THE CONDENSATION OF DIMETHYLAMINOBEKZALDEHYDE. 1207 CXX1.-The Condensation of D.rmethylam.inobenxalde- hyde with p-Naphthol. By JOHN THEODORE HEWITT, ALFRED JOHN TURNER, B.Sc., and SIDNEY WALLACE BRADLEY. THE condensation of aldehydes with P-naphthol has been studied by various chemists with the general result that one molecule of the aldehyde unites with two molecules of the naphthol to give derivatives of the type R*CH(C,,H,*OH),, or corresponding internal anhydrides, R*CH(C,,H,),O. Substances of the first series have been obtained from formaldehyde (Hosaeus, Ber., 1892, 25, 3213; Abel, Ber., 1892, 25, 3477), 0- and m-nitrobenzaldehydes (Zenoni, Gaxxetta, 1893, 23, 2 16), and benzalde- hyde (Hewitt and Turner, Ber., 1901, 34, 202), whilst internal anhy- drides have been produced from P-naphthol and acetaldehyde and benzaldehyde (Claisen, Annalen, 1887, 237, 270), the three nitro- benzaldehydes (Zenoni, Zoc.cit.), and various other aromatic aldehydes (Rogoff, Ber., 1900,33, 3535). Considerable interest attaches to the compounds of the anhydride type, since they may be regarded as leuco-derivatives corresponding with carboxonium salts, and the authors were engaged in a study of their oxidation products when they were anticipated by Werner (Beg*., 1901, 34, 3300), who published an account of oxonium salts derived by the action of oxidising agents on phenyldinaphthylene oxide, c,H,*cH<~~o~~>o. C H 10 6 In the present communication, the condensation of P-naphthol with dimethylaminobenzaldehyde is described. It is a pleasant duty for the authors to record their best thanks to Geb.-Medizinalrath Professor1208 HEWITT, TURNER, AND BRADLEY: THE CONDENSATION OF Ehrlich for the kindness he has show'n in placing a considerable quantity of the latter substance in a pure condition at their disposal.Conndemation of Dimethylaminobenealdehycle with P-Naphthol in Cold Acetic XoZution.-If a glacial acetic acid solution of dimethylamino- benzaldehyde (1 mol.) and P-naphthol (2 mols.) be acidified with con- centrated hydrochloric acid (2 mols.) and allowed to stand at the ordinary temperature for a week, crystals are deposited. When collected, washed, and then recrystallised from a large quantity of glacial acetic acid, small, hard, brilliant prisms are obtained, which for analysis were dried a t 110': - 0-1296 gave 0.3615 CO, and 0.0658 H,O, 0,1227 ,, 3.3 C.C.nitrogen a t 17' and 756 mm. N=3*07. C = 76.07 ; H= 5.64. 092006 ,, 0.0659 AgCl. C1= 8.13. C,9H2,0,NCl requires C = 76.36; H = 5.76; N = 3.08; C1= 7.78 per cent. On heating, the substance darkens somewhat at about -150' and finally melts a t 215" with decomposition. Although the crystals are practically colourless, the hot concentrated solution in glacial acetic acid appears blue; after cooling, when the greater portion of the substance has been deposited, the shade is red, whilst a green fluorescence is observed. Probably the coloration is to be ascribed to limited oxidation, the direct product being the hydrochloride OF a, base, (CH,),N*C,H,* CH( C,,H,-OH),. A specimen of the chloride which had been kept for some months exhibited a lower melting point.As it was possible that the result might be due to a partial formation of an anhydride a t the expense of the hydroxyl groups whereby, owing to mixture, the original melting point would be lowered, the salt was dissolved in glacial acetic acid, an excess of concentrated hydrochloride acid added, and the solution boiled for a few hours under reflux. The boiling solution was filtered hot and the crystals deposited on cooling were collected and dried. The melting point was then found to be 257'; the substance gave on analysis numbers which proved the loss of a mol. of water: 0,1469 gave 0.4282 CO, and 0.0777 H,O. 0.1450 ,, 3.97 C.C. nitrogen at 17' and 758 