For example, where a quinone is provided which is unsubstituted in at least one quinoid ring position adjacent a carbonyl group (e.g., a 2-or 3-ring position in the case of 1,4-benzoquinones and 1,4-naphthoquinones), an amine such as ammonia can react with the quinone at the unsubstituted ring position to form the corresponding amino-1,4-hydroquinone.