Cyclic Structure for Glucose CHO -OH H03 6 -H CH,OH H OH H CH-OHO H H H O OH -OH H 4K OH H 义1+Ht 一OH H HO HO HO 3 H 。CH,0H OH OH 分 OH Fischer projection on right side C6 rotated up Haworth projection ■ Glucose exists almost entirely as its cyclic hemiacetal form. Five-or six-membered ring hemiacetals are more stable than their open-chain forms. The Haworth projection,although widely used,may give the impression of the ring being flat. Chapter 23 13 Chapter 23 13 Cyclic Structure for Glucose ▪ Glucose exists almost entirely as its cyclic hemiacetal form. ▪ Five- or six-membered ring hemiacetals are more stable than their open-chain forms. ▪ The Haworth projection, although widely used, may give the impression of the ring being flat