1202 BEWITT AND AULD: THE ACTION OF CXX.-The Action of Substituting Agents o n Benzene- axo-6- Naphthol. By J, T, HEWITT and S. J, M. AULD. THE authors recently communicated the results they had obtained in studying the action of bromine on benzeneazo-a-naphthol, and now describe the action of bromine as well as of nitric acid on benzeneano- @naphthol. Some years ago, Margary (GTaxxetta, 1883, 13, 438) added bromine in molecular proportion to a solution of benzeaeazo-P-naphthol in glacial acetic acid; the product obtained melted at 160-161' andStJBSTITUTINa AGENTS ON BENZENEAZO-B-NAPHTHOL. 1203 was recognised as p-bromobenzeneazo-/I-naphthol from the fact that p-bromoaniline was obtained on reduction with stannous chloride and hydrochloric acid, As has frequently happened in cases of this sort, no precautions were taken to avoid the influence of mineral acids, and it was thus of interest to repeat the bromination with addition of sodium acetate, as well as to study the action of nitric acid of various concentrations.Action of nitric Acid. Action of Nitric Acid of sp. gr. 1.15.--Two grams of benzeneazo-/3- naphthol were added to an excess of nitric acid (sp. gr. 1-15). Apparently no change took place in the cold; the mixture was then heated over wire gauze until a vigorous reaction set in, when the flame was withdrawn. The reaction being finished, excess of cold water was added, the solid residue collected, and mashed free from nitric acid. After drying and recrystallisation from benzene, a brownish-red powder was obtained melting at about 168', and obviously consisting of a mixture of substances.The powder proved to be for the greater part soluble in hot dilute sodium hydroxide solution; on cooling, a sodium salt separated in such quantity as to form a thick, crystalline paste, The crystals were collected, again recrystallised from hot water, and decomposed with hydrochloric acid, The substance obtained melted a t 191' (uncorr,) after recrystallisa- tion from hot glacial acetic acid, from which solvent it was deposited as small, pale yellow needles : 0.1479 gave 15.4 C.C. nitrogen at 19' and 745 mm. N= 11.90, C,,H,0SN2 requires N = 11.99 per cent. The identity of the compound with 1 : 6-dinitro-P-naphthol, C,,H,(NO,),*OH, was fully established by the fact that when mixed with a specimen of this substance it did not depress its melting point.The small residue left after extraction with sodium hydroxide was bright red in colour, and after recrystallisation from glacial acetic acid melted a t 241-242' (uncorr.); its identity with p-nitrobenzeneazo-P- naphthol was established by the fact that when mixed with the synthetical product no depression of melting point could be observed. A repetition of the nitration with acid of sp. gr. 1.15 resulted in the production of 0.5 gram of p-nitrobenzeneazo-/I-naphthol and 1 *6 grams of dinitronaphthol from 2 grams benzeneazo-/3-naphthol, The weights refer to crude products ; recrystallisation from benzene was omitted. Practically the whole of the azonaphthol employed is accounted for, about one-fifth of the benzeneazo-P-naphthol employed being nitrated in the benzene nucleus, whilst the other four-fifths are attacked in the naphthol nucleus, the benzeneazo-group in position 1 4 L 21204 HEWITT AND AULD: TEE ACTION OF being replaced by the nitro-group, whilst substitution also takes place in position 6.This result is, however, not inconsistent with initial nitration in the benzene nucleus and subsequent destruction of the nitrobenzeneazo- group. To test the possibility of this explanation, 2 grams of p-nitrobenzeneazo-P-naphthol were heated for some time with an excess of dilute nitric acid of sp. gr. 1-15, On treatment of the product with sodium hydroxide solution in the manner already indicated, it was found that most of the p-nitrobenzeneazo-p-naphthol remained unattacked, and only a small quantity of the 1 : 6Ldinitro-P-naphthol was obtained.The resistance displayed by t h i s nitro-substituted azo- compound towards the action of dilute nitric acid compared with the readiness with which the parent benzeneazonaphtho1 is attacked, shows that 1 :6-dinitro-P-naphthoI must be looked on as a primary product of the action of dilute nitric acid on the latter substance. Action of a Mixture of Concentrated Nitric and Xu@hzcric Acids.- Nitric acid added to a solution of benzeneazo-/3-naphthol in excess of con- centrated sulphuric acid, converts the substance nearly quantitatively into p-nitrobenzeneazo-/3-naphthol. Two grams of benzeneazo-P-naph- thol were made into a paste with 20 C.C. of concentrated sulphuric acid, and 0.76 gram of nitric acid (sp. gr.1.4) mixed with concentrated sulphuric acid gradually added, the mixture being cooled and well stirred. After standing overnight, the mixture was poured into water and the precipitate collected, washed, and dried. The weight of substance obtained was 2.30 grams. Replacement of one hydrogen atom by one nitro-group should have given 2.36 grams. To ascertain how far the product consisted of p-nitrobenzeneazo-P- naphthol, it was warmed with dilute sodium hydroxide solution ; the residue weighed 1-78 grams and melted at 2 3 4 O , but after recrys- tallisation from glacial acetic acid, the melting point was 239' (uncorr.). The hot alkaline filtrate deposited solid matter to the extent of 0.14 gram on cooling; this was not a sodium salt, but melted in the crude condition at 221', and after recrystallisation at 239' (uncorr.), the substance did not depress the melting point of p-nitrdbeneazo-P-naph- thol.On acidification, the final filtrate deposited a tarry mass which was disregarded. Action of Bromine. In Absence of Sodium Acetate.