INTEB~CTIONS OF TELLURIUM TETB~CHM;BIDE ETC. 2625 CCCLX.-lnteractions of Tellurium Tetrachloride and 2MolnOketonM. By GILBERT T. MORGAN and OLNER CECIL ELVINS. A COMPREHENSIVE study of the interactions of tellurium tetra-chloride and p-diketones summarised in the preceding communi-cation furnishes considerable experimental evidence in support of the view that condensations leading to cyclotelluripentmedione dichlorides are due not to median enolisation of the p-diketones, but to a twofold terminal enolisation of these tautomeric substances. Tellurium tetrachloride combines additively with the two double linkings a ring structure is set up and then by loss of hydrogen chloride (2 mols.) the telluripentanedione ring is stabilised this condensation being characteristic of the majority of known (3-dikefones (see p.2612). If this explanation of the cyclotelluripenwedione condenst&ion is correct then it should be possible to bring about an interaction between tellurium tetrachloride ‘and a monoketone provided that the latter is capable of enolisation. The general chemistry of the monoketonm provides many examples of reactions explicable on the supposition that the immediately effective reagent is a dynamic isomeride produced by enolic change: RCOCH RC(OH):CEI& Our earlier knowledge of organic tellurium derivatives is derived largely from the researches carried out .by Michaelis and his pupils in the &stock laboratories. An investigation dealing inter dia with monoketones is due to Rust (Ber. 1897 30 2833) who described the reaction in anhydrous ether between tellurium tetra-chloride and acetophenone as leading to teUurium bbaeeto-phawm diclzhide (“ dichlorotelluroacetophenon ”) yellowish-white needles 2626 MOWAH AND ELVINS INTERACTIONS OF m.p. 186-187”. We have confirmed this observation except as regards the colour; we cannot substantiate the statement that “Mit gewohnlichen Aceton gelang es jedoch nicht ein solches Produkt zu erhalten.” Although the experimental difficulties are greater in the case of acetone than with some of its immediate homologues neverthe-leas interaction does occur with the formation of tellurium bisacetone dic?ihicZe (CH,*CO*CH,),TeC&. The yield is small-about 170//, of theory-due to the comparative instability of the purely aliphatic dichloride and also owing probably to the formation of an even more readily hydrolysable trichloride.The latter supposition is confirmed on passing to the next homologues of acetone methyl ethyl ketone and diethyl ketone which furnish respectively, in excellent yield tellurium methylethylketone trichlmide, CH3*CH,*CO*CH,*TeC13 and tellurium diethylketone trichloride, CH,-CH,*CO*CH(CH.,)*TeCl,. The lengthening of the normal chain in di-n-propyl ketone does not appreciably modify this tendency for in this case also the sole product is tellurium di-n-propylketone trichloride, CH3*[CH,],~CO*CH(C,H,)-TeC1,. On the other hand methyl n-propyl ketone methyl isopropyl ketone methyl n-butyl ketone and methyl isobutyl ketone resemble acetone itself in furnishing dichlorides (pp.2628-9). Accordingly the two modes of reaction may be generalised as follows : 1. RC(0H):CHR’ + Re?( OH)*yHR’ + R-CO-YHR‘ Cl-T&& Cl TeCl (1.1 TeCl, 2. R*C(OH):CHR’ R*CCl(OH)*yHR’ C & x e & + TeCl + (RCO*CHR‘),TeC4. The c a e of pinacolin or methyl tert.-butyl ketone is noteworthy, for in this instance both products were identified namely tdurium p i d i n trichloride (111) and tellurium bispinacolin dichbride (IV) . R*C( 0H):CHR’ R*CCl( OH)*CHR’ (11.) With pinacolin the enolisation can occur only in one way whereas in the other foregoing unsymmetrical ketones there are alternative possibilities of enolic change and these complications combined with the hydrolysable nature of the trichlorides have prevented the isolation of both telluriferous products.The respective solubilities of the di- and tri-chloro-derivatives vary irregularly with th TEIUJIUUM TETRACHLOBXDE AND MONO~ETONES. 