Phenylazopyrazines

Few nitro- and phenylazopyrazines are known, and these too are discussed in this chapter. 

Reduction of 2-hydroxy-3,6-dimethyl-5-phenylazopyrazine (8) with sodium hydrosulfite (dithionite) gave 2-amino-5-hydroxy-3,6-dimethylpyrazine (872), and vigorous reduction of the disodium salt of 2-(p-sulfophenylazo)-3-methyI-5-hydroxypyrazine with stannous chloride and hydrochloric acid gave 2-amino-5-hydroxy-3-methylpyrazine (434). 2-Hydroxy-5,6-diphenyl-3-phenylazopyrazine in methanol was reduced with hydrogen over Raney nickel to 2-amino-3-hydroxy-5,6-... 

Hydroxy-3,6-dimethyl-5-phenylazopyrazine is more acidic than 3-hydroxy-2,5-dimethylpyrazine (1125). The reduction of phenylazopyrazines to aminopyrazines has been described in Section 1 A(7). 

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