[danini]

Hey everyone,

I have 2 open-chain molecules : the ribosic acid and the arabinosic acid.
From this 2 forms, i need to convert it into the Haworth form bu i don't know how to do it.

Can someone please help me?

[Babcock_Hall]

Can you show us what you have done or tried, so far?

[danini]

i thought maybe something like this?

But i don't know if it's correct.

[Babcock_Hall]

Your attached scheme prompts many questions.  If I understand correctly, ribosic acid is a derivative of ribose (an aldopentose) with carbon-5 oxidized from a primary alcohol to a carboxylic acid.  Your drawing shows a four-carbon carbohydrate being converted into a 5-carbon amide derivative of a carbohydrate.  However, in your drawing the primary alcohol is intact; therefore, it does not resemble ribosic acid.  Instead your product might be the amide derivative of arabinonic acid or ribonic acid, although I am not sure.  In other words, it resembles these sugars but with carbon-1 (not carbon-5) in a different chemical form.

[Babcock_Hall]

Haworth projections are most commonly used for carbohydrates and their derivatives that are capable of forming a cyclic hemiacetal or a hemiketal.  Lactone derivatives of carbohydrates can also be represented with Haworth projections.

Your opening post mentioned ribosic and arabinosic acid, which are both carboxylic acid derivatives.  However, the product of your scheme cannot be either of these two molecules for two reasons.  One, the product is an amide, which is related to but not identical to a carboxylic acid.  Two, ribosic and arabinosic acids are derived from ribose and arabinose via the oxidation of carbon-5.  The product you drew could be derived from ribose or arabinose by oxidation of plus addition of an amine group to carbon-1, which is at the opposite end of the molecule.  I am having a difficult time relating what you wrote to what you drew.

[Babcock_Hall]

Start by drawing Fischer projections of ribosic and arabinosic acids and showing what you have.