PREPARAnON AND PROPERTIES OF BRONOLAPACHOL. 15 111.-Prepuration a id Properties of Bromolcipctcl~ol. By SAMUEL c. HOOKER. IN my researches on the constitution of lapachol and its deril-atipes, I have shown that these substances are of peculiar interest, ot\-ing to the changes which readily occur in the quinone group, some of the componn& being derivatives of a-naphthaqninone, and some, deriva- tives of @-naphthaquinone. In order to furnish further examples of these changes, and in the hope of subsequently being able to formulate some general rules regarding them, I have prepared the compounds described in this paper. The preparation of dibromo-P-lapachone was described in a paper. recently presented to the Society (Trans., 1893, 63, 424) ; this com- pound, which can he readily obtained in comparatively large quanti- ties by following the directions there given, has furnished the material for this investigation.In a previous communication, I discussed at length the reconversion of bromo-,%lapachone into lapachol (Trans., 1852, 61, 615). I have EOW found that dibromo-p-lapachone may be, in like manner, readily converted into bromolapachol. The preparation of bromolapachol in this indirect manner is the more interesting because i t has so far proved impossible to obtain a simple bromine derivative of lapachol by the direct action of bromine.16 HOOKER : PREPARATION AND PROPERTIES I have previously called attention (Trans., 1892, 61, 621) to the Tery remarkable change which 13-lapachone undergoes in contact with concentrated hydrochloric acid, being fhereby quantitatively con- verted into a-lapnchone.It was also shown at the same time that a-lapachone can be quantitatively reconverted into /3-lapachone by merely dissolving it in concentrated sulphuric acid. Similar changes occur with the bromolapachones described in this paper. The relation hetween these compounds is shown in the following formulae. ~r-Bromo-~-lapachone.# nz-Bromo-a-lapachone. mz-Bromo-B-lapachone is an orange-red compound which melts a t about 205" ; it interacts very readily with orthotoluylenediamine yielding a yellow azine. nS-Brom-a-lapacbone is a pale yellow snbstance which fuses at 172*5-173*5". 0 On boiling with dilute aqueous alkalis, both cornpounds are readily converted into the same bromhydroxyhydrolap-achol, EXPERIMENTAL PART.0 To prepare bromolapachol, 10 grams of finely-powdered dibromo- p-lapachone are moistened with a 10 per cent. solution of sodium hydr- oxide: and very thoroughly ground to a paste; the quantity of the alkaline solution is then gradually increased until 100 C.C. in all have been used, t,he mixing being continned so as to insure entire freedom from lumps. The solution with the substance in suspension is then transferred to a small flask, 10 grams of zinc dust are added, and the flask is loosely corked, and slightly agitated at intervals during an hour, after which it,s contents are rinsed out and diluted with about * This compound is isomeric with the bromo-6-lapachone preViOUdy described (!ham, 1892, 61, 638), obtained by the action of bromine on lapachol. I hare added bhe prefix rtx to its name for purposes of distinction, intending to wnvq by the same that the bromine is situated in the naphthalene ring, but that ita exact position has yet to be determined.OF BROXOLAPACHOL.17 1500 C.C. of water. The zinc dust is separated as completely as pos- sible by decantation, and the diluted solution is then oxidised by drawing air through it by means of an ordinary filter pump. When the oxidation, which usually takes some hours, is complete, the solution is of a rich claret colour, and can be readily filtered off from the green, orange, and other particles in suspension. The solution should remain absolutely bright after filtration: if it passes through the filter paper with difficulty, or if a film forms over its surface, the oxidation is incomplete and should be continued.When thoroughly oxidised, the solution is poured" into an excess of dilute hydrochloric acid, and the resulting light yellow precipitate is washed and dried. Bromolapachol is thus obtained in a pure form, the yield being 6 grams. The reactions involved in its formation are precisely similar to those concerned in the reconversion of bromo-P-lapachone into lapachol (Tmns., 1892, 61, 615 and 642), and need no further explanation here. Bromolapachol may be obtained crystallised in leaflets very closely resembling lapachol, by boiling the substance, as a.bove obtained, with a quantity of alcohol insufficient to dissolve it. When a larger quantity of alcohol is used and the substance passes entirely into solution, it is redeposited, on cooling, in very characteiistic, golden scales, which reEemble flattened needles.The substance, crystallised from alcohol, gave the following figures on ad-jwis. 01570 e v e 0,3218 CO, and 0606 HzO. 0.1679 ,, 0.0975 AgBr. Br = 24.71. C1J313Br03 requires C = 56.07 ; H = 4.04 ; Br = 24.92 per cent. Bromolapachol can be reconverted into dibromo-p-lapachone by the action of bromine. The change corresponds precisely to the forma- tion of bromo-/3-lapachone from lapachol (Trans., 1892, 61, 639). 