Azides reduction with ammonium

Lithium aluminum hydride is a convenient reagent for reduction of nitro compounds, nitriles, amides, azides, and oximes to primary amines. Catalytic hydrogenation works also. Aromatic nitro compounds are reduced best by reaction of a metal and aqueous acid or with ammonium or sodium polysulfides (see Section 23-12B). Reduction of /V-substituted amides leads to secondary amines. 

Reduction The stable Ni(0) complex is a useful catalyst for reduction of carbonyl compounds (to alcohols), sulfonyl azides (to sulfonamides), imines and nitro compounds (to amines) with ammonium formate. 

Nitrite interferes, since it may be partially converted into nitrate under the conditions of the determination. When the concentration of nitrite is not higher than that of nitrate, tlie effect is negligible. Large quantities of nitrite must be removed, e.g., by reduction with sodium azide, urea, or hydrazine. Ammonium ions cause low results wheti nitrate is determined. Preliminary expulsion of ammonia by heating the solution after it has beett made alkaline with sodium hydroxide is recommended. 

Azides react with epoxides too. This epoxide is one diastereoisomer (trans) but racemic and the symbol ( ) under each structure reminds you of this (Chapter 14). Azide attacks at either end of the three-membered ring (the two ends are the same) to give the hydroxy-azide. The reaction is carried out in a mixture of water and an organic solvent with ammonium chloride as buffer to provide a proton for the intermediate. Triphenylphosphine in water is used for reduction to the primary amine. 

Treatment of enecarbamate 344 with sodium azide and ceric ammonium nitrate (CAN) in acetone furnished azidocarbazole 345. The low yield in this oxidative cychzation reaction is due to formation of the diastereomer consisting of stereochemical inversion at the azide-substituted carbon. At this point, azide reduction employing the Staudinger conditions of triphenyl-phosphine in a mixture of water and THF led to an amine, which was subjected to trichloroacetyl chloride in a solution of dichloromethane and triethylamine to yield amide 346 (Scheme 49). 

Hydrazotc acid, HN,. ply.. = 4.72, and most of its covalent compounds (including its heavy metal salts) are explosive. It is formed (1) in 90% yield by reaction of sodium amide with nitrous oxide, (2) by reaction of hydraztntum ion with nitrous acid, (3) by oxidation of hydrazimum salts, (4) by reactio n of hydt azinium hydrate with nitrogen trichloride tin benzene solution). Hvdrazoic acid forms metal azides with the corresponding hydroxides and carbonates. It reacts with HC1 to give ammonium chlonde and nitrogen, with H2SO4 to form hydrazinium acid solfate, with benzene to form aniline, and it enters into a number of oxidation-reduction reactions. 

Nitrogen halides are destroyed with cold base. Azides and fulminates-may often be destroyed with acid, while heavy metal acetylides are decomposed by ammonium sulfide. The removal of peroxides by reduction has been described above. 

The synthetic potential of reductions by formate has been extended considerably by the use of ammonium formate with transition metal catalysts like palladium and rhodium. This forms a safe alternative to use of hydrogen. In this fashion it is possible to reduce hydrazones to hydrazines, azides and nitro groups to amines, to dehalogenate chloro-substituted aromatics, and to carry out various reductive removals of functional groups. For example, phenol triflates are selectively deoxygenated to the aromatic derivatives using triethylammonium formate as reductant and a palladium catalyst. - These recent af li-cations have been reviewed. 

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