Alkylamines, diazotization

Nitrous acid reacts with 1 ° alkylamines and arylamines to form diazonium salts. This reaction is called diazotization. 

Diazotization reaction (Section 25.13A) A reaction that converts 1 ° alkylamines and arylamines to diazonium salts. 

This behavior is typical of alkylamines. The arylamines behave similarly at higher than room temperatures. However, at temperatures of 5° or lower, the intermediate compounds, known as diazonium salts, are formed. Because of their great reactivity they are used in the preparation of a large and diversified number of compounds. The formation of the diazonium salts is known as diazotization of the arylamine ... 

Addition of a primary alkylamine to an o-cyanodiazonium salt at low temperature leads to an efficient cyclization. A similar ring is formed in high yield when the aminonitrile (63.1) is diazotized under standard conditions—a reaction which is not shown by simpler aminonitriles. The product is a useful intermediate. 

Since, unlike arylamines, alkylamines cannot be diazotized, special processes are needed for synthesis of aliphatic diazo compounds these mostly involve a... 

Even in series of nitrosations of alkylamines with electron-withdrawing substituents, such discrepancies between comparable compounds are known. Thus, Gilman and Jones (1943) found 70% of l-diazo-2,2,2-trifluoroethane in the reaction of 2,2,2-trifluoroethylamine, HCl, and NaN02. This result was confirmed by Dyatkin and Mochalina (1964). Nevertheless, Atherton et al. (1971) were unable to synthesize l-diazo-2,2-difluoroethane by nitrosation of 2,2-difluoroethylamine and with 2,2,3,3-tetrafluoropropylamine they obtained a yield of only 10%. Good yields are reported, however, for the diazotization of the fluorinated aminoalkane 2.21 (Coe et al., 1983) and of 2-amino-l,l,l-trifluoro-3-nitro-propane (2.22, Aizikovich and Bazyl, 1987). Jin et al. (1992) claim that l-diazo-2,2,2-trifluoroethane can be ob-... 

Another important diazotization method is the use of glacial acid for the nitrosation of alkylamines, because of the formation of an ion pair 7.12 between the acetate ion and the diazonium ion. In water the influence of acetate ion is small. 

Carbodi-imide-mediated reaction with alkylamine glass reaction with diazotized arylamine glass glutaraldehyde cross-linking onto alkylamine glass... 

The driving force for this reaction is the formation of N2, an exceptionally stable molecule. The carbocations generated in this manner react like others we have seen by nucleophilic attack to give substitution, by proton loss to give elimination, and by rearrangement. Because of the many competing reaction pathways, alkanediazonium salts usually decompose to give complex mixtures of products. Therefore, the diazotization of primary alkylamines is not widely used for synthesis. 

Diazotization of alkylamines represents the most direct conceivable route to diazoalkanes (2). However, isolation of non-stabilized diazoalkanes by this strategy is not feasible they fail to survive the strongly acidic conditions of the synthesis. If diazotization is performed on 1,2-amino alcohols with sodium nitrite at low pH, Tiffeneau-Demjanov rearrangement (TDR) [64, 65] occurs through a cationic (vs zwitterionic) intermediate to give a rearranged ketone (3). 

Primary arylamines react with nitrous acid, HNOg, to yield stable arenediazo-nium salts, Ar—N=N X , a process called a diazotization reaction. Alkylamines also react with nitrous acid, but the corresponding alkanediazonium products... 

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