536 MORGAN: ACTION OF FORMALDEHYDE ON AMINES OF THE

LVI.-Action o f Fownaldehyde on A.mines of the Naphthalene Sei-ies. Part I. By GILBERT THOMAS MORUAN, B.Sc.

THE interaction of formaldehyde and the amines of the benzene series has been extensively atudied in the past, especially since some of the compounds formed have been employed in the synthetical production of colouring matters. The production of the acridine yellows from condensation products of formaldehyde with certain of the benzenoid metadiamines and the synthesis of pararosaniline and its homologues (Meister, Lucius and Briining, D.R.P., 5393'7) may be quoted in illustration.

When formaldehyde acts on the primary benzenoid amines, the initial stage of the reaction gives rise to a series of unstable com- pounds which can be converted, usually by the action of acids, into more stable derivatives. Tollens found (Bey . , 1884, 17, 657, and ib id . , 1885, 18, 3300) that when formaldehyde was added to aniline suspended in water, anhydroformaldehyde-aniline, C,H,N:CH,, mas produced, and Eberhardt and Welter (Ber., 1894, 27, 1804), by the action of these substances in alcoholic potash, obtained methylene- diphenyldi-imide, CH,(NH* C,H,),. These two compounds are very unstable ; on boiling with solvents, they pass into oily, uncrystallisable forms, and on hydrolysis with dilute acids, aniline and formaldehyde are regenerated. When either of these compounds is heated with aniline and aniline hydrochloride, a rearrangement occurs whereby the methylene group becomes attached to two aromatic nuclei, and diamidodiphenylmethane is produced (Meister, Lucius, and Bruning, Zoc. cit. , and Eberhardt and Welter, Zoc. c i t , ) . This attachment may take place in two stages, for Meister, Lucius, and Briining (D.R.P., 87934) found that the intermediate compound, paramidobenzylaniline, is capable of existence, and on warming with dilute acids passes into the diphenylmethane derivative.

Orthotoluidine and formaldehyde give rise to a precisely similar series of compounds (Eberhardt and Welter, Zoc. c i t . , and Meister, Lucius, and Briining, D.R.P., 55565, 1890).

Paratoluidine yields an anhydro-base, C,H7N:CH, (Tollens, Ber., 1895, 18, 3302), and also methylenediparatolyldi-imide (Eberhardt and Welter, Zoc. c i t . ) ; the latter, when warmed with paratoluidine and i ts hydrochloride, yields a small quantity of diamidodiparatolylmethane inwhich the methylene group probably occupies the ortho-positionineach of the aromatic nuclei. Troger, by the action of methylal on paratolu- idine hydrochloride, obtained a base, CI7HlsN2, to which he ascribed the

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NAPHTHALENE SERIES. PART I. 537

constitution C,H,*N: CH* CH,*CH:N*C7H7 (J. p. Chem., 1887,36,226). I n the case of dimethylaniline, a preliminary attachment of methylene to the side chain is impossible, and accordingly tetramethyldiamido- diphenylmethane is the first product of the action of formaldehyde on the tertiary base (Troger, Zoc. ci t . ) . These examples indicate that, in the benzene series, formaldehyde is one of those numerous reagents which first attack the side chain, when, by rearrangement under the influence of acids, the methylene group enters the nucleus.

The action of formaldehyde on the two naphthylamines and their derivatives has been far less extensively studied. Reed (J. p 9 . C?tem., 1886, 35, 314) examined the products of reaction between methylal, acetone, and P-naphthylamine and obtained naphthacridine and a base, C2,H,,N2, melting at 202-203°, besides a small amount of methyl-/I-naphthoquinoline. By acting with methylal alone on P-naphthylamine, he obtained nothing but naphthacridine. 0. Fischer prepared a series of naphthimidazoles from formaldehyde and sub- stituted 1 : 2-naphthylene diamines (Ber., 1894, 27, 2773), and in this case the methylene group remained attached to the side chains. Formaldehyde and 1 : 2-aminonapht halenesulphonic acid produce diamidodinaphthylmethanedisulphonic acid, in which the methylene group has entered tho ring in a para-position relatively to the amido- groups (Meister, Lucius, and Briining (D.R.P., 84379, 1894).

I n the following experiments, P-naphthylamine was treated with formaldehyde under various conditions, in order to see how far the course of the reaction is comparable with that obtaining in the benzene series. It mill be seen tha t condensation between the aldehyde and the base may be accompanied by the elimination of ammonia and hydrogen, The tendency to form compounds in which the elimination of water is accompanied by the removal of hydrogen has already been noted in the formation of alkyl naphthocinchonic acids by the action of aldehydes (other than formaldehyde) and pyruvic acid on P-naphthylamine (Doebner, Ber., 1894, 2'7, 2020). Reed (Zoc. cit .) found that methylal acting on P-naphthylamine hydrochloride in excess of acid produced naphthacridine melting at 216".

+ 2CH,*OH + NH, + H2.

Troger (Zoc. cit.), performing a similar experiment on paratoluidine obtained a compound which indicated that a simple condensation had occurred between three molecules of the aldehyde and two of the base.

(2.) 2C7H7*NH2 + 3CH2(OCH,), = (C,,H,,N23CH2) + GCH,*OH.

I n my experiments, naphthylsmine not only reacts according to

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538 MORGAN: ACTION OF FORMALDEHYDE ON AMINES OF THE

Reed’s equation, but also in a manner analogous to that of para- toluidine.

A third mode of reaction occurs, giving rise to a small quantity of product in which hydrogen alone is eliminated, probably owing to the oxidising action of some of the other substances present.

