1. The reaction of nitrous acid on chlorophyll yielded four compounds,
denoted for convenience as A, B, C and D.
2. The compounds are all distinctive in appearance, are highly coloured and
three of them have sharp melting points.
3. A convenient process of separation of the compounds and easy methods
for the purification of A, B and C have been found.
4. A, B, and C all appear to be tetra-substituted pyrrole derivatives. A and
B each exhibit tautomerism, probably of the nitroso-isonitroso type, whereas C
appears to have only one form.
5. A and B form mono-acetyl derivatives, but C yields no derivatives of this
6. Formulae have been tentatively proposed as follows: A
(Molecular formula): C₁₄ H₁₃ N₃ O₃
B (Molecular formula): C₁₄ H₁₆ N₂ O.
C (Empirical formula): C₁₃ H₁₀ N O or C₁₃ H₁₁ N O.
7. None of the compounds exhibited icterogenic or photosensitising properties
when administered to sheep, either by subcutaneous injection or by oral
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