66 AESOHLIMANN, LEES, MCCLELAND, AND NICKUN :

X.-Organic Compounds of Arsenic. Part II . Deriv- atives of the Arsenic Analogue of Carbaxole.

By JOHN ALFRED AESCHLIMANN, NORMAN DEIMPSTER LEES, NIAL PATRICK MCCLELAND, and GEORGE NORMAN NICKLIN.

TURNER and BURY have shown (J., 1923, 123, 2489) that the closure of five-membered arsenic rings of the type As-methyl- dihydroarsindole can be accomplished without difficulty, and two of us have found (J., 1924, 125, 2025) that the same applies to certain five-membered rings containing three atoms of carbon, one atom of oxygen, and one of arsenic.

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ORGANIC COMPOUNDS OF ARSENIC. PART II. 67

It is now shown that the five-membered arsenic ring of analogues of carbazole can be closed with similar ease and it is hoped to give in a future communication an account of the formation of arsenic a,nalogues of indoxyl and related substances.

o-Aminodiphenyl, subjected to the Bart reaction, yields diphenylyl- o-arsinic acid (I), and this is converted by warm concentrated sulphuric acid int'o 00'-diphenylyleneaminic acid (11).

Similarly, diphenylyl-o-arsenious chloride, on distillation in a vacuum, is converted into 00'-diphenylylenearsenious chloride. Various other derivatives of 00'-diphenylylenearsine have been prepared, but the parent substance could not be isolated owing to the readiness with which it is oxidised in the air,

The derivatives are all beautifully crystalline, colourless with the exception of the iodide, and non-fluorescent. The melting point is usually about 100"thigher than that of the corresponding diphenyl derivative.

E S P E R I J I E X T A L .

o-Amino~iiphe72yZ.-Hirsch's method for the preparation of this base (Ber., 1892, 25, 1973) was modified in that the diazoamino- benzene was prepared as a separate operation, whereby the volume of solvent was much reduced and the tedious drying over potash obviated. Further, since it was not necessary to isolate p-amino- diphenyl, the separation of the required base from the other products of the reaction was considerably simplified.

Diazoaminobenzene (150 g.) is covered with 400 g. of aniline (both thoroughly dry) in a large distilling flask, and heated until (at about 150") a brisk evolut'ion of nitrogen begins; after which the reaction should proceed smoothly to completion, the tem- perature slowly rising to 180". Care is necessary not to overheat the mixture, as the reaction may then get out of control. After removal of the aniline, the residue is distilled to about 250" (20 mm.) or until the distillate is very much coloured. The oily distillate is treated with warm dilute sulphuric acid (60 g. in 1 litre for 100 g. of the oil), the residue (diphenylamine and p-aniinodiphenyl sulphate) removed, and the solution concentrated, alinost to dryness. The sulphate of o-aminodiphenyl crystallises, while most of the aminoazobcnzene sulphate remains in the mother- liquors. The base is obtained from the sulphate in the usual manner and distilled in a vacugm (yield about 25 g.). For further

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68 AESCHLIMANN, LEES, MCCLELAND, AND NICKLIN :

purification, crystallisation of the hydrochloride from concentrated hydrochloric acid by cooling a saturated solution to - 10" is recommended.

Diphenylyl-o-arsinic Acid (I).-Sodium arsenite is coupled with diazotised o-aminodiphenyl in alkaline solution a t 50-60" in pres- ence of a cupric salt. The acid crystallises from boiling water in bristle-like needles, m. p. 205". Yield about 60% (Found : C = 51.7 ; H = 4.1. C,,H,O,As requires C = 51.8 ; H = 4-00;;).

Diphenylyl-o-arsenious chloride, obtained by the reduction of the above dissolved in warm concentrated hydrochloric acid, by sulphur dioxide in presence of an iodide, is a heavy oil, soluble in chloroform, insoluble in water. On distillation in a vacuum, it loses hydrogen chloride and yields 00'-diphenylylenearsenious chloride.

DiphenyhyZ-o-arsenious oxide, obtained by the action of alcoholic potash on the above, is an amorphous substance with no definite melting point.

