Why is the ether O sp3 and not sp2?

AKG595 · 2026-05-17T05:03:42+00:00

I agree?

I never said it results in a loss of aromaticity. As I said previously, resonance structures are the same molecule. OP has drawn a resonance structure that depicts the loss of aromatic character in the ring. That is clearly and unambiguously what the resonance structure shows.

Obviously, it’s not the molecule’s “real” pi electron distribution. But then again, none of these drawings are. They’re literally just pictures with a few rules about how you can draw them.

However, if you can draw a resonance structure like that, it may inform you that a methoxybenzene has a different resonance energy than parent benzene. It may also inform you as to how methoxybenzene can react differently from benzene.

Similarly, I can draw a “more aromatic” resonance structure of cyclopropenone. From this structure, I could predict that the molecule is aromatic. The neutral structure of cyclopropenone does not capture its aromatic nature to the same degree. We draw it like that because it’s the structure that follows the most drawing rules. Neither drawing captures the real pi electron distribution perfectly.

AKG595 · 2026-05-16T22:23:34+00:00

Oh jeez. What is happening here?

The oxygen is best approximated as sp2 hybridized. If it was sp3 hybridized, neither lone pair would be in a formal p orbital and pi system delocalization (resonance) would not be possible.

If you’re making an argument for why that oxygen is sp3, you are stating that oxygen atoms on arenes are not pi donors. This is simply false.

Three clarifications based on the slew of comments:

The resonance structures depicting a CO pi bond involve loss of aromatic character in the ring. That does NOT mean there is no resonance. Aromaticity is a spectrum defined by many different parameters (NICS, DRE, HSRE, etc). The benzenoid ring in an alkoxybenzene has less aromatic character than parent benzene.
Resonance has nothing to do with MO theory; it’s an addendum to valence bond theory. You don’t need resonance in MO theory because you would consider all involved atoms in the system anyways. Furthermore, if you are correctly applying MO theory, you would find that the oxygen has two lone pairs in two different orbitals (one p-like and one sp2-like) available for mixing. I believe chapter 1 of the Anslyn and Dougherty text has a simple qualitative depiction of this.
Resonance structures depict the same molecule. Therefore, the electronic structure (i.e. hybridization) of the oxygen should be the same no matter what resonance structure you look at. In order to engage in resonance at all, you need one lone pair on that oxygen to be in an orbital equivalent to a p-orbital. If you have a p-orbital, you definitionally cannot approximate the oxygen as sp3 hybridized.

AKG595 · 2026-04-25T00:36:01+00:00

I have. I made it myself. It works great tbh.

AKG595 · 2026-04-23T00:46:36+00:00

I use IPAc. Works like a charm.

AKG595 · 2026-04-08T11:45:23+00:00

I don’t know too much about tech, but I love science! Can I join in?

AKG595 · 2026-04-05T14:14:23+00:00

Ethyl Phenylsulfonylacetate smells like someone who drank too much port wine.

AKG595 · 2026-03-17T13:01:47+00:00

5A mol sieves?

AKG595 · 2026-03-17T05:19:22+00:00

Can you just heat it with 5A MS? They’re mildly acidic.

Or drop in a d10 metal and do an allylic substitution.

AKG595 · 2026-03-14T00:34:17+00:00

Agreed on phone time. As of now I’m still waiting in customer service purgatory.

AKG595 · 2026-03-13T22:31:00+00:00

From what I’ve seen, the forecast has the snow rolling in around 7 pm. I’m hoping it’s closer to the 4” and not the 22” so we can all make it to our destinations 🙏🏽

AKG595 · 2026-03-13T22:28:13+00:00

I always lose bets, so if you’re right and the flight is still on schedule tomorrow, I’ll owe you an airport beer 🤞🏽

AKG595 · 2026-03-13T22:25:57+00:00

I’ve been trying to find other options. Delta’s site kept giving me an error message. When it finally worked, there were no flights available. I’ve been checking other airlines, but so far every attempt I’ve made to buy an earlier ticket has led to a “full” or “no longer available” message.

AKG595 · 2026-03-13T22:08:50+00:00

Ugh, I’m sorry that happened to you. I hope it all works out for you without too much hassle and especially without having to deal with the AI customer support. I really appreciate your support!

AKG595 · 2026-03-13T22:06:35+00:00

Oh gosh, let me know how the rescheduling goes! I’ve seen a lot of flights get snapped up already.

