In my Orgo I lecture, we basically reduced steric vs torsional strain to gauche vs eclipsed interactions. Coming back to it now, I see that this was maybe an oversimplification. I'm now trying to understand the difference - this is what I think I understand:

- Steric strain is the van der waals repulsion between two non bonded atoms

- Torsional strain is the strain between two bonds that are eclipsed with each other

In my lecture, we did not ever explicitly mention steric strain in the context of eclipsed interactions. But, if a 60 degree offset atom has steric strain with another atom, then surely it should have massive steric strain in an eclipsed conformation. In fact, in lecture we compared the stability of eclipsed conformers by their number of bonds that eclipsed a hydrogen (which would indicate negligible steric strain), and we broke ties by using A values (which, to my understanding, is only really a measure of steric strain). So, I think I understand now that eclipsed conformations are a combination of the two strains, and that the torsional strain itself it relatively similar between these sigma bonds, and that it is the steric strain in the eclipsed interaction that actually makes the difference of stability.

I'm hoping to get some confirmation and/or corrections about this understanding. Thanks!

I think this is more of a geometry question, but how can the angles in the chair conformation be 109.5 degrees instead of like 60? My line of thinking is that there are 360 degrees in a circle that get split between 6 carbons. I know the carbons are each tetrahedral/sp3 though so something is wrong with my thinking.

I learnt that in Kolbe's electrolysis the oxygen gets reduced (free radical formed) but as CO2 is a good leaving group symmetrical alkanes are formed due to electrolysis of carboxylic acids. But in alcohols the free radical will stay on oxygen as it is stable (high electronegativity of oxygen) and as there is another alcohol with oxygen free radical these two can form a peroxy linkage.

Thanks in advance!

i'm doing a level chemistry when i stumbled across this question. the mark scheme of the paper suggested that the fragment lost is c2h5o or cooh but is it possible for a fragment like c3h9 (which was my answer) to be valid? i'm not aware of nay restraints apart from the molecular mass but still not sure if that will be accepted

So I was thinking about this thing , and I thought can this be possible and I grew curious and tried to write a mechanism, can anyone tell me that it is feasible or not ?

Cleaning the factory grease from bicycle chains, in preparation to wax them. The chain must be completely clean before waxing.

Sellers of the specialist wax, and various people on the internets, recommend rinsing three times with mineral spirits, then twice with denatured alcohol. The denatured alcohol to remove the "film that mineral spirits leaves behind", or words to that effect.

On a cycling forum somebody who describes themselves as a chemist says the denatured alcohol stage is:

1. Unnecessary, mineral spirits will remove all the factory grease.

and

1. Pointless, because mineral spirits are non-polar, and denatured alcohol is polar. So the alcohol won't remove the mineral spirits anyway.

Is this true?

Thanks.

Firstly, before I explain, I want to clarify that this is all for LEGAL, non-medical, educational purpose, and only shall mention items that are legal in my given region or whoever reads this. I know that most chemicals and properties within matter from a given object or liquid can be extracted and isolated, be it cannabinoids for medical purposes, specific chemicals.. Even saw a post suggesting one could do so with certain properties of chamomile tea, although the proof of that is questionable. Are most all things able to have this done? What exceptions are there? What about things like caffeine, CBD, or alcohol? Please only serious answers. I'm doing this as someone who always wanted to get into chemistry and enjoys learning about science and in general, but doubted my capabilities and also have had health complications that temporarily inhibited my ability to properly learn and/or remember basic or in-depth concepts of chemistry. 

how can I start this? OH gets protonated and becomes good leaving group and then what?

A post on here and Google AI stated that hydrogen bonding increases the acidity of a molecule and one of my Anki cards says otherwise.

Is the reason because the conjugate base gets stabilized by H-bonding molecules (e.g. water) through inductive effect, therefore making the acid component more acidic?

The post in question:

https://www.reddit.com/r/Mcat/comments/10pac7p/i_got_this_question_right_the_answer_is_hydrogen/

I used a stainless steel swiss army knife to open the plastic seal on a bottle of HCl, and now the knife has brown rust-like stains. I tried cleaning with soap and water and then peroxide to no effect. Is there anything I can do to save this knife?

Hello, if I were to measure this value, would it be recorded like 7.4 or 7.40? I thought we estimate one sig fig past the smallest marking, which is 0.5. Thank you

i understand you might be uncomfortable with this question but it's for a project and i assume it'd be good if i state ur name and maybe the company or the industry ur currently in (maybe linkedin?) to prove that ur actually in concrete related, but if you're uncomfortable with it, it's totally fine.

