Fischer Projection Stereochemistry How to find R and S configurations FAST: Chirality Vid 6
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- Опубликовано: 3 ноя 2015
- Fischer Projection Stereochemistry - Learn how to find R and S configurations on Fischer Projections FAST given a single or multiple chiral centers. By leah4sci.com/chirality
📺Watch Next: How to Draw Fischer Projections • How to Draw Fischer Pr...
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This is Video 6 in the Chirality/stereochemistry series. Catch them all including the stereochemistry practice quiz and cheat sheet by visiting Leah4sci.com/chirality
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If there's an H on the side of the chiral center, find R and S normally and the opposite is the answer. if H is on the top/bottom and there's no other hydrogen on the sides, find R and S normally and that's your answer.
thank you stranger
Yes exactly, came here to find this comment. I don't know why she chooses to make it this complicated lol
That's a great way of looking at it!
Yes! H on the side is forward so you must reverse as you do when #4 is forward
H up or down means it's in the back and so you're good to go
Thank you so much! I was wasting so much time trying to visualize this all in 3D. This makes it so much faster now! :)
Glad it helped you!
Wow! You make O Chem so easy to understand! You have the best O Chem videos out there! Thank you so much!!!!!!
You're very welcome, so glad to hear how much it helped you!
Thank you so much for this, years after and its still a blessing to me
God bless you
Thanks so much!
The most amazing teacher I have ever seen!!! Born talent!! I wish you good luck for everything for your future!!!
Thanks so much, and I'm happy my resources are helping you!
You the real mvp for these orgo videos. Thank you so much! :)
You're very welcome!
love these vids! literally saving me in my summer orgo class!
So happy to help!
thank you so much mam for these videos ,earlier I wasn't able to understand this topic but now I saw your whole playlist and I understood each and everything completely . thanks again ,
your all video are so nice
it cleared all my concepts on chirality .
Glad the video helped! You are very much welcome!
seriously, your videos are really lovely, i cant stop loving ochem!!
You are incredible
Thanks for your kind words, I'm so glad to help you!
I love your videos. Now, I understand this well because of them. I still watch them over and over because they're just fun to see how simple this is if it's explained the way you always do. 6:26 This is a Carbon attached to who cares :). Thank you!!
Thank you so much!! Your videos are so helpful!
You're very welcome, so happy to help!
You made this become so much easier! Thank you for your help! I'm thankful God led me to this video.
You're very welcome!
You are like patrickjmt but for chemistry and I love your videos.
Thank you so much!
u made it soo easy.....
I was having a lot of confusion earlier...
u are amazing...
Happy to help!
thank u so much.. the whole series helped a alot
You are very welcome! I'm so glad it helped
Fischer projection was named after you wasn't it 😂
lol!
Your videos are so helpful even 8 years in!!
Glad you like them and that they are standing the test of time!
the thing i was hunting since days... got it in this video!!!... 🙌😊😊
Awesome!
Superb explanation...U saved a life....
Happy to help!
So easy, thank you!
You're welcome!
good to explain ,,, i realy like it
Glad you liked it
Tht was Really Helpful....😊
Glad you liked it
now only i came to know clearly compound with two chiral centers thanks mam.
Glad it helped
Ur the greatest of all time
Wow, thank you!
This is awesome
Glad you liked it, thanks for watching!
thanku u make it easy for me
You're so welcome, I'm happy to help!
I love visualizing the molecule as opposed to doing the whole swap thing. You get FAST at it once you do a light load of practice problems.
Awesome! Do what works best for you :)
What if the substituents are A,B,C & D . Then we can't use the r and s. So how to differentiate which molecules are enantiomers, diasteromers,etc. Please make a video regarding such type of problemS.
When #4 is on the side, can you not trace 1-3 and do the opposite answer? Or do you have to do swap method for fischer projections? Because you did examples for newman projections with #4 in the front & doing the opposite answer rather than the swap method. I just want to make sure the same rules apply. Thank you :)
Yes, that is an excellent observation. The same rules would apply, and your method would work as well. Trace groups 1-3 when #4 is on the side of the Fischer projection and then change your answer to the opposite configuration.
Excellent... I loved you didn't prefer wedge and dash
Glad you liked it!
Thank you so much!!!!!!!!
You're very welcome!
With Fisher I find it easier to imagine the Fisher projection as 3D and than either see the above group as in the back (just rotate your screen with the top to the right) or with the right group in the back (means that the left group is shifted to the right in its Fisher projection.)