1 gram of bromolapachol dissolved in 35 C.C. of chloroform was added t o 0.5 gram of bromine in 15 C.C. chloroform. After standing a few minutes, the chloroform was distilled off from a water bath, and the residue dissolved in 10 C.C.of boiling alcohol ; dibromo-/I-lapachone began to crystallise out almost immediately; 0.95 gram was obtained.+ Bromolapachol dissolves in concentrated sulphnric acid forming * Not vice versd, or the precipitated bromolapachol will enclose considerable quantities of its undecomposed zinc salt. t The mother liquor was allowed to stand for some time ; it sloml~ deposit& yellow needles in small quantity, beSeved to be the previously described compound, 2C,,HI3Br3O3,HBr (Trans., 1893, 63, 433), which it resembled in appearance aa well as in its properties, as far 8 s the small quantity obtained rendered comparison possible. It melts at 170-171". C = 55-90; H = 4-28. VOL. LXV. c18 an intensely precipitated HOOKER : PREPARATION AND PROPERTIES orange-red solution, from which 12~-bromo-/3-Iapachone is on adding water.Tbis compound is formed by the action of concentrated sulphnric acid on bromolapachol, on bromhydroxyhydrolapachol, and on n”-brorn-a-lapachone ; in all three cases the conversion occurs quan- titatively. It is most conveniently prepared by dissolving 5 grams of bromolapachol in 25 C.C. of concentrated sulphnric acid, and pour- ing the solution into a, relatively large volume of water; bromo-p- lapachone separates in a crystalline condition, and, when well washed, is pure enough for most purposes. For analysis, it was crystallised from alcohol. C = 56-48 ; H = 4-64. I. 0.1815 gave 0.3759 CO, and 0.0758 HzO. fII. 0.1864 ,, 0.3832 ,, ,, 0.0736 ,, C = 56.06 ; H = 4.38. 111. 0.1212 ,, 0.0716 AgBr. Br = 25.13.ClaH13Br0, requires C = 56.07 ; H = 4.08 ; Br = 2492 per cent. n~-Bromo-/?-lapachone separates from alcohol in orange-red needles, which slowly darken on exposure to diffused daylight. It melts and decomposes at about 205” when the temperature is rapidly raised, and at lower temperatures when more slowly heated. It dissolves in most of the organic solvents without difficulty, although it is in most cases considerably less soluble than p-lapachone, which it closely resembles in appearance as well as in its reactions. It is converted by hjdrogen bromide or chloride into nZ-brom-a-lapachone, and by boiling aqueous alkalis into bromhydroxyhydrolapachol. nx-Bromo-P-lapachone combines very readily with orthotoluylene- diamine, in acetic acid solution, giving a yellow azine which dissolves i n concentrated snlphuric acid, forming an intensely violet solution.0 nx- B rom-a-lapachone, (?) Br This compound can be readily obtained by the action of hydrogen bromide on the corresponding Plapachone, It is most conveniently prepared as follows. 4 grams of ?zx-bromo-(3-lapachone, free from large crystals o r lumps, are immersed i n 120 C.C. of a solution of * I a m indebted to Mr. Ellwood Wilson for this combuslion.OF BROMOLAPACHOL. 19 hydrogen bromide, sp. gr. 1.49. The acid is then slowly heated, being finally kept at a temperature just. below its boiling point, until the orange crystals have disappeared and entirely given place to yellow ones, a change which soon occurs. When the solution is cold, it is diluted with water, and the compound is collected and thoroughly washed.It may be further purified by crystallisation from alcohol, in which it is not very soluble. 0.2039 gave 0.4180 CO, and 0.0765 H,O. 0.1463 ,, 0.0875 AgBr. Br = 25.45. nZ-Brom-a-lapachone crystallises from alcohol in pale yellow scales or plates which melt at 172-5-173-5". If the compound is dissolved in concentrated sulphuric acid, and the solution, after standing aboui 15 minutes, is poured into an excess of water, the isomeric nZ-bromo-/?-lapachone is obtained as an orange, crystalline precipitate. ns-Brom-a-lapachone is converted by boiling aqueous alkalis into bromhydroxyhydrolapachol. A 2 per cent. solution of sodium hydr- oxide is conveniently used for the purpose, the boiling being con- tinued until the greater part of the compound, which should be finely pdverised, is dissolved. The filtered alkaline solution is acidified with acetic acid, and bromhydroxyhydrolapachol is a t once precipi- tated in a crystalline condition. C = 55.90; H = 4-16. CISHl&3r03 requires C = 56-07 ; H = 4.04; Br = 24.92 per cent. 0 This compound may be most conveniently obtained by the action of a 2 per cent. solution of sodium hydroxide on nz-bromo-/?-lapachone, the directions above given for the conversion of nz-brom-a-lapachone into the same compound being followed. After crystallisation from absolute alcohol, bromhydroxyhydrolapachol gave the following re sulta on analysis. 0.2715 gave 0.5260 COz and 0.1082 H,O. C = 52-83 ; H = 4.42. 0.1997 ,, 0.1096 AgBr. Br = 23.35. ClaH,Br04 requires C = 53.09; 3 = 4.42; Br = 23.59 per cent. Bromhydroxyhydrolapachol separates from alcohol in two forms. It is sometimes obtained as golden leaflets or scales, and sometimes as dense crystals, which, when deposited slowly, attain considerable size. It melts at 164.5-165.5", and is readily converted into nz-brom-p-lapachone by concentrated sulphuric acid. c 2