UERIVATIVES OBTAINED FROM #-PYROCRESOLE. 51 X.-Some Derivatives and New Colouring Matters obtained from a-Pyrocresole. By WILLIAN BOTT Ph.D. Berkeley Fellow of Owens College and J BRUCE MILLER A.I.C. Owens College. THE authors have been investigating the reactions of a-pyrocresole and its derivatives with a view of definitely ascertaining its consti-tution and expect shortly to be able to publish their results. I n t'he meantime it seemed worth while to describe a number of new derivatives which have been obtained and whose preparation is not directly connected with the main reaearch as yet uncompleted 52 BOTT AND MILLER SOME DERIVATIVES AND Trichlol.-a-PyrocresoZe C15H,,Cls0. This compound was obtained by the protracted action of chlorine on solutions of a-pyrocresole in chloroform or carbon tetrachloride, and repeatedly recrystallising the product from boiling benzene.It forms a white bulky mass consisting of slender silky needles which under the microscope are resolved into characteristic aggregates of thin transparent flat prisms or bars. The compound is insoluble in water alcohol ether and acetic acid but soluble in chloroform and still more SO in boiling benzene. Its melting point is very high but cannot be determined with precision as the substa,nce although quite pure melts only gradually first showing signs of melting about 225". The following numbers were obtained on analysis :-Oombustion. I. 0.198 gram substance gave 0.418 gram I T . 0.268 gram substance gave 0561 gram H20. HZO . Chlorine Determination.CO and 0.0625 gram CO and 0.0'775 gram I. 0.1995 gram substance gave 0.2796 gram AgCl. Pound. Calculated for r-&-T C1,H,iCl,O. I. 11. C 57.41 p. c. 57.30 57-83 p. c. H . . 3-50 , 3-43 321 ,, CI 33.98 , 34.62 - . 7 7 0 (by difference). 5.11 , 5.11 5.11 ,, It will be seen that in both analyses the carbon found is too high and the hydrogen too low this discrepancy being accounted for by traces of chlorine that is of hydrogen chloride having found their way into the potash bulbs during combustion. The chlorine in the sub-stance cannot be readily determined by Carius' method as the compound is not always completely decomposed by nitric acid ; the chlorine therefore was estimated by heating with pure lime. Dinitro-a-Pyrocresole Oxide C1bHIO(NO,),O,.In a former paper the three tetranitro-derivatives of the pyrocresoles have been described no other nitro-compounds being known. We have lately obtained the first intermediate nitro-derivative namely, dinitro-a-pyrocresole oxide and are now trying to obtain the corre-sponding compounds from p- and ypyrocresole. The a-derivativ NEW GOLOURING MATTERS FROM a-PYROCRESOLE. 53 was prepared by adding a-pyrocresole oxide to cold concentrated nitric acid in small portions at a time until a dark reddish-brown solution was obtained. Upon the addition of water a yehowish precipitate was thrown down consisting of a mixture of the dinitro-product with unaltered oxide. The latter was removed by extraction with boiling alcohol and the residue recrystallised from glacial acetic acid or nitrobenzene.The pure substance forms yellowish-white crystals which are very slightly soluble in hot water slightly soluble in alcohol a little more so in glacial acetic acid and freely in hot nitrobenzene. They melt at about 235" with very slight decomposi-tion and when heated more strongly decompose but do not burn with a flash like the tetra-nitro-compound. On annlysis the corn-pound gave the following numbers :-0.192 gram substance gave 0.4075 gram CO and 0.063 gram H20. 0.195 , , 15.6 C.C. moist N at 15" and 748.5 mm. Calculated for Ci5H10(N02) 2O2. Found. C 57.32 p. c. 57.88 p. c. H 3-18 , 3.64 ,, 0 30.51 , (calc.) 30.57 ,, N 8.92 , 9-22 ,, Reduction of the Nitro- compounds. The formation of amido- and other reduction-products has already been observed by W.Bott a considerable time ago but we have only recently begun a closer study of the action of alkaline and acid reducing agents on the nitro-derivatives of the pyrocresoles. The results so. far obtained open out a wide field of investigation and comprise the beginnings of a new series of colouring matters which probably differ essentially in composition and structure from the azo-colours already known. The compounds of a-pyrocresole only have thus far been examined. Tetramido-a-Pyrocresole Oxide CI5H,( NH,) &O,. This compound has been obtained by the reducing action of tin on the corresponding nitro-derivative suspended in a mixture of strong hydrochloric and glacial acetic acid. The reaction is hastened by working under pressure.The amido-derivative is also formed by means of zinc-dust and acetic acid hydriodic acid and similar reduc-ing agents in acid solution but tin answers the purpose best. After complete reduction the brownish-yellow solution is evaporated to expel excess of acid the tin removed by sulphuretted hydrogen aa 54 BOTT AND MlLLER SOME DERIVATIVES AND the filtrate made slightly alkaline with caustic soda or ammonia, which precipitates the amido-compound as a greenish-yellow mass. This is well washed with water and niay be further puri6ed by redis-solving it in dilute hydrochloric acid passing sulphuretted hydrogen to remove traces of tin which obstinately adhere to it and reprecipi-tating the base with alkalis. I t is not necessary to recrystallise the compound from alcohol in which moreover it is not readily soluble.Tetramido-a-pyrocresole oxide thus prepared forms a greenish-yellow powder sparingly soluble in alcohol and ether and almost insoluble in benzene. It is soluble in acids and the solutions give a dark red-dish-brown coloration with sodium hypochlorite. The melting point appears to lie considerably above 300° but has not yet been accurately ascertained. 