Convert a 3-D drawing of a molecule into a 2-D Fischer projection.?

Question

how to Convert a 3-D drawing of a molecule into a 2-D Fischer projection please explaine it to me ???

Answer 1

The idea of a Fischer projection is to arrange the molecule so that the groupson the top and bottom are angled away from you and the ones on the side are angled toward you.  The structure is then flattened onto your paper.  First of all, this is best done with a model.  However, you can use your fingers as a model if you do not have one.  It is difficult to explain with just text, but here goes.  

If the 3D drawing uses solid lines, wedges and hashed lines, hold your thumb, forefinger, middle finger and wrist so they are like the wedge/hash/solid picture.  Your wrist and forefinger will serve as the solid bonds, your thumb as the wedge and your middle finger as the hashed bond.  If you are using your left hand, your fingers point to the right; with your right hand, they point top the left.  Memorize what actual group is on each of the bonds and which finger it corresponds to, or you can write the groups onto your fingers.  Draw a cross on the paper.  Turn you hand so that the fingers point toward you then adjust it a little so that your thumb and middle finger are toward you and your forefinger and wrist angle away.  On the top of the cross draw the group represented by your forefinger and on the bottom draw the one represented by your wrist.  The two represented by your thumb and middle finger go on the cross bar of the cross.  You can do this with the original structure in any orientation, but for the first few, it is easiest to have the solid bonds point straight up and angled down to the right or left.  The wedge and hashed line will be angled down and point opposite of the solid line that angles down.  After you are able to do such cases you will find that all you need to do for ones not in this position is to rotate your hand appropriately or even change hands.  Hope this works for you