synthetic chemistry roles are thin on job boards and buried under analytical and QC postings, so i pulled only medicinal, process, discovery and synthetic organic chemistry roles from employers' own careers pages:

https://github.com/mehek-builds/Synthetic-Organic-Chemistry-Jobs

• 37 roles at 25 employers (GSK, Gilead, Vertex, Pfizer, AstraZeneca, Amgen, Roche, Organon)
• 12 medchem, 12 process chemistry and process research, 15 discovery and synthetic, 12 internships and co-ops
• 8 in the UK and Europe
• analytical, QC and director-level roles are left out

it's a small list because there aren't many of these open right now. rebuilt every monday.

comment which area you're looking for (medchem, process, peptides and oligos, internships) and i'll send you anything that comes up.

Question: I am in the UK and have had a job for a year and a bit and a second I am currently in for five years. Both senior scientist roles with a mix of process development, scale up and a bit of small scale medchem type stuff. At the time of searching, nearly all the interviews required extensive general knowledge and retro synthetic questions.

Having been many years from my PhD and lacking general chemistry theory practice I am a bit scared about looking for another position as I struggle with the revision (time and energy). Is there a point when your ability to do retro synthetic problems without reaxys or other aids isn't being examined?

In fact my current employer was the only one where questions were more on the line of "look at this proposed process and tell us what would concern you, and what changes might you explore" and a few conditions for various transformations of a compound.

Hi all,

I am desperately needing help on my peptide synthesis project. I need to selectively deprotect a hydroxy group on my peptide. It is now a TBDPS silyl ether. TBAF is the most straightforward way to do this but I’m having issues with visualizing my LCMS. Not sure because of ion supression or what. Is there a subreddit for peptide chemistry?

Any help is appreciated.

Thanks!

I work in an environmental lab-- water quality, inorganics (metals, ion chromatography, ph/titrations, misc other services)-- and we get undergraduate students on work study. They of course learn some things through the tasks they are assigned but I do want to make sure they get some basic lab skills to put on their resume and develop enough familiarity to do well in interviews and not be overwhelmed if hired as a lab tech in the future. What skills do you like candidates to have when hiring? Any recommendations for things I should make sure they know would be appreciated. Leaving this fairly vague and open ended intentionally but also because it would be tedious to enumerate what they have learned in the course of the work we have them do. Thanks!

I am carrying out a mCPBA induced Bayer Villiger oxidation. My reaction has worked, sadly I cant share too much information on the product but I can see from shift in NMR that the oxidation i needed to happen has happened. I do have an impunity in my product which I have spent days trying to remove. I was fairly confident that it was meta chlorobenzoic acid or residual excess mcpba. But no matter what I try I cant get rid of it.

It matches literature in terms of its splitting for meta chloro benzoic acid but bicarbonate, carbonate washings or even hydroxide is not removing it. Please help. Photo of nmr attached. The multiples for 4H and 4H are my product.

I took an nmr of my mcpba commercial sample and the peaks are in that too but as a minor impurity. I just cant get rid of whatever it is

Hi everyone, I am currently working in organometallic chemistry, making some diamagnetic complexes. However, one of the complexes already decomposes during the synthesis (as in, there is no signal in the 31P NMR, and a very broad signal in the 1H NMR spectrum). However, I do observe some black powder being formed, which I assume is the metal falling out.

My supervisor suggested to take an EPR spectrum, to check if there was any paramagnetic species being formed, but we don't have such an instrument at our institute (and there is basically no other group that does organometallics who I could ask for help) and so I want to make sure that that measurement is useful, before going through the hassle of preparing it and sending it to another institute.

I've read a bit about EPR now and I think I understand the principle behind it, but my question is, if I have a reaction mixture of which I don't really understand what happened, will EPR even give something useful? As I understand it (and I might be wrong because this is really not my expertise), EPR is something that you use when you already kind of know what you are looking at, because it is quite complicated to analyze, or will it give me information even if I don't exactly know what I am looking for yet?

Thank you in advance, any advice is super appreciated! (Also, I'm sorry if this is a very basic question)

Good afternoon! I was wondering if anyone else has encountered this problem.

