INTERACTION OF ETHYLENE ETC. 1453 CLXI.--Interaction of Ethylene and Selenium lionochloride . By HAROLD WILLIAM BAUSOR CHARLES STANLEY GIBSON and WILLIAM JACKSON POPE. IN a previous paper (this vol. p. 271) we have shown that ethylene is absorbed by sulphur monochloride giving a quantitative yield of @'-dichloroethyl sulphide in accordance with the following equation : 2CHz:CH + S,Cl = (CH,Cl*CH,),S + S, It is now shown that ethylene reacts with selenium monochloride to give /3B'-dichloroethyl selenide dichloride and selenium ; the reaction proceeds in good accord with the following equation: 2CH,:CH + 2Sc3ClZ= (CH,Cl*CH,),SeCl + 3Se. Whilst it thus appears that sulphur monochloride and selenium monochloride are acted on quite differently by ethylene it is possible that the action proceeds analogously in both cases so as to yield BB'-dichloroethyl sulphide or selenide but that the selenide is further acted on by selenium monochloride giving selenium and the new derivative of quadrivalent selenium now described ; this suggestion is supported by the observations of Evans and Ramsay (T.1884 45 64) which indicate that selenium nionochloride readily decomposes into selenium and chlorine. Preparation of Selenium Monochloride, Selenium monochloride is conveniently prepared in quantity by a modification of the method described by Divers and Shimose (T. 1884 45 198'). Finely powdered selenium (80 grams) is added with constant shaking to fuming sulphuric acid (320 c.c.) containing 15 per cent. of dissolved sulphur trioxide; the mixture is warmed to 45-50° with shaking allowed to cool and treated with a current of dry hydrogen chloride.When the gas is no longer absorbed the product is poured into concentrated sulphuric acid (450 c.c.) and the residue washed in with the same liquid (35 c.c.); the lower layer of cruds selenium monochloride contain-ing suspended selenium is drawn off mixed with fuming sulphuric acid (containing 15 per cent. of sulphur trioxide) (100 c.c.) and treated with a brisk stream of dry hydrogen chloride for an hour and a-half. The product is now poured into concentrated sulphuric acid (150 c.c.) when much hydrogen chloride is evolved 1454 BAUSOR UIBSON AND POPE INTERACTION OP and the lower layer of selenium monochloride (99 grains) drawn off. Thus obtained it forms a deep red liquid containing a little free selenium in suspension; i t is further purified by keeping over dry potassium chloride and filtering in a dry atmosphere./3fi/-Dichloroethyl Selenide Dichloride (CH,Cl*CH,),SeCl,. Selenium monochloride (55.5 grams) is dissolved in dry benzene (50 c.c.) and a current of dry ethylene passed through the solu-tion; considerable evolution of heat occurs and the liquid should be kept cool. Absorption commences rapidly and selenium is almost immediately precipitated ; i t is desirable to add further quantities of dry benzene (20 c.c.) to prevent blockage of the delivery tube. When no further absorption occurs more benzene is added and the liquid filtered boiling hot the residue being extracted with boiling benzene until the filtrate deposits no more crystalline product on evaporation.P,B’-Dichloroethyl seleiiide dichloride (27.5 grams) remains in the form of white crystalline needles after distilling off the benzene and may be purified from slight admixture with selenium by recrystallisation from boiling benzene. From observation of the quantity of selenium recovered (30.0 grams) it is concluded that the reaction proceeds in accordance with the equation given above. Bfi’-Dichloroethyl sdenide dichloride is about ten times as soluble in boiling benzene as in the cold solvent; it’ crystallises in long, colourless prisms (see figure) which melt a t 122’5O and are slightly hygroscopic. The crystallographic description given below was furnished by Miss I. E. Knaggs working under the direction of Mr.A. Hutchinson. Crystal System.-Monosymmetric holohedral. A xial Ratios.-a ; b c = 0.6345 1 0.5359. Forms Observed.-C(OOl) m(110) of(ll1). P = 75O5Of. No. of mertsiite-Angle. ments. Limits. Observed. Calculated. - mm=iio y o ...... 9 62’38’- 63’46’ 63’12’ rnn%=_llO :?lo ...... 9 116 14-117 22 116 52 116’48’ O‘C = E l l 001 ...... 7 66 24- 66 43 66 2 65 69.6 - mo’-llO 111 ...... 9 35 2 5 - 36 24 36 2.5 mC =110 001 ...... t i 101 40 -102 23 102 2 -Cm =001 Ti0 ...... 7 77 2 5 - 78 28 77 49 77 58 No cleavage was observed. The crystal habit is prismatic and is terminated by small basal and pyramidal planes. The crystal faces are very much rounded and badly developed arid it was only possible to obtain approximate angular measurements.The1 opti ETHYLENE AND SELENIUM MONOCHLORIDE. 1455 axial plane is perpendicular to the plane c;f symmetry and the acute bisectrix lies in the plane of symmetry being inclined at 22O to the z-axis in the acute axial angle. The refractive index P, was found by the immersion method to bs approximately 1-65; the index a is slightly less than this and y is somewhat higher than 1.75 and could not be determined. The double refraction is hence strong and positive in sign; this was verified by observa-tion on a section cut nearly perpendicular to the acute bisectrix. The optical axial angle was measured as 31O13’ for sodium light in a liquid of refractive index 1-65. Moderate dispersion of the optic axes was observed the angle for red being greater than that for blue light ; horizontal dispersion was not observed.The compound dissolves freely in cold water t o an acid liquid, which gives a precipitate of silver chloride with the nitrate; a viscous liquid remains on evaporating the aqueous solution. One half of the chlorine present is hydrolysed to hydrogen chloride by the action of water (Found C=17*5; H,=2.70; C1=51.4; Se=29*1. 0.1591 required 11.5 C.C. N/lO-AgNO,. Hydrolysable chlorine = 25-7. C,H,Cl,Se requires C = 17.3 ; H = 2.89 ; C1= 51.3 per cent.). On passing sulphur dioxide into a cold dilute aqueous solution of the dichloride a heavy oil separates; this when collected and left in a coo1 place crystallises to a mass of almost colourless, prismatic needles. This compound is very readily soluble in benzene and when crystallised from a small quantity of this solvent melts a t 23-25O ; it is possibly @P’-dichloroethyl selenide 1456 MORGAN AND DREW RESEARCHES ON RESIDUAL and as special precautions must be observed in handling such a substance its further examination will be continued later. We are engaged on the further study of the interaction of ethylene and other non-metallic chlorides. The work described in the preeent paper was carried out for the purposes of the Chemical Warfare Department and permission for its publication has been given by the General Staff. THE CEEMICAL LABORATORY, UNIVERSITY OF CAJTBRIDOE. [Rrc~iucd Octobpr 1.5th 1920.