2627 ascent of the homologous series so that except in the case of the pinacolin producfs only the less soluble compound is isolated. Moreover with the substitution of alkyl radicals for the hydrogen atoms of acetone there will be a diminished tendency for enolisation. With the p-diketones this substitution was found to be a deter-mining factor ; diisobutyrylmethane { (CH3)2CH*CO)2CH2 had lost the property of giving a cyclic tellurium derivative possessed by dibutyrylmethane (CH,CF&*C~CO),CH2. The effect of progressive alkylation of acetone has been tested. Methyl ethyl ketone diethyl ketone and methyl isopropyl ketone have given characteristic telluriferous derivatives.Two higher homologues ethyl isopropyl ketone and dikopropyl ketone also have been compared. The former undoubtedly reacts with tel-lurium tetrachloride for the inorganic reagent passes into solution and hydrogen chloride is evolved. The telluriferous product is, however oily and readily hydrolysable ; so that it was not isolated. Diisopropyl ketone behaves entirely Merently from all the other aliphatic ketones examined. Under the same experimental conditions the tellurium tetrachloride remains undissolved no hydrogen chloride is evolved and both reagents may be recovered quantitatively. Our observations were extended to mixed ketones containing aromatic radicals and the aliphatic homologues of acetophenone were shown to M e r from this substance in yielding tric-.An exceptionally stable t m ' c W e was also obtained from phenyl benzyl ketone. It is noteworthy that these arylated derivatives including tel-lurium bisacetophenone dichloride are colourless. The yellow tinge of the latter described by Rust may be due to a trace of the yellow etherate of tellurium tetrachloride due to the employment of dry ether as solvent (compare Rohrbaech Annalen 1901 315 9). E X P E R I M E N T A L . I. Alipilatic Ketones. Tellurium Bisacetone DicWde (CH3-CO*CH,),TeCI,.-Two g. of redistilled acetone (2 mols.) were heated under reflux with 4.7 g. of teIlurium tetrachloride (1 mol.) and 30 C.C. of dry chloroform. The turbid yellow solution rapidly evolved hydrogen chloride and after 40 minutes the filtrate from less than 0.1 g.of tellurium was concentrated to a brown syrup in a vacuum desiccator. A small portion was extracted with petroleum (b. p. 4-0-60") dissolved in carbon tetrachloride and the solution diluted with petroleum; crystals then separated which were used for seeding the remainder of the syrup. The resulting crop of colourless needles was draine 2628 MORGAH AND ELVINS INTERACTIONS OF on porous plates when 0.9 g. waa obtained being 16.7% of theory. Recrysfallised from carbon tetrachloride and chloroform in equal volumes the substance separated in colourless nacreous plates, m. p- 126-128" (Found C 22.8; H 3.35; Te 40-7 ; Cl 22-7. C,H,,O,~Te requires C 23.0; H 3-2; Te 40-8; Cl 22.7%). T'eUuriurn bbmetone die-e also separated from chloroform and light petroleum in colourless crystals a small amount of tel-lurium being eliminated.When reduced with aqueous bisulphite, the compound was decomposed with separation of tellurium. Tellurium Meth ykth yl ketone Trichbride C,H,*CO*C%TeCl .-The boiling turbid yellow solution of 4 g. of tellurium tetrachloride, 1.9 g. of methyl ethyl ketone and 28 C.C. of dry chloroform rapidly evolved hydrogen chloride and only a trace of tellurium separated. On concentration the brown syrup yielded 3.5 g. of trichlmide (75% of theory) which crystallised from carbon tetrachloride in small colourless prismatic needles m. p. 101-101-5" (Found: C1 34.7; Te 42-35. C4H70C&Te requires C1 34.9; Te 41.80/). The trichloride was readily soluble in chloroform; it decomposed slightly in b0iI.q solvents and blackened on keeping.TeUur i um Bismethpl -n-ywop yl ketone Dichlorid e, (C,H,*CO-CH,),TeCI,. -The yellow solution from 3 g. of methyl n-propyl ketone (b. p. 101~5-102") 4.1 g. of tellurium tetrachloride and 25 C.C. of chloro-form when decanted from tellurium (0-2 g . ) and concentrated to a syrup did not solidify until triturated with petroleum ; colourless needles then separated (0.8 g.). As this substance decomposed in contact with its mother-liquor it was rapidly dried on porous tile and recrystallised from carbon tetrachloride; m. p. 92-93" (Found Cl 19.5; Te 34.3. CloHl,O,C&Te requires Cl 19.3; Te 34.6%). Tellurium Bismet h ylisoluropy 1 ketone Dich bride, ((CH,),CH*CO*CH,)2TeC12.