/r/chemistry

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A community for chemists and those who love chemistry

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Past Weekly Topics

/r/chemistry

2,809,954 Subscribers

2

Gimme your gnarliest mechanism

My undergraduate research group is doing an exercise in our weekly group meetings where someone comes with a transformation (simple example: ethyl bromide becomes butane in the presence of sodium) and the group works together to figure out the mechanism of the reaction. I'd like something that'll really knock their socks off.

To be clear, we're a synthetic organic laboratory so the reaction should probably be solvent phase, organic, etc. and the reaction should be something well outside of what is generally covered in undergraduate o-chem. But pretty much anything in that vain is on the table.

6 Comments
2024/06/19
20:49 UTC

1

Windshield De-icer Exposure (Methanol + Propylene Glycol)

I was recently cleaning out my (quite messy) car and found a half-empty gallon of Windshield De-icer (Methyl Alcohol + Propylene Glycol) sitting upright with no lid. This was in late May. The last time I used the stuff would have been in the winter months. I am not sure when/how the bottle was left with the lid off. What is the exposure/contamination risk having unknowingly driven around with this in my car, for 3-5 months?

7 Comments
2024/06/19
20:21 UTC

1

Question about chlorine gas at workplace

Hello sorry if this is the wrong place to ask but i have some concerns regarding the cleaning at my workplace.

I will try to explain as good as i can. So every week we clean our "garbage room" with this https://www.tingstad.com/se-sv/stad-hygien/rengoringsmedel/grovrengoringsmedel/grovrent-klenz-skum-special-5l-1707335 (all this is in swedish maybe you can translate the pdf. anyway its some type of chlorine.

And after that we clean our floors indoors with this https://www.tingstad.com/se-sv/stad-hygien/rengoringsmedel/koksrengoringsmedel/grovrent-renolit-clean-s-5l-9064160 all i can find about this in the pdf is that it contains "sodium p-cumenesulphonate"? and C8-C10-polyglykosid?.

We use a kind of foam lance or something that sucks in some of the cleaning agents and sprays them out together with water to leave foam on the floor.

Anyways so since we use the same floor brushes for both theese rooms i am concerned about there being a possibility we could create Chlorine gas. Or would there be way to little chlorine on the brush itselft to create a reaction?

I have not gotten any strong reaction other than i feel like its "heavier" to breath sometimes "Tho this is probably just anxiety"

Since im in this room more or less 8hours a day i would like to know if we did make some kind of gas how long would it take for it to dissapear. it's been about a week now. And i would like to work without feeling like im contantly taking "damage" from this.

Sorry for such a long rant im just trying to get some help with this.

7 Comments
2024/06/19
20:12 UTC

4

Chromatography(?) and if so, what principal?

hey, my kids left the highlighter open. and maybe it’s a silly question and after a few sentences on wikipedia i could help myself but i wanted to share this question. so what method or which attributes of paper made the colors seperate. thanks to all chemistry enthusiasts.

8 Comments
2024/06/19
19:28 UTC

0

can anyone recommend a good workbook?

I’m interesting in becoming a chemical operator and for that I need to follow the course “chemical process techniques” I have almost to no knowledge about chemistry but I’m always excited to learn new things. Could anyone recommend a good workbook with excersises that revolves around my topic and something about general chemistry aswel? I have an entire summer to see if I could really handle chemistry and the course that I will be following if I like it I could go for it.

2 Comments
2024/06/19
18:46 UTC

6

If a hydroxyl group can bind, can a keto also?

I want to find out if a ketone-group can bind to a silanol-group.

I found literature confirming a hydroxyl-group can bind to a silanol-group, and my feeling tells me this means a ketone-group should be able to do the same.

What do you think?

11 Comments
2024/06/19
18:42 UTC

2

Free IR Spec Simulator Web App!

I've been thinking about building a diy IR spectrometer for a min now, but since I've had some productive experiences with simulation software so far I thought I'd look into simulating a few IR spec scenarios first. After some googling I came across this article in ACS:

https://pubs.acs.org/doi/10.1021/acs.jchemed.1c01101

The IR spec simulator can be found here:
https://ir.cheminfo.org/

If anyone has tried it before or plans to, please share your thoughts here. Have fun guys!