Using either of these methods you can instantly draw an arrow with group 4 on the top (first method), the right (second method). Or inversed (group 4 is in the front) on the bottom (first method) or left (second method).
I'm glad you've found a method that works for you!
Question: I thought that most amino acids have the absolute configuration of "S" while cysteine is supposed to be the exception, having "R"? However, you list cysteine as having an S configuration.
at which point in the video? they can exist as R and S, it's just a question of knowing which one exists in the human system.
Why do we have to use the swap method (3:20) if #4 comes out of the page? Wouldn't it be correct if we just reversed the configuration? I don't get it... :
you don't have to, but it helps to keep things organized. You're right though
The Amino acid in the beginning is Cysteine
Yes!
In the multiple chiral center example doesnt it break the carbon skeleton if we use swap method on it . Can we break the carbon skeleton ? Will it not alter its original stereochemical position ?
We're not actually breaking bonds within the carbon skeleton. We are simply rearranging/swapping positions of priority for the purpose of assigning a configuration to the chiral center. Think of the swap method as a tool for determining configuration, not as a mechanism or a method of breaking or reforming bonds.
the first molecule in this video is a cysteine :)
You're right!
I have a question: in the last example, what would happen if we had Cl also in the first chiral centre, at right? In this way there would be a plan of symmetry in the molecule, so, would it been still chiral? Thank you so much, your videos are so helpful!!
You're so welcome! Unfortunately, I don't offer tutoring over social media. For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/
@@Leah4sci thank you!
you are saving lifes
Aww thanks!
Hi I was watching this video and for the Fischer projection atoms you start by putting H at the top of the atom in the first molecule but at the bottom in the next one which creates two molecules one which is S and one which is R how do you get around this as it is really confusing for me
Sorry to hear that you are confused. In a Fischer projection, the spine of the molecule is really on a ‘dash’ notation. Both the group that’s going up and the group that’s going down are ‘into the page.’ That means, if we can make sure #4 (the lowest priority group) is in the up OR down position of the Fischer projection, then we’re good to go and do NOT need to use the swap method to determine configuration.
Why we did swaps min7:29? The H is out so why we did not track 123 and take the opposite of R which is S
This is just my method for determining R/S configurations in Fischer projections in the LEAST amount of time. You may find something else works for you! My method is to first swap the lowest priority group to the back of the molecule by placing it in either the up or down position and then to make a second swap for a total even number of swaps. This is so we don't have to reverse the direction of the configuration.
Hii madam in last example of this vedio what was the exact answer this one R or S configuration
The chiral carbon at the top of the molecule had an S configuration, and the chiral carbon at the bottom had an R configuration.
0:30 cysteine
Yes!
Nice
thanks!
At 2:25, why does your amine have lower priority then oxygen? Nitrogen come before oxygen?
yes, Br first, then O, then N. it goes by atomic number (highest to lowest)
the N is compared to C , not O
Take a look at my other video on how to rank atoms. Higher atomic number gets higher priority and so oxygen outranks nitrogen which outranks carbon and so on
If no. 4 is at the horizontal R becomes S and S becomes R
Simple as that
Thanks for sharing!
2:52 make me confused because back mean, i thought OH(2) but Br(1) becomes to (4)
In this example, we chose to make two swaps because an even number of swaps means that the configuration at the chiral center will not change. We want to maintain the chirality, so that we read the molecule correctly as either R or S. So the first swap was (1) with (4). And the second swap was (2) with (3).
It is better lectures
I'm glad you like it!
OK good
:)
Dont you have conversion vedios
The free videos are what I do as I have time. For more help with this topic, feel free to contact me through my website: leah4sci.com/contact
Hi
Hello
I really don’t understand the swap method. Why can’t you just switch the configuration. Seems like extra steps
This method for determining R/S configurations might not work for everyone, but if you’d like to learn more, watch my previous video at leah4sci.com/swap-method
gooated ahh video
Glad you liked it!
This swapping thing is a bit confusing
nvm. I understand what is happening. I realized that I didn't really need to do the swapping thing 3 times at the end. As long as we remember our swapping technique, we can assume the other configuration after swapping once.
Glad it cleared up for you!
She's god
I just checked, looks like I'm still human!
Leah4sci Thank you for replying
God is a woman
Oh I am confused now
Oh no! I'm sorry to hear that; feel free to contact me through my website: leah4sci.com/contact
@@Leah4sci Thanks a lot. I'll do that
cysteine
Yes!
She said a naughty word...Thats a dislike for me
huh?