-The bromination of benzeneaso-P- naphthol has been studied by various chemists. Typke (Ber., 1877, 10, 1550) stated that bromine entered the naphthalene nucleus; the result was contradicted by Margary (Gaexetta, 1883, 13, 438), who ob- tained a substance melting at 160-161' which furnished p-bromo- aniline on reduction. Margary conchded that the substance producedSUBSTITUTING AGENTS ON BENZENEAZO-P-NAPHTHOL. 1205 was p-bromobenzeneazo-P-naphthol, a result confirmed by Zincke and Bindewald (Ber., 1884, 17, 3032), who, however, gave the melting point as 167-1 68'.Finally, Bamberger synthesised p-bromobenzene- azo-/?-naphthol from p-nitrosobromobenzene, /?-naphthol, and hydroxyl- amine, giving the melting point as 172-173' (Ber., 1895, 28, 1222). We find that if finely powdered benzeneazo-/3-naphthol be suspended in ten times its weight of glacial acetic acid and brominated in the cold with the calculated quantity of bromine dissolved in acetic acid, p-bromobenzeneazo-P-naphthol is obtained in practically quantitative amount ; aftev recrystallisation, the substance melts a t 170' (uncorr.). The identity of the substance was confirmed by mixing with the syn- thetical compound, when no depression of melting point was observed.The formation of p-bromoaniline on reduction was also put beyond doubt by distilling the reduction mixture, after rendering alkaline, in a current of steam, and benzoylating the base contained in the distil- late. The recrystallised benzoyl derivative contained bromine and melted at 200° (uncorr. j. In Presence of Sodium Acetate.-Experiments mere next made on the action of bromine in preseiice of sodium acetate. At the ordinary temperature, bromine appears to be without action on a solution of benzeneazo-@naphthol in glacial acetic acid if sodium acetate has been added. Even on boiling, reaction, if it takes place at all, is extremely limited. A t 165-170O under pressure, the bromine is used up in half- an-hour. On pouring into cold water the product of the action of 3.5 grams of bromine on 5 grams of benzeneazo-@naphthol dissolved to- gether with 3.5 grams of fused sodium acetate in 50 C.C.of gIacial acetic acid, a brown tar was deposited which liquefied completely below looo. Attempts to separate the mass into its constituents were extremely un- satisfactory ; a small quantity of a crystalline powder was obtained on one occasion by dissolving the mass in ethyl acetate and adding acetic acid, the excess of ethyl acetate being removed by distillation. The substance melted a t about 260° (uncorr.) and contained bromine : C = 65.8 ; H = 3.5. 0.0818 gave 0.1936 CO, and 0.0261 H,O. 0.0810 ,, 0.0231 AgBr. Br= 12.1. 0,1068 ,, 0-0308 AgBr. Br = 12-3 per cent. The substance is evidently not a monobromobenzeneazo-&naphthol, which would require 24.4 per cent.of bromine ; probably it is formed by the condensation of 2 mols. of the azo-compound. The quantity of the substance produced is so extremely small, that, whatever its structure, it can have but little bearing on the constitution of benzene- azo-P-napht hol.1206 HEWITT AND AULD : BENZENEAZO-&NAPHTHOL, Bromobenxeneaxo-/3-nap?~tho Is. During the progress of the work described above, the three bromo- benzeneazo-/I-naphthols were prepared for purposes of comparison, and further characterised by conversion into acetyl or benzoyl derivatives. o-Bromo6enxene~z0-P-n~~htrllol was prepared in the customary manner ; it melts at 165O. It is best obtained by recrystallisation from boiling benzene, from which it is deposited as small, brownish plates; it dissolves easily in carbon disulphide, and is taken up fairly readily by acetic acid, acetone, ethyl acetate, ether, or light petroleum.Its soh- bility in alcohol is slight : 0.1472 gave 0.0847 AgBr. The acetyl derivative separates from glacial acetic acid as small, 0.1368 gave 0.0698 AgBr. Br = 24.49. C1,Hl10N2Br requires Br = 24.43 per cent. brown crystals with a bronzy lustre and melts at 157' : Br = 21.94. C,,H,,O,N,Br requires Br = 21.69 per cent. m-Bromobenzeneaxo-~-naphthot, recrystallised from benzene, forms broad, red needles exhibiting a beautiful reflex; it melts at 172' : 0.2239 gave 17.0 C.C. nitrogen at 20" and 737 mm. 0.2460 ,, 0.1414 AgBr. Br= 24.22. N = 8.61. Cl,Hl10N2Br requires N = 8-59 ; Br = 24.43 per cent. The acetyl derivative melts at 88O:af ter recrystallisation from glacial acetic acid : 0.3012 gave 20.5 C.C. nitrogen a t 20' and 759 mm. The benzoyl derivative is a beautiful, dark red substance, crystallising 0.2176 gave 12.0 C.C. nitrogen a t 22O and 770 mm. N = 7.72. C,,H,,O,N,Br requires N = 7.48 per cent. in obliquely terminated prisms and melts at 159O : N = 6.45. C23H1502N2Br requires N = 6.49 per cent. p-Bromobenxeneaxo-/3-naphthoI has already been described ; the melt - ing point we observed for the substance agreed with that given by Bamberger. The acety2 derivative forms beautiful, dark red needles and melts at 136' : 0.1784 gave 0.3813 CO, and 0.0598 H,O. C = 58.29 ; H = 3.68, Cl,Hl,0,N2Br requires C = 68-53 ; H = 3.52 per cent.THE CONDENSATION OF DIMETHYLAMINOBEKZALDEHYDE. 1207 The benxoyl derivative melts at 157*, and separates from glacial 0,2344 gave 0°1012 AgBr. Br = 18.41, C2,HI50,N2Br requires Br = 18*05 per cent. acetic acid as very dark red needles : EAST LONDON TECHNICAL COLLEGE.