1456 MORGAN AND DREW RESEARCHES ON RESIDUAL CLXI1.-Researches on Residual A f l n i t y and CP ordination. Part I I . Acetylacetonev of Selenium and Tellurium. By GJLBERT T. MORGAN and HARRY DUGALD KEITH DREW. THE acetyla.cetolne derivahives of t,he metals metlallaids and non-metals ma,y be classified into three main groups. I. Meta.llic ac:eltylacelttosnea in which t'he principal valeaoiee of t$hel metal are complet,ely satisfied by the univalent a.cetylamtone radidel, C5H702 such as t'he thallous glucinum oupric zinc sca,ndium, aluminium chromic ferric a.nd t,horium derivatives amd numerous others. In many instances aoetylacehm has gimn wings to the metals for certain of these compoanda are va1a;tilei without decom-pmit(ion (Combes C'om.pt. rend. 1894 117 1222 ; Kurwski Ber., 1910 63 1078; T.1913 103 81; 1914 105 189). 11. Aceltylaaekmes of thel noln-rnet$als and metlalloids in which the principad vadenues oC the delment8 as@ only pastdy &isfied by tthe univalent amtylamtonel radicle. Such are the colmpaunds of boron, silicon and tit,anium B (C,H70,),Cl Si(C,H,O,),Cl and Ti(C,H70,),C1 which function. a8 meltdlic ahlorides givin,g rise t,o rema,rkable double salts (Dilthey AnmaZen 1905 344 326). 111. Aeet4ylamtones o f . sulphur whiah behave as true olrganic deriva.tives of sulphur carbon being attacheld d i r e d y to this non-metlal and not through the intmmediasy of obxygen as in the two1 preceding classes (Angelli and Magnani Gazzetfn 1893 23 ii 415; 1894 24 i 342; Vaillanb Compt. rend. 1894 119 647). There is also a t<ransitioa group of metallio ac&ylawbnes behween tqhe+ maSn groups I and 11 in which the prindpa*l valendes of t,he met a1 aTet only pastly satisfied by t,he acetylaeelt'one complen.Thi AFFINITY AND CO-ORDINATION. PART II. 1457 transition group includes the complex amtylacebnes of plakkmm (Werner Ber. 1901 34 2584) and the colbaltia amtylaceitone corn-pounds of the general type [C,H,O,Col e%]X (Werner Helv. Chirn. A cta 191 8 1 78) wheret en = elthylenediamine. The latter series of acetylacetone detrivativm axhibits optical activity and the existence of enantiomorphous pairs of isolmerides aff olrds definite information as to the arrangement of the1 acetylacetom nucleus in these sub-st8ances and justifies .the belief tlhat the univalent group CH,-CO* CEI C (CH,) 0 fun d i o n s as two asc oci a t i ng uni tg,* forming a ring structure in which the inetallia atom is implicated.The relsearah described below which is still in a preliminary stage shofws that the intelractisns of acetylacetone and the tetlra-chlorides olf selenium and tellurium lead to prolducte differing considerably in type1 frofm thoset classified above. Altholugh there are many points of differcmm bertwelen the1 various members of the three main groups of acekylacetone delrivakives they possess one attribute) in common namely the univalent acetylacetone radicle of which oiie or morel arg present) in the moletcule of every one oC thew derivatives hikhelrta described. I n the acetylacetones of selenium and tellurium these metalloids are found to be associatled with a bivalent radicle @,H,O,”.Selenium tetrachloride and acetylacetone interact in ethereal solutioln in aocordancel with the following equation : (1) 2SeCl,+ 4C,H80 = [C,H,O,:Sej + 2C,H7C10 + 6HC1, the products being seleniicm acetylacetone a well-detfind pale yellolw orystalline compolund chloroacetylacetone and hydrogen chloride. This seileniuni acetylacetone which is bimo~lmlar in benzene1 solution is readily