Sentence Examples


  • A-pyrone condenses with the benzene ring to form coumarin and isocoumarin; benzo-'y-pyrone constitutes the nucleus of several vegetable colouring matters (chrysin, fisetin, quercetin, &c., which are derivatives of flavone or phenyl benzo-y-pyrone); dibenzo--ypyrone is known as xanthone; related to this substance are fluorane (and fluorescein), fluorone, fluorime, pyronine, &c. The pyridine ring condenses with the benzene ring to form quinoline and isoquinoline; acridine and phenanthridine are dibenzo-pyridines; naphthalene gives rise to a-and /3-naphthoquinolines and the anthrapyridines; anthracene gives anthraquinoline; while two pyridine nuclei connected by an intermediate benzene nucleus give the phenanthrolines.
  • The first class includes those substances which require no preliminary treatment, and comprises the amides and ammonium compounds, pyridines, quinolines, alkaloids, albumens and related bodies; the second class requires preliminary treatment and comprises, with few exceptions, the nitro-, nitroso-, azo-, diazoand amidoazo-compounds, hydrazines, derivatives of nitric and nitrous acids, and probably cyanogen compounds.
  • The aldehydes condense readily with acetoacetic ester in the presence of ammonia, to pyridines (see Pyridine), whilst 0.
  • Acetoacetic ester is a most important synthetic reagent, having been used in the production of pyridines, quinolines, pyrazolones, furfurane, pyrrols, uric acid, and many complex acids and ketones.
  • In this reaction the proportions of aldehyde and acetoacetic ester may be interchanged and ay disubstituted pyridines are then obtained.

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