I almost forgot; did you see my DAT practice exams that are currently available free of charge?😊 courses.chadsprep.com/courses/chads-dat-practice-exams
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)
You prioritize carbons by looking at which one gets more interesting quicker.... a carbon double bonded to an oxygen (carbonyl group) is more interesting than a methyl group (CH3). Oxygen has a higher atomic number, so it is prioritized more than hydrogen, which is always the lowest priority since you are looking at atomic number. For carbon number two, oxygen takes priority because it is not attached to another carbon and then an oxygen, but an oxygen directly. Then, the carbonyl group is the second highest priority because it is getting more interesting faster with a double bond to carbon, which basically accounts for two single bonds to oxygen. The other alcohols are further away and not directly bonded to the chiral center but have carbons in between, so it takes longer to reach them than the carbonyl, making them the third priority. Once you reach the third carbon, the second priority carbon has a carbon bonded to an oxygen and a carbon double bonded to an oxygen. This side of the molecule is getting more interesting than the other side of the molecule, which is just carbons and oxygens. That's how my professor taught us priorities. Sometimes, I feel like I am guessing or second-guessing which side of the molecule is more important, so I try to remember which side is getting more interesting faster.
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.
At 5:14 why is the third chiral carbon why is the carbon on top #2 in priority? wouldn't it be the one on the bottom since OCH OCH and then C-O vs C-C O>C?
@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 😭
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?
@@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!
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 th-cam.com/video/n9mWVM0ShTk/w-d-xo.html
Thank you for your videos!!!!! I watch them before my lecture class and then the lecture actually makes sense! My professor doesn’t write anything on the board 🥲
You are the sole reason I passed some of my undergrad classes and I am back for DAT prep 🤩
Excellent, viktoria - keep up the hard work!
I almost forgot; did you see my DAT practice exams that are currently available free of charge?😊
courses.chadsprep.com/courses/chads-dat-practice-exams
You do an amazing job at using common words to describe what's going on rather than overly complicating the material trying to be learned
Thank you - glad you think so!
I am trying to study ochem by myself with no prior knowledge and you are making the process quite easy and enjoyable! great work!!
Glad to hear it, Steven!
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)
You prioritize carbons by looking at which one gets more interesting quicker.... a carbon double bonded to an oxygen (carbonyl group) is more interesting than a methyl group (CH3). Oxygen has a higher atomic number, so it is prioritized more than hydrogen, which is always the lowest priority since you are looking at atomic number. For carbon number two, oxygen takes priority because it is not attached to another carbon and then an oxygen, but an oxygen directly. Then, the carbonyl group is the second highest priority because it is getting more interesting faster with a double bond to carbon, which basically accounts for two single bonds to oxygen. The other alcohols are further away and not directly bonded to the chiral center but have carbons in between, so it takes longer to reach them than the carbonyl, making them the third priority. Once you reach the third carbon, the second priority carbon has a carbon bonded to an oxygen and a carbon double bonded to an oxygen. This side of the molecule is getting more interesting than the other side of the molecule, which is just carbons and oxygens. That's how my professor taught us priorities. Sometimes, I feel like I am guessing or second-guessing which side of the molecule is more important, so I try to remember which side is getting more interesting faster.
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.
Thank you for the explanation and constraint of Fischer projection
You are most welcome.
This dude is the most famous man in my College chemistry class, lol
Wow!
Awesome video. You remind me of my first chem professor who was absolutely stellar
Excellent!
Thank you so much for the videos :) Having no knowledge of organic chem, your videos are only thing that are taking me through DAT. 🥰
Glad the channel is helping you - Happy Studying!
Made me miss my grandma 🥰🥺 Also another awesome video. Thank you!
You're welcome
Your such a great teacher wish u were at my university.
Thanks!
At 5:14 why is the third chiral carbon why is the carbon on top #2 in priority? wouldn't it be the one on the bottom since OCH OCH and then C-O vs C-C O>C?
oh nevermind i get it the very top is OCH and bottom is OHH
you are unmatched
Wow - thanks!
For 1,2-dichlorocyclopentane shown in Fischer projection, how will we determine R S configuration?
Hello. I'm still confused on how you convert the chemical formula of glucose into Fischer projection. Can you please explain to me.
@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 😭
wondering this too since the bottom one had an OH that was closer
double bond to oxygen is greater priority
SHAKE YO DREADS SHAKE YO DREADS SHAKE YO DREADS
They see me mowin' My front lawn
I know they're all thinking I'm so white 'n' nerdy
Fischer projections, a rolodex of chiral centers that just wanna reach out and hug you
👍
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?
Hey Justin! which example (time) in the video is this about?
The C in COOH, shouldnt it be 2 since C has 00H (double bond Oxyden will count as two O atoms??)
Hey Saimoon - do you mean priority? Is this about a specific time in the video?
@@ChadsPreplike at 4:34, you put OH on 1 st priority and not COOH
@@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!
Thanks alot for the fast reply.That makes sense. @@ChadsPrep
@@saimoon4232 Most welcome.
Definitely makes it enjoyable!
Glad to hear it!
I noticed that a lot of commentators are undergrads, lol we are doing this in school!
Come one, come all!
@ChadsPrep wow! It's an honor to have your recognition sir. I am very thankful for your teachings.
@@sumantchaskar49 Glad the channel helps all who find it of value - Happy Studying!
Well done
Thanks
Than you so much
You are welcome, Asma.
@@ChadsPrep sorry but I have question how can l convert bond line structure to Fischer projection?
you're a life saver
Excellent!
A true chad
Happy Studying
that eye u drew is spooky lol
Bwahahahahah!!!!
👍👏
Thank you!
4:56 I don't get why you are switching R and S
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 th-cam.com/video/n9mWVM0ShTk/w-d-xo.html
Thank you for your videos!!!!! I watch them before my lecture class and then the lecture actually makes sense! My professor doesn’t write anything on the board 🥲
Glad the videos/channel is helping you out!