0.140 gram substance gave 23.5 C.C. moist N at 12" and 756 mm. bar. Calculated for C15Ht3 (N H2) 4O2. N 1 9 . 7 1 ~ . c. Found. 19.55 p. c. Diamido-a- Pyrocresole Oxide C,H, (NHJ 202. This substance is obtained from the new dinitro-compound in the same manner as the previous derivative. Its properties have not yet been closely examined but in appearance and solubility it greatly resembles the tetramido-compound.0.161 substance gave 16 C.C. moist N at 16" and 761 mm. bar. Calculated for C15H10(NH2) 2O2. N 11.02 p. c. Found. 11.40 p. c. Azo-dei-ivatives of a-Pyrocresole Oxide. Both the tetra- and di-amido-derivatives of a-pyrocresole oxide cau be diazotised in dilute acid solutions in the ordinary manner. It will, in all probability be impossible t o isolate the diazo-salts from these solutions on account of the unstable character peculiar to these sub-stances but from the examination of some more stable derivatives, their composition that is the number of diazo-groups present may, we hope be deduced. The solutions of these diazo-salts react in the well-known manner with phenols giving rise to the formation of oxyazo-compounds.This reaction takes place most readily with alkaline solutions of /I-naphthol and the compounds thus formed represent the first colouring matters obtained from pyrocresoles. I f a diazotised solution of tetramido-a-pyrocresole oxide is adde NEW COLOURING MATTERS FROM a-PTROCRESOLE. 55 to an alkaline solution of (3-naphthol a bright-red precipitate is immediately thrown down consisting of the oxyazo-compound. After washing with cold water and drying on a water-bath it foi-nis a dark-red powder insoluble in water but soluble in alcohol ether, chloroform and benzene. With concentrated sulphuric acid it gives a beautiful and characteristic reaction dissolving in the strong acid with st dark-green colour which on gradual dilution with water changes to red the colouring matter being reprecipitated in red flakes.This reaction somewhat resembles the test given by safranine, which also dissolves in concentrated sulphuric. acid with a green colour. With safranine the green colour is however readily dis-charged by a drop of strong nitric acid which i n the case of the new colouring matter changes the colour from green t o purple but does not discharge it. By means of fuming acid containing 30 to 60 per cent. of SO, the colonring matter can be sulphonated and obtained in solution It dyes silk and wool a fine maroon shade. By the action of diazotised solutions of diamido-a-pyrocresole oxide on alkaline solutions of &naphthol a red colouring matter is formed resembling the previous compound in all respects but pos-sessing a brighter and finer shade.Like the preceding compound it gives a highly characteristic test with strong sulphuric acid and yields soluble sulphonic acids suited for dyeing purposes. It imparts to silk and wool a bright salmon colour. By the action of the diazo-salts on an alkaline solution of a-naphthol a brownish colouring matter is formed which dissolves in strong sulphuric acid with a beautiful dark-blue colour and is repre-cipitated by water. The closer examination of the above colours is being proceeded with and we shall extend the reaction to other mono-phenols and to the meta-series of the diphenols and arnidophenols. Regarding the composition of these new colouring matters we can at present only conclude from their mode of formation that they nre oxyazo.compounds or trapzeolins but the number of azo-groups con-tained in their molecules remains to be ascertained by a careful esti-mation of the nitrogen in the purified products. We shall then also be able to deduce the formuh of the diazo-compounds originally present in solution. The action of reducing agents in alkaline solution on the nitro-derivatives of a-pyrocresole oxide gives rise to the formation of azo-compounds and also of small quantities of amido-products. The reaction with ammonium sulphide is particularly interesting. If a small quantity of tetranitro-a-pyrocresole oxide is heated with alcohol and a few drops of ammonium sulphide the supernatant liquid assumes a reddish-brown colour and on the addition of hydrochloric acid and warming a red precipitate is thrown down insoluble in wate 56 LING SOME METALLIC DERIVATIVES but soluble in chloroform ether benzene and acetone with a reddish-violet colour.It is practically insoluble i n carbon bisulphide and may thus be separated from any admixture of sulphur. It dissolves in concentrated sulphuric acid yielding a yellow solution and is re-precipitated by water in dark-red flakes. If in the above experiments the action of the ammonium sulphide is allowed to continue €or some time the solution with hydrochloric acid no longer yields a red colour ; on diluting with water a yellow precipitate is formed soluble in alcohol ether and chloroform but almost insoluble in benzene. It is very sparingly soluble in cold water a little more so in hot water, the solution dyeing silk a bright-yellow shade. As the red and yellow substances have only been prepared quite recently we have not had time to study them more closely. From the manner in which they are produced it appears probable however, that the red substance is an azoxy- or oxyazo-derivative whilst the yellow substance is derived from it by reduction. The probable constitution of the derivatives described in this com-mimication will be discussed in our next paper on the structure of a-pyrocresole