{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Ch_322b_22.06 - Some Problems with the Open-Chain(Fischer...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Some Problems with the Open-Chain (Fischer) Structure for D-(+)-Glucose CHO CH 2 OH OH OH OH HO H H H H the Fischer structure for D-(+)-glucose The open-chain aldose structure is not consistent with some of the chemical and physical properties of glucose. (1) Certain standard aldehyde reactions, such as bisulfite addition, do not occur. Also the Schiff reagent test (a color test based on the easy oxidation of the aldehyde function) fails. (2) D-(+)-Glucose obtained from a solution of water shows a mp of 147 o C (dec). This sample redissolved in water has an initial specific rotation of [ ! ] = +112 o . But over time, the specific rotation drops to [ ! ] = +52 o . This change in rotatory power is called mutarotation . A trace of acid or base accelerates mutarotation. (3) A second form of D-(+)-glucose can be isolated that shows an initial [ ! ] = +19 o in water. Over time, the specific rotation of this solution changes to [ ! ] = +52 o .
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The Cyclic Hemiacetal Structures These observations of the properties and behavior of D-(+)-glucose are not consistent with the simple aldose structure. It soon became
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern