/sci/ - Science & Math

>>10401009
And by who is right, I mean, are these molecules the same or are they enantiomers?

>>10401024
They're the same. I'm very confident of this answer.

>>10401071
Thanks anon, shes under the impression that you can not rotate the molecule without breaking the bonds, even though there is zero reason that you cant, a waiting more responses, can't just show one anonymous response and expect that to get through.

>>10401071
>>10401092
I also don't see any reason why the orientation of COOH side chain should matter.

>>10401237
I mean rotate the entire molecule, she seems to think that turning the whole thing on its head will break bonds.

I think you are right. You could prove it by putting either molecule into a 3D model program (Mol cubed or jsmol or something) and rotating it to be the other molecule.

>>10401274
I've actually used 3d models to try to show her, she just told me I cant rotate molecules.

>>10401291
Don't molecules rotate all the time?

>>10401299
Yes, there are no forces magical or scientific keeping molecules right-side up.

>>10401291
That's just wrong. What school does she teach at?

>>10401009
Your professor is probably wrong this happens all the time just know this and move on

you aren’t going to crack her ego and honestly it’s a bit mean/pointless

The best you can hope is that she secretly learned her lesson and in the future she will accept your answer from other students

>>10401315
I suppose it is a bit pointless, its just this is in organic chemistry and I know that some students may potentially need this point to push them over the edge.

I don't see how it's mean though.

>>10401092
>she
why do you even bother

>>10401315
Agreed. The most egotistical people in existence are college professors. Never argue with them, you're just wasting your breath.

>>10401009
The NH2 bond on the right should extend behind the plane if it's a result of turning the left molecule around.

So it should look like #1 in this:
https://chemistry.stackexchange.com/questions/28503/what-are-the-meanings-of-dotted-and-wavy-lines-in-structural-formulas

So the molecules aren't the same.

>>10401346
Don't turn it around, turn it upside down, like you would rotate an image.

>>10401363
You have to flip it like a pancake, rotating isn't enough.
That's when the 'protruding out from the plane' changes into 'extending behind the plane' of the drawing surface.

>>10401363
in that case it's still not the same molecule, as mirroring is a transformation of image. If you look at a normal and mirrored image of a human holding a cup, you would get different information on which hand he's picking up the cup with from mirrored image.

>>10401092
>>10401258
>>10401291
>she
Okay i understand now

>>10401386
>>1040>>10401389
I'm not mirroring it, I'm rotating it, those are not the same.

Busting out the model. Orange is aldehyde.

Does this match the left molecule?

>>10401417
And does this match the right?

>>10401417
>>10401421

you can always rotate simple bonds

when you're classifying it as r or s you have to left the hydrogen on top of the molecule

>>10401009
The question says STEREOISOMERS you dumbfuck. Honestly if you've been stuck on this point for two days you deserve to fucking fail out.
https://en.wikipedia.org/wiki/Stereoisomerism

>>10401417
If you are rotating it, the bond goes from being in front of plane to being behind the plane, and should be a dashed line, exactly what >>10401346 said

>>10401465
I'm aware of that but the images are not stereoisomers.

Errr, if you rotate this molecule 180 degrees clockwise, you'll also need to "rotate" the OH and O to get the same molecule, where O has a double bond. I'm don't think you can just rotate that arm without changing electronic properties of the molecule.

>>10401476
Can't rotate chiral centers, can rotate anything else.

>>10401476
You 8only need to rotate the single bond connecting the aldehyde group to the chiral carbon.

Have you tried searching google for "L alanine isomers"

>>10401493
There's a hidden H on the one C, that's what's fucking everything up

>>10401291
Jesus Christ
Why can’t these female teachers just admit to making a mistake?

>>10401500
It's not hidden it just has the least prority.

>>10401493
>>10401500
This. You can't just rotate to 'swap' the ammonia with the methyl group, because it's actually three things getting rotated: ammonia, methyl, and an H. The drawings depict two different orientations.

>>10401526
Visual aid.

>>10401493
>>10401538
Alright, hows this.

If A and B are mirror images, and B and C are mirror images, then A and C are the same molecule, because C is just A mirrored twice.

>>10401600
Every image I post is right side up when I open it on my computer, not idea why they go sideways.

>>10401417
>>10401421
>>10401600
You need to clip your nails.

>>10401491
Sure, but that will change where the center of charge is.

>>10401009
These are the same molecule. She probably fucked up with the orientation of the amine and hydrogen and meant to flip which one is forward and which one is back. Can you go to another chemistry teacher in your department?

>>10401449
Counting depends on if which direction the smallest group is facing. Did you fail ochem?

>>10401291
Molucules rotate/detach all the time. Am i missing something here??

>>10401009

> who is right

that's not the question here, the question is, why are you wasting your time arguing with a female?

