{TAIL ~ This invention} provides 3,7 diamino phenazine leuco dyes with {HEAD ~ acyl substituents} in the 10 position, said acyl substituents being themselves substituted with electron withdrawing groups 
{ TAIL ~ This invention } provides 3,7 diamino phenazine leuco dyes with { HEAD ~ acyl substituents } in the 10 position , said acyl substituents being themselves substituted with electron withdrawing groups
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