Define the term anomeric carbon. Which carbon is the anomeric carbon in glucose? In fructose?

Name: Problem 20, Chapter 20: Introduction to General, Organic and Biochemistry
Uploaded: 2020-07-14T05:30:39-08:00
Duration: 13 min 27 s
Channel: Megha Ramappan
Description: Define the term anomeric carbon. Which carbon is the anomeric carbon in glucose? In fructose?

Define the term anomeric carbon. Which carbon is the...

Key Concepts

Anomeric Carbon

In carbohydrate chemistry, the anomeric carbon is the carbon atom that was originally part of a carbonyl group in the open-chain form of a sugar and becomes a new stereocenter during ring closure. This carbon is pivotal as it determines the formation of ?- and ?-anomers in the cyclic form, affecting the sugar's chemical behavior and reactivity in glycosidic bond formation.

Cyclization of Sugars

Cyclization is the process by which a linear sugar undergoes an intramolecular reaction where a hydroxyl group attacks its own carbonyl carbon, leading to the formation of a ring structure. This reaction results in the creation of a hemiacetal (or hemiketal) group at the anomeric carbon, a transformation that underlies the equilibrium between open-chain and cyclic forms in carbohydrates.

Differentiating Aldoses and Ketoses in Cyclic Forms

In cyclic forms of sugars, the position of the anomeric carbon differs based on whether the sugar is an aldose or a ketose. In aldose sugars, like glucose, the anomeric carbon is at the position of the original aldehyde group (typically C1), while in ketose sugars, like fructose, it originates from the ketone group (typically C2). This distinction is essential for understanding the structural and functional diversity of carbohydrates.

Transcript

00:01 Before we even start, it's important to know the definition of an animeric carbon.

00:06 After all, they're asking us to identify the anameric carbon.

00:10 So, the anomeric carbon is the new carbon stereocenter that is made due to the formation of the six -centor.

00:59 Structure.

01:02 So up until the cyclic structure is also known as the hawthorne projection or structure, whereas the straight line like carbon chain structure is known as a fisher projection.

01:23 So another way to think about the animeric carbon is that it is also the hemisital in the cyclic form.

02:00 Okay.

02:02 So now that we know what an animeric carbon is, let's move on to glucose.

02:11 Okay.

02:13 So we know that the anemaric carbon is what forms, like the new carbon series into that forms after it goes into the cyclic structure.

02:22 So what we're going to do here is we're going to start from the chain, the fisher projection, and move to the hawthorne projection and keep track of all of our carbons to figure out which one would be the animeric carbon.

02:34 So first things first, we want to kind of, we want to put it in an orientation that will allow us to make a cyclic formation.

02:50 So from this, we start with, to keep it in black for now.

03:05 So we have carbon bonded to oxygen and hydrogen, have this structure going on, which i'm going to redraw.

03:33 That is ugly.

03:44 Okay, let's try this again.

03:47 So we're going to start.

04:06 We have this carbon here, another carbon here.

05:05 So we're going to look at that structure.

05:07 Now let's go ahead and number everything.

05:09 So this is our first carbon.

05:13 Carbon two, three, four, five, and six.

05:21 So you can see how, with a number, you can see which carbon is what, right? so now we're halfway through.