Replacement azides

Recently Hofmann has found that when the azide hydrochlorides of the lysergic and fsolysergic acids, or of their dihydro-derivatives, are boiled in dilute hydrochloric acid, a Curtius reaction occiys and the carboxyl is replaced by an amino-group. In this way he has prepared the following amines. They melt with decornposition and the specific rotations are for pyridine as solvent — ... 

Replacement of one tosyloxy group m 2-fluoro-2-nitro-l,3-propanediol ditosylate by azide ion occurs easily [S5] (equation 75)... 

For long-term column storage, it is recommended to replace the mobile phase with distilled water with 0.05% sodium azide. The columns can then be stored at room temperature. For shorter storage times, e.g., a long weekend, the column should be stored in the mobile phase after making sure that the end plugs of the columns have been tightened well. 

In this last reaction Na can be replaced by the azide NaN3 to give the same products. The normal oxides of the other alkali metals can be prepared similarly. 

The molecule has an almost linear N3 group and an angle C-N-N of 112.4° (Fig. II.4a).( ) The (linear) azide ion, N3", is isoelectronic with N2O, CO2, OCN", etc. and forms numerous coordination complexes by standard ligand replacement reactions. Various coordination modes have been established, including end-on bridging... 

Because of resonance stabilization of the anion, a tet-nazolyl moiety is often employed successfully as a bioisosteric replacement for a carboxy group. An example in this subclass is provided by azosemide (27). Benzonitrile analogue is prepared by phosphorus oxychloride dehydration of the corresponding benzamide. Next, a nucleophilic aromatic displacement reaction of the fluorine atom leads to The synthesis concludes with the 1,3-dipolar addition of azide to the nitrile liinction to produce the diuretic azosemi de (27). ... 

Replacement of chlorine on the pendant benzoyl group by azide is apparently consistent with antiinflammatory activity. Acylation of indomethacin intermediate with p-nitrobenzoyl chloride leads to the corresponding amide (7). Saponification ( ) followed by reduction of the nitro group gives the amine 9. The diazonium salt (10) obtained on treatment with nitrous acid is then reacted with sodium azide there is thus obtained zidomethacin (11). 

Replacement, of a chloro atom in ester using azide ion, 46, 47 of hydrogen atom on C 18 of steroid by hydroxy group or iodine atom, 46, 57... 

Procedure. The water sample should be collected by carefully filling a 200-250 mL bottle to the very top and stoppering it while it is below the water surface. This should eliminate any further dissolution of atmospheric oxygen. By using a dropping pipette placed below the surface of the water sample, add 1 mL of a 50 per cent manganese(II) solution (Note 1) and in a similar way add 1 mL of alkaline iodide-azide solution (Note 2). Re-stopper the water sample and shake the mixture well. The manganese(III) hydroxide forms as a brown precipitate. Allow the precipitate to settle completely for 15 minutes and add 2 mL of concentrated phosphoric(V) acid (85 per cent). Replace the stopper and turn the bottle upside-down two or three times in order to mix the contents. The brown precipitate will dissolve and release iodine in the solution (Note 3). 

Bromo-6,7,8,9-tetrahydro-l//-3-benzazepin-2-amine(6) with thiocyanate ion undergoes substitution of bromide to give the thiocyanatotetrahydro-l//-3-benzazepine 7.105 Attempts to replace bromide by azide ion failed, as did diazotization of the amine group with sodium nitrite in 6 M sulfuric acid. Oddly, treatment of the aminobromo compound with sodium borohydride in methanol results not in reduction, but in methoxy-debromination to give the 2-methoxy derivative which, on the basis of HNMR spectral data, is best represented as the 2-imino tautomer 8. 

Quinone diazides can also be obtained by the diazo group transfer reaction of 4-tosyl azide. For example, 9-diazo-10-anthrone (2.55) is formed from anthrone (2.54) if the reaction is carried out in an ethanol-piperidine mixture. On the other hand, if ethanol is replaced by pyridine, dimerization with loss of molecular nitrogen takes place and the azine 2.56 is isolated (Scheme 2-32 Regitz, 1964 Cauquis et al., 1965). In the preceding discussion tosyl azide was shown to be an electrophilic reagent. It therefore seems likely that it is not the anthrone 2.54 but its conjugate base which reacts with tosyl azide. 

Compounds in which the anomeric hydroxy group is replaced by a halogen atom are named as glycosyl halides. Pseudohalides (azides, thiocyanates etc.) are named similarly. 

The two halopropoxy compounds react with sodium azide in DMF to afford the azido intermediate Ifl. We used the method of KNOUZI et al.(ref. 11) but we replaced DMSO by DMF. 

Besides short ELPS, longer ELPs have also been conjugated to synthetic polymers. In one approach, Cu(I)-catalyzed azide-alkyne cycloaddition click chemistry was applied. For this purpose, ELPs were functionalized with azides or alkynes via incorporation of azidohomoalanine and homopropargyl glycine, respectively, using residue-specific replacement of methionine in ELP via bacterial expression [133]. More recently, an alternative way to site-selectively introduce azides into ELPs was developed. Here, an aqueous diazotransfer reaction was performed directly onto ELP[V5L2G3-90] using imidazole-1-sulfonyl azide [134]. 

Reaction of 47 with NBS in carbon tetrachloride afforded the tribromide (240, 100%). After replacement of the primary bromo group with benzoyl-oxyl, the product (241,47%) was debrominated with zinc dust in ethanol to give the diene (242,64%). Epoxidation of242 produced the isomeric compounds 243 and 244, which were transformed into the azides (245 and 246), convertible into valienamine isomers. ... 

While it was felt that some of the individual issues above could be addressed using the same synthetic sequence (e.g., alternate catalysts for the reduction step) it seemed unlikely that all the above would be solvable, especially as efforts to replace sodium azide with other nucleophiles had failed. Based on this assessment the team felt it would be necessary to evaluate a fundamentally new approach to taranabant and, in particular, to look for a method for installation of the chiral centers without the intermediacy of an alcohol. 

Many other methods of making lead azide in a safe form have been described, but the only one to have found commercial importance consists of replacing the dextrine by a small proportion of gelatine. When properly made this form of lead azide is as safe to handle as the dextrinated form and has improved sensitiveness to flame. It can therefore be used by itself in electric and delay detonators, but not in plain detonators as it is not ignited with certainty by safety fuse. 

The original initiating explosive used by Nobel and all manufacturers for many years was mercury fulminate. This had the disadvantage of decomposing slowly in hot climates, particularly under moist conditions. For this reason mercury fulminate is no longer widely used. In most countries it has been replaced by a mixture of dextrinated lead azide and lead styphnate. In the U.S.A. some detonators are made containing diazodinitrophenol. 

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