00'- Diphenylylenearsinic Acid (II).-A solution of diphenylyl- o-arsinic acid in concentrated sulphuric acid is warmed on the water-bath for a few minutes and poured into water. 00'-Diphenylylenearsinic acid can be crystallised from very much

boiling water, m. p. 290" (Found : C = 55.2; H = 3.5. C,,H,O,As requires C = 55.4; H = 3.5%).

00'-Diphenylylenearsenious Chloride.-Diphenylylenearsinic acid is suspended in concentrated hydrochloric acid, an equal volume of chloroform added, and sulphur dioxide and hydrogen chloride are passed in through a wide delivery tube opening under the surface of the chloroform. After some minutes, a little potassium iodide is added and the reduction carried on under reflux on a water-bath, when diphenylylenearsenious chloride passes into the chloroform layer. It is recrystallised from benzene. 00'-Diphenylylenearsenious chloride crystallises with remarkable

readiness, in colourless plates, m. p. 161", b. p. about 230"/25 mm., readily soluble in chloroform or carbon tetrachloride, less soluble in benzene or alcohol (Found : C1 = 13.3. C,,H,CIAs requires C1 = 13.5%).

Diphenylylenearsenious Iodide.-A suspension of diphenylylene- arsinic acid in 10% sulphuric acid is saturated with sulphur dioxide at 60°, and a strong solution of potassium iodide added. After further reduction for an hour, the solid is removed and taken up in benzene; the solution is dried, filtered, and evaporated to small bulk. It forms very beautiful, golden plates, m. p. 166", soluble in benzene or chloro- form, practically insoluble in alcohol.

The iodide is then precipitated with alcohol.

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ORGANIC COMPOUNDS O F ARSENIC. PAET 11. 69

oo'-Di23heizySylenearse72ious oxide, obtained by the action of warm alcoholic potash on the chloride, or of concentrated aqueous am- monia on the iodide, forms white crystals, M. p. 178", readily soluble in organic solvents (Found : C = 61-4 ; H = 3.4. C24H,cOAe2 requires C = 81.3; H = 3-47;). From alcohol it crystclllises in needles, m. p. 117", containing alcohol of crystallisation.

oo'-l)iphe72ylyleizca?;fenious Cya nide.-The oxide is dissolved in the least quantity of cold chloroform or of absolute alcohol and treated vi th anhydrous hydrocyanic acid (4 vol.). The product is crystallised from warm absolute alcohol to which a little anhydrous hydrocyanic acid is added as the temperature falls. The cyanide forms long, silky needles, in. 13. 178" (like the oxide), soluble in the usual organic solvents (Found : C = 61.5; H = 3.1 ; N = 5.5. C',,H,KAs requires C = 61.7: €1 = 3.2; K = 5.60,/,). d tt em pi c to Pre;iarc! oo '-Biphenyl y leizeu rsin e .-To diphenylylene-

arsinic acid mixed with amalgamated zinc, hydrochloric acid was added and the whole covered with a layer of ether, the air in the flask being replaced by hydrogen. After some days, the clear ethereal layer became cloudy after a short exposure to the air, indicating the presence of the arsine, which could not, however, be isolated. The solution was colourlcss and non-fluorescent .

Diphen ylylemrnet h ylarsine .--By the action of magnesium methyl iodide on diphenylylenearsenious iodide suspended in ether, the yellow coiour of the latter was discharged. On working up the product in the usual way, a substance was obtained which crystal- lived froin alcohol in large, transparent prisms, m. p. 46". It was probably the arsine required, but analytical results were not very satisfactory even after several crystallisations (Found : C = 65.0, 63-1 ; H = 4.4, 4.4. C,,H,,As requires C = 64.5; H = 4-57;). The substance had a pleasant orange-like smell.

nipF,eizylylenedimethyla1.3o?zi~m iodide, obtained by heating the above with methyl iodide, forms needles, m. p. 190", soluble in alcohol, insoluble in ether. The iodine is ionic and may be deter- mined by titration with silver nitrate (Found : I = 33.3. C,,HI4IAs requires I = 33-1 "6). Methylcarbazole does not combine with methyl iodide.

THE UNIVERSITY CHEMIC-AL LABOR \TORY,

CAVBRIDGE. [Received, October lGth, 1924.1

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