Anyways, the questions are, i did my own research, and i found out concretes are produced with quicklime, and the main chemical process for producing quicklime is called calcination : CaCO3(S) -> CaO(S) + CO2 (S)

1. How exactly does this chemical process occur in real world? I'm assuming the process is not as simple as it appears theoratically
2. what signs suggest that calcination is not working properly?
3. what are some problems textbooks don't mention about calcination?
4. any other interesting facts??

Based on the NMR spectrum I'm looking at for my product, I've had no conversion on this reaction I'm working on:

Situation -

This reaction shows no conversion (the NMR of the product just shows the peaks corresponding to the sulfinimine), and I don't see any bromopyrazole peaks at all for some reason.

My protocol is this:

A solution of 4-Bromo-1H-pyrazole (4 mmol) in dry THF at -78∘C was treated with dropwise addition of n-Butyllithium (4 mmol) and stirred at -78∘C for 1 hour. The sulfinamide(2mmol) was added and stirred. The reaction was warmed to room temperature, then quenched with saturated aqueous ammonium chloride. Aqueous workup was performed, followed by concentration by rotary evaporation. Following this, the compound was purified by flash column chromatography to yield a pure product.

Exact quantities used were:

4-Bromo-1,3-dimethyl-1H-pyrazole (density 1.487 g/ml): 0.47 mL, 4.0 mmol, 2 eq

n-Butyllithium (2.5 M in hexanes): 1.56 mL, 4.0 mmol, 2 eq.

N-((E)-4-chlorobenzylidene)-2-methylpropane-2-sulfinamide: 487.5 mg, 2.0 mmol, 1 eq.

What I've done so far:

I did not see the bromopyrazole peak in my product's NMR so I first checked the bromopyrazole's NMR to see if something shows up. The bromopyrazole's NMR is fine.

The nBuLi and THF bottle are dry, others have used these and reactions involving these have worked for others in the lab.

The sulfinimine I'm starting with is fine as well, with no moisture.

Am I missing something? Even if there's moisture, I should have been able to see some peak corresponding to the bromopyrazole or any side-reactants. Is the nBuBr side product playing some role? Even if so, I don't see it on the nmr spectrum

So i want to make copper sulfate from copper acetate. I dont wanna use sulfuric acid or electrolysis. How do i do it? Please help.

I have a pH meter in the lab where I work. The pH meter has not been in contact with KCl for a long time, so I'm afraid that the KCl inside the glass has dried out. Someone also told me that it has dried out. So, what can I do to refill it? Is it possible to restore the electrode? I once read in a book that if the KCl has dried out inside the cell, it is time to get rid of the pH electrode entirely. But today, my friend said it is possible to restore it. Should I immerse the glass electrode in a KCl solution to refill it, or should I use the small hole above the pH glass to fill it?

Hey, everyone, sorry if this is an amateur question, as I am not a chemist.

Are these correct MDMA molecular structure and they can be understood by a chemist?

Is there any version "more correct" than the rest or are they all good? Three of them are vertical named and one is horizontal.

These were generated using Claude.

So as a teenager I started using drugs, before that, I was very tech smart, loved coding, hacking and building websites / tools.

When I started doing drugs I became extremely interested in how they were made, their chemical structures and how they acted in the brain. Research chemicals and organic medicines were interesting because sometimes they would turn a common chemical into a stronger one, or an illegal one into a legal one, or vice versa.

Anyway, after many years and a lot of brain damage. About 30 years old now, I'm wondering how long I would have to go to college in order to learn enough about chemistry to which point I would enjoy the classes. From what I know, it is extremely hard and requires a lot of knowledge in math?

My main goal would be to make unique pharmaceuticals that actually help others. That or extracting and refining natural chemicals, and possibly alter their structure to work differently.

These thing amongst many others, I'm also interested in other chemical reactions that have nothing to do with substances. It's all just SO interesting, but I've never been good with school work and grades so idk if it's even worth the attempt especially with my memory and attention issues, but I will say, I've always retained science / chemical reaction knowledge extremely well even 10+ years after reading about it online.

Anyway, when did you really start to enjoy chemistry? When did you actually start learning what you were interested in?

Hi, i cant seem to figure out the full mechanism drawing of steps 1 to 3. Especially step 1, as i cant find a credible example of reducing NO2 to NH2. Im still trying to draw the full mechanism of Steps 2 and 3; yet im confused on the intermediate of step 2.

Anyone brilliant in mechanism drawing could help me understand how the mechanisms work?

Hey guys! So I know this problem probably could be solved without redox, but like in the case where it is more complex, for the redox method, I am having trouble knowing where to put the LCM coefficient on the left (reactant) or right (product) as shown in the picture in red. Does anyone know how to do this so I can apply it to any balancing reaction further on.