Glucose (c6h12o6) can exist as both an open-chain form and a closed-ring form. before 1900, glucose was only thought to occur as an open chain. now we know that over 99 percent of the time, glucose occurs in the closed-ring form. what possible difference between these forms would give chemists a clue that the open-chain form was not present?

An open-chain structure of glucose presents unbranched backbone of six carbon atoms, where C1 atom has functional group, aldehyde and glucose failed to undergo typical aldehyde reactions. Glucose has no end functional groups in a ring structure. The open-chain form of glucose makes up less than 3% of the glucose molecules in a water solution.

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