All Questions
Tagged with stereochemistry carbohydrates
15
questions
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Converting structures into Fisher projections
I am really struggling with converting pyrano/furanosides into their Fisher projection counterparts. Especially when they are drawn like in the shown projection. When do you know to connect the ...
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-2
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1
answer
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D and L configuration of monosaccharides
I got this question in the last week's test from Organic Chemistry.
I am a bit confused in assigning D and L configuration.
Help me understand the topic of D and L configuration and help with this ...
3
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1
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Why are there two structures of L-Glucose in the Fischer projection?
We are told that L-Glucose is an enantiomer of D-Glucose, which would mean that they are mirror images of each other. But then we're also told that the L and D forms is determined by the spacial ...
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2
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1
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Why glucose and other similar carbohydrates are oxidised fully by HIO4?
$\ce{HIO4_{(aq)}}$ requires the vicinal diols to have syn configuration, as it forms a cyclic periodate ester.
But glucose does not have syn configuration at C3, and if you consider cyclic forms of ...
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Are Anomers Epimers?
epimers are the class of stereoisomers which differ along configuration at any carbon in a carbohydrate(generally),
And anomers are the kind of stereo isomers that differ at the carbonylic carbon, ...
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3
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1
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D/L and +/− labels of glucose
I had just started to read about carbohydrates when I came across D-(+)-glucose. My book says that the '+' sign refers to its optical rotation measured through the polarimeter, and that it could ...
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3
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3
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Are glucose and galactose cis-trans isomers of each other?
Glucose and galactose are diastereomers of each other. However, is it correct to say that they are cis-trans isomers of each other? Does it make a difference with regard to terminology if glucose and ...
- 470
5
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4
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Why is it important that glucose’s third OH group points to the left?
My question pertains to the location of the OH group on the 3rd carbon in a glucose molecule. If atoms can rotate freely around single bonds, then why is this important? Why can't glucose be drawn ...
- 171
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What is the absolute configuration of carbon 4 in glucopyranose?
My colleague and I have been wrestling with the assignment of chirality to the 4th carbon atom in glucopyranose. In the linear form of glucose, the 4th carbon is definitely (R); therefore it will ...
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4
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1
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1k
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l- versus d-glucose
I recently purchased Dextrose from a local bulkfood store. I want to use it instead of table sugar. My concern is that it may be l-glucose instead of d-glucose. According to Wikipedia l-glucose is too ...
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6
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1
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Identifying chiral carbons
Looking at this structure, I would say this molecule has five chiral carbons. However, its IUPAC name (3R,4R,5S,6R)-3-amino-6-(hydroxymethyl)oxane-2,4,5-triol suggests that there are only four. Which ...
6
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2
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Why is H bonded to C5 drawn below the plane in Haworth formula for D-glucose?
I have always seen the hydrogen atom bonded to C5 drawn below the plane as in the following figure. Shouldn't it be drawn above the plane since it is drawn on left side in Fischer projection?
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5
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1
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Carbohydrate conformations
I have to questions regarding the conformations of carbohydrates.
There are 38 different conformations for an aldohexose or ketohexose, including $\alpha$ and $\beta$ anomers, namely 2 chairs, 6 ...
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7
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1
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In the Haworth projections of D and L glucose, is the stereochemistry at every carbon except the anomeric carbon just inverted?
I'm having a bit of trouble grasping sugar stereochemistry.
Using glucose as an example, if you cyclize D and L glucose, is the stereochemistry at every carbon just inverted from the other form?
...
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17
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1
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What's the difference between alpha-glucose and beta-glucose?
What's the difference between $\alpha$-D-glucose and $\beta$-D-glucose? Are they isomers? Or do they differ in their elemental composition?
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