-Methyl isopropyl ketone (3 g.) 4-1 g. of tellurium tetrachloride, and 28 C.C. of chloroform rapidly evolved hydrogen chloride and the concentrated solution yielded 3-4 g. of crystalline product (52y0 of theory). The dichloride crystallised readily from carbon tetrachloride in colourless needles softening at 85" and melting at 90" (Found Cl 19.4; Te 34.3. C,,H,,O,Cl..Te requires CI = 19.3; Te = 34.6%). Tellurium Bismeth yl-n- but yl ketone Dichloride, ( C4€&*CO-CH,),TeC1,. -Methyl n-butyl ketone (3 g.) 2-7 g. of tellurium tetrachloride, and 20 C.C. of chloroform were treated as in the preceding preparation. The brown syrup yielded no solid product until extracted wit TELLURIUM TETFUCELOIUDE AED MONOKETOXES. 2629 petroleum to remove unchanged ketone.Thie extract yielded a small amount of solid and a further amount w a ~ obtained by extracting the residual oil with carbon tetrachloride (told yield 1.1 g.). After two crystallisations from this solvent nacreous, colourless plates were obtained m. p. 62" (Found Cl 17-8. C,,H&O,C&Te requires Cl 17.9%). TeUum'um B i s ? n e t h y l i a o h t y l ~ Dicklmi.de, { (CH,)2CH*~.CO=cH2),TecZ,. -The addition of 3.6 g. of tellurium tetrachloride to 3 g. of methyl isobutyl ketone in 20 C.C. of Chloroform resulted in a bulky yellow precipitate which decomposed rapidly on exposure to the atmo-sphere. On hating the mixture under reflux this precipitate dissolved with evolution of hydrogen chloride and the clear brown solution on concentration yielded 2-7 g.of colourless needles (45.5% of theory). Recryshllised from carbon tetrachloride the sub-stance separated in colourless plates m. p. 95"; the acicular form gave the same mixed melting point (Found Cl 17.8; Te 31-75. C,,&O,$Te requires Cl 17.9; Te 32.2%). TeUurium DietAylketone T r z k M CH,*C~CO~CH(CH,)-TeCl,. -Less than 0.1 5. of tellurium waa eliminated on boiling together 2 g. of diethyl ketone 3-1 g. of tellurium tetrachloride and 22 C.C. of dry chloroform; the filtrate on concentration yielded several crops of trichloride (3.1 g. or 84-6y0 of theory). R e c r y a m from carbon tetrachloride the t r i c M e separated in colourless plates m. p. 77-78' (Found Cl 33.4; Te 40-5. C,€€,OCl,Te requires c1 33.5 ; Te 40.0:/,). The trichloride decomposed shghkly in hot solvents.T eUurium Di -n-propgl ketone T richloride, CH3-CH,-CH2CO*CH( CH,*CH,)*TQ. -The concentrated solution from 3 g. of tellurium tetrachloride, 1.3 g. of butyrone and 20 C.C. of chloroform deposited mawes of greyish-brown silky needles (3 g. or 77% of theory). Recrystal-obbined in colourless needles m. p. 70" (Found Cl 30.7 ; Te, 37.1. C,H,,OCI,Te requirea Cl 30.7; Te 36.7%). This t'richloride waa somewhat unstable in hot acetone and underwent hydrolysis on exposure to moist air. Interactim of TeUurium T e t r a e m and Pidin.-The turbid yellow solution of 2.5 g. of pinacolin 3.4 g. of tellurium tetrachloride and 25 C.C. of chloroform evolved hydrogen chloride on boiling and after 40 minutes the brown liquid when treated with half its bulk of petroleum (b.p. M") yielded Wurium pinacolin t- . (formula 111) in colourl~ plates. When this waa recrys-tallised from carbon tetrachloride some elimination of fellurium lised from carbon tetrachloride and petroleum the triddmde W 2630 MORUAN AND ELVINS INTEEA~ONS OF occurred in the hot solvent; the filtrate deposited colourless, rhomboidal platelets softening a t 110" and melting at 114-115". The yield was 0.9 g. or 21% of theory (Found C1 32-0; Te 38-1. C,H,,ocI,Te requires Cl 32-0; Te 38.3%). The mother-liquor from the trichloride preparation furnished on concentration a crystalline residue which after two crystaktions from carbon tetrachloride separated in colourless needles m. p. 191-192"; yield 1.6 g. or 26% of theory (Found C 36.0; H, 5.7 ; Cl 18.25 ; Te 32.3.C,,GO,qTe requires C 36.3 ; H 5-55 ; a 17.9; Te 32.27'). Tellurium bbpinacolin dichlmide (formula IV) was much more permanent in air than the preceding trichloride but all attempfs at removing the chlorine were unsuccessful; the use of potassium metabisulphite or neutral sodium sulphite (Vernon J. 1920 117, 892) led to elimination of tellurium. Interaction of Tellurium TetrachEom'de and Ethyl isoPropyl Ketone. -Fifteen g. of diethyl ketone were alkylated with methyl iodide and caustic potash at 120-130" (Nef Annalen 