I'm running a column chromatography purification and have noticed that my reaction mixture contains many byproducts. However, I'm able to isolate the fraction corresponding to the spot I'm interested in on TLC. Despite this, when I analyze that fraction by NMR, I still observe impurity signals, mainly in the 1–4 ppm and 6–8 ppm regions.

I've tried different hexane/ethyl acetate and hexane/DCM (dichloromethane) ratios, but I still haven't been able to obtain the product at the desired purity.

My product consists mostly of hydrocarbons.

I apologize if this information isn't sufficient to assess the problem. I'd appreciate any suggestions. Thank you in advance!

Hey everyone,

I’m currently working on a research project using spectroscopy to detect diacetyl in a beer matrix. We’re aiming to measure in the gas phase, but we’re running into the issue that water vapour is extremely prominent in the same absorption bands. Does anyone have ideas on how to efficiently separate the volatile compounds from the water vapour when heating beer? Are there any filters that could help? I’m not a specialist on the chemistry side, so I might be overlooking a very obvious solution.

Hi Chempros community,

I am currently dealing with really sensitive compounds that unfortunately degrade on normal silica gel, and I have to use special silica gels such as C2-functionalized silica gel and the 3-aminopropylfunctionallized silica gel.

As these silica gels are insanely expensive, and while I can make C2 using the protocols published, I can't really seem to find a protocol for making the 3-aminopropylfunctionalized silica gel like the one displayed at Merck or Silicycle:

https://www.sigmaaldrich.com/NL/en/product/aldrich/364258?srsltid=AU7gw4U2KL3R8G9_pLynTp3EQV6hjiiSu3mnSV1MoT98QYXuqLn0TmaT

https://www.silicycle.com/products/amine-wax-silica-phase

Did anyone make, and has a reliable procedure to make a homemade version that worked a lot? Also, any experience/tips handling this silica for purification would be greatly appreciated!

Thank you very much for the help in advance :)

I order from maybe fifteen different chemical suppliers for our research lab. The big suppliers like Sigma-Aldrich and Fisher have comprehensive SDSs that cover all sixteen sections with detailed information. The smaller specialty suppliers? Some of their SDSs are missing entire sections. Others have sections filled with "no data available" or "not tested."

I ordered a custom synthesis product last month and the SDS had a Section 2 classification based on the starting materials rather than the actual product. Section 11 toxicological data was blank. Section 12 ecological data was "not determined." Half the sheet was either missing or placeholder text.

Am I supposed to accept these? Can I use a product in my lab if the SDS is incomplete? What's the minimum standard for an SDS to be usable?

Hi All,

One of the professors where I work wants to use HF to digest insect samples, but as far as I know, all of our fume hoods/ductwork are standard and hence not compatible with this acid. Is the incompatibility really an issue with long term use, and if so, does anybody know a work around?

We are planning to protect of an allophanoyl group (RC(O)NHC(O)NH2), to allow for dibromination of a vinyl group elsewhere in the molecule. It occurs to me that BSTFA/1%TMSCl might be a good TMS donor. However, I am not sure about a good choice for conditions (time, temperature, solvent). My literature searches have not turned up much but are are ongoing. We are also open to using other protecting groups, including TBDMS.

I think r/biotech is probably better for this post, but I find the people in that sub incredibly negative and pessimistic...so would rather post here if possible as I find people to be a bit more neutral/level-headed here.

Job opened up at a big pharma company for a DS MSAT PM, primarily responsible for Process Validation, sitting inbetween CMC and commercial. So getting involved towards the end of development, being in charge of PV, and then handing over to the product supply colleagues.

Problem is, I know someone in that department and she says it's a new department, and there's no SOPs, therefore things can get chaotic. On one hand, it could be good experience to dive in the deep end and give input on how things should be run since I have experience of PV and the transition to commercial, but on the other hand, I am worried that things could go very wrong regulatory or cGMP-wise if there are no SOPs to guide us.

Has anyone been in this scenario before? Is it worth a try or just a complete red flag?

Hello community :) does anyone know of any databases where I can download both experimental IR and Raman spectra for a specific compound?