1 Comment
2024/06/19
18:16 UTC

1

Calcium Chloride Pellet Deicer

I keep a bucket of deicer in my garage to use throughout the winter. I left the lid off last year, exposing the pellets to the environment in my garage. Come mid-spring, I noticed a significant amount of water in the bucket. I kind of brushed it off assuming I might have left it outside or whatever, dumped it out, and forgot about it.

This year I did the same thing - left the lid off and forgot about it in the corner of my garage. I just found it and again there is a ton of water in the bucket. I know I didn't leave it outside and there are no leaks or anything in my garage.

What's going on that's causing water to accumulate?

Thanks, all!

2 Comments
2024/06/19
17:41 UTC

13

coumarin dye synthesis

here are some pretty coumarin crystals i synthesized abt a year ago :)

1 Comment
2024/06/19
16:50 UTC

0

Is there any substance other than barium sulphate used as a contrast agent in X-rays of gut?

Barium is renownedly very toxic; & even if its solubility in water is exceedingly low, it's reasonable to ask whether absolutely zero of it is absorbed in the obviously rather agressive - chemically-speaking - environment of a digestive tract.

Just casting-around for something else that could possibly be used: we need a substance containing an element with an atomic № @least that of barium … or @ the very least with an atomic № only slightly less than it. One that occured to me would be hafnium dioxide : it would possibly be chemically much like titanium dioxide (or would it!?) which I'm fairly sure is totally inert in the digestive tract - it's used as an excipient in pills, anyway … & from what I gather, there's no toxicity of hafnium known. The precious metals, I should think, would be prettymuch ruled-out: I can't think of any reason why they'd be worth the extra expense (the quantity given of radio-opaque material is substantial - like in the ~100g or ~4oz 'ball park), & also there's a toxicity issue @ least in the case of platinum … so I think it's pretty safe to say that those can be ruled-out. I don't know what, if any, extremely insoluble mercury compounds there are. Lead sulphide is a possibility : lead & mercury are obviously toxic, but the solubility of lead sulphide is extremely low … but on-balance IDK whether lead sulphide is safe to ingest … but if it is safe to ingest, then by the time we're that far up the periodic table the atomic № is beginning to be significantly greater than that of barium … but I doubt that would be enough of an advantage to offset the very concern - ie the toxicity - that prompted this query in the firstplace! And lastly there's bismuth: IDK which bismuth compounds are the least soluble … but, what with it not being a toxic metal, as in the case of hafnium, it probably wouldn't be necessary for it to be really really exceedingly insoluble, which opens-up the scope for choosing something containing that element. As for thorium & uranium: I think those two can be dismissed as viable choices out-of-hand .

Going downwards from barium: there might-well be some iodine compound that can be used. Obviously, though, we aren't as free to search down the periodic table as we are to search up it, as, searching down, the radio-opacity de-creases, whereas searching up it only in-creases.

On-balance, I would speculate that the most promising alternatives would be hafnium dioxide, or some bismuth compound … or maybe some iodine compound. But maybe it's been established with certainty that barium sulphate is the best. I should think barium can easily be assayed for, & that it's been established that there isn't anything anyone could plausibly have eaten or drunken that contains anything that could chemically interact with barium sulphate to yield a compound in which the barium is bio-available … afterall, the use of barium sulphate in that capacity is, by-now, a very mature technology.

 

The frontispiece image is of hafnia pellets supplied by

#####MSE Supplies .

^(There are other brands of pelleted hafnia available .)

Quite frankly, I'm appalled by the price, though: £197 for 50g !!

#😳

: I wasn't aware that hafnium is quite that expensive! Maybe there just simply wouldn't be enough advantage to it to justify that sort of cost.

Afterall: @

#####Philip Harris

^(- there are other brands of barium sulphate available -)

there's a 500g tub of barium sulphate available for £8½ . There's probably some additional cost in getting it up to medical grade … but I doubt the cost of that process is anywhere near enough to lift it into the price-brackett of that hafnia!

Oh yep: according to

#####Z2 Insights — Impact of the Rising Cost of Hafnium on Semiconductor Manufacturing

The price of hafnium is roughly a tenth that of gold ! … or possibly a tad more, even. I think I might've found-out why folk don't get a hafnium drink when they go for a gut X-ray!

3 Comments
2024/06/19
15:57 UTC

0

Used small bottles of chloroform outside fume hood semi-regularly for 6 months

Hi all,

I work in a lab handling lipids dissolved in chloroform, these are 20mL and 5mL glass bottles. Stupidly, I forgot to handle them in the fume hood, and was pipetting them from the bottle into other glass vials for about 6 months, on and off, roughly twice or three timee a week. There was about 4.5 weeks of time where I didn't handle it at all.

