I need advice about best options to sell decommissioned lcms and associated lab equipment; all on manufacturers maintenance contracts and trouble free operating history. Thanks.

Hello,

I'm regularly doing 1H NMR in CDCl3 on some products and I'm facing a huge problem. A broad OH peak right on my peaks of interest. This peak is probably due to me using HFIP for my synthesis. You will tell me just remove HFIP, it's pretty easy but I can't because my reaction medium crosslinks if I do evaporate it so I need to analyze it in solution. I tried deuterated MeOH or TFA but spectra were ugly. Any solution ? I know that changing experience temperature can shift the peak but I don't know if it's really effective.

Thanks.

Those who work in these departments in pharma companies/CROs: Did you interview for both med chem and process positions? Would you go back and “switch sides” if you could?

In patents many compounds are often mentioned that are not specifically described with a synthetic procedure and yield. For example, in the first couple of pages a general structure is drawn with general substituents (G1, G2, ...). Then in the text is something written like: G1 is a C1 - C12 alkyl, G2 is a C2 - C12 alkoxy etc.

Does that mean that all of these compounds are automatically patent-protected? If not, how can I see if they are protected or not?

I recently completed my Honours year (biology/chemistry). I was planning on asking my supervisor if I could stay on as a paid research assistant for 1-2 months to acquire some more data and publish my honours project. I just had some questions:

• What's the best way to ask? I was planning on just emailing with my plans for future work and directly asking to become an RA, I have a good relationship with my supervisor. I assume this is fine, but if anyone has other advice or experience, let me know.

• Is the length of the 'contract' (is it a 'contract') typically pre-determined, ie. you know in advance that the paid position will only last say 6 weeks or 10 weeks.

• What's a reasonable/common hourly rate? I don't plan on discussing this and I certainly wouldn't haggle, just curious.

• Is it legal for me to just work for free? I assume not, but I wouldn't be opposed to working 10-20 hours a week for a month or 2 just to try to finish things off. Not very pro-workers rights of me admittedly, and I assume my supervisor wouldn't ask me to work for free anyway.

Let me know if there's any Australians who have some insight here.

EDIT: If it matters, also been accepted for a PhD with the same supervisor in 6 months. Just want to polish off this specific project and move on to new things.

Hi all

I'm doing a PhD in physics designing a sensor that measures refractive index. I'm currently using Acetone, Methanol, Ethanol and IPA but finding the Acetone is dissolving the tape ruining my measurements (it uses an optical spectrometer so when the tape melts it gets cloudy). I got this list from Chat GPT about some solvents I could use but it says most of them require a fume hood (including methanol which people in my lab have used routinely outside with no issues). I drop cast and wait to evaporate before placing the next drop so I only use 10 ml of each max per day in a well ventilated room and are stored properly.

Is there any on this list that wouldn't be safe to do in my lab outside of a fume hood for how low volume I'm using?

• Water - Safe to use outside a fume hood.
• Methanol - Should be used in a fume hood due to toxicity and flammability.
• Ethanol - Can often be used in a well-ventilated area, but a fume hood is preferable due to flammability.
• Isopropanol (IPA) - Generally safe in a well-ventilated area; fume hood recommended if frequent use.
• Acetone - Can be used in a well-ventilated area, but a fume hood is safer due to flammability.
• 2-Butanone (MEK) - Requires a fume hood due to flammability and respiratory irritation.
• Ethyl Acetate - Fume hood preferred because of its strong odor and flammability.
• Diethyl Ether - Must be used in a fume hood; very volatile and highly flammable.
• Isopropyl Ether - Must be used in a fume hood due to high flammability and volatility.
• n-Butanol - Fume hood recommended; it is moderately toxic and has a strong odor.
• Cyclopentane - Fume hood required due to high flammability.
• Tetrahydrofuran (THF) - Should be used in a fume hood due to flammability and potential toxicity.
• Pentane - Must be used in a fume hood; extremely flammable.
• Hexane - Fume hood required due to toxicity and flammability.
• Heptane - Fume hood required because of high flammability.
• Dimethyl Carbonate - Fume hood recommended; while less toxic, it is still flammable.
• Ethyl Lactate - Generally safe in a well-ventilated area; fume hood recommended if used frequently.
• Methyl tert-Butyl Ether (MTBE) - Fume hood required due to toxicity and volatility.
• Dichloromethane - Must be used in a fume hood due to toxicity and potential carcinogenicity.
• 1-Butanol - Fume hood recommended; moderate toxicity and flammability.