mm. N=3*14. C = 79.49 ; H = 5.87. C,,H,,ONCl requires C = 79.50 ; H = 5.54 ; N = 3.21 per cent.Condensation of DimetI~yZ~minobenxaldei~~~e with P- Naphthol in Hot Xolutiom-Salts of the base C,,H230N are immediately obtained if the condensation is carried out in hot instead of i n cold solution. The following method of preparation is satisfactory both in point of yield and purity of product. Twenty grams of P-naphthol and 10 grams of dimethg laminobenzaldehyde are dissolved in 120 C.C. of glacial acetic acid, Twenty grams of strong sulphuric acid diluted with 10 c.cDIMETHYLAMINOBENZALDEHYDE WITH ,&NAPHTHOL. 1209 of water are next added and the mixture boiled for one hour. More dilute sulphuric acid is added and then hot water until a specimen shows that a copious crystallisation takes place on cooling; the bulk OF the solution is then cooled and the crystalline mass collected, well washed, digested for some time with hot potassium hydroxide solution, filtered off, well washed, and dried. For purification, the substance is recrystallised several times by solution in boiling pyridine and addition of light petroleum; it then separates on cooling in a beautifully crystalline condition.It is, however, remarkable that the crops obtained from the first crystallisation, although appearing to consist of a practically pure substance, melt-at 194-197' (199-202O corr.), and give numbers on analysis too low in carbon, If the substance be recrystallised subsequently from boiling xylene, it is obtained as colourless prisms melting a t 2 14-215' (corr.), and furnishing the following results on analysis : 0.2321 gave 0,7354 CO, and 0.1223 H20.0.2248 ,, 6.47 C.C. nitrogen at 5' and 756 mm. N=3.47. C = 86.42 ; H = 5*85. C,,H,,ON requires C = 86.72 ; H = 5.79 ; N = 3.50 per cent. The substance is very easily soluble in pyridine bases whether hot or cold, boiling aniline dissolves the compound readily, but it is not very soluble in the cold solvent, in alcohol it is very sparingly soluble; hydrocarbons of the benzene series dissoive it fairly easily, especially if hot, hence xylene on account of its higher boiling point makes a better solvent than benzene. Acetic acid if hot dissolves the base with ease, probably in the form of an acetate. Although salts are formed with many acids, the latter do not form good solvents, as most of the salts are practically insoluble in water.The chloride, C,,H2,0N,HCl, is obtained either by passing dry hydrogen chloride into a benzene solution of the base, or more easily by dissolving the base in boiling glacial acetic acid and adding fuming hydrochloric acid until the beginning of a disturbance. The chloride separates as a colourless, crystalline powder consisting of obliquely terminated prisms melting at 257-260'. The substance is thus seen to be identical with the chloride obtained by boiling dinaphthol- dimethylaminophenylmethane hydrochloride with a mixture of acetic and hydrochloric acids, 0.1455 gave 0.0470 AgC1. C1= 7.98. C,,H,,ONCl requires C1= 8.09 per cent. The pZatinichZoride, (C,gH,,ON),,H,PtCIG, was prepared by adding a solution of platinum tetrachloride in- concentrated hydrochloric and acetic acids to a solution of the base in ten times its weight of acetic acid.The substance separated in-small, yellow, rhomboidal tablets melting at On analysis :1210 HEWITT, TURNER, AND BRADJ,EY: THE CONDENSATION OF 256'. following result on analysis : 0,1543 gave 0.0246 Pt. The suZpiuxlte, C,,H,,ON,H,SO,, obtained by the action of sulphurio acid in excess, and purified by recrystallisation from a mixture of alcohol and sulphuric acid, was obtained as small, colourless needles melting at 231-232O with decomposition. The melting point depends somewhat on the rate of heating, and may vary by several degrees : It is very sparingly soluble in all