I would pipette what I needed and immediately close the bottles, maybe up to 5 min of open time. I couldn't smell anything at all, no physical symptoms. The lab is a little small, not sure if there's ventilation controls. I realised my mistake and am now doing everything in the fume hood. It's been about 5 months since I stopped mishandling it.

I've been worried about potential repeated exposure leading to cancer. I've looked at the (M)SDS and the EPA/OSHA/International guidelines, which state that the carcinogenic effect is only likely under "all routes of exposure for high level exposures that lead to cytotoxicity and regenerative cell proliferation". Carcinogenic effects are not considered under these limits, but how do I know whether or not this is happening?

I asked a senior lab member with a chemical background and they said they had been handling the same size bottles/chloroform sample type for years throughout their PhD outside the hood. It seems that, for the volumes that we use, a fume hood is not really necessary but we use in the hood as an extra precaution. They said that for my situation, it is not likely to cause any ill effect as I am under the exposure limits in the SDS.

Just wanted to get other people's opinions on this. Should I be concerned?

9 Comments
2024/06/19
13:56 UTC

2

How many hours on average do you spend studying or using anki each day?.any tips for studying chemistry as a undergrad.preferably anki related

20 Comments
2024/06/19
14:43 UTC

1

Specific hydroxyl radical scavenger

Hi all, Doing mechanistic studies on a catalytic system that may involve hydroxyl radicals in aqueous system. I’m wondering if some specific scavengers/quenchers existed for the hydroxyl radical to see if it is really an intermediate or not in the radical chain. I’m looking for specific because I trap both hydroxyl and alkyl radicals with dmpo and I’m wondering if I can trap the hydroxyl specifically and see if my products are unafected or totally disappear. Any help is welcomed! Thank you all and have a good day!

4 Comments
2024/06/19
14:11 UTC

3

My reaction is just NOT working

Hi guys! I’m doing my bachelors thesis on carboxymethylchitosan but my reaction is just not giving what it should. I have analyzed my starting materials: chitosan, monochloroacetic acid and NaOH and they’re all fine. I’ve followed many procedures, most have the same: alkaline chitosan, you add the acid and boom, Na-carboxymethylchitosan. It’s a very straightforward reaction, but I’ve tried so many time varying things like temperature and concentration but nothing. Problem is I need it like right now, and I don’t know what else to do to make it work. Please help, any advise or knowledge is welcome and appreciated, I just really can’t think what else am I doing wrong. Seems like I either get chitosan or sodium salt of the acid.

6 Comments
2024/06/19
14:04 UTC

1

What chemical/compound would you add to a solution of water, sodium carbonate and sodium bicarbonate for a "highly alkyline tri- salt polymer"

Per title, I ran out of concrobium mold control - bought 8 gallons, but not another store within an hour has it. I've seen "homemade recipes" online, but don't want to create a dangerous mixture. Company claims: "Concrobium Mold Control is a patented solution that contains purified water, sodium bicarbonate (baking soda), sodium carbonate (washing soda), and trisodium phosphate. These ingredients combine to form a tri-salt polymer that is highly alkaline and dries to form an invisible film that kills mold and prevents new growth." Is there a simple household additive that would achieve a similar solution? Tia

3 Comments
2024/06/19
13:43 UTC

0

How to purify cinnabar? (HgS)

I'm wanting to mess around with making crystals and making cinnabar lacquer but I'm unsure how to go about it. I am NOT interested in extracting metallic mercury from cinnabar. I just want a mostly pure cinnabar. It would be very cool to be able to grow my own pure cinnabar crystals.

I've seen that not much dissolves it, but I don't know I'd there's something I'm missing. Surely there's a process for purifying it as I doubt throughout history when making cinnabar jewelry, they would only grind up pure crystals of it.

4 Comments
2024/06/19
13:37 UTC

13

If you mix pure ethanol with a strong saline solution, will the ethanol separate into a separate layer?

19 Comments
2024/06/19
13:33 UTC

6

What does a parenthesis after a number mean?

I found several numbers in chemistry with parenthesis and numbers inside them. What do those numbers in parenthesis mean?

The atomic mass of ^(64)Zn is 63.929 142(5). What does that (5) mean?

