Sugars Question: Is Galactose Formed from Glucose?

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Discussion Overview

The discussion revolves around the relationship between glucose and galactose, specifically whether galactose can be formed from glucose through carbon rotation. Participants explore the structural differences between the two sugars and raise questions about chemical reactions involving reducing sugars.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant suggests that when glucose is dissolved in water, it exists in equilibrium with its alpha and beta isomers, questioning if carbon rotation could lead to the formation of galactose.
  • Another participant asserts that carbon rotation alone is insufficient to convert glucose into galactose.
  • A participant points out that the only difference between glucose and galactose is the positioning of the OH/H groups, implying that this could be seen as a form of rotation.
  • One participant clarifies that the difference involves chiral carbons, which may not be altered by simple rotation.
  • A later participant asks about the role of OH- ions in the reducing sugars test and whether they originate from the self-ionization of water, expressing uncertainty about the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether carbon rotation can lead to the formation of galactose from glucose, and there are differing views on the implications of chiral carbons.

Contextual Notes

Some participants express uncertainty about the chemistry involved, and there may be limitations in their understanding of chiral centers and the specifics of chemical reactions.

Who May Find This Useful

This discussion may be useful for high school students studying organic chemistry, particularly those interested in carbohydrate chemistry and the properties of sugars.

mattg443
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Hi.

When glucose is dissolved into water it forms d-glucose where it is equilibrium with its alpha and beta glucose isomers since the end carbon can rotate. (yes?)

Just wondering if it was possible that some of the middle carbons rotated and then some galactose was produced (since it differs only in the position of OH groups in the ring).

Any thoughts?
 
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Carbon rotation is not enough to change one into another.
 
Last edited by a moderator:
No, it is a chiral carbon.
 
Okay, haven't come across that yet. But thanks.
Another related question - in the reducing sugars test, using beddedicts solution, the reaction involves OH- ions, yet Bennidicts solution is CuSO4. Do the OH- ions come from the self ionisation of water?
Thanks (im only in high school, so sorry if my questions seem basic (pun not intended))
 

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