decomposed by concentrated hydro+ chloiric acid and by reducing agents such as the alkali hydrogen sulphitea. The former of these decompositions takes plam readily, giving rise to1 elonieatal selenium and chlolrolacetylaceltonel, (2) [C513[602:Se]2 + 2HC1= 2Se+ 2C,H702C1. * The adjective “ chelate,” derived from the great claw or “ chela” (“ chely ”) of the lobster and other crustaceans is suggested for these caliper-like groups which function as two associating units and fasten on to the central metallic atom so as to produce heterocyclic rings.Among the compounds which by virtue of their residual affinity function a.s chelate groups are ethylenecliamine (en) propylenecliamine aa-dipyridyl and dimethylethylene sulphide (T. 1912 101 1798). Many unsaturated radicles also function as chelate groups partly owing t o their principal valencies and partly owing to residual affinity for example. the acetylacetone and oxdate groups and the univalent groups in dimethylglyoxime, CH;C( :NOH)*C(CH,I:NO*, izitroso-p-naphthol 0 :C,,H,:NO’ and many other lake-forming complexes. In the present communication tho bivalent radicle C,H,02” functions as a chelate group entirely owing t o its principal vnloncies 1468 MORGAN AND DREW RESEARCHES ON RESIDUAL The latter demmpodtion which proceeds quantitatively is an interestling example of the1 way in which organic reselarch sometimes leads tlo improvelmeata in inorgania syntlheses.Four moilecular prol-portions of alkali hydrogen sulphitel reduce the1 dimeric setlenium amtylaceitoae quantlitlaflive~ly into amtylacetonel and alkali seletnudi-thiolna#k : (3) [C,H,O,:Se] + 4KHS0 = 2C5H802 + 2Se<s0:K. SO. K I n the earlier preparations these selenodithionates were obtained in a laborious manner together with alkali thioselenates by digesting sulphites with selenium or selenious acid (Rathke J .pr. Chem., 1865 95 8 ; 1866 97 56; Schultze ibid. 1885 [ii] 32 399). The acetplacettonel setj free in the forelgoing reduction and in other similas reactioizs is convenielntly mtima8teld by coupling with sodium iso-p-nitrobenzenediaxo-oxidel to f o m the sparingly soluble p-nitro-b~nzen~soaceityla~t~ne N02*C,H,*N,*C5H702 (Bulow and Schlot-t.erb& Ber. 1902 35 2191). The foregoing equatJolns representing the farmatian and quanti-tat,ive decolmpositim of selenium acekylacetone are acEnsistenti witlh the view that this associateid compound may be represented by ths graphio formula 0 0 /\ /\ \/ \/ CH,*S Se==Se C*CH, I I 11 HA CH CH CH co co /\ /\ - . S- 'HA CHn CHn ' \7 (1.1 This canalusion is confirmed by the rwults obtained in studying the intoradion of tellurium tstraclhlolride and acetylacetme.In moder rately concentrated chlorolform solution theae reagents give rise t o a cololurleas substance tellurium acetylacetone dichloride, (4) TeC1 + C5H80 = C5HG0,:TeC1 + 2HC1. The didhlotride when cautiously reduced with sulphurous acid or alkali hydrogen sulphites 1mes its ohlorine and yields tellurium acetylacetme a golden-yellow compolund whioh unlike its selenium analogue does notl exhibit association in organic solvelnts : (5) C,R,O,:TeCl2 + H,S03 + H,O = C5H602:Te + 2HC1+ H2S04. Tellurium acetylamtone is decomposed quantitatively into tellurium and acetlylacetoine by suah reducing ageinta as an aluminium-mer-cury coluplei or alkali hydrogen sulphites. In the1 l a t h case a tellurium analogue of tlhO alkali sele~ndithio~natlw was not detected : (6) C,H,O,:Tel + 2KHS0 = C,H,O + TO + li,SO + SO, AFFINITY AND CO-ORDINATION.PART 11. 