With Hydrohalic Acids

2-Carbonyl-substituted phenyl organo tellurium compounds react with hydrohalic acids with cleavage of a Te —C bond and the formation of a stabilized aryl tellurium halide. 

2-Methoxycarbonylphenyl Tellurium Bromide 7.2 g (20 mmol) of 2-methoxycarbonylphenyl phenyl tellurium arc dissolved in 50 ml of glacial acetic acid saturated with hydrogen bromide. This solution is diluted with 50 ml of acetic acid, the mixture is heated under reflux for 24 h, and then cooled to 20° to allow the product to crystallize yield 6.25 g (87%) m.p. 127-128°. 

When acetals are used as starting materials, the carbonyl function is restored under the conditions of these reactions  

Treatment of 2-carboxyphenyl aryl tellurium compounds with zinc(II) chloride in butyl dichloromethyl ether at 100° converted the carboxylic acids to the acid chlorides and subsequently isomerized the thus formed 2-chlorocarbonylphenyl aryl tellurides to 2-arylcarbonylphenyl tellurium chlorides  

2-Benzoylphenyl Tellurium Chloride In a dry, 100 ml flask fitted with a reflux condenser topped with a drying tube are placed 6.5 g (20 mmol) of 2-carboxyphenyl phenyl tellurium, 5 ml (30 mmol) of butyl dichloromethyl ether, and 0.2 g (1.5 mmol) of anhydrous zinc chloride. The mixture is heated on a boiling water bath for 2 h, then diluted with carbon tetrachloride, charcoal is added, and the mixutre is filtered. The filtrate is evaporated to dryness and the residue is recry stallized from benzene/hexane yield 6.3 g (80%) m.p. 113-114 . 

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Fig. 14. Equipment for the hydrothermal method, with hydrohalic acids as solvents.

Reaction of diazo ketones with hydrohalic acids... 

Dick (38, 39) has shown that a number of 1-alkylaziridines are converted into the corresponding 1,4-dialkylpiperazines in yields as high as 95%, when treated with hydrohalic acids in acetone or methyl ethyl ketone. Perchloric acid and p-toluene-sulfonic acid resulted in the formation of poly(l-alkylaziridines) rather than piperazines. The major products formed in a water solvent were the polymers with 1,4-dialkylpiperazines being formed in maximum yields of 27% in the case of hydroiodic acid. The mechanism proposed by Dick is, that the piperazine are formed via a dimer in which the halogen atom of the initiating acid has formed a covalent bond with a... 

With hydrohalic acids as catalysts, the hydrolysis of 1,3,2-dioxathiolane 2-oxide (16) is considered to occur (partly or entirely) via a halosulfite intermediate, e.g. (138 X = C1). The marked acceleration of the aqueous hydrolysis of catechol cyclic sulfite by small amounts of fluoride ion is likewise attributed to a nucleophilic catalysis (76CRV747). The nucleophilic attack of (16) at carbon by halide ion on reaction with phenylmagnesium bromide has already been discussed in Section 4.33.3.3.4. 

The compound is insoluble in all solvents but reacts with hydrohalic acids to form tellurium... 

From Heterocyclic Tellurium Compounds with Hydrohalic Acids, Sulfuryl Chloride or... 

Tropylium aryltetrahalotellurates can be prepared from tropylium bromide and an aryl tellurium trihalide. A more convenient procedure avoiding the laborious preparation of the tropylium bromide uses cycloheptatricne and triphenylmethyl perchlorate2. The product of this reaction can then be converted to the tetrahalotellurate by treatment with hydrohalic acids. 

The diorgano tellurium oxides or dihydroxides need not be isolated. Treatment of diorgano tellurium dihalides with silver oxide2,3 or ammonia and silver nitrate4 forms solutions of diorgano tellurium dihydroxides, which can be immediately reacted with hydrohalic acids. 

Benzotellurazoles react with hydrohalic acids to form 1,3-benzotellurazolium halides, which, upon treatment with aqueous solutions of ammonia or sodium hydrogen carbonate, are converted back to the benzotellurazoles1. 

Summary Sn2 Reactions OfTosylate Esters 478 11-6 Reduction of Alcohols 478 11-7 Reactions of Alcohols with Hydrohalic Acids 479... 

Limitations on the Use of Hydrohalic Acids with Alcohols The reactions of alcohols with hydrohalic acids do not always give good yields of the expected alkyl halides. Four principal limitations restrict the generality of this technique. 

A -l//-Phosphirene imides prepared by [2+1] cycloaddition of iminophosphines with alkynes can be protonated with hydrohalic acids to afford phosphirenium halides bearing an amino substituent on the phosphirene phosphorus (Equation 10) <1995ZOR400>. 

Diorgano tellurium oxides react with hydrohalic acids by regenerating the diorgano tellurium dihalides, the common starting materials for the preparation of diorgano tellurium oxides. The reactions with hydrochloric acid, hydrobromic acid , and hydroiodic acid, therefore, are not of synthetic importance. The reaction with hydrofluoric acid , however, is a convenient way of preparing diorgano tellurium difluorides. 

Write equations describing reactions by which the following compounds can be prepared (a) hypohalous acids of Cl, Br, and I (in solution with hydrohalic acids) (b) hypo-halite salts (c) chlorous acid (d) perchloric acid. 

Substitution yields products with other single-bonded functional groups. With hydrohalic acids, many alcohols give haloalkanes ... 

Reaction with P4 and NaOH 5, 3.3.5.6 Reactions with hydrohalic acids 4, 2.8.8.3 CuH3Ll2 Li2CuH3... 

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