1900 310 325). The product was fractionated and ethyl isopropyl ketone boiling at 114-116" was employed in the following condensations. Tel-lurium tetrachloride (2.7 g.) .was readily dissolved by boiling in 20 C.C.of dry chloroform containing from 1 to 2 g. of the ketone. Hydrogen chloride was evolved only a small amount of tellurium (0.1 g.) was eliminated and on concentration a brown syrup was obtained which did not however yield a crystalline product. Extraction with organic solvents' and the addition of hydrogen bromide or ferric chloride also failed to furnish solid derivatives. On exposure to air the oily syrup slowly evolved hydrogen chloride, and the final residue contained only inorganic compounds of tellurium. Tellurium Tetrachloride and Diisoprop yl Ketone.-Bisopropyl ketone b. p. 123-124" was prepared by Nef's method (loc. cit.) from ethyl isopropyl ketone and purified through its crystalline oxime (m. p. ZS") which was distilled under reduced pressure and hydrolysed with concentrated hydrochloric acid.Tellurium tetra-chloride ( 2 6 g.) was boiled for an hour with 2 g. of diisopropyl ketone and 20 C.C. of dry chloroform a process which in all the preceding experiments had led to condensation. In this case, however the tellurium tetrachloride remained insoluble and unchanged. 11. Mixed Retones containing Aromatic Radicab. Tellurium bisacetophenone dichloride prepared by Rust (h. cit.) by heating 2 mols. of acetophenone with 1 mol. of telluriu TELLURIUM TETRACHLORIDE AND MONOKETONES. 2631 tetrachloride in ether was then described a,s cryatallising in yellow needles m. p. 186-187". Three g. of acetophenone 3.5 g. of tellurium tetrachloride and 15 C.C. of chloroform were boiled under reflux and the dark brown solution was concentrated to a crystalline maw of dichloride.After two crystdbtions from chloroform tellurium bisaceto-phenone dichloride separated in colourless needles m. p. 18& 187" (Found (3 16.2. Calc. Cl 16.3%). Reduction of this dichloride with potassium metabisulphite led to the elimination of tellurium. Tellurium Phenylethylktone T & W , C ,H ,*CO-CH ( CH,) *TeCl . -After boiling for 45 minutes the solution of 3 g. of tellurium tetrachloride 3 g. of phenyl ethyl ketone and 25 C.C. of chloroform was concentrated to the crystallising point. The solid (2.5 g. or 61% of theory) was crystallised from carbon tetrachloride in a dry atmosphere to obviate hydrolytic decomposition by moisture when large colourless rhomboidal prisms separated m.p. 116115" (Found C 29.1 ; H 2-5 ; Cl 29.0 ; Te 35-0. C,H,OCI,Te requires C 29.4; H 2.45; (3 29.0; Te 34.7%). Tellurium Phen yl -n-prop ylketone Trichluride, C ,H 5*C 0 CH ( CH,*CH,)*TeC13. -The condensation of 2-8 g. of tellurium tetrachloride and 3 g. of phenyl n-propyl ketone in 20 C.C. of chloroform was carried out as in the preceding preparation. On concentration 2-8 g. of solid were obtained (71% of theory). Recrystallised from carbon tetra-chloride the product separated in colourless prisms blackening at 122" and melting at 128-129" (Found Cl 27.7; Te 33.1. C,,,Hl10C13Te requires Cl 27-95; Te 33.5%). Tellurium Phenylbenzylketone T r i c M c 6H5*CO*CH ( C6H 5)*TeC13. -Phenyl benzyl ketone was prepared by reduction of benzoin with zinc dust and glacial acetic acid (Sudborough J. 1897 71 219). Two g. were condensed with 2.7 g. of tellurium tetrachloride in 20 C.C. of chloroform. The concentrated solution furnished a greyish-green crystalline mass (2.6 g. or 60% of theory) which was recrystallised from carbon tetrachloride or from chloroform-petroleum when colourlw facetted prisms were obtained m. p. 142-143" (Found Cl 24.7 ; Te 30.1. CI4HllOCI3Te requires C1 24-8; Te 29.7%). This trichloride was readily reduced by aqueous potassium metabisulphite to a yellow solid which however waa very unstable and decomposed rapidly either on exposure or in chloroform solution 2632 EINU AND YURCH TRYPANOCIDAL ACTION The authors desire fo express their thanks to the Advisory Council of the Department of Scientific and Industrial Research and to the Government Grant Committee of the Royal Society for granb which have helped to defray the expense of this investigation. UNIVE~SITY OF BIILM~J~HAM, EDGBASTON. [Received Odober 2nd 1925.