2- naphthyl azide

Azido-4-nitronaphthalene (4-Nitro 1 -naphthyl azide). Yel needles from hot EtOH, mp 99° CA Registry No 6549-18-4. Its prepn is the same as above, using the 4-nitrodiazonium salt (Refs 1 4)... 

Further studies showed that annelated azepines could be obtained from the photolysis of 1-naphthyl azide and 5- and 8-azidoquinolines in the presence of primary amines.247 However, 6- and 7-azidoquinoline again gave only the o-diamines (Eqs. 55 57).247... 

On the basis of product studies, it is clear that irradiation of the naphthyl azides leads to loss of nitrogen with the likely consequent formation of nitrenes. Just as for phenyl azide, the initially formed singlet nitrenes may intersystem cross to the triplet and then dimerize to azo compounds. Clearly in the case of 2-naphthyl azide, but not 1-naphthyl azide, a closed-shell ground-state intermediate that can be trapped with diethylamine can be generated. The intermediate was formulated as the azirine on the basis of product studies [57]. Low temperature absorption spectroscopy and time-resolved laser flash photolysis experiments to be described later support the formation of azirines and provide an explanation for the different reactivity observed between the 1- and 2-substituted azides. 

Reiser et al. [18] found that on photolysis of 1-naphthyl azide in a clear... 

Figure 7. A comparison of the spectra of the 1-naphthylaminyl radical and triplet 1-naphthyl nitrene. The spectrum of the radical was produced by laser flash photolysis of di-tcrt-butyl peroxide containing 1-naphthylamine. The spectrum of the nitrene was produced by photolysis of 1-naphthyl azide in EPA glass at 77 K.

It is now clear from the work of Leyva and Platz [85] (see Section VI.2) that photolysis of 1-naphthyl azide at 77 K produces triplet 1-naphthyl nitrene as the first persistent species in low temperature glasses, and that... 

Recall that photolysis of 2-naphthyl azide in the presence of diethylamine gives l-amino-2-diethylaminonaphthalene but that irradiation of 1-naphthyl azide under these conditions gives only 1-aminonaphthalene. However, irradiation of either 1- or 2-naphthyl azide in a low-temperature matrix was shown to give azirines by infrared spectral analysis. Since azirines are the likely precursors to substituted diamines, these findings pose a dilemma that was resolved by application of time-resolved spectroscopic methods. 

Flash photolysis of an oxygen-free benzene solution of 2-naphthyl azide leads to the slow appearance of 2-azonaphthalene from a precursor having a lifetime of several hundred microseconds. In contrast, irradiation of 1-naphthyl azide under these conditions shows more complex behavior. In the... 

With the assumption that the undetected precursors to triplet 1- and 2-naphthylnitrenes are the azirines seen in the low temperature experiments, we can reach useful conclusions about the photochemistry of polynuclear aromatic azides. First, unlike phenyl azide where the closed-shell singlet intermediate formed in room temperature irradiations is dehydroazepine [46, 49, 69], the intermediates formed from both 1- and 2-naphthyl azide are azirines. The difference in the chemistry of 1- and 2-naphthyl azides is traced to a difference in the lifetime of the respective azirines. The azirine from 2-naphthyl azide survives at least 200 times longer than does the azirine formed from 1-naphthyl azide. The increase in lifetime permits the bimolecular trapping reaction by diethylamine to compete with isomerization to the triplet nitrene in the case of the 2-naphthyl but not the 1-naphthyl azides. 

The discovery of the temperature dependence of the photochemistry of phenyl azide prompted Leyva and Platz [85] to reexamine the photochemistry of 1-naphthyl azide. As mentioned previously photolysis of 1-naphthyl azide at 298 K in the presence of diethylamine fails to produce an azepine adduct, instead only a trace of diamine 9 is observed along with small amounts of azonaphthalene [51, 57, 91], The major product is 1-naphthy-lamine. Carroll et al. [51] improved the yield of diamine adduct with piperidine by adding N, N, N, N tetramethylethylenediamine (TMEDA) to complex with singlet 1-naphthyl nitrene. TMEDA did not improve the yield of diethylamine adduct, however. 

TABLE 5 The Distribution of Products Formed on Photolysis of 0.04 M 1-Naphthyl Azide (1) in the Presence of 1.0 M Diethylamine at Several Temperatures (R - 1-naphthyl) (85 ... 

Tsunoda and Yamaoka [173, 174] also condensed formyl-1-naphthyl azide with poly(vinyl alcohol). All steps in the synthesis were not disclosed. The preparation was illustrated as follows ... 

The same authors also condensed formyl-1-naphthyl azide with poly(vinyl... 

Scheme 11.46 Photochemistry of 1-naphthyl azide 79 in solution at ambient temperature...

Leyva, E. and Platz, M. S., The temperature-dependent photochemistry of 1-naphthyl azide. Tetrahedron Lett., 28, 11, 1987. 

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