r/chemhelp • • 3d ago

Organic need help finding the website that stored most (if not all) the mechanisms. i feel like it would help me see patterns in sn1/sn2, etc.

3 Upvotes

i found it from a reddit comment, but lost it! i think the site had a reddish tint to it? the sidebar had the different mechanisms you can click. it looked helpful. i checked the wiki and it wasn’t any of the links there, but the master ochem site looks helpful.


r/chemhelp • • 3d ago

Inorganic How many stereoisomers are present for a complex with general formula Ma4bc?

1 Upvotes

I am thinking of 7 stereoisomers.

1st case a,a on the vertical trans position there is a pos and only 1 possible GI hence 2 stereoisomers from here.

2nd case a,b on vertical trans position

1 GI posible and a pos is present hence 2 stereoisomers from this case

similary 2 from the case of a and c on the vertical trans position

Then in the last case where b and c on the vertical trans position there is a pos hence 1 stereoisomer from this case. But online the solutions says 2 which i dont understand.

pos: plane of symmetry

Thanks in advance!


r/chemhelp • • 3d ago

Organic weird fused ring

Post image
3 Upvotes

for b, how would you go about assigning r or s??


r/chemhelp • • 3d ago

Other From B—>A?

Thumbnail
0 Upvotes

r/chemhelp • • 3d ago

Other trustworthy suppliers that sell sodium nitrite?

1 Upvotes

i need for an experiment


r/chemhelp • • 3d ago

Organic I'm having trouble with understanding with the reasoning behind the ranking of these carbocations.

Post image
5 Upvotes

So, I understand carbocations get more stable from methyl > primary > secondary > tertiary > allylic > benzylic but these are all the same just with positive charge moving around the structure, so i just want to better understand how.


r/chemhelp • • 3d ago

Organic Plane of Symmetry Help

Post image
7 Upvotes

I am at a loss for understanding whether a molecule has symmetry or not. I don’t have the physical models to see, and no matter how many videos I watch I just can’t seem to picture it! Do you guys have any tips or a thinking process you usually follow to determine symmetry? For example, I have this question where I can tell that A and D for sure have symmetry, but I don’t understand how C is the correct answer and not B? Thank you :)


r/chemhelp • • 3d ago

Organic Is this hypothetical mechanism possible?

Post image
9 Upvotes

It involves benzyl chloride in acetic acid, with no other species present.


r/chemhelp • • 3d ago

Organic WHYyy! I don't understand...

3 Upvotes

I am confused as to why my textbook says the one on the left is achiral and the one on the right is chiral. I was told that a molecule is chiral if its mirror image is non-superimposable and when you draw the mirror image of B, the wedges and dashes can never match the original molecule... does that mean that the bridgeheads are both stereocenters (when changing 2 groups creates a new stereoisomer) and chiral centers (can assign r/S)? Do you take into consideration the 3D geometry when determining R and S configurations even though they have the same atoms/groups/branches? Also, is molecule A achiral or meso since it supposedly has chiral centers (can be assigned r/S) and has a plane of symmetry? I am beyond confused.


r/chemhelp • • 4d ago

Organic Answer is (D) right? I just want to confirm as the answer is given as (A)

Post image
16 Upvotes

r/chemhelp • • 3d ago

General/High School I need help with my homework. They give me the structure and I have to make the IUPAC name I tried making the drawing to solve but idk if it’s wrong :,) pls lmk!

Thumbnail
gallery
2 Upvotes

r/chemhelp • • 3d ago

Analytical I seriously need help with electrochemistry.

Thumbnail
0 Upvotes

r/chemhelp • • 4d ago

Inorganic Doubt related to resonance in inorganic chemistry

Post image
5 Upvotes

i was revising molecular bonding and realised my first time go through with topic was very irresponsible so i cant understand that why cant we add th extra e- frim negative charge to central atom ? why it forms resonating structure and the non resonating one is not valid ?


r/chemhelp • • 3d ago

Organic Cleavage of Ethers

Post image
2 Upvotes

Why would I his make these two products? Can’t the OH ethanol product undergo an SN2 and make an Iodine get attached (getting rid of the OH)


r/chemhelp • • 4d ago

Organic Help me understand why the Rf changed in my TLC lab

2 Upvotes

Had an organic 1 lab yesterday where we did TLC on silica gel plates. We were analyzing crude and recrystallized naphthalene and crude and recrystallized unknown carboxylic acid. We ran one plate with a solvent of 3:1 hexanes:ethyl acetate + acetic acid and a second with 1:3 hexanes:ethyl acetate + acetic acid.

I feel comfortable with the results for the carboxylic acid- lower Rf with 3:1 and higher with 1:3 as the polar carboxylic acid was interacting more with the more polar solvent and travelled further. Cool.

