1,2,4,5-Tetrazine-3,6-dicarboxylic acid, 1,2-dihydro-, disodium salt

Disodium dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate 1,2,4,5-Tetrazine-3,6-dicarboxylic acid, 1.2-dihydro-, disodium salt (11) (96898-32-7)... 

A [3 + 3] atom fragment method for the preparation of dihydro-1,2,4,5-tetrazines is the dimerization of diazo compounds under the influence of bases. In 1900 Hantzsch and Lehmann observed the formation of a new compound when ethyl diazoacetate (312) was treated with sodium hydroxide (00CB3668). The structure which they proposed originally was incorrect it was shown later that the product isolated was the disodium salt of l,2-dihydro-l,2,4,5-tetrazine-3,6-dicarboxylic acid (313) (or the 1,4-dihydro compound) <78HC(33)1075, p. 1078). 

Liberating the acid from the disodium salt with H2S04 decreases the yield of this step considerably. Dimethyl t,4-Dihydro-i,2,4J-tetrazine-3,6-dicarboxylate (2b) ... 

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