Halogenation with concentrated halogen acids

Jsomerides of Morphine and Codeine. When morphine is treated with thionyl chloride, phosphorus trichloride or tribromide, the alcoholic hydroxyl group is replaced by the halogen, forming a-chloromorphide and bromomorphide respectively. The former on treatment with concentrated hydrochloric acid is converted into /3-chloromorphide. Schopf and Hirsch have provided evidence that the two are structural isomerides. With the same reagents codeine yields a parallel set of compounds, viz., a- and -chlorocodides, and bromocodide. The chief characteristics of these products may be summarised thus —... 

The furoxan ring is notably resistant to electrophilic attack and reaction normally takes place at the substituents. Thus aryl groups attached to monocyclic furoxans and the homocyclic ring of benzofuroxans are nitrated and halogenated without disruption of the heterocycle. Reaction with acid is also slow protonation is predicted to occur at N-5 <89KGS1261> and benzofuroxans have pKj, values of ca. 8, similar to those of benzofurazans. Monosubstituted furoxans are, as expected, less stable and can be hydrolyzed to the corresponding carboxylic acid. Treatment of the parent furoxan (3) with concentrated sulfuric acid results in rearrangement to (hydroxyimino)acetonitrile oxide (HON=CHC=N —O ) and subsequent dimerization to bis(hydroxyiminomethyl)furoxan... 

When arsenic trisulphide is exposed to dry hydrogen chloride or hydrogen bromide, it liquefies at the ordinary temperature and on heating complete volatilisation occurs.9 It is not readily attacked by halogen acids. When boiled with concentrated hydrochloric acid it is decomposed, but with great difficulty, and the hydrogen sulphide and arsenious chloride evolved reproduce arsenious sulphide in the receiver.10 A similar reaction occurs when heated with a chloride in the presence of concentrated sulphuric acid, but the decomposition is incomplete.11 The reaction is facilitated by the presence of cuprous chloride or ferric chloride. Only a slight reaction is observed with dilute acid,12 and the... 

Over a dozen oxides of the halogens have boon characterized, many of them quite unstable. Perhaps the most important are chlorine dioxide, CJ02, and iodine pentoxide, I2O5. Chlorine dioxide (boiling point 11° C) is an odd molecule (p. 62), but apparently it shows no tendency to dimerize. Although it has been used as an antiseptic in water purification and as a bleach, it must be handled in diluted form for it is explosive when alone. It is formed, along with HCIO4, when chlorates are treated with concentrated sulfuric acid, but a safer preparation involves reduction of a chlorate with oxalic acid. 

Nitrate in the presence of bromide and iodide The brown ring test for nitrates cannot be applied in the presence of bromides and iodides since the liberation of the free halogen with concentrated sulphuric acid will obscure the brown ring due to the nitrate. The solution is therefore boiled with sodium hydroxide solution until ammonium salts, if present, are completely decomposed powdered Devarda s alloy or aluminium powder (or wire) is then added and the solution gently warmed. The evolution of ammonia, detected by its smell and its action upon mercury(I) nitrate paper (see Section III.38, reaction 1) and upon red litmus paper, indicates the presence of a nitrate. 

Jacobsen rearrangement. Reaction of po-lymethylbenzenes with concentrated sulfuric acid to give rearranged polymethylbenzenesulfonic acids. Under identical conditions, halogenated polyme-... 

On treatment with concentrated sulphuric acid /3-chloromorphide yields a sulpho-/3-chloromorphide C17H180BNC1S [71], probably a sulphonic acid, which gives a halogen-free compound on heating with water[ 71]. a-Chlorocodide does not give a crystalline derivative in this way [71],... 

Tetrahydrotellurophene is oxidized rapidly in air to tetrahydrotellurophene 1-oxide (25) it reacts with halogens and methyl iodide to give 1,1-dihalo (22) and 1 -methyl- 1-iodotetrahydrotelluro-phene (26), respectively, and gives molecular complexes with mercuric chloride it reacts explosively with concentrated nitric acid and develops a red coloration with sulfuric acid.66... 

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