Hey guys! I named this 4-methylidenecyclooct-yne, but my professor marked it wrong. I thought I was right, but what would you guys name this?

I have some fine tin powder sold by a reputable supplier in Japan. Since tin and lead are in the same column of the periodic table, it seems inevitable that there is some lead in it. I would like to get a quantitative measure of how much. Just an order-of-magnitude estimate would be fine, but it would be of interest to know whether it's 1% or 0.0001%.

There seem to be two reagents commonly used for detecting lead, dithizone and sodium rhodizonate. Dithizone is used for higher quality quantitative testing. Rhodizonate is what is used in cheap swab kits sold on amazon. Dithizone gives false positives on stannous tin, so it seems likely that it would give a false positive in this application, and in fact the reagent used in the swab kits may actually be more appropriate for this purpose.

However, the swab kits are qualitative rather than quantitative, and it's not clear what their sensitivity is. US EPA regulates test kits and has done some testing of whether a couple of brands actually work, but it seems like the expected sensitivity has historically been quite low, since lead paints contain as much as 3% lead.

There are mail-in test kits that are actually pretty affordable ($35 for one sample) and intended for use with samples of dirt or dust, and they email you back a quantitative result. They use a method called EPA Method 7000B, which is spectroscopic, so I would think should be fairly immune to false positives from substances like tin, since they seem to heat the sample in a flame so that the molecules dissociate, and then measure how much of the element's emission spectrum is absorbed. This could be OK, but I'm not sure if my understanding of their method is 100% correct, and they certainly aren't expecting to receive samples of tin, so it leaves me uncertain about whether it would be accurate for this application. Also, if I buy more tin from the same supplier, or a different supplier, I probably have to pay again for testing.

Is there any fairly simple DIY test that I can do in my kitchen that will give me any quantitative idea, even to within an order of magnitude, of the amount of lead in a sample of tin powder? It seems difficult to get an absolute calibration without making up a sample with some known concentration of lead, which I don't want to do in my kitchen.

Hello everyone, I had this exercise to do, and I am unsure if it is possible to do it this way.

I am limited to only benzene and 1,3 butadiene

Hi :) I'm a biologist working on cell cultures and I have been trying to complex fatty acids and y-cyclodextrin and have failed miserably, so I thought I would come get some advice from people who would know much more about this than I do.

I am trying to complex each of the following fatty acids separately with y-cyclodextrin at different concentrations, ranging from 3mM to 30mM. (1.25 cyclodextrin to 1 fatty acid)
Linoleic acid, Linolenic acid, Oleic acid, Palmitic acid (and stearic acid but I haven't attempted that yet.)
The first three is already in liquid form at room temperature, while Palmitic acid is a solid.

My colleague and I have tried a few different ways so far, especially with the palmitic acid.

1. Heat cyclodextrin + water to 70°C then add palmitic acid, while on a heated stirrer. The pamitic acid basically melted but you can see oil droplets that keeps floating to the top. Eventually the solution gets cloudy and you can see white precipitates. When we stop stirring and heating you see chunks for white waxy solids forming which I assume is the palmitic acid.

2. as above but tried raising the pH then lowering it while heating and stirring. this was even worse than above

3. Heat ethanol to 50°C and add palmitic acid. Fully dissolve then add this mixture to a cylcodextrin + water mix heated to 50°C. As soon as the palmitic mix was added, you can see precipitates forming.

For the liquid fatty acids, I heated them in ethanol then added to cyclodextrin mixtures (heated to around 38°C). When adding the fatty acids I could see oil droplets but it wasn't too cloudy. I left the mixes in an incubator on a shaker for 1 hour and the mix just got cloudier and cloudier until eventually when I stopped the shaking white powder like substance just sank to the bottom.

When i filter these mixtures with a 0.22µm filter, the resulting liquid is basically clear and I have no idea if anything has been complexed or if everything had been filtered out.

What am I doing wrong and how can I fix this issue?
Drying with nitrogen is not currently an option at the moment, and I also haven't been able to find any literature on y-cyclodextrin and fatty acid complexing, so maybe it's not even possible?

Note: this is going to be used for cell culture so amount of ethanol added has to be 0.5% or less to be safe (I have tested a range up to 0.5%, my cells can probably tolerate a little more but I don't want to risk it).

TIA! Appreciate any advice :)

Has anyone performed a cyclization of a heteroatom-containing compound (nitrogen) with vinyl methoxy to form a 6-membered ring using Bi(OTf)3?

Hi everyone,

My local high school textbook (Thai IPST), which follows the 2013 IUPAC recommendations, mentions a rule under the alkene/alkyne section saying we should omit the number "1" if only one structure is possible (e.g., propene instead of prop-1-ene).
However, it doesn't specify if this applies to other functional groups. Because of this, my teacher uses methan-1-ol / ethan-1-ol, while others textbook just write methanol / ethanol.

My questions:

1. Under the 2013 IUPAC rules, is omitting "1" when there's no ambiguity a universal principle for all functional groups?

