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Finally, the acyl azide reacts in the normal manner to give the urethane. Studies show that DPPA reacts with amines giving the corresponding phosphoramidates; it therefore appears that formation of the amide similarly involves the intermediate anhydride, followed by nucleophilic substitution by the amine.
The acyl azide is usually made from the reaction of acid chlorides or anhydrides [6] with sodium azide [7] or trimethylsilyl azide. [8] Acyl azides are also obtained from treating acylhydrazines with nitrous acid. [9] Alternatively, the acyl azide can be formed by the direct reaction of a carboxylic acid with diphenylphosphoryl azide (DPPA ...
Some azide reactions are shown in the following scheme. Probably the most famous is the reaction with phosphines, which leads to iminophosphoranes 22; these can be hydrolysed into primary amines 23 (the Staudinger reaction), [31] react with carbonyl compounds to give imines 24 (the aza-Wittig reaction), [32] [33] [34] or undergo other ...
Since the ends are condensed, its formula has one less H 2 O (water) than tripolyphosphoric acid. The general formula of a phosphoric acid is H n−2x+2 P n O 3n−x+1, where n is the number of phosphorus atoms and x is the number of fundamental cycles in the molecule's structure; that is, the minimum number of bonds that would have to be ...
Reaction mechanism for the amine formation from a carboxylic acid via Schmidt reaction. In the reaction mechanism for the Schmidt reaction of ketones , the carbonyl group is activated by protonation for nucleophilic addition by the azide, forming azidohydrin 3 , which loses water in an elimination reaction to diazoiminium 5.
The gas phase reaction between dilute F 2 and HN 3 produces FN 3. [44] [45] Chlorine azide, also a gas, can be produced from passing chlorine gas through a solution of NaN 3. [46] Chlorine azide tends to explode spontaneously even at reduced temperatures. Bromine azide is a liquid but is also treacherous. [46] BrN 3 hydrolyzes readily.
The reaction mechanism of the Mitsunobu reaction is fairly complex. The identity of intermediates and the roles they play has been the subject of debate. Initially, the triphenyl phosphine (2) makes a nucleophilic attack upon diethyl azodicarboxylate (1) producing a betaine intermediate 3, which deprotonates the carboxylic acid (4) to form the ion pair 5.
Solvents are often not used for this reaction, though there is precedent for the improvement of selectivity with its usage. [5] Phosphonites are generally more reactive than phosphite esters. They react to produce phosphinates. Heating is also required for the reaction, but pyrolysis of the ester to an acid is a common side reaction. The poor ...