We got a new toy in my lab: a X-ray fluorescence spectrometer.

Sample material is delivered to HDPE cups with a film cover. The machine analyzes the samples with the cups in a vertical standing position, and my samples tend to solidify at room temp. So, when I'm prepping up a batch of samples, I needed a way to stand them up in the same orientation that they'd be analyzed in.

Tinkercad to the rescue!

The cover is because the HVAC in my building is only \sorta kinda maybe\** filtered and dust & dead bugs tend to affect the results.

https://www.printables.com/model/1869312-xos-petra-max-sample-tray

I'm currently preparing the SI for a total synthesis paper and wondering how you handle minor impurities in your NMR spectra.

For example, one of my intermediates contains around 9 mol% DCU (~4.5 wt%) that survived column chromatography but is otherwise perfectly clean. Would you explicitly mention this in the SI or just leave the signals in the spectrum, it serving as declaration of the material? And would you adjust/calculate the yield and analytics like optical rotation accordingly?

I'm mainly worried about a reviewer requesting cleaner spectra if I explicitly note the impurity as a footnote, potentially forcing me to repeat several steps of the synthesis just for characterization. A colleague mentioned that I then just should purify the aliquot I kept back for analytics via prep HPLC but that feels even more dishonest as it no longer would represent the bulk materials purity.

On the other hand, repeatedly purifying the whole bulk material just to get perfectly clean spectra feels like a waste of time and material, especially when the impurities don't affect the next steps anyway.

How do you usually handle this, and where do you draw the line? I personally feel that acting in good faith and being transparent is how such things should be handled but I am also aware how easily a reviewer might demand perfectionism as they are not the one bearing the cost.

does anyone has a database with pka values for formic acid in alcoholic solvents? i've seen a lot of computarional methods already published, but the results i'm getting from following them are kinda weird and i wanted some data to check against

Anyone have a metrology/calibration/recertification service that they recommend? Ideally one that comes to you as opposed to mailing the stuff off. The one we have used for years blew us off and won't be able to come until after our annual audit. Environmental lab for context. Thanks!

While writing my PhD thesis, I, like all students, recognised how annoying and tedious compound numbering becomes, particularly keeping the numbering consistent between the LaTeX text and ChemDraw schemes.

I used a small system where compounds are referred to by permanent IDs (e.g. lab-book references) in both LaTeX and the original ChemDraw files. A central CSV maps those IDs to the actual compound numbers, and a Python script and AppleScript automatically relabels the ChemDraws, exports them as PDFs, and keeps the LaTeX references in sync.

So if the numbering changes, I just edit the CSV and recompile rather than manually renumbering everything.

I used it successfully for my thesis and have put a minimal working example on GitHub:

https://github.com/BrennanGroup/compound-relabelling

Mostly posting because I'm curious whether other chemists would find this useful, or whether people have come up with better/different systems for solving the same problem. Would be interested to hear how others handle it.

New grad student, have done research in a synthetic lab for a while now and just curious how people approach handling dangerous chemicals/doing risk assessment for the first time from a practical standpoint. Are there any resources that are particularly helpful when trying to mitigate risks for a reaction that has the potential to be dangerous?

For instance, working with something like bromine I know I need to keep a solution of sodium thiosulfate on hand incase of any spills (and for quenching once the reaction is done) but aside from that I feel like I’m probably missing a lot of nuance. (Eg: elemental bromine is very dense, so maybe there are some precautions one should take that they don’t realize before having actually worked with it before. Maybe because it has a high vapour pressure I need to make sure I’ve got an outlet so that pressure doesn’t build up in the chamber, or avoid using a micropipette since the fumes will mess it up)

As another example: I wouldn’t know I have to wash a rotovap with acetone several times after rotovapping TFA if I hadn’t been explicitly told by a mentor. This isn’t something you can find in an SDS and while it makes sense when you actually think about it, it’s probably not smtn you think about the first time you use TFA.

I know my question is very broad, and the answer is probably “read the SDS”… but an SDS only contains so much practical information and for many dangerous chemicals it feels like knowing that they’re pyrophoric, or particularly toxic, etc will only get you so far.

I appreciate any insight.