>>10402403
Probably but it's a single point on a test that I got a 98 on, I really just wanted confirmation that I wasn't going retarded, so I think I'll just drop it if she doesn't try to fuck with me in the future.
>>10402405
She was basically saying that I can't rotate a molecule without breaking bonds, which is horseshit, see
>>10401421
>>10401417
Which are the same model, rotated 180 degrees, with no bond breaking.

Anyways OP you stuck at describing stuff. They're the same. What you want to describe, is orientation and not rotating because that will confuse the living shit out of chem students and they'll think you mean rotating around bonds. Anyways, I'll explain this nice and simple for /sci/, not that they would be able to follow anyways.

>Take the first molecule and turn it 180degrees along the XY plane.

Surprise it matches the other molecule and you didn't fuck with any of the bonds, just the orientation of the molecule itself.

>>10402415
Thanks, anon.

>>10401009
Put your thumb in direction of the H (thumb toward or away page to match dashed or solid representation) and curl your hand in direction of the oxidation rank.
Left is (S) and right is (R) they're enantiomers. Sorry anon you're retarded.

>>10402469
You get the same answer if you use that method. Try again.

>>10402412
>the question is, why are you wasting your time arguing with a female?
This. Does OP also also argue with downies?

>>10401009

hey man, i don't usually give advice since this whole site is 100% shit posting but:
the time you have on this planet is limited, the energy you have is limited
you will regret wasting your time on this stupid bitch down the line
so stop doing it

>>10401024
They are very clearly enantiomers. Build a molecular model.

Whats so hard to understand about this you mongs

This is why you need a model kit.

>>10401346
Yes, the molecules are different (orientation of =O and -COOH in carboxyl group), but they are both S chiral forms.

>>10403185
But of course in the form of anion it doesn't differ at all, since the real form is pic related

>>10401009
no they are not the same..
retard

>>10403278
Anon, the aldehyde group on the right is connected to the central carbon by a single bond, it can freely rotate around that bond.

The direction that that double bonded oxygen is pointing doesn't matter.

You guys are all retarded. The fact that the O and OH are reversed in the molecules causes different bond strengths and technically different spatial orientations. These are 100% enantiomers

>>10403311
same molecule, different conformations. single bonds can rotate.

>>10403347
It's not actually a single bond though. Theres 3 there. Anyone who says different is abusing the notation but the energetics dictate they're different.

You are confused.

https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Map%3A_Organic_Chemistry_(Bruice)/02%3A_An_Introduction_to_Organic_Compounds%3A_Nomenclature%2C_Physical_Properties%2C_and_Representation_of_Structure/2.10%3A_Rotation_Occurs_About_Carbon-Carbon_Single_Bonds

The COOH group is single bonded to the other carbon. That COOH group can freely rotate. Yes, they have different energies in different conformations, but that doesn't make them different molecules

>>10403278
Can you show your teacher this picture actually. Probably the easiest way for your professor to realize her mistake.

> the way a molecule is depends on the way you look at it

>>10401668
really isn't that bad

>>10403436
Of course, just like the observer effect in quantum physics.

>>10401315
>it’s a bit mean
If she's made it to a tenured faculty position and she can't handle her feelings hurt when she gets shit wrong, she doesn't belong in academia. Fight.

Your prof and half the people in this thread are brainlets. The only thing that's different if you rotate it 180 degrees - JUST rotate it - as in not change the molecule, is how the carboxylic acid group looks. In actuality the COOH group is the same in either orientation because it freely rotates around the carboxylic carbon.

>>10403365
The bond with the big arrow 100% freely rotates. Even if it didn't rotate the doubly bonded oxygen and -OH group tautormerize at physiological pH.

>>10401092
>she
not surprised.

You're definitely right. Too bad you have a female professor. She can't lose a fraction of credibility or she could be let go easily. She probably noticed she was wrong but silenced it at you since she would have to regrade everything and that would look really bad over a basic chirality/stereochemistry question. Your only hope would be to gather 5+ students in the same lecture on the same page as you and surround her before lecture starts when everyone is staring at her. But she would do what all professors do about that shit, "Save your questions for office hours". You know, when you probably have a different class scheduled you can't get out of, when 10+ students are in line ahead of you, or when she is nowhere to be found/getting food. It's hopeless m8.

>>10401309
Athens Tech

>>10401009
>>10401071
>>10401258

AP-Chem level brainlet here, why does it not matter that the Hydroxide is attached on the CH_3 side in one, and on the NH_2 side on the other?

>>10404529
The single C-C bond can rotate.

nice larping, op

>>10401668
Do you even have nails?

>>10401009
>>10404529
>>10404554
The electron pair locations are different. In both pictures, the NH2 is at the same direction. If you spin them so that the CH3 configuration is the same, it'll be poking out in the other direction

>>10404604
Sorry. I mean that the NH2 is coming out of the page (unless I've mixed up that signal and it's going into the page). It's a 3d image that OP is trying to treat like a 2d one

>>10401291
You did your 3d model wrong. You forgot about the electron pair

>>10403851
stop trying to trigger physicist with this bullshit

>>10401523
>females
>admitting any wrong doing ever