1459 Tellurium acetylacotone differs from the selenium analogue in its dwompolsition with colld concentrated hydrochloric acid (compare equation 2); it yiellds acetylacetone a8nd half the tellurium as the1 tetrachloride : (7) 2C5H,02:Te + 4HC1= 2C,H80 + Tel+ TeC1,. These1 relactioas support the view thatl tellurium aceltylacet\one didloride (11) and tellurium acetylacetolne (111) may be repre-sented respectively by the following folrmulaa : 0 0 0 /\ \/ CH,*C X /\ \/ Ct'l,*C Te /\ \/ H& CH C CH~*C ?<:; (nascent Fi?) II I RC CH, UO 7+ -- a II HC aCC2 CO dK (111.) (IV.) Selemium and tdlurium acet;ylacetoirx?s f unatiofn as weiak aaids and dissolve in aqueous alkali hydroxides.It is therefore evident that they may have an alternative einolic configuration (IV) which would correspoad with that of their unstable a,lkali salts. E X P E R I M E N T A L . * Se 1 e nium ,4 c e t y lac e t one [ C5H602 Se],. Sellenium tetlrachlomridel was preIpa,red by passing dry chlorine in elxoe,ss over coasselly polwdefred sellelnium at tlhe ordina,ry temperature, t,he da,rk red mo~nochlo,ride being f olrmeld as a,n intleme~diacte phase. The pale yelllolw crystiallinel tet'rachlolridel (14.3 grams) suspended in 140 C.G. of dry sther was tseatled at the oBrrdina8ry. temperature witlh 13 grams of aceltylaceitsne (2 molls.) dissollved in 30 G.C. of the same solveliit8.Hydrogen chlolride was f olrhhwith emlved the solution reddelneld t8her t'eltlra,chloiride slolwly passeld intlol sollution while a yellolw pre8cipit'atte appea,red asld reldissollveld in about tlhirty minutes to a tsanspa8rentl pa,lel red f Liming la.chryma.t,ory sollution which was elvaporat'ed rapidly a t the1 oirdinasy tlempesature in a cu'rreat of air. Hydro'gen chloride elthetr and ohlo~rooacet~la,aet~oins were1 t'hus remowd; tlhe reaidueb a palei red oil sollidified on stbrring. The product (10 gra,ms yield 90 per eetntf.) cryst,allis,eld from benzene in pale primroseyellow glistening plates or lath-like needles giving yellow ,solutjiolns in 0rgani.c me.dia.; oln exposure] t'ol light far pro+ longed pelrio*ds its surface. becamel thinly colated with pink selenium.* The authors are indebted t o Dr. Scott for a gift of pure tellurium, and to Professor Ling for specimens of this metalloid and of selenium 1460 MORGAN AND DREW RESEARCHES ON RESIDUAL During this incipient decomposition the odour which at first was pleasing and fa8rinacwus beoamei fainbly nauseiatling a result whioh was due pro*bably tIo liberation of traces ojf hydrogen selenide. The substance reddened atl about 140° and subsequently melted and demmposeld atl 175O. In a sealed capillary tlube heated from 150° it meltled to an orangel-red liquid at 185O. The selenium was determined by heating the weighed substance with 5 a.0. of fuming nitria acrid in a flask with ground-in air con-denser. Oxidatioln being ao~mpleted the soilution was boiled with exoe~s of hydrolchloria acid untdl all nitIraus coimpolunds were destroyed the metlalloid pre&pittated as the red moldifiaatim tsam-forming into the dark grey variety oln warming with sodium sulphitle or aqueous sulphurous acid was colllelded and weighed.Carbon and hydrogen atimatiolns were made in mmbustion tubee charged with fine copper oxide a long length oC lelad ahramate and a spiral of aopper oxide a lit& of this oxide! beling also placed in the polrcelain boat. In the eombustioln od sellenium and tellurium deriva,tivea more acwuratx resulbs were obtained by burning with oxygen alme than with air follolwed by oxygen (Found C = 