1All compounds having the arrangement similar to (+) - Glyceraldehyde are called 'D' while the other 'L'. ( the last C in case of Glucose )
CHO
|
H-C-OH
|
CH2OH
(+) - Glyceraldehyde
CHO
|
OH-C-H
|
CH2OH
(-) - Glyceraldehyde
Why diz compund is named as α-D-glucopyranose.
i just want to know that, what is the significance of 'D' ?
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13 Answers
1
1it is named as D because the carbon atom attached to the lowest chiral carbon has the OH group to its right (dextro rotatory)
and that's the general rule
1The structure of α-D-glucose is
-----------
| |
H-C-OH |
| |
H-C-OH |
| |
OH-C-H O
| |
H-C-OH |
| |
H-C---------
|
CH2OH
Which is got from
O
||
H-C
|
H-C-OH
|
OH-C-H
|
H-C-OH
|
H-C-OH ---> is similar to (+) - Glyceraldehyde
|
CH2OH
Therefore it is called α-'D'-glucopyranose.
1the lowest chiral carbon , when the most oxidised carbon is at the top.
1It is not 'D' because it is dextrorotatory ....
It is shown if it is dextrorotatory by putting the sign (+)
1considering the structure i have posted, how can we say that OH attached is at right.... may be i m confused
1In the structure you posted, the OH has added with the CHO group..and H is on the left .. so OH must have been on the right.. the open chain and ring structure exist in equilibrium..
1varun you explained good but i am not getting. rohan said that carbon atom attached to the lowest chiral carbon is having the OH group to its right carbon atom attached to the lowest chiral carbon is marked 5 but it does not have any OH. Rather it has CH2OH & H.
1check this out , it's good , read only the D/L part and tell.
http://en.wikipedia.org/wiki/D-form#By_configuration:_D-_and_L-
1so aman with this fig. u can apply d concepts which others have given.. and u r right D doesnt mean its dextro or something... Its just given on the basis of the presence of OH bond on glyceraldehyde..........
1but OH group at 1 & 4 are above the plane becoz equitorial bond is above the plane