alcoholic solution or, with greater certainty, by crystallisation from glacial acetic acid. A t about 200° the red form is also transformed into the ochreous modification, so that the melting points of both modifications are practically identical, namely, 224-22507 with previous softening. Analyses of various preparations are given below, the results indicating that the com- pound is:

3 : 5-Dinitro-2-phenyEaminoaceto-p-a~zisidide ( = 3 : 5-Dinitro-1- methoxy-4-acetylaminodiphenylamine) (Formuls I, 11, and I11 above).

(1) Compound crystallised from glacial acetic acid ; ochreous

(2) The above recrystallised from alcohol ; ochreous needles

(3) Red modification separated from preceding. (4) Red crystals converted into ochreous form by crystallisation

from acetic acid. (5) Red scales obtained from ochreous needles by dissolving the

latter in alkali and precipitating by acid, as in the process described above : (1) 0.0786 gave 10.8 C.C. N, (moist) a t 18O and 776.4 mm. N = 16-22. (2) 0.0986 ,, 0.1878 CO, and 0.0364 H,O. C=51*94; H=4*10. (3) 0.1820 ,, 24-5 C.C. N2 (moist) a t 17O and 778.2 mm. N=16*00, (4) 0.1002 ,, 0.1912 CO, and 0.0376 H,O. C=52*04; H =4.17. (5) 0.1017 ,, 0.1944 CO, and 0.0370 S O . C=52.13; H=4.04.

needles.

separated from red prisms by selection.

0*1050 ,, 14.2 C.C. N, (moist) a t 1l0 and 758.7 mm. N=16*10. C,,H,,O,N, requires C = 52.0 ; H = 4.08 ; N = 16.19 per cent.

The identity of the two forms is established by these results; the formulze assignable fi the two modifications, respectively, have been discussed in the introductory portion of this paper.

Attempts to hydrolyse this acetyl derivative by acid or alkali proved that the acetyl group could not be easily removed without

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984 NELDOLB AND HOLLELY: SYNTHESES WITH PHENOL

iiiore profound decomposition of the conipound taking place. Could this hydrolysis be effected, the product would no doubt be the same as that produced by the action of aniline on the trinitro-anisidine, but the study of this series of derivatives does not come within the scope of the present researcli (Reverdin, Arch. sci. phys. nut., 1910, Liv], 29, 480).

Compounds containing the 4-amino-group in place of the 4-acetylamino-group do not appear to be so readily susceptible of tautomerisation. Some members of this series have been described in a former paper (Meldola and Reverdin, T., 1913, 103, 1490).

3 : 5-Dinitr0-2-phe~7 yluce tyla minoace to-p-ui~isidide (Formula IV) . Both forms are readily acetylated and yield the same compound

when dissolved in acetic anhydride containing a IittIe concentrated sulphuric acid. The product, after precipitation by water and removal of the excess of acetic acid by washing, crystallises from

melt- dilute alcohol in small rosettes of very pale, ochreous needles, ing a t 240° with previous softening:

N = 0.0998 gave 12.2 C.C. N, (moist) a t 17O and 761.7 mni. C,,H,,O,N, requires N = 14.43 per cent.

4.22.

3 1 5-Dit~i tro-2-N-ni trosophei1~~lanLinouceto-p-a~~i~id~~e (Formula V).

The phenylamino-compound is suspended in cooled glacial acetic acid, and solid sodium nitrite added in small quantities until a clear solution is obtained. After standing for about an hour, the iiitrosoaniine is precipitated by the addition of water, collected, and washed and crystallised from dilute alcohol. The compound crystallises in nearly colourless scales, which have no definite melting point, but begin t o decomEose a t about 140°, and fuse finally a t

0.0945 gave 15.4 C.C. N, (moist) a t 1 8 . 5 O and 750.5 nim. N=18.54. C15H,,0,N, requires N = 18-67 per cent.

An attempt was made to transform this nitrosoamine into a nitroso-derivative according to the well-known method of 0. Fischer and Hepp:

158-166':

-N (N 0) CGH 5 + -N H C,H,* N 0. F o r this purpose, some of the compound was dissolved in alcohol

saturated with hydrogen chloride, and the cooled solution allowed t o stand for a day. The product proved to be the original phenyl- amino-derivative, so that in this case the alcoholic hydrogen chloride does not effect isomerisation, but simply removes the nitroso-group. Tlie nitrosoaniine dissolves in dilute aqueous alkali with a yellow colour, and is precipitated unchanged by acids.

