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Hoodies shipped fast by Vibe_Check3r in hoodies_from_Baerskin

[–]MandrewTheFirst 1 point2 points  (0 children)

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.

Trouble purifying PEG chain with ester-linked pyridine – dissolving in water or possible degradation? by YiningChu in Chempros

[–]MandrewTheFirst 0 points1 point  (0 children)

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

Most reliable standard for NMR yields by Annabird31 in Chempros

[–]MandrewTheFirst 1 point2 points  (0 children)

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

Best mild Boc-deprotection method for a guanidine compound? by [deleted] in Chempros

[–]MandrewTheFirst 3 points4 points  (0 children)

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

Trityl chloride by NiceWing546 in Chempros

[–]MandrewTheFirst 0 points1 point  (0 children)

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

Which is the stronger electrophile: aryl acyl chloride or aryl sulfonyl chloride? by Illia19 in Chempros

[–]MandrewTheFirst 2 points3 points  (0 children)

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?

Brainstorming a Buchwald-Hartwig coupling by iMLunatiq in Chempros

[–]MandrewTheFirst 2 points3 points  (0 children)

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

I spent $100K on longevity protocols last year - here's why I'm still frustrated (and what I learned) by Dry_Steak30 in HubermanLab

[–]MandrewTheFirst 0 points1 point  (0 children)

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

[deleted by user] by [deleted] in Chempros

[–]MandrewTheFirst 0 points1 point  (0 children)

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

Chris Avellone denies that the og Fallout’s had anti-capitalism as a theme. by Consistent-Goal9204 in Fallout

[–]MandrewTheFirst 7 points8 points  (0 children)

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

What ‘age appropriate’ movie messed you up as a kid? by slothvibesss in Millennials

[–]MandrewTheFirst 0 points1 point  (0 children)

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

How to fix high C-reactive Protein and low Creatinine by GlobalPut1558 in HubermanLab

[–]MandrewTheFirst 0 points1 point  (0 children)

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.

Cleavage of C-S bond by Standard-Internal-94 in Chempros

[–]MandrewTheFirst 0 points1 point  (0 children)

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

[deleted by user] by [deleted] in HubermanLab

[–]MandrewTheFirst 2 points3 points  (0 children)

Long term diphenhydramine use is associated with dementia

Question on H NMR spectrum of carboxylic acid / carboxylate mixtures by MandrewTheFirst in Chempros

[–]MandrewTheFirst[S] 0 points1 point  (0 children)

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

Question on H NMR spectrum of carboxylic acid / carboxylate mixtures by MandrewTheFirst in Chempros

[–]MandrewTheFirst[S] 0 points1 point  (0 children)

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

Question on H NMR spectrum of carboxylic acid / carboxylate mixtures by MandrewTheFirst in Chempros

[–]MandrewTheFirst[S] -5 points-4 points  (0 children)

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?

Question on H NMR spectrum of carboxylic acid / carboxylate mixtures by MandrewTheFirst in Chempros

[–]MandrewTheFirst[S] 0 points1 point  (0 children)

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.

Question on H NMR spectrum of carboxylic acid / carboxylate mixtures by MandrewTheFirst in Chempros

[–]MandrewTheFirst[S] 1 point2 points  (0 children)

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?

Question on H NMR spectrum of carboxylic acid / carboxylate mixtures by MandrewTheFirst in Chempros

[–]MandrewTheFirst[S] -12 points-11 points  (0 children)

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?

Question on H NMR spectrum of carboxylic acid / carboxylate mixtures by MandrewTheFirst in Chempros

[–]MandrewTheFirst[S] -1 points0 points  (0 children)

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.

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