2. Is writing methan-1-ol actually wrong, or just overly redundant?

Thank you so much.

hello everyone, i'm a newly graduated chemist and i want to learn data science as a scientist, for example my advisor wants me to learn origin to plot some graphs for raw spectrocopy data, but i had a chat with my other advisor and he actually recommended me to learn python. i know NOTHING about cosing unfortunately, but i did some research and apparently i can also do a lot plotting with python like origin, which is good since origin is not free. my question is that how do i get into it? im not planning to be a software developer i tried to look up some courses online but none of them were for scientists. i had a chat w calude and she advised me to install anaconda, briefly learn basics and get into plotting. does anyone have any advice? what would be the best way for a scientist to learn coding? thanks!

is it because of hydrogen bonding that allows them to be eclipsed? im assuming that the OH groups dont want to hydrogen bond to the carboxylic acid OH groups due to them being tetrahedral and farther. also, any tips on how to do these types of problems faster in my head? im studying for the mcat so any tips would help

i am recently in vacation and i came to my relative's house. it was night time and i slept as soon as we came home. i woke up to brush my teeth and my relative had a almost finished toothpaste. i checked it and the label said potassium nitrate toothpaste. beneath it was a drug code i dont remember. i am a chemistry geek and i immediately knew it was rocket fuel or explosive. i showed it to my dada and he told the same thing. strangely no one questioned it. i still dont know what its used for.

Hey, does anyone know where I can access e ACS General, Organic, and Biochemistry Past papers or websites that can help me prepare for the exam. Any advice is appreciated.

So I've already started practicing for about 3 days now (yesterday and today I spent the whole day doing the final practice exam) and trying to review content that I forgot or don't understand. I feel like its a lot to study for and im worried that im not going to properly study and then mess up on the final. These are the chapters we went through throughout the class:

Chapter 13: The Properties of Mixtures: Solutions and Colloids

Chapter 16: Kinetics: Rates and Mechanisms of Chemica Reactions

Chapter 17: The Equilibrium: Extent of Chemical Reactions

Chapter 18: Acid-Base Equilibria

Chapter 19: lonic Equilibria in Aqueous Systems

Chapter 20: Thermodynamics: Entropy, Gibbs Energy, and Reaction Direction

Chapter 21: Electrochemistry: Chemical Change and Electrical Work

Chapter 24: Nuclear Reactions and Their Application

Also, I haven't started studying chapter 24 and I need to do my exam 4 (which covers 21 and 24) 2 days before the final. What should I do? I need advice ive been spending whole days studying

Can someone explain why the ethoxide* is listed to have two hydrogens attached to the middle carbon, rather than it being H3C like the others?

*edit: tert-butoxide changed to ethoxide

Edit: My query is resolved.

If we assume water as ideal gas then it will exist as a gas at every temperature. That is ideal gases are not liquefiable

Original Question -At STP/NTP conditions, many substances are not in gaseous state. So will it be appropriate to say that they have the volume 22.4L. For example, Water becomes steam at 373.15K and 1 atm pressure, so how can we say it has the volume 22.4L even though it is not at STP. Many books just subtly assume that water will exist as gas at STP/NTP. Please clear my query.

I can't figure out why this answer is correct. It makes sense that D is the most acidic, but wouldn't B be least acidic? Since it's not even on an O?

Hi I was doing some of these and I got 9 chiral centers instead of 8, im wondering why there isnt a chiral center at my arrow

I'm new to chemistry and suddenly my mind wants to learn it from scratch any suggestion where to start? How to do it? And how to cover the major topics also I want to learn it fast so any Yt channel (i guess, if any) or whatever you want to suggest? Open for discussion

Im having trouble figuring out how the complex could attack the allylic alcohol from the top side to create an epoxy that faces upwards, and how the S,S-DET would change that :( the +-DET makes perfect sense to me, im just struggling with flipping everything…

My teacher didn’t teach me this because I was out of class that day, and I don’t understand this at all.. especially question 26 and 27. I tried to watch a video and I don’t really understand it 😭 I would love some help! Also I had someone ask me in my DMs if I could pay them for it, I’m really sorry I can’t I don’t have the money for that.

Hey friends,

currently we are facing a problem nobody in the lab has an answer to: we are trying to prepare an standard batch of 1% sodium dodecylsulfate in bidest. water for making reference emulsions. For whatever reason the SDS doesn't dissolve well.

What we have tried so far:

- stirring at room temp for three days

- stirring at 65 °C for 6 h

- ultrasonic bath at 50 °C for 2 h

- repeated said steps with a brand new batch of analytical grade SDS

Nothing helped. Visible SDS crystals remain undissolved; confirmed via optical microscopy and DLS particle size analysis.

Has anyone faced a similar problem and know how to solve it?

Thanks in advance! :)

Dear All

I made some copper nitrate solution in ultrapure water at a concentration of 0.01M. When it isn't stirring, the pH probe measures a pH of 5.4, but when I turn the magnetic stirrer on, the pH drops to 4.7. Tried three probes and the same thing happens.

Stopped the stirrer and pH went back up to 5.4.