TIA. Let me know if you have any question, any help is much appreciated as chemistry is not my thing

I'm planning on using factorial design to screen factors affecting the yield of a chemical reaction. However, I’m unsure how to appropriately determine the "high" and "low" levels for each factor. For instance, when considering reaction time, should I define low as 20 minutes and high as 40 minutes, or go with longer durations like 10 hours and 20 hours? I want to ensure I cover the relevant range for each factor effectively.

Who needs a UV lamp or a iodine jar when you can see your TLC in a million dollar PET-CT machine?

I’m manually making short peptide analogs (6 AAs). Im having the problem that every now and then the resin becomes really hard to wash. im using syringe barrels with a filter to synthesize but they shouldnt be the problem

it also doesnt really seem to be sequence specific as ive had it happen after the first coupling.

does anyone have experience with this? im washing with dmf

Hi chem pros-

Is triphenyl methanol esterification possible? I have tried conditions with EDC and DMAP, but all of them failed to yield the desired ester product. Starting to think it may not be possible due steric hindrance…

Okay another LCMS question for the agilent fans out there: AJS vs ESI for everyday synthetic organic work.

For people in Synthetic Organic and Medicinal Chem Labs, do your labs have a standard “general purpose” method for LCMS? Currently looking for a good starting point for our labs LCMS method (we are a new lab and dont have an old method to go off of).

Is there a convenient and safe method to dispose of this? Contains about 200 g. My EHS manager wants it converted to something less hazardous as opposed to paying a large amount (his words) to have an outside firm handle it. This is a legacy material from a small company we acquired.

Is peek resistant to HF? I'm looking to run HF solution in my ICP and would like to know if I can use a peek neb

Has anyone had success with using solid-bound piperidine/piperazine for Fmoc deprotection?

I currently do this deprotection in solution phase but I’m wondering whether using resin-bound reagents and removing via filtration could speed up my workflow

For some context I am currently working on synthesizing and characterising a series of lanthanide complexes, unambiguous structural determinations were made using SCXRD, however for the mononuclear complexes La (97%), Ce (113%), Nd (107%) , relative to the di-nuclear complexes Y (50%), Er (57%), Yb (52%) my yields equate to greater than 100%. For context, these were dried in a dessicator for 2 weeks and so i'm reluctant to believe my products are still wet, side products include salts and so are unlikely to contribute significant mass as most are washed away with water after synthesis.

approximately 0.5mmol of limiting reagent (lanthanide metal salt as hydrate) is used to determine the theoretical yield in each case.

0.20965g Lanthanum (III) Nitrate Pentahydrate (99%) 415.01g/mol-1 was used to synthesize 0.36645g {[La(4NPhAc)3(H2O)2]·2H2O}n (C24H26LaN3O16) Mw: 751.39g/mol-1. (97% yield)

0.18780g Cerium (III) Chloride Heptahydrate (99.9%) 372.59g/mol-1 was used to synthesize 0.40988g {[Ce(4NPhAc)3(H2O)2]}n (C24H22CeN3O14) Mw: 716.56 g/mol-1 (113% yield)

0.18563g Neodymium (III) Chloride Hexahydrate (no purity) 366.57g/mol-1 was used to synthesize 0.40977g {[Nd(4NPhAc)3(H2O)2]·2H2O}n (C24H26N3NdO16) Mw: 756.72 g/mol-1 (107% yield)

Is this something to do with the 2 metal centres? am I missing something obvious in my calculations?

Has anyone tried suzuki reaction in ehtanol (and water) with precatwlysts like pd(oac)2? I came across a paper and wonder if this is common? I found one paper on the scifinder…

https://doi.org/10.1016/j.bmc.2016.05.030

Edit 1- so the paper above is not good. Ignore it

but I did come across another paper using ethanol /water mixture for the solvent system so im assuming this is real deal.

https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/ejoc.200800874

They used aryl halide and boronic acid while my stuff is bulkier structure so im slightly worried about steric and I will do at higher temp and higher loading of Pd2, but still exciting find this

I heard that Microsoft AQE uses QCSerenity. Wondering if anybody here has used it, and how it compares with Orca, GAMESS, QChem, etc.

I was reading an article in which it was mentioned that "all the pyrroles began to darken in color immediately after concentration, but NMR spectroscopic analysis showed no loss in purity." I know pyrroles turn dark due to oxidation, but the text says "no loss in purity." If the change of color is not due to oxidation, is it because of pi-pi interaction after the solvent was vacuumed?