Besides Reed’s naphthacridine (m. p. 2 1 6 O ) , another substance of like composition, C21H,,N, is produced according to the first equation ; this crystallises in orange-coloured needles, melts at 225--226O, and behaves in a peculiar manner with hydrogen chloride. When triturated with concentrated hydrochloric acid, or submitted to the action of the dry gas, a green hydrochloride is produced, from which the original base may be regenerated by the action of aqueous alkalis ; but on passing hydrogen chloride into a solution of the base in glacial acetic acid, or in benzene, a yellow hydrochloride is precipitated which yields Reed’s naphthacridine on treatment with alkalis. The same change is brought about by boiling the glacial acetic acid solution of the orange-coloured base for several hours; and also by the action of certain solvents, as, for example, acetone. When the substance is boiled for some days with acetone, orange needles no longer separate on cooling, but amber-coloured prisms of naphthacridine .are produced ; the conversion, however, when induced by this means is slow and incomplete. On the other hand, it appears that naphthacridine itself can be partially reconverted into the orange-coloured base by long boiling with a solution of sodium amyl oxide in amylic alcohol, but hitherto only about 30 per cent, of the naphthacridine has been changed into its isomeride.

The relationship between the constitution of these two bases must be a simple one, and it is quite conceivable that the orange base may be a quinonoid form of naphthacridine.

The formulae for the two bases would be

the former corresponding with naphthacridine and the latter with the orange-coloured base. The latter will be referred to as isonapl& acridine.

The formation of green salts from the orange-coloured isonaphth- acridine is a remarkable example of colour change. I n the benzene series, a colour change in the opposite sense is observed in the produc- tion of a yellow salt from green nitrosodimethylaniline. A remark- ably similar case presents itself in the naphthalene series, which, even i f only a coincidence, is worthy of note. a-Nitroso-P-naphthol is a yellow compound of admittedly quinonoid structure, and is usually represented by the formula O:C,,H,:NOH. This substance is acidic,

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NAPHTHALENE SERIES. PART I. 539

and its alkali salts are green (Ilinsky, Ber., 1884, 17, 2585). The imido-compound which is obtained from nitroso-/%naphthol is also green, and has the constitution NH:C,,H6:NOH (Ber., 1886, 19,343). It is quite possible that this colour change is characteristic of certain derivatives of P-naphthaquinone.

It will be somewhat difficult to obtain direct ev-idence in support of the two formulae suggested for the naphthacridines, for in the case of isonaphthacridine it is: difficult to select reagents which will act on it without first converting it into the more stable naphthacridine. When isonaphthacridine is heated with methylic or ethylic iodide in sealed tubes at 150°, a yellow methiodide or ethiodide is .produced ; both these substances, on treatment with alcoholic ammonia, give rise to naphthacridine, and are identical with the iodide produced by the alkyl iodides and this base. The salts of naphthacridine are all yellow, and the hydrochloride, hydriodide, methiodide and ethiodide possess the noteworthy property of crystallising from aniline without decom- position,

Reed supposed that acetone was necessary for the production of the base melting at 203O, to which he gave the formula C24H30N2, assum- ing it to be formed in the following manner.

......._ / - '\ ; ; ;C.H ..... -.-_ -

! .H . + . . ._ H ..- ;CloH6NH, '.' N i / .... ; H

C P H 3

C l o H 6 < N y + H20 + H,.

H\CH*C,,H,~NH~ y-Methyl-B-amidonaphthylhydronaphthoquinoline.

It has been shown conclusi ely, by the experiments described below, that acetone takes no part in the formation of this base, and that it is produced simply from formaldehyde and P-naphthylamine according to the following equation.

(3.) 2C,,H7*NH, + 3H*COH = C23HIgN2 + 3H2O. This compound is one of the products of the action of methylal on

P-naphthylamine hydrochloride, and is also obtained when form- aldehyde acts on the base in alcoholic, glacial acetic, or ethereal soIu- tions. The percentage of carbon required by the two formuls,

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540 MORGAN: ACTION OF FORMALDEHYDE ON AMINES O F THE

C2,H,oN2 and C23HlsN2, is the same, namely, 85.71, but the second contains less hydrogen and more nitrogen than the former, and the analyses given below agree more closely with the latter formula.

Many experiments were instituted with a view of determining more exactly the constitution of the base. From the above equation ex- pressing its formation, it will be seen that the compound cont,ains three 'methylene groups associated with two naphthylamine residues, C,oH6N(P) ; the problem was to trace the distribution of these radicles. The substance is very feebly basic, crystallises from glacial acetic acid in the free state, and does not form salts with acids in aqueous solutions. When nitrous acid acts on it in glacial acetic acid, a nitrite is produced which is easily decomposed by aqueous alkalis regenerat- ing the base. It appears to be a base containing only tertiary nitro- gen. This condition would be satisfied if each nitrogen atom were attached to a methylene radicle. When the base is heated with hydriodic acid and red phosphorus in sealed tubes a t 180°, it is found that two methylene radicles and one atom of nitrogen are eliminated, and that naphthacridine is produced, This indicates that the third methyl- ene group was directly attached to both the naphthalene nuclei, and accordingly the formula of the original base is best expressed in the following manner.

The first action in the sealed tube experiment is probably one of hydrolysis,

This diamine is not isolated as such, but undergoes condensation in accordance with the following equation.

The ammonia is eliminated in theoretical quantity, and the yield of naphthacridine is not less than 69 per cent. The formaldehyde which should be formed could not be detected, but it was scarcely to be expected that it would remain unchanged under the conditions of the experiment.

If this explanation of the experimental results is correct, the base Cj23H18N2 should be called dimethylenediaminodinaphthylmethane.

