Лако-красочные материалы — производство

Spironaphthooxazines are generally prepared by condensation of 2- alkylidene heterocyclic compounds with an o-nitrosonaphthol in methanol or ethanol, as shown in Scheme 18.73

o-Nitrosonaphthol is prepared by reaction of P-naphthol with sodium nitrite in aqueous solution.74 Similarly, 5-nitroso-6-quinoline, 9-nitroso-10- phenanthol, and other o-nitroso arylols useful for the preparation of spirooxazine derivatives, have been prepared.72 Only one absorption band (Vmax 500 nm) for the colored form of 1,3,3-trimethylspiroindolinobenzo-

xazine 38 was listed in the previous review,1 and other spectral data for this class are very limited. Other spiroindolinobenzoxazines from 3- or 5- methoxy-2-nitrosophenol or 3,3 ‘-dinitroso-4,4 ‘-dihydroxy diphenylmethane have been documented in the patents.75,76

Indolines, benzoxazole, and benzothiazole are possible as 2-methylene heterocycles. The number of known spirooxazine derivatives is much less than for the spiropyrans. This may be partly due to lack of many substituted o-nitrosonaphthols and partly due to lack of sufficient stability of spiro — oxazines. The structures of parent spirooxazines and the Xmax of their photomerocyanine forms are listed in Table 5. The Xmax of the colored forms of compounds 41-43 are not described in the literature.

Experimental Preparation of Spironaphthooxazine 33 (N-Bu). Tri-

ethylamine (3.54 g, 35 mmol) was added to a suspension of 2,3,3-trimethyl — N-butylindolinium iodide (12.0 g, 35 mmol) and o-nitrosonaphthol (6.1 g, 35 mmol) in EtOH (100 ml) under stirring. The mixture was refluxed for 2 h, cooled, and evaporated under reduced pressure. The residue was chroma­tographed on silica gel with benzene as an eluent, and then recrystallized from methanol to give spiro(N-butylindolinonaphthooxazine) 33 (6.6 g, yield 51%).