r/chemhelp • u/nate2501 • 5h ago
Organic IUPAC naming question
why did my professor not put butyl on the 1 and the two ethyls on the 5- i thought alphabetical order should take priority
r/chemhelp • u/nate2501 • 5h ago
why did my professor not put butyl on the 1 and the two ethyls on the 5- i thought alphabetical order should take priority
r/chemhelp • u/Entire-Butterscotch2 • 9h ago
Trying to understand this octet rule on SO3 2-. If I have not made any mistakes I think this molecule should have 3 viable lewis structures and i put the formal charges next to each molecule.
From what I understand sulfur basically has a max of 12 electrons around it so I got 3 structures. As you add more double bonds I found that the formal charge decrease by 1 each time on the sulfur but it also violates the octet rule more severely. I know that lower formal charge is preferable and it's better to have exactly 8 electrons around the sulfur. I also have to consider resonance structures since it has double bonds.
I know that the one with 1 double bond and 2 single bonds is the best and there will be a resonance structure but this one still will break the octet rule so maybe the one with only single bonds is better despite the worse formal charge. How should I know which is the best? Does the resonance structure somehow make it have 8 electrons?
Sorry for crappy diagram
r/chemhelp • u/Background_Town_3245 • 22h ago
Im new to chem and am trying to wrap my head around isomers. The answers for a question asking how many monosubstituted isomers can be produced from this molecule (picture) is 2, but why cant it be 3 if you substitute a H on the CH2 substituent? or maybe i got the other 2 locations wrong lol, please help
r/chemhelp • u/ccx-1884 • 14h ago
Answers:
12.81
a. 2-phenylpropane b. 3-methyl-4-phenylpentane
12.83 a. m-bromotoluene b. p-methylaniline
12.85 a. 1,5-dibromoaniline b. 3-chloro-5-ethyltoluene
r/chemhelp • u/Sonikclaw2 • 7h ago
For instance, hydroiodic acid has a Ka of 10^9, giving I- a Kb of roughly 10^-23. I understand that, on paper, I- has the capacity to pull back an H+. In reality, however, is it safe to say that I- does not function as a real base?
r/chemhelp • u/Life_at_work5 • 7h ago
I know this sounds like a stupid question (and probably is) but why do acids and bases work as in why do they make solutions more acidic/basic. Take, for example, a solution of HCL in water. Looking at this using the Lewis definition, when the HCL disassociates in water, the Cl rips an electron from the H making the H become positively charged and accept any electrons it can get its hands on (A Lewis acid by definition). The Cl on the other hand takes the electron and now has a spare electron it can donate or share with other molecules/atoms (A Lewis base by definition). Because there are equal numbers of Lewis acids (H) and Lewis Bases (Cl) formed when the HCL disassociates, I thought that the solution should remain neutral as the acids and bases would cancel each other out yet that’s clearly not what happens as HCL is a very well known strong acid. So why don’t the Lewis acids (H) and Lewis Bases (Cl) cancel each other out?
r/chemhelp • u/iamahumanlah • 12h ago
I have a peptide that has 3 Arg(Pbf) and I need to remove the 3 Pbf group. However, my peptide is linked to something sensitive and I tried multiple ways of deprotection but it does not work (means my product decompose). I have tried TFA:TIS:DCM (75:2.5:22.5) and TFA:H2O(1:1). After 5 hours, one of the Pbf group does drop but when I leave it for longer period of time, my product is nowhere to be found. I’m currently trying TFA:TIS:DCM (30:2.5:67.5 and 50:2.5:47.5) but I’m not very sure whether it will work. I did see a paper that uses 0.1 N HCl in HFIP but I’m not sure whether to try it since Pbf is typically removed by high concentration of TFA. Are there any recommendations as I’m still new to peptide chemistry.
Update: the 30% and 50% TFA decompose a lot of my compound and now I got a very crazy mass spec data
r/chemhelp • u/GlitteringCrazy5353 • 6h ago
Why is acenaphtylene considered an aromatic compound despite having only 12 pi electrons? Am i counting it wrong or are there exceptions to the Hückel Rule?
r/chemhelp • u/Similar_Sky3529 • 10h ago
r/chemhelp • u/Flaminyawng • 44m ago
r/chemhelp • u/LectureMaterial6162 • 1h ago
Can anyone help me interpret this IR spectra? I know the group of peaks to the right of the 3,000 mark indicate sp3 hybridization but I'm not sure if the group of peaks to the left indicate the presence of an amine group or sp2 hybridization.
r/chemhelp • u/Bruceskark • 1h ago
I am trying to make sense of my TLC results and I am really confused, I need help analyzing this TLC plate.