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DERIVATIVES CONTAINING A MORTT,E NITRO-GROUP. 085

The substitution of acid radicles (acetyl and the nitroso-group) for the hydrogen of t,he phenylamino-group thus completely changes the colour of these compounds, and prohibits bautomerism. The theoretical bearing of this fact and of the phenolic character of the acidyl derivatives has been discussed in the introductory portion of this paper. It appeared of interest at this stage t o consider also the special influence of the acid radicle attached t o the 4-NH-group on the tautomerism. For this purpose the phenylamino-compound from aniline and 2 : 3 : 5-trinitroanisidine (Reverdin, Arch. sci. phys. nat., 1910, [iv], 29, 480) was benzoylated by treatment with benzoyl chloride with the object of obtaining the 4-benzoylarnino- derivative. The product proved, however, to be a mixture of mono- and di-benzoyl derivatives, resulting from over-benzoylation, and the experiments in this direction have for the present been dis- continued for want of material.

Action of Benzylamine 01% 2 : 3 : 5-Triiait9.0nceto-p-n,iisidide.

The reaction takes place on boiling the trinitro-compound in alcoholic solution with excess of benzylamine for two to three hours. The product is isolated by *diluting the alcoholic solution with water, adding excess of hydrochloric acid, collecting and wadling the precipitate, and purifying by crystallisation from alcohol. The substance crystallises in pale yellow, silky needles, melting a t 198-200°. Analysis proved the compound t o be 3 : 5-&nitro-2- 7) en z?/lnniinoaceto-p-aiaisidide :

0-CH, O*CH, /\NH*cH,*C,H, or in alkaline /\NH*C H 2q.~

NO,j/NO, sol 1 1 ti on + r\’ 02+ N021Y1’ --

NH’CO-CH, N.CO*CH, (1. ) (11.)

0.1013 gave 0.1968 CO, and 0*0410 H,O. C=52*98; R=4*49. 0.0774 ,, 10.4 C.C. N, (moist) a t 19O and 767.9 mm. N = 15.61. CI6Hl6O6N4 requires C = 53.30 ; H = 4-48 ; N = 15-56 per cent. So far as visible difference of colour reveals tautomerism, this

compound appears t o be homogeneous in the solid state, no modifi- cation being producible by different methods of crystallisation. I ts phenolic character is shown by its dissolving in dilute alkali with a yellow colour, and being precipitated unchanged by acids. The change of colour in presence of alkali suggests for the “ phenolic ” salt the constitution shown in the second of the above formulg.

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986 XlELUOL.4 AND HOLLELT : SYNTHESES Wl'L'H PHENOL

A ctioti of p-Toluidane O I I 2 : 3 : 5-Trinitrouceto-1~-anieadcdr.

The trinitro-compound was dissolved in an excess of fusetl p-toluidine, and the solution kept a t looo for two to three hours. Purification was effected in the usual way, by dissolving out the excess of toluidine with hydrochloric acid and crystallising the residual product from alcohol. The compound crystallises in long, silky needles of an ochreous colour ; the melting point is 210--211° :

0.1108 gave 14.7 C.C. N, (moist) a t 1 6 . 5 O and 773.8 mm. N=lS+ ' i l . C,,H,,O,N, requires N = 15.56 per cent.

The substance is accordingly 2 : 3-diiiitro-2-p-tolylun~inoaceto-p- tr~risidide, and the usual constitutional formula may be assigned :

O*CH, O*CH,

'"=C?H7tP) -+ N02\/:N02M' /\NH-C,H,(p) , NOd,,!N02

NH* COO CH, N*CO*CH, No tautomerism of the crystalline solid was observed in this case,

the p to ly l group apparently being incapable of conferring stability on the " inner salt " (red) modification. The phenolic character is less pronounced than in the corresponding compound from aniline, as the compound does not dissolve so. freely in aqueous alkali. It can, however, be brought completely into solution by means of a little alcoholic sodium hydroxide, and subsequent dilution with water. The alkaline solution is deep orange in colour, and the sub- stance is precipitated unchanged by acids.

