Ordination. Part VIII. Interaction of Tellurium Tetrachloride and P-Diketones

View Article Online / Journal Homepage / Table of Contents for this issue 922 MORGAN AND DREW : RESEARCHES ON CVL-Researches on Residual A finity and Co- Published on 01 January 1922. Downloaded by University of California - San Diego 20/06/2017 09:27:26. ordination. Part VIII. Interaction of Tellurium Tetrachloride and P-Diketones. By GILBERTT. MORGANand HARRYDUGALD KEITH DREW. OF seventy-seven elements possessing chemical properties no fewer than fifty-seven have been shown to yield with acetylacetone derivatives containing a univalent radicle C5H702). These products have in part been classified in an earlier communication (T., 1920, 117, 1456), and a summary, already rendered incomplete by subsequent researches, is given of their properties, in ‘‘ Beilstein’sHand- buch ’’ (edition 1918, vol. I, pp. 781-784). On condensing acetylacetone with the tetrachlorides of selenium and tellurium we have obtained evidence that this p-diketone gives rise to a bivalent radicle C,H,O,”, the condensation taking a View Article Online RESIDUAL AFFINITY AND CO-ORDINATION. PART VIII. 923 different course from the reactions hitherto recorded with the other elements. The singular behaviour of the tetrachlorides of selenium and tellurium towards acetylacetone has now been examined more closely and our investigations have been extended to other 13- diketones in order to find an explanation for the nature of this exceptional condensation. In the present communication, we deal with the case of tellurium tetrachloride, the reactions of which with acetylacetone and benzoylacetone have already received attention (loc. cit.; T., 1921, 119,611). A detailed examination of the condensation between tellurium tetrachloride and acetylacetone in chloroform B.P. shows that three products are obtained which represent the three different types of compounds formed in the condensation of this tetrachloride and the other @-&ketones. These typical substances from acetylacetone have the following molecular formulse : i. (C5H,O2),TeCl2. iii . C&,o (O*C,HS)TeC1,. Tellurium bisacetylacetone dichloride, the first product (i) containing a univalent radicle C5H,0,’, may be regarded as representing the normal condensation, yet it will be shown below that this univalent group is in all probability not identical but isomeric with the organic complexes present in metallic acetylacetones. Tellurium acetylacetone dichloride (ii) contains the new bivalent radicle (T., 1920, ibid.), whereas the third compound, tellurium 0-ethylacetylrtcetone trichloride (iii) arises from the intervention of ethyl chloride formed during condensation from the alcohol present in chloroform B.P. The other P-diketones containing an acetyl group furnish tellurium Published on 01 January 1922. Downloaded by University of California - San Diego 20/06/2017 09:27:26. derivatives conforming to one or other of the preceding types, but of the examples so far studied only acetylacetone gives rise to all three products. These practical results are explicable on the view that tellurium tetrachloride reacts initially with the terminal methyl group of the p-diketone, the subsequent course of the condensation depending on the enolic condition of the reactive primary product. 1. Tellurium Tetrachloride and Acetylacetone. The initial reaction between these reagents proceeds with elimination of hydrogen chloride to the following primary product, CH,*CO*CH2*CO*CH,-TeC13(I), which, although not isolated, may be regarded as the parent substance of the three stable tellurium derivatives subsequently produced. Enolisation of the primary product leads alternatively to the forms Ia and Ib. View Article Online 924 MORGAN AND DREW : RESEARCHES ON In the former condition (Ia),there is no tendency for the molecule to lose hydrogen cl-loride, since this condensation would lead to the formation of a highly strained, four-membered ring joining tellurium and the enolic oxygen, and accordingly condensation occurs with a second molecule of acetylacetone, leading to the production of tellurium bisacetylacetone dichloride (11). This compound retains the enolic properties of acetylacetone and gives characteristic ferric and copper derivatives. Hence the univalent acetylacetone radicle, C,H,02’, present in this tellurium derivative is essentially different from the isomeric complex in such metallic acetylacetones as the aluminium, gallium, and copper compounds. Owing to the spatial arrangement of the molecule in the alternative enolisation (Ib) of the primary product I, the enolic group becomes adjacent to the tellurium radicle, TeC13, and, in pure chloroform, elimination of hydrogen chloride occurs with the production of tellurium acetylacetone dichloride (111) owing to the Published on 01 January 1922. Downloaded by University of California - San Diego 20/06/2017 09:27:26. general tendency to form six-membered rings. If, however, ethyl chloride is either added or present as an impurity in the solvent, then ethylation of the enolic group occurs with the formation of tellqium 0-ethylacetylacetone trichloride (IV), this product also arising from the joint action of hydrogen chloride and ethyl chloride on tellurium acetylacetone dichloride. 