34.23, 33-74 ; H =3-45 3.72 ; Se= 44.10 44-17. (C,H,02Se) requires C = 33-86 ; H = 3.41 ; Se= 44.68 per cent.). Molemlar determinations by the elbullimaopia method in benzene gave 316 312 (0.65 and 1-18 grams per 100 C.C.respectively) thus indioating association n = 1 o r 2 requirea 177 or 354. Selenium aaeltyla8wtone is notl obtained unless the presaribed elxperimelntal conditions are followed aloselly in regard to tempelra-tlure concentration proportion of reagents and remowal of the volatile pr0duat.e a t the ordinary temperature. The proportion of two molecules of amtlylacetone to me of selenium tetraahloride has been found t a give the optimum yield whereas ratios of m e or four mo~leaulee of the dikebne do not give rise to any crystalline product. Experiments carried out in chloroifmm or with selenium dibrolmide, S%Br, and acetylwetolne in ether have led 50( far to dimination of selenium and to( the production of lauhrymahry oils.A preliminary experimentl with benzoylacetonne and selemium tetraahloride in cold ether indicated the formation of a pale yellolw selenium benzoyl-acetone (m. p. 212O) having similar properties to1 seilenium amtyl-aceltonel. Selenium acetylacetone which has a faintly acidic sweetish taste, di-lves slightly in holt waker the solution being distinctly acid; it is somewhat sparingly soluble in boiling ethm ethyl alcohol amhne or chloroform and dissolves more freely in hot glacial acetic acid. Its solubility in boiling benzene is about 1.5 grams in 100 c.c. but is ten times less in the cold AFFINITY AND CO-ORDINATION. PART 11. 1461 Selenium amtylambnet dissollves readily in cold aqueous alkali hydroxides or ammonia to bright yellow solutions which regenerate the ampound if neutralised a t onm with dilute a&d.The alkaline solutions speedily decampme red sellenium being precipitated whilst a nauseating odolur is devdopd. Although insoluble in aqueous soIciium earboiiatle prollonged treatment witIh this reagentl leads tto the foregoing demmpoaition. The orgalliu product of theee alkaline decmmpositioas is an oil having a plelasaiit ketonic odour. Dilute mineral acids are without &eot on selenium awtylacetone, concentsated nitric and sulphurio adds have 8 destructive adioln, whelreas odd concentrated hydrochloric acid decomposes itl smoohhly into red selenium and ahlolroaoetylaaetone identified by its bailing point lachrymatory properties and grwn copper derivative.Ferria chloride &her in aqueom or alcoholic solution giveis no reld cololration with selenium acetylamtone even a f k two hours. I n twenty-four hours ~JI orange tint is discernible and this coloration is dwelopeld more quickly on holdmg but selenium is set frw simul-taneously. When distilled with zinc dust selenium acetylacetone loses selenium evolves a nauseating vapour and gives rise to an oil whioh after rectificatioa gives a red mloration with ferria ahloride and has a pleasant ketonic; udour. Iodine in chloroform solution has no action on selenium ac&ylamtone but chlorine in the same solvent gives selenium teltrachlorida and chlolr mcety1mt8one whereas bromine yields Iachrymatory produate and a wlourlm crystalline substance (m.p. 1 8 0 O ) . Aqueous hydrogen sulphide decomposes it slowly in the cold with liberat\ion of sulphur and selenium. Hydr-oxylamine phenylhydrazine p - brolmophenylhydrazinel 11 - nitro-phenylhydrazine and 6-chlolro4 4-tollylenediamine induce a mom or less rapid elimir?;ttion of selenium. By-products of the Formution of Selenizcm A eety1acetime.