Abstract: The preparation of a variety of quinones by oxida- tion of hydroquinones with manganese dioxide and manganese dioxide impregnated with nitric acid, in methylene chloride solution, is described. ... 1,4-benzoquinone (Id, le). In relation with our interest ... 1,4-benzoquinone (Id) and related substances starting from ... The study of the preparation of 1b from acetyl- ... R2 R3 found reportedb found reported Ref. H ... H H 90 58 114-115 111-113 10 Me