Skip to main content
Library homepage
 
Chemistry LibreTexts

Haworth Formula

  • Page ID
    14961
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    Traditionally, in carbohydrate chemistry, the furanose rings and the pyranose rings in carbohydrate molecules are shown in the planar conformation, placed on the plane perpendicular to the plane of the paper.

    haworthformula1.png

    This representation of rings is known as the Haworth formula. eg: cyclic forms of D-glucose

    haworthformula2.png

    To generate the Haworth formulas of the cyclic forms of a monosaccharide, use the following procedure, explained using the pyranoses of D-glucose.

    Step 1: Draw the Fischer projection of the acyclic form of D-glucose. (See D,L convention)

    haworthformula3.png

    Step 2: Number the carbon chain in 1 starting at the top.

    haworthformula4.png

    Step 3: To generate the pyranose ring, the oxygen atom on C-5 in 1 needs to be attached to C-1 by a single bond.

    haworthformula5.png

    In 1, C-1 is behind the plane of the paper and the hydroxy group on C-5 is in front. For the pyranose ring to be planar, both C-1 and the hydroxy group on C-5 have to be either behind or in front of the plane of the paper. C-5 is a chiral center. In order to bring the hydroxy group on C-5 to the site occupied by the \(CH_2OH\) group without changing the absolute configuration at C-5, rotate the three ligands H, OH, and CH2OH on C-5 in 1 clockwise without moving the fourth ligand. (See Fischer projection)

    haworthformula6.png

    1 and 2 both represent D-glucose, but, in 2, unlike in 1, C-1 and the hydroxy group on C-5 are on the same side of the plane of the paper.

    Step 4: Ignore that 2 is a Fischer projection and rotate it clockwise by 90º.

    haworthformula7.png

    Step 5: Redraw the atom chain along the horizontal axis as follows.

    haworthformula8.png

    Step 6: Add the ligands on C-2 through C-5 in 4. The ligands pointing up in 3 are pointing up in 4; those pointing down in 3 are pointing down in 4.

    haworthformula9.png

    Step 7: Remove the hydrogen atom and the oxygen atom on C-1 and the hydrogen atom in the hydroxy group on C-5 in 5 and connect the two atoms by a single bond.

    haworthformula10.png

    Step 8: Add the two remaining bonds to C-1 in 6.

    haworthformula11.png

    Step 9: Attach a hydrogen atom to the bond pointing up and a hydroxy group to the bond pointing down on C-1 in 7.

    haworthformula12.png

    Step 10: Interchange the hydrogen atom and the hydroxy group on C-1 in 8.

    haworthformula13.png

    8 and 9 are the Haworth formulas of the pyranoses of D-glucose. If, in the acyclic form of a monosaccharide, the hydroxy group that reacts with the carbonyl carbon is not on a chiral carbon (eg: D-fructose→pyranoses), skip step 3.

    Contributors and Attributions


    Haworth Formula is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

    • Was this article helpful?