The fourth substance obtained by the action of formaldehyde on P-naphthylamine is formed according to this equation,

(4.) 2CloH7*NH2 + 2H* COH = c22H16N2 + 2H20 + H,,

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NAPHTHALENE SERIES. PART I. 541

but has hitherto only been obtained in small quantity, the yield being about 2 or 3 per cent. Its complete analysis gives the empirical formula Cl,H8N, and the analysis of its salts indicates that it is a monacidic base having the molecular formula C22HIGN2. The nitrite, which is produced by adding sodium nitrite t o its glacial acetic acid solution, has the formula C22H16N,,HN02, and again yields the base on treatment with aqueous alkalis. It appears, therefore, to be a tertiary base, but a more detailed investigation of its constitution will only be possible when a larger amount of the substance is available.

EXPERINENTAL.

Action of Formaldehyde on P-Naphthylamine in Acid$ecl Alcoholic Solution.

One hundred and forty-three grams of P-naphthylamine (1 mol.) were dissolved in 400 grams of alcohol, and 80 grams of 40 per cent. formaldehyde (1 mol.) were added to the warm alcoholic solution; the liquid became turbid and a heavy brown oil separated. On adding 37 grams of concentrated hydrochloric acid (3 mol.) slowly, the oily layer disappeared, and the clear solution, which was at first reddish- brown, on being heated on the water bath, changed to green. After boiling for half a n hour, a yellow, granular precipitate appeared and rapidly increased in quantity until the contents of the flask became almost solid, and. a t the same time an ammoniacal gas mas evolved. This was collected in hydrochloric acid and the platinochloride pre- pared, which, on analysis, proved to be the ammonium salt.

0,1334 gave 0.0582 Pt. Pt = 43.63. 0.0982 ,, 0.0429 Pt. Pt =43*68.

(NH,),PtCl, requires Pt = 43.80 per cent.

The yellow precipitate, after being collected and washed four times with hot alcohol to remove some ta r ry impurity, was dissolved in benzene and the solution allowed to crystallise, when orange-coloured needles were obtained. A portion of this was again crystallised from benzene, and then twice from alcohol, in which solvent it is only sparingly soluble ; it then melted at 225-226', sintering together a t about 221O.

0.1387 gave 0.4598 CO, and 0.0618 HO,. 0.2264 ,, 9.5 C.C. moist N at 20' and 1768.5 mm. N = 4.85.

C2,H1,N requires C = 90.32 ; H = 4.66 ; N = 5.02 per cent.

C = 90.41 ; H = 4.94.

The benzene mother liquor gave another crop of orange-coloured needles on standing for several days. The filtrate was then consider- ably concentrated, from 2 litres to about 250 c.c., when it deposited

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542 NORGAN: ACTION OF FORMALDEHYDE ON AMINES OF THE

a mass of pale yellow crystals melting at about 192'. This product, dissolved in ethylic acetate and allowed to evaporate spontaneously, yielded successive crops of mixed crystals containing two dissimilar kinds ; the predominant substance crystallised in irregular clusters of short, colourless prisms melting at 202-203', whilst the substance occurring in smaller quantity crystallised in amber-coloured prisms of a more acicular habit. The latter, on being picked out and recrystal- lised from alcohol, finally yielded straw-coloured needles melting at 21 6'. These properties identified the substance as Reed's naphth- acridine. The substance melting at 208-203°, when twice recrystal- lised from ethylic acetate, was obtained in well-defined, colourless prisms often exhibiting cruciform twinning.

0,1271 gave 0.3984 CO, and 0.0664 H20. 0.3122 23.2 C.C. moist nitrogen at 18.6' and 769 mm. N = 8.66.

C2,H,,N, requires C = 85.71 ; H = 5.59 ; N = 8.70 per cent. The alcoholic mother liquor from the original yellow precipitate,

when distilled on the water bath as long as alcohol came over, left a residue which separated into two layers, namely, an upper, aqueous layer which was found to contain only ammonium chloride and a little resinous matter, and a lower, brown, tarry mass which partially solidified on cooling. The latter was boiled with aqueous alkalis to decompose any chlorides which might be present, then extracted with benzene, petroleum carefully added to the benzene solution, and the clear solu- tion decanted from the tarry substance which separated; on now adding more petroleum, a substance crystallising in rosettes of small, yellow needles appeared on the sides of the beaker. This, after being collected and freed from admixed tar by washing with a little cold alcohol, was crystallised from the latter ; when pure, it is only sparingly soluble in alcohol. For the purpose of analysis, it was recrystallised repeatedly from ethylic acetate, from which it separates in tufts of woolly needles melting at 186-18'7'.

C=85*48 ; H = 5 * 8 0 . ,,

0.1297 gave 0.4055 CO, and 0.0617 H,O. C = S5.27; H = 5 * 2 8 . 0.1639 ,, 0.5144 CO, ,, 0.0766 H20. C = 8 5 . 6 0 ; H = 5 . 1 9 . 0.1699 ,, 13.60 C.C. moist nitrogen a t 17.5'and 768 mm. N = 9-37. 0.1342 ,, 10.6 C.C. ,, ,, 16' ,, 755 mm. N = 9 - 1 5 .

(C,,H,N), requires C = 85.71 ; H = 5-19 ; N = 9.05 per cent. I n this experiment, the total weight of recrystallised products was

about S6 grams, and was made up as follows: Isonaphthacridine, orange base, 35 grams ; naphthacridine, 7 grams ; C23H18N2, 41 grams ; and 3.5 of C,,H16N2.

Another series of experiments was made, using the same quantities as in the one described above, but in which the hydrochloric acid was added before the formaldehyde. The reaction in this case was more

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NAPHTHALENE SERIES. PART I. 543

violent, no separation of heavy oil occurred, and after one-fourth of the aldehyde had been added the whole turned green and became nearly solid, with considerable development of heat. The rest of the aldehyde was added more rapidly, when the whole mass became yellow, and after boiling for 2 hours the precipitate was collected and re- crystallised from benzene as in the preceding experiment. The yield of isonayhthacridine obtained by this method was larger than in the previous experiment, 70 to 80 grams being usually obtained, and the amount of the base, C23H1SN2, was less, usually about 18 grams. The amounts of naphthacridine and of the base, C2,H1,N,, remain about the same.