2. Tellurium Tetrachloride and the 3-Alkylacetylacetones. The condensation between tellurium tetrachloride and C-methyl- acetylacetone or C-ethylacetylacetone takes a simple course, only one product being obtained in either case, namely, tellurium 3-methyhcetylacetone dichloride (VI) or tellurium 3-ethylacetylacetone dichloride (VII), respectively. In these instances the reactive primary product, CH,*CO*CHR*CO*CH,*TeC13(V), View Article Online RESIDUAL AFFINITY AND CO-ORDINATION. PART VIII. 925 enolises on the side remote from the tellurium radicle to the modification Va, from which hydrogen chloride is eliminated readily owing to the tendency to form six-membered cyclic systems, thus leading to the production of the two tellurium 3-alkylacetylacetone 3. Tellurium Tetrachloride and 3-Chloroacetylacetone. In the condensation between the tetrachloride and 3-chloroacetylacetone two substances are obtained corresponding with types i and ii. The main product is tellurium bis-3-chloroacetylacetone dichloride (IX), the by-product being tellurium 3-chloroacetylacetone dichloride (X). This result is explicable on the same general hypothesis ; the formation of a reactive primary product, CH3*CO*CHCl*CO*CH2*TeC13(VIII), which then enolises into one or other of two modifications VIIIa and VIIIb. ‘CCY The enolic form VIIIa condenses with a second molecular proportion of 3-chloroacetylacetone to yield tellurium bis-3-chloroacetylacetone dichloride, which retains two enolic groups, as is shown by the Published on 01 January 1922. Downloaded by University of California - San Diego 20/06/2017 09:27:26. production of copper tellurium bis-3-chloroacetylacetonedichloride. The formation of tellurium bis-3-chloroacetylacetonedichloride (IX), an enolic substance yielding metallic derivatives, is a crucial proof of the general hypothesis that tellurium becomes attached initially to a terminal methyl group. The alternative possibility of replacing the hydrogen of the chloromethylene group would not give rise to an enolic compound. Owing to the spatial arrangement of the groups in the second enolic form, VIIIb, the enolic and tellurium radicles become neigh- bours, so tfiat hydrogen chloride is eliminated between them with the f ormahion of tellurium-3-chloroacetylacetone dichhride (X). VOL CXXI. E’K View Article Online 926 MORGAN AND DREW : RESEARCHES ON 4. Tellurium Tetrachloride and Pivalylucetone (Acetylpinacolin). The interaction between the tetrachloride and pivalylacetone in chloroform B.P. leads to the formation of two compounds; the main product is tellurium 0-ethylpivalylacetone trichloride (XII), the by-product being tellurium bispivalylacetone dichloride (XIII). It is evident by the absence of a cyclic compound (type i, page 923) that in this instance enolisation of the primary product (CH,)3C*CO*CH2*CO*CH2*TeC1, (XI) has occurred on the side remote from the tertiary butyl group. This mode of enolisation (XIa) inhibits any formation of a six-membered ring and tends either to ether formation (XII) or to condensation with a second molecule of pivalylacetone to tellurium bispivalylacetone dichloride (XIII). 5. Tellurium Tetrachloride and Benxoylacetone (T.,1921, 119, 617). In this condensation using chloroform B.P. only two products are obtained, tellurium bisbenxoylacetone dichloride (XVI) and tellurium 0-ethylbenzoylacetone trichloride (XV). This practical result can be explained on the basis of the same hypothesis as that employed in the preceding condensation. The primary product is the reactive compound Published on 01 January 1922. Downloaded by University of California - San Diego 20/06/2017 09:27:26. C,H ,*CO*CH2*CO*CH2*TeC13 (XIV), which enolises only on the side remote from the phenyl group to give the enolic modification XIVa. (XVI.) When ethyl chloride is present etherification of the primary enolic compound takes place readily and tellurium O-ethylbenzoylacetone trichloride (XV) results. In the absence of ethyl chloride View Article Online RESIDUAL AFFINITY AND CO-ORDINATION. PART VIII. 927 the primary product condenses with another molecule of benzoylacetone and tellurium bisbenzoylacetone dichloride results. This compound is enolic and yields a copper derivative. The condensation was repeated in pure chloroform free from alcohol or ethyl chloride in the hope of producing a cyclic

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