Hi all -

I have a Waters HPLC system running Masslynx 4.1 on Windows XP. I’ve gotten everything to work so far (pump, injector, detector). Because of this, we got a Gilson FC-204 fraction collector (manual says it can work with Masslynx, and it was the cheapest fraction collector we could find).

However, upon testing it, Masslynx will not recognize that it was the fraction collector installed. Upon further reading, I found that I need a Gilson 506c adapter that essentially converts from RS-232 to RS-485. I instead purchased a cheap converter on Amazon, but it’s still not being recognized. I was wondering if it’s possible to utilize this cheaper alternative, or does it have to be the Gilson 506c adapter? If it can work, do you know how to get it to connect via Masslynx and what I’m doing wrong?

Thanks so much in advance! This HPLC has been the death of me.

What options are there for quantitatively measuring the concentration of a small molecule of interest in a crude mixture.

For example, in high throughput synthesis, you may have too many compounds to purify and dry down to measure mass. So you want to send them straight into the bioassay. You know that the containment levels do not affect the assay, but the yield of the synthesis could be variable. Assume that the crude is mostly pure due to washing.

To run an informative bioassay, you need to know the effective concentration of your molecule of interest in the crude solution.

What techniques are there for this? Can you use analytical HPLC traces with tandem mass spec to estimate total mass? I have heard that ELSD might be helpful? I don’t think it would be possible to have a standard that is informative because the molecules are too different from each other.

Thanks in advance

I'm developing an magnetic adsorbent for magnetic solid phase extraction and I can't find what type of magnet is used for separating the magnetic adsorbent from the solution. The articles I've read didn't mention the type and brand of magnet they used.

So I am not a synthetic chemist by any means, (currently doing my PhD in physical inorganic). Very occasionally, I do have to synthesize my own molecules, just because the molecule I’m studying isn’t available commercially. This only involves following procedures for molecules where the synthesis is already known. A large part of my lab does synthesis, but I am not one of those people.

For those of you doing synthesis regularly, what techniques have you found make your reactions work better or worse? Obviously, each reaction is different and has different conditions, but are there general lab techniques you learned through your training that have served you for better or for worse? Perhaps little “hacks” that improved your results?

Thanks!

Im in need of monitoring the temperature of hot HBr and tried a supposedly "stainless steel probe", however it turned black and the solution itself got a touch of green which tells me it was probably Ni (or Ni coated)...

What material is generally said to be acceptable for hot HBr? I am currently looking at true ss k type's from a more price-y seller, and some PTFE ones.

Temperatures will be room up to around 423K/302F/150C max. Pressure resistance or threads/fittings are not needed but would not be a nono criteria.

Any help is greatly appreciated.

SOLVED by making a DIY well out of a pasteur.
Credit to User Cardie1303 for the Idea

Hi, I made a mistake and added triple the amount of basic solution (in water) for my suzuki reation with tetraki catalyst.. Will this be a huge problem? the concentration of reagents in solution is about 0.7M which should be fine.. but i'm curious if high water content would affect the reaction because I know that water contents matter with Heck reaction... Currently, for 5g starting material, I have 60mL basic solution and 60mL Dioxane, compared to usual amount of 20mL of basic solution and 60mL Dioxane..

So there are quite a few pharmaceuticals on the US and European markets that exceed concentration limits and PDE limits. I’m wondering just how dangerous this is.

The FDA concentration limit is 530 ppm and the PDE is 5.3 mg. Using Sublocade as an example - Sublocade contains 833 mg on NMP in a 1.5 mL injection for the 300 mg dose. The 100 mg dose contains 278 mg of NMP in a .5 mL injection.

I’ve identified a lot of other injectable drugs that exceed these limits, and it seems like this problem isn’t unique to injections either.

I was able to get the FDA to open an investigation into use of this solvent and awaiting their findings.

Has anyone worked on thiolation of biopolymers? I am starting a project on making thiolated hyaluronic acid (using cysteamine) and need help understanding the reaction conditions.

1. My supervisor says that we don't need nitrogen environment or degassing, but I don't agree with him. Thiols will undergo oxidation to form dithioesters and self-crosslink. The literature seems divided as some papers use it but others don't.

I've reached out to authors of journal papers but haven't received a response. 2. Is the reaction better performed in room conditions or on ice? Again the literature is divided on this.

Any advice is appreciated!