Lastly, the effect of using a larger quantity of formaldehyde was investigated. One hundred and forty-three grams of P-naphthyl- amine were dissolved in 500 grams of alcohol and 12Oigrams (14 mols.) of formaldehyde were gradually added. The first 60 grams appeared t o react energetically, a turbidity was produced, and a large quantity of heavy brown oil separated, but very little action accompanied the addition of the remainder of the aldehyde. Sixty-three grams of con- centrated hydrochloric acid were now slowly added, when the oily layer disappeared, the solution being a deep reddish-brown. After heating on the water bath for 46 minutes, a yellowish-green precipitate appeared; the heating was continued for another hour, and the pre- cipitate was collected and washed with hot alcohol. This precipitate weighed 25 grams. The filtrate, on standing 2 days, deposited a brownish-yellow, tarry precipitate which weighed about 47 grams. I n this experiment, therefore, more than half the product of reaction remains in the alcoholic mother liquor ; this was distilled until all the alcohol was driven off. The aqueous portion of the residue contained ammonium chloride, and the pitchy residue, separated from the aqueous portion, weighed about 100 grams.

The first precipitate, which owed its green colour to the presence of a small quantity of isonaphthacridine hydrochloride, was boiled with alcoholic ammonia to decompose any hydrochlorides, and then dis- solved in alcohol. The solution yielded a crop of crystals melting a t 176-177', but these were found to consist of a mixture of the base, C23H18N2, crystallising in semi-opaque, colourless prisms giving the correct melting point 202--203', and naphthacridine crystallising in amber-coloured prisms melting a t 214-215'. A mixture of the purified substances melted a t 169-170°, which is nearly the same as the melting point of the mixed crystals obtained in this ex- periment.

The second precipitate (47 grams) was extracted successively with hot water, hydrochloric acid, and a littJe alcohol ; the residue appeared t o consist almost entirely of the base C,,H,,N,, and when recrystallised

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544 MORGAN: ACTION OF FORMALDEHYDE ON AMINES OF THE

from glacial acetic acid melted at 201-202' (correct m. p., 202-203'), the weight obtained being 22 grams.

The residue (100 grams) was likewise extracted with hot water, hydrochloric acid, and alcohol, and the almost white product, on recrys- tallisation from acetic acid, gave 60 grams of the base C,,H,,N,.

The aqueous and hydrochloric acid extracts were mixed and neutra- lised with sodium carbonate, and the pale yellow precipitat'e collected, and recrystallised from alcohol, and then from ethylic acetate, when it separated in tufts of woolly needles melting at 186--181O, and was identical with the base, C2,HlGN2, obtained in the former experiment. When formaldehyde is in excess, the chief product is the substance C23H,,N, and in this experiment 100 grams of the recrystallised base were obtained, together with 5 grams of naphthacridine, a small quantity of isonaphthacridine, and 3 to 4 grams of the base C,,H,,N,.

About 20 grams of tarry matter were also formed, from which nothing definite could be extracted. I n these experiments, great difficulty. was experienced in separating naphthacridine from the base, C23H1SN2, for they crystallise together from their solutions in alcohol, acetone, ethylic acetate, and benzene, and from glacial acetic acid the acetate of naphthacridine separates along with the free base, C2,H18N2. Further experiments have shown that they can both be obtained with great ease by reactions which yield them as the sole products.

Isonaph t ha w i d ine, C ,, H, SN.

The analysis of the orange base, C,,H,,N (page 541), indicates that it is isomeric with Reed's naphthacridine, and it has been found possible to prepare i t by a method not involving the use of acids, or of any solvent which might convert any portion of it into the latter base.

Meister, Lucius, and Bruning (D.R.P., 53937, 1889) employ anhydroformaldehyde-paratoluidine as a carrier of the methylene group in the formation of diphenylmethane derivatives, for example, when aniline is heated with it, diamidodiphenylmethane is produced and paratoluidine is regenerated,

When this reagent is heated with P-naphthylamine, the chief product is isonaphthacridine; in this case, ammonia and hydrogen are eliminated.

C,H7*N:CH2 + 2U,,H7*NH2 = C,,H,,N + C,H,*NH, + NH3 + H2.

The hydrogen probably acts destructively on a portion of the reacting materials, for some tarry matter is always produced, and the yield is only about 44 per cent. of the theoretical.

Seventy grams of P-naphthylamine were melted with 35 grams

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NAPHTHALENE SERIES. PART I. 545

of anhydroformaldehyde-paratoluidine, and the fused mass kept at 170-180" until the evolution of ammonia had ceased. The brownish- yellow melt after being broken up into small pieces, was steam distilled until all the paratoluidine and some of the P-naphthylamine had passed over into the distillate, and the residue, freed from the remaining P-naphthylamine by repeated extractions with hot water, was recrystal- lised from benenze; the weight of crystallised isonaphthacridine obtained was 30 grams. The filtrate, on concentration, deposited nacreous plates, which, after recrystallisation from ethylic acetate, melted a t 169'. A small portion mixed with a little pure PP-dinaphthylamine also gave this melting point, thus identifying the substance with this base. The mother liquor from the dinaphthylamine deposited a brown sub- stance, which, on crystallisation from alcohol, melted at 175'. The addition of petroleum to the benzene filtrate caused the separation of a tarry oil, and on adding more petroleum to the clear solution a semi-solid, brown mass separated a t the bottom of the beaker, and after some time a brownish-yellow deposit formed on the sides ; on recrys- tallisation from alcohol, this yielded a substance melting a t about 175', which was added to the former crop melting a t this temperature, and the whole recrystallised several times from alcohol, when 1 a 8 grams of a pale yellow substance melting at 178-179" were obtained.