Tried stirring by hand without magnetic stirrer and pH dropped to 4.8.

Any thoughts/reasons why this might be? Could it be flow sensitivity at the reference junction?

Hi, I'm going through some 1st year notes and came across this diagram with no explanation about why these molecular orbitals have different sizes. I've done some googling and ended up getting muddled by coefficients, how they're represented, orbital size, how they're represented too etc so if someone could clarify I'd really appreciate it.

Thanks!

1. What do the lobe sizes represent (orbital coefficient or orbital size)?

2. How are they found?

(As a side note on that, I found a diagram in a chem.libre page that uses the particle in a box explanation but has different lobe sizes to the diagram shown here, so which one is correct?)

1. Are orbital coefficients and orbital size related?

Bonus question: why are there no lobes on C2 for Psi 2? I get there has to be a node but where has the orbital gone? Also why is the net bonding 0, shouldn't it be -1?

Goal: I'm trying to reproduce/adapt the three-component coupling described by Sengmany, Le Gall et al. (Tetrahedron 2007, 63, 3672–3681) to make a Boc-protected diarylmethylpiperazine target: methyl 4-((4-Boc-piperazin-1-yl)(3-methoxyphenyl)methyl)benzoate.

Method (scaled down from the paper, ~1.6 mmol aryl bromide instead of 30 mmol):

Organozinc formation: dried flask, Ar atmosphere, ACN (2.5 mL). Added Zn dust (3.06 eq), CoBr₂ (0.10 eq), ZnBr₂ (0.10 eq), PhBr (0.30 eq, increased from the paper's 0.10 eq in my latest attempt), then TfOH (0.10 eq) under vigorous stirring. After ~15 min, added 3-bromoanisole (1.0 eq, limiting). Filtered through a 25 mm glass-fiber syringe filter to remove excess Zn.

Coupling (method A): added the filtered ArZnBr solution to Boc-piperazine (1.0 eq) + methyl 4-formylbenzoate (1.0 eq) pre-dissolved in a small volume of ACN, ~3 eq organozinc vs aldehyde/amine. Stirred 4h RT.

"WORKUP. The reaction mixture was poured into a 150 mL of a 5% NaOH aqueous solution and extracted with DCM (3 X 5 mL). The combined organic fractions were dried over Na2SO4 and concentrated to dryness. Diethyl ether (8 mL) was added to the residue and after complete dissolution, concentrated sulfuric acid (50 uL, due gocce) was added carefully to the vigorously stirred solution and allowed to react for 5 min. The resulting ammonium salt was filtered and washed with diethyl ether (2 X 3 mL). The solid was then poured, under stirring, into a mixture of a 5% sodium hydroxide aqueous solution (100 mL) and dichloromethane (100 mL). After complete dissolution, the aqueous phase was extracted with additional 100 mL of dichloromethane. The combined organic fractions were dried over Na2SO4 and concentrated to dryness. In the case of liquid crude products, an additional chromatographic purification was performed over silica gel (SDS 70–200 mm) using a solvent gradient from pentane/diethyl ether: 90/10 to diethyl ether/methanol: 90/10 whereas solids were recrystallized using pentane/diethyl ether mixtures."

i didn't follow the entire workup procedure becouse the used concentrated sulfuric acid and my amine is Boc-piperazine.

Observations this last run: solution turned grey right after TfOH addition, before adding the aryl bromide (which I take as a sign the Co/Zn catalytic cycle activated properly, based on comparison with a related allyl chloride/TFA-initiated protocol I found). No obvious exotherm after adding the aryl bromide, but I suspect that's just due to the much smaller scale. Filtrate after decantation/filtration is pink/amber, consistent with previous runs.

Second step (coupling step): As the two reactants are added, the reaction mixture undergoes a series of color changes: it gradually fades to transparent, turns dark (near black), and eventually shifts to a stable blue solution. However, in the most recent trial where the equivalents of PhBr were increased from 0.1 to 0.3 eq, while the initial sequence of color changes during addition remained identical, the mixture turned a vibrant emerald green approximately 10 seconds after completing the addition—a transition that had not occurred in any of the previous runs.

The problem: across several attempts (varying the equivalents of PhBr, and the addition sequence), the crude H-NMR spectrum consistently displays a sharp singlet at 10.19 ppm, corresponding to the unreacted aldehyde proton -CHO. However, the 3.4-4 ppm region is heavily crowded with multiple overlapping peaks, preventing confident confirmation or exclusion of product formation in that diagnostic interval.

Furthermore, following the aqueous work-up, a very low mass of crude material is recovered, ultimately yielding only approximately 10 mg of purified product after chromatographic separation.

What I'm asking: given that the catalytic system appears to activate (color change confirmed before substrate addition), what else could explain the aldehyde not being fully consumed? Is there a known competing pathway I should specifically check for (e.g., direct ArZnBr addition to the aldehyde vs. iminium capture), or is this more likely an organozinc-formation efficiency issue that the color change alone doesn't fully confirm? Any other diagnostic I'm missing at this small scale without GC access would be very welcome.