Attempts to prepare N,N′‐ethene indigo. (On indigo VIII)

Abstract An attempt was made tot prepare N,N′‐ethene indigo, the derivative of cis‐indigo in which the nitrogen atoms are joined by an ethene link. A compound was however obtained whose probable formula is that of N,N′‐ethene indigo with a molecule of water added at the double bond between the two indol nuclei. It was found impossible to split off the water from this compound without further decomposition.