This compound crystallises well from alcohol in fine, asbestos-like needles, which spread through the whole bulk of the solution, and show no tendency to cling to the sides of the crystallising vessel. When collected, these shrink together, forming a closely felted mass of a pale yellow colour. The solution in alcohol exhibits a reddish-violet fluorescence like that of naphthacridine.

0.1230 gave 0.3984 CO, and 0.0590 H,O. 0*1680 ,, 8.7 C.C. moist N at 19' and 775 mm. N = 6.08.

C = 88.33 ; H = 5.33.

C,,H13N requires C = 88.88 ; H = 5.35 ; N = 5.76 per cent.

The results of analysis indicate that the substance is probably a tolyl analogue of naphthacridine of the formula,

The alcoholic filtrates from the recrystallisation yielded very small quantities of naphthacridine and of the base C,,H,,N,. A quantity of tarry matter was also produced in this reaction, from which nothing definite could be extracted. A portion of the isonaphthacridine, after being thrice recrystallised from benzene, melted at 225-2269 sintering together before melting at 221'.

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546 M O R G A N : ACTION OF FORMALDEHYDE ON AMINES OF THE

0.0987 gave 0,3254 CO, and 0.0442 H,O. C = 89.92 ; H = 4.97. 0*190’i ,, 0.6291 CO, ,, 0.0873 H,O. C=80*97 ; H = 5 * 0 9 . 0.1495 ,, 7 C.C. moist nitrogen at 24’ and 764 mm. N = 5.28,

C21H,3N requires C = 90.32 ; H = 4.66 ; N = 5.02 per cent.

The remainder of the 30 grams obtained in this operation were recrystallised six times from benzene, but no alteration in the melting point or in the colour of the substance was noticeable. It crystallises from benzene in beautiful, orange needles, and the solution exhibits a reddish-violet fluorescence. When a portion is sealed up with benzene and heated until it has all dissolved and the solution allowed to cool slowly, lath-like, orange crystals are obtained over half an inch long. The compound is sparingly soluble in alcohol, one part dissolving in about 300 of the hot solvent, but it is almost insoluble in the cold. It is three times as soluble in amylic alcohol as in ethylic alcohol, and separates from both these solvents as a felted mass of fine orange needles.

When the base is triturated with strong hydrochloric acid, an in- soluble green hydrochloride is produced. Some of the hydrochloride prepared in this way, after being washed with cold alcohol and ether, was dried over quicklime in a partially exhausted desiccator and nnalysed ; chlorine determinations made with this specimen indicated that the combination with hydrogen chloride in aqueous solution was incomplete, the percentage of chlorine being lower than that required for the monhydrochloride. 0.6035 gram of the base was subjected to the action of the dry gas, when the base turned green, and the tube containing it became perceptibly warm; a stream of dry air was then drawn through the tube for several hours to remove the excess of hydrogen chloride, and the weight of hydrochloride then obtained w s 0.6754 gram. This corresponds with an addition of 10.64 per cent. of hydrogen chloride, the value calculated for the monhydrochloride, C21H13N,HCl, being 11.5.

Conversion of Isonuphthacridine into Nophtimcridine. On passing dry hydrogen chloride into isonapht hacridine dissolved

in dry benzene, a yellow hydrochloride was precipitated which was collected, washed with dry benzene and dry ether, dried at l l O o , and analysed.

0.2349 gave 0.1074 AgC1. C1= 11-31, 0.2220 ,, 8.8 C.C. moist nitrogen at 20° and 760 mm. N = 4.53.

C,,H,,N,HCl, requires C1= 11.25 ; N = 4.43 per cent,

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NAPHTHALENE SERIES. PART I. 3 47

On treating this salt with aqueous alkalis, naphthacridine melting a t 2 16O, and not isonaphthacridine, was obtained, which on treatment with hydrochloric acid again furnished the yellow hydrochloride.

1.2450 grams of isonaphthacridine, recrystallised six times from benzene, were dissolved in about 50 C.C. of glacial acetic acid, and dry hydrogen chloride passed into the warm solution ; the hydrochloride which came down at first had a green tinge, but eventually became yellow; it was collected in a Gooch crucible, washed with glacial acetic acid and dry ether, dried a t 110-120°, and weighed; 1.397 grams were obtained, the theoretical quantity being 1 *4086 grams. The base, liberated by warming the salt with ammonia, was pale yellow and melted at 213-214' (naphthacridine melts at 216'); i t was then recrystallised from alcohol, and the first crop of crystals weighed 1.12 grams and melted a t 215O, and when mixed with pure naphthacridine there was no depression in the melting point.

0.1676 gave 0.5546 CO, and 0.0723 H20. C = 90.23 ; H = 4-79, C2,H,,N requires C = 90.32 ; H = 4.66 per cent.

Action of Solvents on honaphthacridh?.

Isonaphthacridine is f a r less soluble in ordinary solvents than naphthacridine. The alcoholic mother liquors from the recrystallisa- tion of isonaphthacridine slowly deposit amber-coloured prisms of naphthacridine ; 1 -5 grams of recrystallised isonaphthacridine, heated with acetone for several hours, on cooling, deposited 0.6 gram of naphthacridine (m. p. 21 6") in clear, amber-coloured prisms.

