With Monoketones

The interactions of tellurium tetrachloride and aliphatic ketones in refluxing chloroform were investigatedReaction mixtures containing two mol of ketone per mol of tellurium tetrachloride yielded bis[2-oxo-l-alkyl] tellurium dichlorides (Vol. IX, p. 1060) from all alkyl methyl ketones investigated except ethyl methyl ketone. No tellurium dichlorides were isolated from analogous reactions with alkyl ethyl ketones or dipropyl ketones.  

A nuclear magnetic resonance study ( H, Te) of these reaction mixtures established that ketonyl tellurium trichlorides and diketonyl tellurium dichlorides are present. The easily crystallized and less soluble compounds were isolated. Contrary to Morgan s claim, ethyl methyl ketone did react to give bis[2-oxo-l-butyl] tellurium dichloride albeit in very low yield. Alkyl ethyl ketones and tellurium tetrachloride produced very low yields of bis[3-oxo-2-alkyl] tellurium dichlorides. Cyclooctanone and tellurium tetrachloride in refluxing carbon tetrachloride gave bis[2-oxocyclooctyl tellurium dichloride (m.p, 174°) in 40% yield . 

Aryl methyl ketones and tellurium tetrachloride react to form bis[aroylmethyl] tellurium dichlorides . Among these compounds bis[henzoylmethyl tellurium dichloride has received much attention as a component of photosensitive imaging systems . 

Bis[benzoylmethyl] Tellurium Dichlorideh A mixture of 5.0 g (18.5 mmol) tellurium tetrachloride, 9.0 g (75 mmol) acetophenone, and 100 ml dry carbon tetrachloride is refluxed for 8 h. The mixture is filtered and the solvent evaporated from the filtrate. The semi-solid residue is triturated with diethyl ether and then recrystallized from chloroform yield 62% m.p. 195-197°. 

Similarly prepared were the following tellurium dichlorides  

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The reactions discussed in this chapter that depend on the formation of enolate anions (i.e., halogenation, aldol addition, and alkylation) often proceed smoothly and under milder conditions with 1,3-diketones than with monoketones. This is because the 1,3-diketones are stronger acids and therefore can form the enolate anions with weaker bases. The principal synthetic methods for preparing 1,3-dicarbonyl compounds will be discussed in Chapter 18. 

Phenyl- 1-trimethylsiloxyethene, the trimethylsilylenol ether of methyl phenyl ketone, added tellurium tetrachloride across the carbon-carbon double bond. Subsequent elimination of chlorotrimethylsilane produced bis[benzoylmethyl] tellurium dichloride. Addition to enols is also the first step in reactions of tellurium tetrachloride with monoketones and 1,3-diketones (p. 534, 535). 

These reactions are analogous to processes observed with monoketones but their variety is considerably enhanced by the added possibilities for reaction introduced by the second carbonyl group. Reactions in the presence of oxygen will be discussed separately. Before turning to these reactions, a brief summary of spectroscopic properties of diones is desirable. 

With ketones With monoketones With aliphatic ketones Co (C6H5)2-C3(=0), C1, room 5.30 Gouy probably octahedral. 67B24... 

With ketones With monoketones Wth aromatic and heterocyclic ketones [Cr(2-CH3CO-C4H.,N-)3] "") room 3.9 Farad octahedral coordination suggested 72D2... 

With ketones With monoketones With aliphatic monoketones Co CH3CO(=CHN02)- 2 296 9690 c. 4.82 -30 Gouy probably pseudo-octa- 72A31... 

With ketones With monoketones With aliphatic monoketones ... 

With ketones With monoketones aromalk monoketones Co C6H5 CO C6H3(0CH3)0->2 H2O 293 4,82 six-coordination suggested probably polymeric 73U5... 

With ketones With monoketones With alicyclic monoketones [Ni(C4H7NSO)6]Cl2 >) room 3.16 octahedral coordination suggested 74D6... 

With ketones With monoketones fVith aliphatic monoketones With acetone and derivatives [Cu N02 CH=C(CH3)0- 2] room 1.93 square planar coordination suggested 73A16... 

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