page_title: Pyranose
section_title: History
hierarchical_section_title: Pyranose / History
caption_attribution_description: English: Haworth projection of b-glucopyranose
context_page_description: Pyranose is a collective term for saccharides that have a chemical structure that includes a six-membered ring consisting of five carbon atoms and one oxygen atom. There may be other carbons external to the ring. The name derives from its similarity to the oxygen heterocycle pyran, but the pyranose ring does not have double bonds. A pyranose in which the anomeric OH at C has been converted into an OR group is called a pyranoside.
context_section_description: Hermann Emil Fischer won the Nobel Prize in Chemistry (1902) for his work in determining the structure of the D-aldohexoses. However, the linear, free-aldehyde structures that Fischer proposed represent a very minor percentage of the forms that hexose sugars adopt in solution. It was Edmund Hirst and Clifford Purves, in the research group of Walter Haworth, who conclusively determined that the hexose sugars preferentially form a pyranose, or six-membered, ring. Haworth drew the ring as a flat hexagon with groups above and below the plane of the ring – the Haworth projection.
  A further refinement to the conformation of pyranose rings came when Sponsler and Dore (1926) realized that Sachse’s mathematical treatment of six-membered rings could be applied to their X-ray structure of cellulose. It was determined that the pyranose ring is puckered, to allow all of the carbon atoms of the ring to have close to the ideal tetrahedral geometry.
caption: Haworth Projection of β-D-glucopyranose
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