-The amount of hydrogen chloride set free in the condensation was wti-mated and found to be equivalent to tIhhree-fourths of the ahlorhe originally present in the) selenium tetrachloride. The chlarmaetyl-acetone (b. p. 148-150°) of whioh morel than two-thirds of the oal-culatd amount were obtained in a purified condition was further identified by conversion into its green copper derivative soluble in chloroform.Thew reaulk support the view expressed by equation 2 (p. 1457). Quantitative Decomposition of Selenium Acetylacetone Alkali Selenodithionates. Two grams of powdered selenium aceltylmtme were added t'o 18 0.0. of water containing 3 grams od potassium meltabisulphite (Z+ mols. oif KHSO equivalentl to 1 atom o t Se) and the mixtur 1462 MORGAN AND DREW RESEARCHES ON RESIDUAL was shaken nielcbafnically for olne hour. A colourless crystlalline prel-cipit'ate o,f pot,assiunn selenodithioaate K,S,SeO, was) then col-lecteld t,hel filtmhe elxtsacted with etther to1 remove a.celtyla,cstsne, and t8hel aqueiolus layer mixed witlh akoho'l tlol complete t.he delposit'ion olf the inolrganic prolduct8 (yield 3.5 gra,ms = 97 per aelnt. olf the t,heoL reticad). Wheln sepa,ra.tdng rapidly f ro'm aquelous soduti.oln tbe sellenoc dithiomte appeare'd in lust,rous scales oc thin pla,t>es ; when cryst8a81-lising slowly itl was o'bt'ain ed in loag transpa,re'nt silky ne1edle.s.Botb folrms o,f the1 saltl were quite collolurlelss a.nd &able when expweld to air a,nd light. On heatJng tlhezy colmmelnced tlo redden a t 190° and a,tl 250° t'he reld sellenium tarneld grey. Mela.nwhile sulphur diolxidel was evollved aad finally a residue of potaasium sulpha.te was ledt (Foand K= 24.59 ; S = 20.06 20.58 ; Se= 25.06, 25.07. Calc. K = 24.63 ; S = 20.19 ; Sel= 24.95 pelr ce8ntl.). Sodium selenodithionut e Na2SzSei06 was prolduce'd by a.dding sellelnium aceltyla.cetloae to! a. cold colncelntsatleld solutlioln of sodium hydrogeln sulphitle (24 moils.) the mixture beling s h a h n until the osga,l.c cotmpound ha3d dissolved and preoipi,t,a,tled by a,dding alcohol in colloarless lust,rous anhydrous scatlels rela,dily solluble in water (Foand Na,= 16.24.Na2S,Sei06 requires Na= 16-12 pelr cent:.). Aqueolus sulphur diolxide ha,d a simila,r a'ctioln 0111 sedelnium aaeltyl-aceltone dissollving it in the cofld t'o a' co1loiurle:ss solution ccmt4ainiag amtyla.cetolne elxt,raoteld by ether a<nd selenodithiolnic acid which slo,wly deconiposeid into1 se'lenium sulphur dio(xi.de amnd sulphuric acid. Estimation of Acety1acetone.-The amty1a.cetone set free in the foregoing cieeompositionst wa8s idelntified by conversion into its pale blue copper a,nd coloarless a,luminium derivatlives. Itl wa,s elsttimalted by coupling witlh s,oldium iso-p-nitlrolbenzeneldiazol-o,xide.Seilelnium anety.laoeltone (0.2 gmm) was sh&e:n for f ojur hours with 0.25 gra,m od polt.assi,um metlabisulphitte aad 3 C.O. oC wa,tleir. Pot'ass-ium selelnolditlhionatete was precipittated by alcolhoil and t,he filtira.te tlr ea,ted wit'h 0 * 2 3 gr a,m od sobdium is o -pnit;l-olbeazelneldi azo+olxide, (NO,*C,H,*N,*ONa,,H,O). The pale olralnge-reld preidpitate of ~n;itsolbeinzeneazola,~~tylacelt'olne aftw wa'shing witlh dilute1 alcohol, wedgheld 0.2 gram (mlc. 0.28 gram) a,nd gave tlhel colrrectl rnellting pointl 219-222O. Tellurium reactsd wit'h dry chlodne evolving heat and fo'rming tellurium tetrachlocide as a yellowish-whit\e liquid in which excess od the1 metallolid dissolved to an almost black solution probably eolntaining tho diclhlmidel.Witlh exoelssl of chlorine tlhe whole! sdidi AFFINITY AND CO-ORDINATION. PART 11. 