The acetyl derivative was prepared by the actiou of acetic anhydride and sulphuric acid in the usual way. It crystallises from alcohol in small, colourless prisms, melting a t 154-155O :

0.0671 gave 8 C.C. N, (moist) a t 15O and 753'8 Inni. N = 13.86. C,8H,80,N, requires N = 13'93 per cent.

The mobility of the 2-nitro-group under the influence of primary arnines having been sufficiently established by the foregoing results, experiments were coiitiiiued with secondary and tertiary amines. In the case of the latter, there was 110 reason to expect any action unless, as seemed improbable, the aromatic nucleus of the amiiie were directly attacked and substitution effected a t the para-position, as when nitrous acid acts on tertiary amines containing an un- substituted aromatic nucleus. An experiment in which methyl- ethylaniline was used as a tertiary base showed tha t no action takes place in this case; the trinitro-compound was heated t o 100' for many hours with excess of the base, bu t was recovered unchanged a t the end of the process. If heated to a higher temperature, coni-

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DERLV.4TIVES COS'I'BINING A XIOBLLE NlTKO-GROUP. 987

plete decomposition takes place, with the production of indefinite resinous substances. With secondary amines, howPver, the reaction readily occurs, as shown by the following cases:

it ctioiL of D i m e t h y l a m i i ~ e on 2 : 3 : 5-Tri~aitroaceto-p-nIlisidide.

The reaction was effected in precisely the same way as with The benzylamine, and the product purified by similar treatment.

cwmpouncl is 3 : 5-dinitr.o-2-di.meth~luti i~?~oflceto-p-u~iis. ldid~ :

O*CH,

1\N(CH,), ,

**,\,NO, NH*CO*CH,

It is phenolic in character, dissolving in dilute alkali with a It yellow colour, and being precipitated unchanged by acids.

crystallises in yellow needles, melting a t 204-205O :

0.1029 gave 0.1662 CO, and 0.0438 H20. C = 44.05 ; H = 4.73. 0.1316 ,, 22 C.C. N, (moist) at 1 9 . 5 O and 750.3 mm. N=18*92.

C,,H,,0,N4 requires C = 44.2'1 ; H = 4-73 ; N = 18-79 per cent. There is no indication of tautomerism in the present case, the

crystalline form remaining homogeneous under all conditions. I n view of the facility with which demethylation takes place in the case of the methylphenylamino-compound from monomethylaniline, described further on, it became of interest to ascertaiii whether demethylation could be effected by the action of aniline on the above compound. Under no conditions, however, could one of the methyl groups be removed, the compound remaining unchanged even when boiled for a short time with aniline. The interpretation of this observation in terms of the hypothesis suggested is t ha t the group D N ( C H ~ ) ~ is less favourable to inner salt formation than the group *N(CH,)*C,H,. The absence of tautomerism in the present case is in harmony with the view tha t the compound exists only in the form shown in the above formula, a view which is coin- pletely borne out by the colour, namely, yellow.

9 ctioti of I'iperidine otI 2 : 3 : 5-Tritiitl.oace:to-p-nirisididr.

The decomposition in this case was effected by dissolving the trinitro-compound in excess of piperidine, and keeping the solution a t looo for about an hour. Purification was effected by acid extrac- tion, as before. After crystallisation from dilute alcohol, the com- pound consists of minute, ochreous needles, which dissolve with a yellow colour in dilute alkali, bu t not. so freely as the foregoing

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compounds, the phenolic character being less pronounced. substance is 3 : 5-rlinitro-2- j’ipP’.idylnceto-p-allisidine :

The

Na-coa H, 0.1140 gave 16.3 C.C. N, (moist) a t 18.5O and 76‘7.4 mm. N z 1 6 . 6 3 .

C,~Hl,OGN, requires N = 16.57 per cent. It fuses

a t about 138O, and then partly solidifies again, melting finally a t 171-173O. It is possible that this behaviour on heating is con- nected with a tautomerisation which is not possible at lower temperatures, the crystals obtained from alcohol, etc., being always homogeneous. The phenomenon was equally pronounced in a speci- men specially purified by alkaline extraction, filtration, yrecipita- tion by acid, and crystallisation from alcohol.

