5.4 Fischer Projections | Organic Chemistry

Chad introduces Fischer Projections and explains how they give us a little different perspective on viewing chiral centers which is convenient for molecules with many chiral centers like sugars (monosaccharides). In a Fischer projection, the horizontal bonds correspond to wedges and the vertical bonds to dashes in the corresponding bond line structure. Chad then draws the Fischer projection of glucose and shows how to assign R and S configurations to the chiral centers in the Fischer projection of glucose. Finally, he shows how to convert Fischer Projections to Bond-Line Structures how to convert bond-line structures to Fischer projections.
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00:00 Lesson Introduction
00:39 Introduction to Fischer Projections and Drawing Fischer Projections
02:57 Assigning R & S Configuration to Fischer Projection
05:59 Drawing bond Line Structures from Fischer Projections
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Thank you - glad you think so!

[@nilsnickname4455]

Very great explained. I studied more than 10 semesters teached by (more than 5) many profs. I just want to refresh knowledge. No one explained it nearly as good as you. Great!
When rotating the Fischer-projection by 90° all stereocenters change I guess. Also when you flip it over.

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[@user-pj5bk7ds8u]

Thank you for the explanation and constraint of Fischer projection

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You are most welcome.

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[@min_g2608]

Hi Chad, can you please explain how you prioritized carbons 2 through 5 (4:55 and on)? Carbon 1's numbering makes sense because of the carbonyl, but the others don't (especially which atoms get assigned priority 2 and 3)

[@HowTo-ly9cm]

Hello. I'm still confused on how you convert the chemical formula of glucose into Fischer projection. Can you please explain to me.

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[@sciencenerd7639]

Fischer projections, a rolodex of chiral centers that just wanna reach out and hug you

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[@justindong7199]

how did you know to draw the OH on top and bottom like that? For example: carbon #2 if I drew the OH on the bottom, that would change the R and S right?

[@ChadsPrep]

Hey Justin! which example (time) in the video is this about?

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[@ChadsPrep]

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[@saimoon4232]

The C in COOH, shouldnt it be 2 since C has 00H (double bond Oxyden will count as two O atoms??)

[@ChadsPrep]

Hey Saimoon - do you mean priority? Is this about a specific time in the video?

[@saimoon4232]

@@ChadsPreplike at 4:34, you put OH on 1 st priority and not COOH

[@ChadsPrep]

@@saimoon4232 we assign priority 1 based on the highest atomic number of the atom directly attached to the chiral carbon. The OH gets 1 because O has a higher atomic number than carbon. Then we have a choice between 2 carbons, one has 2 bonds to the oxygen so gets 2, the other carbon at the bottom has an OH group so gets three. Note that the direct attachment to O preceeds over COOH or C(OH)H because the first atom attached in each of the latter is a carbon. I hope that helps!

[@saimoon4232]

Thanks alot for the fast reply.That makes sense. @@ChadsPrep

[@ChadsPrep]

@@saimoon4232 Most welcome.

[@monpetitgarcon]

@4:59 re: second chiral centre, why the C on the top is second versus the C down the bottom? Same goes onto the 3rd and 4th chiral centre? Someone please help 😭

[@diamondbennett4005]

wondering this too since the bottom one had an OH that was closer

[@yk3315]

double bond to oxygen is greater priority

[@asmamuhammad2174]

Than you so much

[@ChadsPrep]

You are welcome, Asma.

[@asmamuhammad2174]

@@ChadsPrep sorry but I have question how can l convert bond line structure to Fischer projection?

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Glad the videos/channel is helping you out!

[@injhs]

4:56 I don't get why you are switching R and S

[@ChadsPrep]

That top carbon is R because the OH --> COH --> C(H)OH priority is making a right turn into the plane of the screen whereas the second carbon is S because we have a left turn. Watch this video if its still unclear ruclips.net/video/n9mWVM0ShTk/видео.html