Ribose cyclization: pyrane or furane?

  • Thread starter Thread starter Aymeric
  • Start date Start date
AI Thread Summary
Ribose and fructose can cyclize into furanose or pyranose forms, depending on which hydroxyl (-OH) group reacts with the aldehyde. Specifically, if the last -OH connects to the aldehyde, ribose forms ribopyranose; if the second-to-last -OH connects, it forms ribofuranose. Both cyclic forms can exist as alpha and beta anomers based on the orientation of the -OH group during the reaction. This process is characterized as an intramolecular aldol condensation.
Aymeric
Messages
12
Reaction score
0
Hello,

My biochemistry textbook tells me that ribose and fructose give furanes. I had trouble wrapping my head around the cyclization process so I looked for other explanations and I found this one:
http://web.campbell.edu/faculty/nemecz/323_lect/sugars/cyclization.html

It seems to say that ribose can take on two forms : furane or pyrane. I just wanted confirmation that linear ribose becomes a furane or a pyrane depending on which -OH connects back to the aldehyde function (if it connects to the last one, it becomes ribopyranose, if it connects to the one before last, it becomes ribofuranose).

Did I get this right?

Thanks!
 
Last edited by a moderator:
Chemistry news on Phys.org
Sounds right to me. Intramolecular aldol condensation.

edit: But you will get both the alpha and beta anomer for both of these cyclic forms depending upon which 'face' of the aldehyde the OH approaches.
 
Last edited:
It seems like a simple enough question: what is the solubility of epsom salt in water at 20°C? A graph or table showing how it varies with temperature would be a bonus. But upon searching the internet I have been unable to determine this with confidence. Wikipedia gives the value of 113g/100ml. But other sources disagree and I can't find a definitive source for the information. I even asked chatgpt but it couldn't be sure either. I thought, naively, that this would be easy to look up without...
I was introduced to the Octet Rule recently and make me wonder, why does 8 valence electrons or a full p orbital always make an element inert? What is so special with a full p orbital? Like take Calcium for an example, its outer orbital is filled but its only the s orbital thats filled so its still reactive not so much as the Alkaline metals but still pretty reactive. Can someone explain it to me? Thanks!!
Back
Top