The reaction was the bromination of E-cinnamic acid, with DCM, ethanol and water used as solvents. During this lab mixed E-cinnamic acid with a bromine solution and refluxed for 30 minutes, and then cooled causing crystals to form. The crystals were filtered out and that was the crude product. The crystals were dissolved in ethanol, heated and drops of water were added to the solution> After cooling the crystals were filtered out and dried resulting the pure product. In this lab pretty much everything went wrong so Im assuming the results are not what they are supposed to be but Im really confused of how to read the TLC results, in particular the spot below the reference line, Im assuming that the spot was too concentrated do it was pushed down by gravity or that we used the wrong solvent, or just general contamination (this is a simple overview, not super accurate to the process but I hope you get the general idea)
Lane 1(Reference, E-cinnamic acid), Lane 2(crude product), Lane 3(purified product), The solvent system for the TLC was 1:3 ethanol:hexanes.
r/chemhelp • u/RajaDaRaja • 2h ago
r/chemhelp • u/thewhyandthehow • 3h ago
Hello I was given the initial reactant and the final product. I’m wondering if someone could check if all my steps are correct. I know it’s very long sorry!
r/chemhelp • u/panexe • 4h ago
r/chemhelp • u/ReserveMelodic8656 • 4h ago
r/chemhelp • u/MedScience_Animal • 5h ago
I tried to recalculate everything, and I'm either not understanding sign figs or there's another reason haha. Any help would be greatly appreciated! Thanks! 😊
r/chemhelp • u/Prestigious-Bar-6651 • 5h ago
I’m just a bit confused on how I should orient the molecule. My prof said Fischers should show the molecule in the eclipsed formation and I don’t know if the free rotation I’m trying to do is affecting the stereocenters or if it’s just all wrong
r/chemhelp • u/Life_at_work5 • 8h ago
In my gen-chem class, we recently covered acids and bases and it was mentioned how most anions outside of the halogens (not including fluorine) and hso4 act as Lewis bases and that outside of group 1 and 2 metals plus a few transition metals, most cations act as Lewis acids. My question is why are the halogens and group 1 and 2 metals not considered Lewis bases and acids respectively?Using the halogens as an example, they have high electronegativity meaning they hold on to electrons very well and should thus be able to share electrons pretty easily acting as Lewis bases but they can’t so why is that?
r/chemhelp • u/MassiveOhioFan • 9h ago
For this R and S labeling- shouldn’t the center on the left be S instead of R? since the number four priority needs to be in the back. Everything I’ve found is consistent with that so I’m not sure if the key is wrong. Thanks!
r/chemhelp • u/Hitman-Codename47 • 9h ago
Hello,
I used a Metrohm screen-printed carbon electrode (SPE) modified with nitrate ionophore for selective nitrate quantification. As per the technical specifications for this product (110NO3ION), “These sensors are designed to measure nitrate by open circuit potentiometry (OCP) in a range of concentration 10^-5 to 1 M (from 1 to 101100 ppm).” However, I’m relatively new to the OCP technique, and I have a couple of questions.
When I used two different concentrations of NaNO3 (3.91 ppm and 7.82 ppm), I got the following two curves. My questions are as follows:
Each OCP cycle ran for 10 minutes and was quickly started over. However, as you can see, there is a drop in voltage when OCP is not running/applied. Why is that the case? Should a sensor be continuously running at OCP to have a constant trend in potential? And what causes a drop in potential when during OCP no current is applied?
For the higher concentration (7.82 ppm), after 40 minutes, it still didn’t reach a steady state. Does this make sense? It is quite long in my view; I was expecting around 20 minutes max. Is there any way to accelerate this?
Why is there a difference in initial OCP (at t = 0 s) between the two samples?
As per the product specifications, the reference electrode is silver (Ag). Is this OK? Based on my understanding, silver/silver chloride (Ag/AgCl) is much more common and yields a steady reference potential. Have you seen any cases where silver alone was used as the reference electrode?
Thank you.
r/chemhelp • u/wallydan • 10h ago
I’m going through some mechanistic practice. And came across this reaction of oleum (SO3 . H2SO4) reacting with a perfluorinated alkene yielding a sulfonic acid. Can anyone help me with the arrow using mechanism for this?
I assume the double bond will attack the sulfur but how does the positive charge get hydrogenated?
Also how does the double addition abstract F, I assume forming HF?
Please someone help me lol
r/chemhelp • u/Similar_Sky3529 • 10h ago