solvents and furnished the Pt = 15.95. (C,,H,,0N)2,H2PtCl, requires Pt = 16.07 per cent.0,1046 gave 09702 CO, and 0.0533 H,O. 0-1649 ,, 0.0764 BaSO,. H,SO,= 19.46. C?29N,30N,H2S0, requires C = 69.67 ; H = 5.16 ; H,SO, = 19.24 per cent. The picrate, C2,H,,0N,C6H307N3, separates on mixing solutions of the constituents in benzene. The salt obtained was at first thought not to be homogeneous, since besides larger well-defined prisms, tufts of small needles were obtained. On heating the solution to the boil- ing point, it was found that the latter went into solution and separated out on slow cooling in the prismatic condition. Since the two crops of crystals exhibited the same melting point, there can be no doubt as to the uniformity of the substance ; the following analysis was carried out with a mixture of the two crops : C = 70.50 ; H = 5.66.0.1042 gave 0.2534 CO, and 0.0428 H,O. C= 66.32 ; H = 4-56. C,,N,,O,N, requires C = 66-62 ; H= 4.16 per cent. The salt forms shining, yellow prisms melting at 194-196'. The methiodide, C,,H,,ON,CH,I, is produced by warming the base for some time with an excess of methyl iodide. At first the base dis- solves completely ; soon small, pale yellow crystals begin to separate, which, after collection, washing with methyl alcohol, and drying in a vacuum over lime melt a t 226-227". 0.1882 gave 0*0807 AgI. Attemptcl at Oxidation.-From the constitution of this base, it seemed I = 23.19. C,oH,,ONI requires I = 23.35 per cent. very probable that a carbinol would result on oxidation :DIMETRYLAMINOBENZALDEHYDE WITH &NAPHTHOL. 121 1 This should correspond to salts of one of the following types : A Experiments made in this direction showed that the substance was very resistant to oxidising agents, a result already foreshadowed by the stability of the platinichloride.Action of Ferric Chloride.-One gram of solid ferric chloride dis- solved together with 3 C.C. of fuming hydrochloric acid in an excess of glacial acetic acid, was added to a boiling solution of the base in glacial acetic acid. After heating for 1+ hours in a reflux apparatus, the solution was poured into an excess of dilute hydrochloric acid ; the crystalline precipitate thereby produced was collected, well washed and dried. The melting point of the substance so obtained was 259-260' ; when mixed with the hydrochloride of the original base, no depression of melting point was observed.Action of Peroxides.-On dissolving the base in hot acetic acid and adding sidphuric acid and lead or manganese dioxide, no oxidation to a colouring matter was effected; the base after recovery melted a t 208' (uncorr.), and did not depress the melting point of the substance prepared directly. Action of Bromine.--Bromine was also employed on account of its greater activity. Five parts of the base were dissolved in glacial acetic acid, the solution well cooled, and 2 parts of bromine diluted with acetic acid added gradually. A precipitate was obtained melting at 196' (uncorr.) ; this was collected and dried : 0.1638 gave 0.1070 AgBr. The salt being somewhat coloured, it was thought probable that an Br = 27.80. C29H230NBr, requires Br = 28-50 per cent. oxonium compound : C H C6H,*C<CIOH6>0 Br , HBr ( CH,) 10 6 had been produced; since, however, alkali only removed a portion of the bromine, and the base obtained contained 72.2 per cent. of carbon, it was evident that only one bromine atom was present in an ionisable condition, the other atom having replaced hydrogen in1212 RUHEMANN: THE ACTION OF ETHYL either the benzene or one of the two naphthalene nuclei. Contrary to expectation, the conclusion seems to be inevitable that xanthen derivatives obtained from dimethylaminobenzaldehyde show little or no tendency to pass into carboxonium compounds on oxidation, EAST LONDON TECRHICAL COLLEGE.