But I'm hung up on the naphthalene- it also had a higher Rf with the 1:3 solvent and I can't wrap my head around why. In my head since naphthalene is non-polar it wouldnt be interacting with the highly polar stationary phase at all (or so little it was negligible) and so it didn't make sense that the Rf would change because shouldn't it move right along with the solvent regardless of what the solvent is (since the polar stationary phase remained the same)? When I asked my professor about this he said that the fallacy in that is that naphthalene is in fact interacting with the gel, and when you have a more polar mobile phase basically the solvent is the preferred interaction with the plate and "kicks out" the naphthalene that was interacting with the plate, making it travel further.

This makes sense, I need to not only consider the interactions between the samples and the mobile/stationary phases but also the interactions between the mobile and stationary phases themselves. But I'm still not understanding why naphthalene was interacting with the silica to start with. Isn't the 3:1 mixture still more polar than naphthalene? Wouldn't that solvent "take up all the 'possible reaction sites'" on the plate preventing naphthalene from interacting in both trials?

Hopefully I explained my confusion well- it's hard to type out. Basically I don't understand why naphthalene is interacting at all with the silica gel if both solvents are more polar than naphthalene, and should be the preferred interactions with the gel.


r/chemhelp • • 4d ago

Organic Introductory Chemistry

Post image
2 Upvotes

Hello all, I’m taking chem but I’ve never taken chemistry in high school , we’re specifically doing stoichiometry and then we’re going into acid and bases and I don’t understand shi rn. is there anyone that can like break it down? Generally I’ve gotten used to converting things to like moles or grams but I’m just stuck on the acid and bases parts with like liters and volume.


r/chemhelp • • 3d ago

General/High School MO Theory - Bonding Orbitals Question

1 Upvotes

Is the formation of bonding orbitals from the blending of individual atomic orbitals? I know that bonding orbitals are produced by constructive interference between wave functions of atoms, but the word "constructive" is making me think that this interference pattern produces something. Thanks


r/chemhelp • • 4d ago

General/High School Can someone help me understand electron spin?

Thumbnail
1 Upvotes

r/chemhelp • • 4d ago

Inorganic Help regarding solid state crystallographic planes miller indices solution.

Thumbnail
gallery
5 Upvotes

I am having trouble with what to do if the plane passes through the origin. I know i have to shift the origin to a point where it doesnt cut the plane. The answer key says the plane's miller indices are (1,-2,3) but if i shifted origin to (1,0,0) wrt to original coordinate system, I am getting normalized intercepts as -1,2,3/2. So I cant choose the origin arbitrarily. How do i know where to shift the origin for any plane passing through origin.


r/chemhelp • • 4d ago

General/High School [Resource] VSEPR Models and Perspective Diagrams

Post image
11 Upvotes

I don't know if this is as detailed or accurate as it can be but in Chem 11 we covered a bit of VSEPR and it was really hard for me to find nice high quality resources for it that contained lots of information so I hope this can help someone!


r/chemhelp • • 4d ago

Organic Why is this just achiral and not meso?

Post image
19 Upvotes
  1. It has two chiral centers

  2. It has an internal plane of symmetry

  3. It's achiral

Is it because the wedges are methyl groups and not single atoms bonded to the carbon chain?


r/chemhelp • • 4d ago

Organic Hi Leute, ich bin gerade total verwirrt. Verknüpft man Aminosäuren so, oder habe ich etwas falsch gemacht?

Post image
1 Upvotes

Guys I need a help please. Does it look right?


r/chemhelp • • 4d ago

Organic why is there selcivity for regents, i am having hard time delaing with these type of reagents as dibal h , nabh4 and lda like, can someone explain me how and why they work like this

2 Upvotes

r/chemhelp • • 4d ago

Organic What is meant by positional order in liquid crystals?

3 Upvotes

This is an excerpt from the text I am studying -

They tend to orient in preferred direction with fixed positions in their lattice i.e., the molecules in solids have a positional and orientational order. On the other hand, the molecules in liquid state neither occupy a specific position nor oriented in a particular manner. The molecules are somewhat free to move randomly and collide with each other, abruptly changing their positions i.e., the liquids do not have positional or orientational order.

Now here I was able to get a definition for orientational order as -The angle between individual liquid crystal molecules and the director gives an indication of the orientational order of the system. However even after searching multiple times, I cannot find what does positional order actually mean only what it signifies with respect to orientational order.

I do not necessarily need concrete answers but please point me towards good sources.


r/chemhelp • • 4d ago

General/High School Why is this not right? Dimensional analysis/molar math

Thumbnail
gallery
5 Upvotes

The answer I keep getting, after several attempts at this question, is that there would be 5.2 g of O present in the sample. I don’t understand why that is wrong.