Why Does the Fischer Projection of Glucose Show Carbon Atoms with Five Bonds?

In summary, the conversation discusses the Fischer formula of D-glucose and the confusion surrounding the upper carbon atoms having 5 bonds and the additional hydrogen atom in the upper left side of the figure. There is also a request for further explanation on how the aldehyde form of glucose can turn into the beta and alpha forms. The conversation ends with a request for clarification on the correctness of the Fischer formula of glucose.
  • #1
Asmaa Mohammad
182
7
Hello,
my book shows this figure of Fischer formula of D-glucose
onrmf.jpg

I don't understand this figure, and I wonder why the upper carbon atoms in both the right and left formulas have 5 bonds.

And from where comes this hedrogen atom in the upper left side of the figure (attached to alpha, D-glucopyranose).

When turning D-glucose to Fischer formula, it seems there's an additional hydrogen atom, isn't it? Why and how this happens?!

Could some one explain for me how the aldehyde form of glucose (the middle structure) to the beta, D-Glucopyranose and the alpha, D-Glucopyranose?
 

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  • #2
Burn that book!
 
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  • #3
@DrDu
Why?! It's the book which the biochemistry department in my college provide, and the book I'm supposed to do my final exam according to it.
Could you please give a further explanation? And hopefully you explain for me where is the correct and wrong parts about Fischer formula of glucose!
 

FAQ: Why Does the Fischer Projection of Glucose Show Carbon Atoms with Five Bonds?

1. What is the Fischer projection of glucose?

The Fischer projection of glucose is a two-dimensional representation of the molecule that shows the linear arrangement of its atoms. It is often used in organic chemistry to depict the structure of sugars.

2. How is the Fischer projection of glucose drawn?

The Fischer projection of glucose is drawn by placing the carbon chain vertically, with the most oxidized carbon atom at the top, and then projecting the other atoms and functional groups onto the horizontal axis. The carbon chain is usually drawn in the "zig-zag" form, with the last carbon atom on the right side being the most oxidized.

3. What is the significance of the Fischer projection of glucose?

The Fischer projection of glucose is significant because it allows us to easily visualize and compare the different configurations of glucose, which is a key molecule in many biological processes. It also helps in understanding the stereochemistry of glucose and its derivatives.

4. How many chiral centers are present in the Fischer projection of glucose?

The Fischer projection of glucose has four chiral centers, which are the carbon atoms that are attached to four different groups. These chiral centers give rise to the various stereoisomers of glucose, such as D-glucose and L-glucose.

5. Can the Fischer projection of glucose be converted into other representations?

Yes, the Fischer projection of glucose can be converted into other representations, such as the Haworth projection or the chair conformation. These conversions are important in understanding the three-dimensional structure of glucose and its interactions with other molecules.

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