1463 lied to a yellaw crystlalline ma.ss of tet,rachloride which was purified by sublimahioln. Sublimed t'edlurium t&rachloride (10.3 gra.ms) was mixed with 7.6 gra?ms olf amtylaaet~o~ne (2 molls.) in. 55 C.C. off dry chloroform and the1 ora,iige sollution heat'ed undelr reflux an the wat'er-bath. The evolution od hydrogeln chloride ce.ased aSter tlwol hours' boliling ; tvhe solution was filtered frolm a heavy dark grey oil and conmntmtod over lime in a desicoator. Crystlals olf tellurium amtylacetone dichloride separahed ; the concent,ra,ted filtrate6 yielded further crops (yiedd 7 grams or 62 per cent'. aaloulateid on TeC1,).The proldud was spasingly solluble in ether benze'ne or ohlolrodorm, ratlhelr moire 501 in hot ahholl and very readily soluble in cold acetone. It! crystadlised from alcohol or benzene1 in a.ciaular forms, and separat'ed slolwly from acetom i n large tlra,mparent hexagonad prisms olft,en twinned. Both forms we're mlourless; they darkened a,t 155-160O a'nd melted and dmmpofjed between 169O and 173O, libelrating t#eJlurium aad evolving hydrogen chloride and a la,chry-matory olil which deivellolpeld a red coloration with aqueous f errio chloride. The tlellurium was wtima,tIed by warming a weighed amountl with i-uming nitlric acid (5 c.c.) in a reflux appa.ratus. After boiling with concentrated hydrochloric acid (25 c.c.) to re8motve nit'rolus compounds the sollution Wacs emaepora8ted ta dryness.The residue dissoIlveld in 15 c.a. od 10 per cent. hydrmhlolric a,cid was wa,rmed with 10 aa. of 15 per ceatl. hydrazine hydrochloride and 35 C.C. of saturated sulphurous acid gradually added the liberated tellurium being dried a t 107O. The chlorine was estimated by alka,line hydrolysis and pre.cipiia,tbn as silvelr chlolridel ; the com-bustions webe carried out as in t,ha case1 ob sedemium aoettylaaeltoae (Foand C=20.72; H=2.07; C1=24.01 23.95; Te=42.87. (C,H,O,Cl,Tel) requires C=20*24; H=2.04; Cl=23.92; Te=43*00 per oelnt,.). ~~o~le~clulas.welightl-weight~ det.elrmina,tlions by the eibullioscolpic method in acet,onel (1.846 and 4.207 grams per 100 c.c.) ga,ve 241 and 255 (Ill = 296.5). Telluriwm acetylncetone dichlom'de does not beaome discoloured on exposure to lightl.It rmdily loses chlorine with hot water or aqueolus a.cids or alkalis. Tellurium is not selt free by bodling wit,h a,queous p&a,ssium hydro'xide. With aquetolus f erria chloride a red collolration is developed only very slowly. When warmed with considerable excess olf aqueous sulphurolw acid this wmpolund i4s decolmpoaeid aompletely yielding tellurium and a.cetyla,mt80me; 1464 RESEARCHES ON RESIDUAL AFFINITY ETC. Tellwium A cetylacet one C,H,O,:Te. The foregoing dichloride (2.2 grams) when tiiturated for ten minutes witlh 1.8 grams of potassium metabisulphite (1 mol.) and 20 C.C. of water yielded a small amountl of tellurium and 1 gram (yield 60-70 per cent.) of a yellow compoand whioh was purified by crystallisatlioa from benzene o r hot water.This product was dsol olbtaind with less libelration of tellurium by boiling the dichloride with a slightl excless of aqueolus sulphur dioxide (Found C= 27-14, 26.62; H=2-88 2.92; Te=56*55. (C,H,O,Te)n relquires C=26.61; H=2.68; Te1=56'52 per cent.). Malemlar-weightt detelrminatbns in boiling benzene and amtone (0.462 and 0.879 gram per 100 c.o.) gave respectively 262 and 185. M.W. for n = l is 225.6. Tellurium acetylacet m e forms heavy goldeln-yelllow