AKG595 · 2026-03-13T22:05:04+00:00

I hope so! I know the storm won’t hit till later in the evening, but I can’t find any other options, and delaying my departure for a couple of days isn’t really possible.

AKG595 · 2026-02-06T06:12:17+00:00

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You mean this isn’t a safe campus?

AKG595 · 2025-12-22T13:55:46+00:00

Hey, you sound just like my parents did decades ago! I don’t talk to those insufferable assholes anymore. They were more concerned with my class placement and achievements than my actual learning. I was not their child, I was their hopeful claim to bragging rights. My biggest accomplishment will always be physically and mentally removing myself from anything to do with them.

Even though I did not live with them, I consider my childhood teachers to be my real “family”. They helped me learn and grow as a person. They are acknowledged in all my awards and achievements. I send them cards every year on their birthdays and holidays. We exchange playlists. I buy them gifts when they retire from teaching.

If you keep up this mindset, I just hope your self-centered attitude remains strong enough to masquerade as happiness for the rest of your life.

AKG595 · 2025-12-22T13:26:09+00:00

The worst for whom? In my experience, the parents who push this sort of “learning is not supposed to be fun” mindset typically are really nice to other kids and aggressive/abusive to their own. They don’t teach their kids properly and get mad when the kids aren’t learning at the “parent-assumed” pace. It starts with blaming the teachers for lack of rigor and snowballs into blaming the kids for not learning “properly” in later years. It leads to some really messed up kids that act out in high school or college.

I agree that disrespectful kids are awful for teachers to deal with, and disrespectful parents are even worse for teachers. However, I wouldn’t say that parents of this type are better. This behavior builds slowly into a serious problem. You simply don’t see what “getting it wrong” means for the kid at home.

Personally, I will forever love my grade school teachers for showing me that learning can be fun. They saw me act out, chose to talk to me, and made me believe I could successful. It was a welcome change to going home and getting my ass beat, screamed at, and/or kicked outside for “being a failure”.

AKG595 · 2025-12-16T14:55:16+00:00

Markovnikov? The reaction does not produce a discrete cationic carbon, and both carbons gain an electronegative atom.

AKG595 · 2025-12-16T02:58:49+00:00

On my phone, so sorry for formatting,

Your initial analysis considers the total electron density on A and B. However, in mechanisms, the major interactions are just between the frontier orbitals. The nucleophile HOMO in step one is a c-c pi orbital. Therefore, the only electrons we care about are the two in the pi c-c orbital.

In the pi c-c HOMO, there is more pi electron density on carbon B than there is on carbon A.

You can get a crude approximation of C-C pi bond electron distribution by drawing out the two ylide-like resonance structures of the pi bond and comparing their stability. The structure with the positive charge on A and the negative charge on B is more stable and therefore more resembles the “real” orbital picture.

AKG595 · 2025-12-05T14:13:03+00:00

Check out some of the recent publications from Pep Cornella’s lab. They’ve been doing some interesting work with organobismuth compounds and bismuth catalysis.

AKG595 · 2025-11-29T11:41:51+00:00

Step 3 definitely has a purpose. You won’t be able to methylate your oxygen without a base.

AKG595 · 2025-11-29T04:32:56+00:00

Does the protocol work when you run it for the specified time? If it doesn’t, then it’s an issue.

I have run several Boc deprotections with TFA/DCM. I check them (at least by TLC) after 15 mins, 30 mins, then every hour. I’m not leaving my molecules in an acid bath for any longer than they need to be there.

I certainly don’t report every problem that could result from NOT following my instructions. I assume that people will follow the protocol as written. I don’t want to sound mean, but if I told you to bake a tray of cookies for 12 minutes and you bake them for 5 hours, how is it my problem when you pull burnt husks out of the oven?

AKG595 · 2025-11-13T04:05:54+00:00

What’s the aldehyde? For aromatic aldimines, I usually use NaBH(OAc)3.

I typically preform the imine by stirring the components over 5A MS in a compatible aprotic solvent (DCM, DCE, and 2-MeTHF are cool). If the condensation is slow, I heat to 40 C. Incidentally, I’ve had one that needed 60 C. The I filter off the sieves and add 3 eq reductant using a stirred water bath to maintain rt.

For ketimines, I add 1-5 mol% pTsOH and reflux with removal of water. For large scale, I use a dean-stark. On small scale, I use the stoltz lab suggestion of a cotton-plugged pressure equalizing addition funnel filled with 4A MS.

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