One gramof isonaphthacridine, after six cry stallisations from benzene, was boiled for 5 days with just sufficient acetone to keep it in solution when boiling; the quantity of orange needles separating was less each morning, until at the end of that time the crystals were no longer of this form, but appeared as amber-coloured prisms. The acetone was dis- tilled off, and the residue recrystallised from alcohol, when 0-65 gram of naphthacridine was obtained in the first crop of crystals, which only gave the yellow hydrochloride; the filtrate, on evaporation, gave a residue which gave a greenish-yellow hydrochloride, indicating that the conversion was not quite complete.

When isonaphthacridine is dissolved in hot glacial acetic acid, and the solution quickly cooled, its acetate separates in rosettes of green needles, but when the solution is boiled for some time, the yellow acetate of naphthacridine crystallises out on cooling.

Isonaphthacridine appears to be a tertiary base ; when treated with benzoic chloride by the Schotten-Baumannmethod, it remains unchanged, but when boiled for some time with acetic anhydride, i t is convertedinto naphthacridine, which crgstallises out in amber-coloured prisms. When

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548 MORGAN: ACTION OF FORMALDEHYDE ON AMINES OF THE

sodium nitrite is added to its solution in glacial acetic acid, a brownish- yellow substance is obtained insoluble in the ordinary solvents, but soluble in aniline, from which i t crystallises in yellow needles ; this is an unstable nitrite of naphthacridine, for on digesting i t with cold alcohol (90 per cent.) i t is decomposed, yielding naphthacridine. As a proof that all the nitrous acid had been removed by this treatment, the nitrogen was determined in the naphthacridine so produced.

0.2772 gave 11.5 C.C. moist nitrogen a t 22' and 764 mm. N= 4.72. C,,H,,N requires N = 5.02 per cent.

Action of Alkyl Iodides on Isonaphthacridine,

Isonaphthacridine was heated with excess of methylic iodide in sealed tubes a t 140'; the yellow methiodide produced was insoluble in the ordinary solvents, but crystallised from aniline in small, golden-yellow plates, decomposing somewhat indefinitely a t 262-264'.

I = 30.60. C,lH,,NCH,I requires I = 30.08 per cent.

0.1368 gave 0,0775 AgI.

The ethiodide was similarly prepared, and crystallises from aniline

0.1148 gave 0.0606 AgI. C,,H:,,N*C,H,I requires I = 29.04 per cent.

Both these substances are derivatives of naphthacridine, for on treating them with alcoholic ammonia, or even on digesting them with undried ether, this base is liberated.

in short, orange-yellow prisms melting at 283-2849 I = 28.52.

Nuphthacridine.

Reed's method of preparation was repeated. A mixture of 33 grams of methylal with 30 grams of acetone was saturated with hydrogen chloride at lo', and then added to a mixture of 65 grams of P-naphthyl- amine and 200 grams of concentrated hydrochloric acid; the temperature rose considerably, and the mixture at once became brown. After being allowed to remain overnight, it was heated for 5 hours on the water bath, and then poured into an excess of caustic soda solution ; ammonia mas evolved, and a brown, tarry mass was obtained, which mas extracted with hot water to remove P-naphthylamine, and then with ether to remove some of the oily impurity. The residue was dissolved in acetone, and the solution treated with alcoholic picric acid solution as in Reed's experiment (loc. cit.). The first crop o€ picrate yielded impure naphthacridine which required many recrystallisations before its melting point remained constant a t 216O, the second crop of

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NAPHTHALENE SERIES. PART I. 549

picrate, obtRi ned after distilling over t wo-thirds of the acetone, yielded the base C,,H,,N,, which was purified by recrystallisation from ethylic acetate.

In Reed's second method, naphthacridine was obtained by the action of methylal alone on P-naphthylamine ; this experiment was repeated, using the proportions employed by Reed. As the mixture of methylal and P-naphthylamine hydrochloride in excess of hydrochloric acid was heated to loo', i t was observed that at a certain stage it became yellowish-green, and on further heating changed to yellow ; this change indicates the formation of isonaphthacridine as an intermediate product, and its subsequent conversion into naphthacridine. The mixture was made alkaline with caustic soda, the /I-naphthylamine removed by hot water, and the residue dissolved in alcohol ; the alco- holic solution deposited light yellow needles mixed with a brown im- purity. The whole deposit was again boiled with alcohol until the greater portion had dissolved, and the residue crystallised from ethylic acetate, when the base C,3H,,N, was obtained, melting at 203' and crystallising in its very characteristic manner, in colourless prisms.

The alcoholic mother liquor yielded impure nnphthacridine which was only obtained pure after a tedious series of recrystallisations.

Naphthacridine is most easily prepared from isonaphthacridine, as the latter is quantitatively converted into it. It is merely necessary to dissolve isonaphthacridine in glacial acetic acid heated to boiling for 6 or 7 hours, and allow the solution to cool, when brownish-yellow crystals of naphthacridine acetate separate. These, after being col- lected and washed with acetic acid and alcohol, are decomposed by ammonia solution ; the naphthacridine thus obtained, after two crys- tallisations from alcohol, is quite pure, and crystallises in beautiful, straw-coloured needles melting a t 2 16'.

0.1384 gave 0.4568 CO, and 0 0585 H,O. C21H13N requires C = 90.32 ; H = 4.66 per cent.

Naphthacridine appears to crystallise in two forms ; from its concen- trated solution in alcohol, i t separates quickly as straw-coloured needles, but when allowed to crystallise more slowly from its solution in alcohol, ethylic acetate, acetone, or benzene, it forms clear, amber- coloured prisms, which become opaque on drying at looo. Both forms have the same melting point, and give the yellow hydrochloride.

The determination of the molecular weight of nnphthacridine was made by the freezing point method.

0.2155 i n 17.46 benzene gave a depression of 0.226".