needles spar-ingly soluble in water ehher chloroform or alcolhol and demmpoe-iag indefinitely a t 145-180°. I n a sealed tube it melts to a yellow liquid which partly sublimes in yellow needles and on further heating decomposes with elimination of tellurium and pruducrtjon of an oil resembling acetylacetone.Under reduced pressure the compound subl'imes a t about 160° in glistening yellow needles. Tellurium acetylamtone resem blels the selenium compound in its chemical reactions. It dissolves in cold aqueolus potassium hydr-oxide t o a bright yellow sodution from which immeldiatle neutral-isatioa with acid regenerates the original colmpolund but after B few minutes the alkaline solutIioln deposits tellurium. Cold concantrated hydroahloria acid decomposes the1 compound with elimination of tellurium. Ferric ahloride develops a reld coloration but only after a long time[. Hydrogeln peroxidel decolorisea immediately the yellow aqueous solutmn of tellurium acetylaoetone giving a white precipi-tlate; hydrogen sulphide produces at once! a black deposit (T& ?), alcoholic mermrio iodide yidds a yellow precipitate and warm aqueous sulphur diolxide reduces the compound with elimination af tellurium.Quun t it at i.v e Decompositions of T el1u.rizl.m A ce t y lace t one. (a) With Bisulphit e.-Tdlurium amtylamtone (0.4 gram) shaken for five hours witlh 0-4 gra,m of potassium metabisulphite~ and 3 0.0. of water yielded sulphur dioxide 0.2 gram of tellurium and 0.3 gram of potassium sulphate the latter pr&pitlakd by alcohol after extracting the aaetylaaetone with ether. Waxm aqueous sulphur dioxide brought about a similar rcwtuc-tion yielding acetyla&tme tehrium and sulphuric acid THE FORMATION AND REACTIONS OF IMINO-COMPOUNDS. 1465 (b) Il/-ith a n A lum.iniicm-Mercwy 6'ouyZe.-Tellurium acetyl-aceltolne (0-4 gram) i n 50 C.C.of hot water was shaken with an aluminium-n:e8rcury co,uple and t'hs solut'io1n filterred from precipi-tlat8ed tlellurium was treated with sodium iso-pnitmbenzadiazo-olxidel (0.37 gmm) in 8 C.C. od glacial acetic acid and 20 C.C. oC abso-lute alcohol. Af telr three; holurs t,he olrangered p-nit3robenzeneam-acetylacetone was collected (0.35 gram yieild 80 per cent.) and crystallised from glacia.1 aceltlic acid; itl then mellt,d at 220O. (c) With Cowentrated Hydrochloric L4 cid.-A preliminaxy experime,nt showed t'hat tellurium a8cetylacetlone unlike its selenium a.n alogue yielded a.celtylan=et olnel and not chloroac&yla,uetoln,e on dscolmposition witlh concentrat'eld hydroahloric acid a polrtion only of the tellurium beling precipi,t,atled whilst the relmainder was left1 in sotlution as t'elluriiim t8etfrachlolride. Tellurium aceltylaaetone (0.1558 gram) was stirred with colld concenttrated hydrochloric acid folr severa,l ho1ul.s. The precipita,teld tellurium which was theln col-lect,etd a,nd washe'd successive'ly wit'h a little mare conceintrated acid a,nd waf,er weigheid 0.0432 gram. The filtsates were then t s e a t d witlh aqueolus hydrazine hydroahloride saturated with sulphur dioxide. 'These relducing agelnts precipita,ted the remainder of the t,ellurium whiah welighed 0.0427 gram (total a.molunt of tellurium found = 0.0859 gram. ; cak. 0.0880). These results confirm equation 7 (p. 1459). The authors desire to enprelss their thanks to the Advisory Council for Scientific and Industrial Research for grant8 which hame partly defrayed tbe expelnses of this iiivwtigation. CHEMICAL DEPARTMENT, UNIVERSITY OF BIRMINGHAM, EDGBASTON. [Received October 25th 1920.