The ratio of atomic mass to mass number of ^(1)H is 1.007 825 031 898(14). What does that (14) mean?

(Sources: Zinc - CIAWWAtomic mass - Wikipedia)

5 Comments
2024/06/19
13:01 UTC

0

Whats wrong our RI-Detector is showing strange singals…

We already cleaned with NaOH…

8 Comments
2024/06/19
11:22 UTC

1

Handling 20% Oleum for Reflux Experiment: Seeking Advice

Hi! I'm planning to run a reflux experiment that requires using 10-15 mL of 20% oleum for functionalization. Given the highly toxic and corrosive nature of oleum, I'm feeling quite anxious about handling it safely.

I've reviewed the SDS and general handling guidelines, but I'm looking for more specific protocol tips and best practices from those who have experience with this chemical. Your insights and recommendations would be incredibly valuable and could potentially save a life.

Specific Concerns:

  1. Safe Handling: What are the best practices for safely handling and transferring oleum?
  2. Personal Protective Equipment (PPE): What specific PPE should I wear in addition to the basic lab coat, gloves, and goggles?
  3. Reflux Setup: Are there any particular precautions or setup modifications needed when using oleum in a reflux apparatus? I'm kind of concerned about the acid gas during the process though.
  4. Spill Management: How should I prepare for and manage spills or accidental exposure?
  5. Storage: Any tips on short-term storage during the experiment?

Thank you in advance for your help and advice!

5 Comments
2024/06/19
11:05 UTC

2

Research S.O.S.—Ask your research and technical questions

Ask the r/chemistry intelligentsia your research/technical questions. This is a great way to reach out to a broad chemistry network about anything you are curious about or need insight with.

0 Comments
2024/06/19
11:00 UTC

0

What is the mechanism behind the orange dye Quinizarin changing color to blue/purple at higher pH?

5 Comments
2024/06/19
10:42 UTC

0

What happens when you mix acetone and ammonium sulfide?

I mixed it on accident in water solution and it was quite a stench. Became colorless and I saw three phases.

2 Comments
2024/06/19
10:41 UTC

6

Blue copper water XD

So I’m just now picking up some small scale chemistry as a side hobby and I’m currently working on making copper oxide through electrolysis and I was wondering what is the “blue copper water” actually called and what can it be used for?

BTW I know my equipment is terrible. I’ve got some legitimate stuff coming in later.😂

8 Comments
2024/06/19
09:31 UTC

1

Liquid-liquid Extraction

Does contact time affect the efficiency of liquid-liquid extraction? If I let the organic phase in contact with the aqueous phase for a longer time, will more solute get transferred from the aqueous phase to the organic phase?

7 Comments
2024/06/19
09:27 UTC

168

Yellow stain on fingers

Fingers turned yellow after lab work today. Haven't been working with Nitric acid or Bromine, and have been wearing gloves, mostly. Only solvents I've been around is Acetone, EtOAc, Methanol and Toluene for the most part. Any idea where this could be from?

93 Comments
2024/06/19
06:23 UTC

3

The best kind of puzzle!!!

I’ve come with a puzzle, and a possible solution. I’d love some backing/support/alternative hypotheses, etc.

Long backstory short, I’ve found myself in the midst of a building wide high rise condo inspection. The results of which, are totally unimportant. What is interesting is that the interior handles to the stairway doors are warm. All of them. 13 floors in a row. Like, 100° warm. The ambient temperature is closer to 70°. The stairway interior is closer to 65°.

“Silky, this is an electrical issue!”

No, it’s not. That’s what we thought, but after careful inspection - there is no electrical wiring in the door. None. No switches, sensors, releases, etc. None.

Only the interior handle is warm. The stair-side handle is cool. The door is cool. The strike plate is cool. Only the handle.

A reminder, the handles are all, roughly 30°F warmer than the surrounding materials.

Also: no direct sunlight on any doors. There are baseboard heaters, but they are (1) about 6 feet away and (2) off.

My theory is: the high-quality finish handles, and the lower quality high carbon steel handles, have created a weak galvanic cell - the resulting in exothermic transfer.

Who can help me confirm, or disprove, my hypothesis?

11 Comments
2024/06/19
03:18 UTC

21

I know this overlapped to anatomy and physiology but,

Would you fine fellows happen to recall the chemical test strip that we used in class: some people would have a bitter taste others hand none

10 Comments
2024/06/19
02:50 UTC

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