The molecular weight of isonaphthacridine could not be obtained

VOC. LXXTTT. 0 0

C = 90.03 ; H = 4.68.

Jf = 280 ; C,,H,,N = 279.

in this way, owing t o its great insolubility in cold benzene.

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550 MORGAN: ACTIOX OF FORMALDEHYDE ox AMINEY OF THE

Naphthacridine, heated with methylic iodide in sealed tubes a t 140°, gives a yellow methiodide insoluble in all lorn boiling point solvents, which crystallises from aniline in golden-yellow scales decomposing near 263", and is identical with that obtained by the action of methylic iodide on isonaphthacridine.

0.0973 gave 0*0550 AgI. I = 30.54. C,,H,,NCH,I requires I = 30.08.

The ethiodide prepared in a similar manner is identical with that from isonaphthacridine ; it crystallises from aniline in orange-yellow prisms, and decomposes a t 282-283O.

0.1 160 gave 0.0637 AgI. C2,H1,N*C,H,I requires I = 29.04.

In studying the products of the hydrogenation of isonaphthacridine and naphthacridine by the action of sodium and amylic alcohol, it was noticed that both compounds yielded a substance crystallising in red needles, which is being further investigated ; isonaphthacridine also appeared to remain partly unacted on, whilst naphthacridine, under similar conditions, gave a certain quantity of isonaphthacridine. An experiment mas therefore made with a view t o determine whether naphthacridine could be reconverted into isonaphthacridine by the action of sodium amyloxide. Five grams of naphthacridine were dis- solved in 100 grams of amylic alcohol, mixed with 60 grams of amylic alcohol in which 7 grams of sodium had been dissolved, and the mixture heated for 24 hours. The amylic alcohol was then driven off by steam distillation, and the residue dried and dissolved iu benzene, A crop of orange needles separated which weighed 2 grams ; these did not melt at 216O, but at 225-226", and yielded the green hydrochloride. The filtrate contained a mixture of isonaphthacridine and naphthacridine, and it has not been found possible to make this conversion complete.

I = 29-66.

The Base C,,H,,N,.

This base is obtained by the action of methylal or of formaldehyde on P-naphthylamine in the presence of hydrochloric acid.

Action of Fomnaldehyde on P-Naphthylamine in Glacial Acetic Acid. -Seventy-two grams of P-naphthylamine were dissolved in 250 grams of glacial acetic acid, the solution cooled to 3", and 60 grams of 40 per cent. formaldehyde solution" (18 mols.) slowly added with con-

* Although the formaldehyde solution employed in these experiments gave no indi- cations of acetone when submitted to the tests for this substance, an experiment was made with a sample of formaldehyde solution prepared from pure methylic alcohol

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NAPHTHALENE SERIES. PART 1'. 351

stant stirring. A white, amorphous precipitate separated until the mixture acquired a pasty consistency, but, on standing for about an hour, the precipitate redissolved, and the clear liquid was decanted from a slight amount of tar which remained insoluble. A crystalline precipitate then gradually separated ; this was filtered off, and alcohol added to the filtrate, and tbe whole heated to boiling; on cooling, a second crop was obtained; on pouring the mother liquor into a large quantity of water, a resinous mass separated, which, after being ex- tracted with a little alcohol, became granular and crystalline. The entire crystalline product weighed 68 grams, and was purified by re- crystallisation from glacial acetic acid, when it melted at 202-203'. The crystals may be obtained colourless by boiling the acetic acid solution with a little zinc dust.

A portion, after four crystallisations from alcohol, gave the following numbers on analysis.

0.1364 gave 0.4312 CO, and 0.0694 H20. C = 86.21 ; H = 5.65. 0.1409 ,, 0.4437 CO, ,) 0.0721 H,O. C = 85.87 ; H = 5.68. 0.1 128 ,, 0.3549 CO, ,, 0.0576 H,O. C=85.81 ; H=5*67. 0.2040 ,, 16.2 C.C. moist N a t 24.5" and 766 mm. N= 8-95.

An analysis of this base made from formaldehyde and P-naphthyl- amine in alcoholic solution gave the following.

0.1328 gave 0,4172 CO, and 0.069 1 H,O. C = 85.68 ; H = 5-80, 0,3200 ,, 23.4 C.C. moist N at 16.5" and 768.5 mm.. N = 8.62.

The mean of these analyses including those of page 542, gave the following values.

C = 85.81 ; H = 5-72 ; N= 8.77 per cent. C,,H,,N, requires C = 85.71 ; H = 5.59 ; N = 8.70.

A molecular weight determination by the freezing point method

0.4106 in 18.87 benzene gave a depression of 0*340°.

C,,H2,N, ,, C = 85-71 ; H = 5.95 ; N = 8.33.

gave the following results.

M = 326. 0.1660 ,, 26.84 ,, 9 , 9 9 0.099O. M = 320.

C,,HI,N2 = 322 ; C,,H,,N, = 336.

I n preparing the base by the method just described, the soIution must be kept quite cold during the addition of the formaldehyde, otherwise the temperature rises very rapidly to 40' or 50°, the solution turns green, and a large amount of tarry matter is produced, from

which was kindly placed at my disposal by Messrs. Mercklin and Losekann, of Hanover. As the base melting a t 203' mas obtained equally readily under these conditions, there can be no doubt that acetone plays no part in the condensation.

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552 IMORGAN: ACTION OF FORMALDEHYDE ox AMINES OF THE

which the base cannot be obtained. One quantity which had been spoiled in this way was examined, in order to see whether any definite product could be isolated. For this purpose, the green, tarry mass was extracted with benzene, to which sodium carbonate was added, in order to decompose any acetates which might be contained in the tar. The benzene solution deposited orange needles of isonaphthacridine, the yield being about 10 per cent. on the amount of P-naphthylnmine employed.