This compound shows marked peculiarity on heating.

A ctz‘oic of il.iotromethylartilit~e 0 t h 2 : 3 : 5-Trit~ifronceto-p-nlt~isitliIle.

A solution of the trinitro-compound in excess of monomethylaniline was kept a t looo for about three hours, the product being isolated by acid extraction in the usual way. On crystallising from alcohol, the first crops of crystals proved to be unchanged trinitro-corn- pound, showing that the reaction was incomplete. The mother liquor after concentration was theref ore diluted with water, the precipitate collected and washed, and then warmed for soiiie time with dilute sodium hydroxide, so as to decompose any unchanged trinitro-compound which might remain in admixture with the pro- duct of the reaction.* The latter was recovered from the alkaline solution by precipitation with acid, and, after being collected and washed, purified by crystallisation from alcohol. A deposit of mixed crystals of ochreous needles and red scales was thus obtained, and it was at first concluded that the methylphenylamino-deriv- ative had the same property of tautomerism as the compound from aniline itself. Analysis and further examination showed, however, that the product was the same as that previously obtained by the action of aniline on the trinitro-compound, the identity being proved by the melting point, namely, 224O, and the transformation

* The original trinitro-compound dissolves in cold dilute alkali without clecom- position. If, however, the solution is warmed for some time decomposition takes placc with the formation probably of an acetglamino-guai,zcol derivative, The latter is soluble in water and is thus retained iu the inother liquor when the niain product is precipitated by acid. The reaction coiild, no doubt, be completed by longer heating of the solution of the trinitro-componnd in n~ono1neth~1:~nilinc.

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DERIVATIVES CONTAINING A MOBILE NITRO-GROUP. 989

of the red into the ochreous form a t 200O. A mixture of the crystals with some of the original aniline (phenylamino-) compound had the same melting point:

0.0924 gave 12.8 C.C. N, (moist) a t 17'5O and 764 mm. N=16*12.

As it was thought probable that this result might be due to the presence of aniline in the methylaniline, the experiment was re- peated with a specially purified specimen of monomethylaniline, purification of the latter being effected by fractional distillation. The purity of the base was proved by acetylating a portion and taking the melting point of the acetyl derivative. The crystals obtained, without further purification, had the melting point of methylacetanilide (101-102°), so that the specimen used was quite free from aniline. The mechanism of the process of demethylation has been discussed in the introductory portion of this paper. We may add that an attempt t o obtain a methylphenyl derivative by the direct methylation of the phenylamino-compound led to a negative result.

cI5Hl4o6N4 requires N = 16.19 per cent.

Action of Aniline o n 2 : 3 : 5-Trinitro-p-acetylaminophenol.

The trinitro-compound was prepared by the method described in a former paper (Meldola and Reverdin, T., 1913, 103, 1492). As the yield is not very good, and the initial 3 : 5-dinitrodiacetyl-p aminophenol somewhat difficult to prepare, we have had but a small quantity of material a t our disposal, and the results made known must be regarded as a preliminary contribution to this part of the subject.

The trinitro-compound is more sensitive towards bases than the corresponding trinitro-anisidine, since heating with aniline to looo for a short time results in complete decomposition, with the forma- tion of resinous products. A definite product was obtained by allowing aniline to act on the trinitro-compound a t the ordinary temperature for some days, and then isolating the product by acid extraction, as before. The compound was further purified by solu- tion in dilute alkali, filtration, and precipitation by acid. It crystallises from dilute alcohol in orange prisms, melting and d e composing a t about 214-216* :

N=17*13. 0.1293 gave 19.5 C.C. N, (moist) a t 19O and 751.5 mm. clgH1206N4 requires N = 16-87 per cent.

The compound is distinctly phenolic, dissolving in aqueous alkali with a yellow colour. The chief interest attaching to this

VOL. cv. 3 T

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990 FRANKLAND AND BARROW: MENTHYL ESTERS OF

3 : 5-dinitro-2-p~e?2.ylamilzo-p-ace tylaminophenol, from the point of view of the present research, is tha t the substitution of hydroxyl for the methoxy-group appears to destroy the faculty of tauto- merisation.

CITY AND GUILDS OF LONDON INSTITUTE; FINSBURT TECHNTCAL COLLEGE.

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