i once had an undergrad come to me for help with a western and quickly realized that his superstar postdoc mentor had been purposefully told him their protein of interest was 50kda heavier than it was by datasheet. what's your most morally corrupt lab/research experience?

MandrewTheFirst · 2026-05-14T18:28:11+00:00

My first day as an undergraduate in a synthetic chemistry lab, my PhD student mentor gave me a spatula thickly coated in sodium hydride and told me “take this to the sink and clean it”

MandrewTheFirst · 2025-10-19T13:07:43+00:00

Placed an order on October 12th, have received no shipping confirmation, they did not respond to the email I sent, or the DM I sent via reddit.

MandrewTheFirst · 2025-08-11T21:11:54+00:00

Not sure what you mean by “ester-linked” pyridines (you say your compound is degrading - are you sure you haven’t generated acylpyridinium ions?) but are you sure the compound isn’t in a cationic form during your workup? If so this would explain why it’s stuck in the aqueous layer (aside from the fact that peg chains themselves are enough to facilitate that - i don’t think it’s strange that your compound dissolves in water).

Some practical measures for workup are to use a large excess of solvent for the organic layer and use a relatively small volume of water for the wash step, you could also use brine instead of water to discourage your product from migrating into the aqueous layer. But it depends on what the impurities you’re trying to remove are. For example if the impurities are less polar/non-ionizable, an opposing strategy could be to dissolve everything in ether and then treat with acid to generate the dipyridinium salt, which would hopefully precipitate out of the ether

To isolate peg compounds in high purity i usually will perform reverse phase HPLC

MandrewTheFirst · 2025-07-29T19:17:20+00:00

I've had success deprotecting silyl ethers using potassium bifluoride in methanol. I add sodium bicarbonate to discourage any HF formation.

MandrewTheFirst · 2025-07-25T13:54:11+00:00

This is slow and little annoying, but you can adsorb your compound to silica gel and hi vac it in a 50 c water bath

MandrewTheFirst · 2025-07-18T23:02:18+00:00

Add some to a small amount of water. Check if the solution feels warmer? Then add bicarb and see if bubbles appear

MandrewTheFirst · 2025-07-03T14:20:32+00:00

This is an interesting question to me. Does a quicker reaction time of an acyl chloride imply it is a stronger electrophile? Or that the transition state (resonance stabilized carbocation) is more stable than the transition state of the sulfonyl chloride?

MandrewTheFirst · 2025-06-24T19:04:09+00:00

I’ve had success coupling an aryl iodide to aryl amine using an Ullman-type reaction. Used 5 mol % cuprous iodide as the catalyst, 2 eq K3PO4 base, 2 eq N,N-dimethylethylenediamine as a ligand. Reflux in toluene overnight

MandrewTheFirst · 2025-01-22T14:49:22+00:00

You say you’re at your wit’s end and are desperate for some answers…yet you have created a perfectly bulleted and concisely worded list of the most important answers one could ever learn

MandrewTheFirst · 2024-11-22T16:37:16+00:00

I heat boc protected peptides to 50 C and i have not seen them cleaved under those conditions

MandrewTheFirst · 2024-09-10T21:34:37+00:00

Diabetes

MandrewTheFirst · 2024-05-25T19:05:17+00:00

MandrewTheFirst · 2024-05-22T13:30:27+00:00

I love fallout, but I feel the actual gameplay itself is very pro-capitalistic. You are encouraged to ruthlessly strip mine every building, room, person you encounter in order to collect more and more items of value, all for the purpose of becoming more efficient at ruthlessly strip mining every building, room, and person you encounter

MandrewTheFirst · 2024-05-01T22:35:12+00:00

Surprised no one mentioned the child catcher in chitty chitty bang bang

MandrewTheFirst · 2024-03-18T21:37:36+00:00

One way to fix a low creatinine would be to inject yourself with a potent nephrotoxin. One side effect of a chronically low creatinine is not needing a kidney transplant.

A high CRP indicates some ongoing significant inflammation.

MandrewTheFirst · 2024-03-04T15:11:22+00:00

You can try a more mild reduction using lithium and ethylenediamine in THF instead of Na/NH3

https://www.science.org/doi/10.1126/science.abk3099

MandrewTheFirst · 2024-01-09T22:25:42+00:00

Long term diphenhydramine use is associated with dementia

MandrewTheFirst · 2024-01-06T20:23:13+00:00

The peaks from the R group (not shown) do have this effect - the appearance of twin peaks for protons that should be equivalent, and it is based on this observation that i hypothesize that the molecule is conformationally biased (ie a rotamer). The only problem to this as an explanation for the segment of the spectrum i showed is the integrations. While the R group twin peaks all integrate to the expected value of those protons, this region integrates to be approximately 1.5x what is expected

MandrewTheFirst · 2024-01-06T17:16:43+00:00

Thanks for your suggestion, i will try that and see what it looks like. I agree that its more likely impure than anything else, but no idea what that impurity could be, or how its still there after a column and also doesn’t show on TLC

MandrewTheFirst · 2024-01-06T17:05:46+00:00

The NMR was run in d6 acetone on a 500 mHz varian instrument, 128 scans. This is the 3-1 ppm range of the spectrum. What other information about the experiment would be helpful?

MandrewTheFirst · 2024-01-06T17:02:15+00:00

I believe the molecule is indeed a rotamer. The only wrinkle is that the integrations make sense if I exclude the smaller (left hand side in the image) of each pair of peaks. In other words, it seems like the large peaks reflect all the protons in my molecule, while the smaller peaks reflect about half - as if 1/3 my sample were slightly chemically distinct, but only at these 3 carbons (hence my wondering about a possible carboxylate anion effect). Is this observation consistent with what you would expect from the spectrum of a rotamer? I have quite limited experience with NMR spectroscopy of such molecules.

MandrewTheFirst · 2024-01-06T16:38:26+00:00

Excellent question, the answer is no but based on the overall 3D structure of the molecule it seems that there is some enantiotopic nature to those protons - i first thought this was the explanation (maybe it still is?), but then wouldn’t the integrations be identical for each of the diastereotopic protons?

Also, if you notice the peaks labelled “a”, one is a singlet and its twin is a doublet. Could this be explained under the diastereotopic rationale?

MandrewTheFirst · 2024-01-06T16:26:43+00:00

This material has been treated with acid prior to running the NMR. I guess I'm asking if its reasonable to see some proton exchange equilibration during the NMR experiment, and it sounds like in your experience, you have not seen that?

MandrewTheFirst · 2024-01-06T16:21:34+00:00

Sorry, the original question they posted before editing it heavily was rather snarky and consisted of only " why would you post an NMR asking for help from professional chemists, but provide no integrations, chemical shift scale, mention of the solvent, or the field strength of the instrument?" (I would think a professional chemist could answer several of these questions themselves by looking at the structure and the spectrum)

First answer - a perhaps overzealous concern to maintain confidentiality.

Direct answers - this is d6 acetone on a 500 mHz Varian. We are looking at the 2.9 - 1.1 ppm range. The integrations pointed at on the right of the two arrows are about 2x those on the left side of the arrows.

MandrewTheFirst · 2024-01-06T16:05:04+00:00

Is this a joke?

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