The base C2,Hl,N2 is readily soluble in acetic acid, benzene, amylic alcohol, and ethylic acetate, sparingly in ethylic alcohol and in ether, crystallising from these solvents in colourless, transparent prisms often showing cruciform twinning.

It remains unchanged under the influence of reducing agents, zinc dust and acetic acid being without action on it, and the greater part of the substance is recovered when subjected to the action of sodium and amylic alcohol. A strong aqueous solution of sodium nitrite, when added to an acetic acid solution of the base, precipitates a colourless nitrite which is decomposed into the base and nitrous acid, even on agitation with moist ether. The non-formation of a nitrosamine o r of a diazo-salt in this experiment points to the conclusion that the base contains only tertiary nitrogen.

When heated with strong hydrochloric acid at 180°, only ammonium chloride and a black, tarry mass are obtained, whilst at lower tem- peratures the base remains unaltered.

Convemion of the Bccse C,,Hl,N2 into 2Vaphthucridine.

Forty grams of the base were sealed up with 8 grams of red phos- phorus and 60 grams of strong hydriodic acid (sp. gr. 1.94) and heated for 5 to 6 hours at 180'. The tubes were found to contain a small quantity of permanent gas which contained phosphine, an aqueous, strongly acid layer, a small quantity of an oil lighter than water and having a penetrating odour, and a brown, resinous mass. The liquid portions were poured off from the resinous product and steam distilled, when the oil passed over with the distillate. This was shaken up with ether, and on distilling off the solvent only about 0.5 C.C. of oil was left. The whole quantity obtained from two series of experiments, when distilled, boiled between 205' and 215'; its solution in chloroform slowly decolorised bromine, with evolution of hydrogen bromide. These properties resemble those of the di- and tetra-hydro- naphthalenes, but the amount obtained was so small that the substance was not further investigated.

The aqueous solution left in the distilling flask after removal of the oil was made alkaline with soda and distilled; ammonia was evolved,

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NAPHTHALENE SERIES. PART I. 553

and on being collected in hydrochloric acid and evaporated to dryness, weighed 6.2 grams. The quantity which should have been obtained, supposing that half the nitrogen was eliminated as ammonia., is 6.4 grams.

The resinous portion was found to be insoluble in all the low boiling point solvents, but it dissolved in aniline, and the solution on cooling deposited bronzy-yellow flakes which were collected and dried on porous plates; 35 grams of the recrystallised substance were obtained. This substance proved to be tho hydriodide of naphthacridine, and the yield of recrystallised product was 69 per cent. of the theoretical.

After three crystallisations from freshly distilled aniline, followed by extraction with dry ether in order to remove the solvent as far as possible, a specimen gave the following numbers.

0.1316 gave 0.0741 AgI. 1=30*41. 0.1344 ,, 0.0759 AgT. I = 30.51.

C,,HI,N,HI requires I = 31 *11 per. cent.

The naphthacridine obtained from the hydriodide by warming it with alcoholic potash, after repented crystallisation from alcohol, melted at 214-215', and the melting point remained unaltered when mixed with pure naphthacridine (m. p. 216').

0,1593 gave 0.5314 CO, and 0.0690 H20. C,,H,,N requires C = 90.33; H = 4.66 per cent.

The result throws considerable light on the constitution of the base C,,H,,N, ; one of the methylene radicles must be directly attached to the two naphthalene nuclei, and since the base is a tertiary one, the other two are probably attached to the two nitrogen atoms.

The formula of the substance may be written in the following manner, CH,( Cl,,H6N:CH2)r An explanation of the reaction with hydriodic acid aud red phosphorus, and the graphical formula of the substance, are given in the theoretical part of the paper.

Although this is such a beautifully crystalline substance, it does not yield well-defized crystalline derivatives. It is sulphonated when treated a t 100' with sulphuric acid containing a little sulphur trioxide, but the free sulphonic acid forms a gelatinous mass and its barium and potassium salts are devoid of any tendency to crystallise. The action of bromine or nitric acid gives rise to indefinite insoluble products.

C = 90.41; H = 4.81.

The Base C22H16N2, melting at 186-187'.

This is the substance which is formed in small amount (about 2 per cent.) when formaldehyde reacts with an alcoholic solution of P-naph- thylamine in the presence of hydrochloric acid.

Its complete analysis (page 542) has indicated the empirical formula

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554 FENTON A N D GOSTLING: ACTION OF HYDROGEN BROMIDE

C,,H,N. Its hydrochloride, prepared by dissolving the base in alcoholic hydrochloric acid, is deposited in tufts of fine, white needles melting indefinitely a t 355".

0.1398 gave 0.0566 AgC1. C1= 10.01. C,,H,,N,,HCl requires C1= 10.30 per cent.

The base is fairly soluble in hot alcohol, but almost insoluble in the cold, and readily soluble in ethylic acetate or acetone, from which it crystallises in tufts of fine, pale-yellow needles. It is sparingly soluble in hot water, and dissolves readily in benzene, from which it is precipitated by light petroleum. It is exceedingly soluble in cold glacial acetic acid, and when sodium nitrite is added to this solution a copious white precipitate, consisting of the nitrite, separates in rosettes of small, colourless needles. A nitrogen determination of the substance gave the following.

N = 12.10. 0.1257 gave 12.9 C.C. moist nitrogen a t 14' and 761 mm. C,,H,,N2HN0, requires N = 11 -83 per cent.

The base is regenerated from the nitrite on treatment with aqueous soda. When treated with hydriodic acid in the cold, i t gives a blue precipitate, and when heated with this acid and red phosphorus at 180°, no definite product is obtained and no nitrogen is eliminated as ammonia.

ROYAL COLLEGE OF SCIENCE, LOXDON.

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