Do you have any advice if I worked with Epoxies for my whole Phd and developed a senzitation in the last two months of it and I just have to finish two experiments?

Hi all,

Unfortunately, my full post about this was deleted from this subreddit... So I'll keep this as short as possible so that this doesn't get deleted. Anyway, some of you may like to know that ChemSketch has now officially been killed by Revvity (the owners of ChemDraw who recently bought ACD/Labs, which owned ChemSketch).

Hello all.

I've been tasked with a scale up synthesis project where one of the pivotal steps is a reduction of an aliphatic ester into an alcohol. The target will be to produce multiple kilos of the product by the end of the project. I've done some legwork to avoid LAH as a reductant since I fear that will make handling difficult at larger volumes, but I was looking for advice and safety considerations as we start planning to scale this chemistry up. It's still at the bench scale for now but the aim will to be to have enough optimization of the chemistry so that it can scale to multi kilo batches relatively seamlessly.

My synthetic experience is predominantly bench scale, but I have done some larger scale steel process vessel work, but not in the context of organic synthesis. I would appreciate any voodoo and wisdom y'all possess on running these types of reactions at scale. Things like quenching protocols and solvent/reagent selections to try would be awesome.

Primary amine capped with Fmoc, mostly wondering what base to combine with an alkyl bromide/iodide. Thinking of using bulky base as OChemPortal seems to suggest LDA and tBuOK are compatible with Fmoc. Anyone got some direct experience working on this? Thanks in advance!

Background
I have been synthesising a series of vinylbenzene derivatives, all of which have been previously reported as solids in the literature. After purification by flash column chromatography, removal of solvent by rotary evaporation, and several hours under high vacuum, however, I am left with oils in some cases. The proton NMR spectra are clean apart from a small water peak (~1.55 ppm in CDCl3) and confirm that the oils are the desired compounds.

I am able to convert these oils into solid powders using the procedure I’ve outline below.

My questions are:

1. What is this process properly called (my lab mates call it freeze-drying, which I don’t think is right, since there is no solvent being sublimed) and; 2. How should I describe this concisely in an experimental? My PI and I have hopes to submit to Org. Left., JOC, or similar at the conclusion of this project and the procedure(s) will most likely appear in the SI.

Procedure
The RB flask containing the oil is placed under static vacuum on a Schlenk line and lowered into a liquid nitrogen bath. After around 5 minutes it is removed and allowed to warm to room temperature. After a further 30 minutes, the material is a powdery solid.

Any thoughts on the correct terminology, and on suitable wording for the SI, would be greatly appreciated.

Additional Note
No literature procedure I’ve come across for these compounds, or similar, describe anything like this.

Hello chempros…., hoping someone can possibly help me out here. We have a system 1 innovative technologies glovebox from 2005 that’s rapidly approaching “ship of Theseus” status. Does anyone have a copy of the operating manual or better yet.. a servicing manual?

Below is my (current) issue… with the box.

The chamber pressure sensor has given up basically, unless the pressure is set at above “12 mbar” on the settings it starts sucking the gloves inside. Last week it was ok as long as above 5, then ok above 7 and today 12. Any advice?

We recently swapped from using argon to nitrogen and there’s been a dramatic increase in static. Could this mess with the pressure sensor component? The attachment on the main circuit/switch board does say sensitive to electrostatic. Would that actually be the cause? I’m confused

Does anyone know where I could find one online besides eBay?

Hi everyone,

I’m a chemistry professional currently working in a synthesis lab, and after 5 years I’m considering switching my career toward patent/IP analysis, particularly in the chemical or pharmaceutical domain.

I enjoy the scientific side of my work, but after having a baby the physical demands of working in a lab—especially long hours of standing—are becoming difficult for me. I’m therefore exploring a career that would allow me to use my chemistry background in a more analytical/research-oriented role.

I’ve started learning about patents, patent searching, prior-art analysis, patent landscapes, PCT/Indian patent procedures, etc., but before I invest significant time or money into this transition, I’d really like to hear from people actually working in the field.

A few things I’d love to know:

What does your typical day as a patent/IP analyst look like?

How much of the job is actual patent searching vs. reading/writing/reporting?

What skills are genuinely important for getting your first role?

How difficult is it to get the first job without prior IP experience?

What is the career progression like after 2–5 years?

How is the salary progression in India?

Are there good opportunities to move into higher-level IP roles later?

What are the biggest disadvantages or frustrations of this career?

Most importantly, if you could go back and choose again, would you still choose patent/IP analysis?

Can I start it as a part-time job as, or as a remote freelance job?

I’m especially interested in hearing from people who transitioned from chemistry/pharma/biotech into patent analysis, but perspectives from anyone in the field are welcome.

I’d really appreciate honest answers—even if your experience has been negative. I’m trying to understand what the job is actually like before making a career switch

Thanks in advance

I've made the subreddit r/ChemistryCareers for people to ask about and discuss college and career choices as chemists and chemistry students.

I'm looking for people to join who would be willing to answer questions, moderators, and suggestions for rules as well as what to make the icon and banner.

Thank you to those of you who are interested.

I’ve noticed that there are a lot of different ways people go about running a column.

Interested to hear how you guys will tend to set up and run a column and the rationale (if any) behind why you do it that particular way. Any particular tips and tricks?

Hopefully the comments (and maybe my procedure – although it is in no way perfect nor do I claim it to be) can help serve as a guide to new researchers.

I pretty much exclusively do dry loads and my typical column procedure is as follows:

1. Add dry silica directly to the column (honestly I just eyeball how much).
   2 Add eluent. With isocratic elution the eluent will be the ‘ideal’ solvent system I selected based on TLCs. With gradient elution the eluent will typically be a system that gives my target compound spot (if I know which spot it is) an Rf of about 0.
2. Stopper the column and shake until I form a slurry.
3. Open the tap and turn on pump until the solvent is a couple of centimetres above the silica, wash down any silica stuck to the sides with eluent, then open the tap again and turn on pump until the solvent is pretty much level with the silica (ensuring I do not dry it though).
4. Add dry load using a solids funnel. Then, using a minimal amount of eluent, wash out the dry load RB and wash down any solids stuck on the sides of the column. I will give the column a couple of light taps to make sure the dry load is level.
5. Turn on pump until the solvent is level with the top of the dry load (I don’t think it matters if it goes below, just as long as you don’t dry the top of the silica).
6. Add a layer of sodium sulfate (again I just eyeball).
7. Add eluent (I should probably do this more slowly and carefully tbh to prevent any chance of disturbance), run the column, collecting the fractions in test tubes whose size was selected based on the crude mass, the closeness of spots on the TLC, and the availability of clean test tubes in our lab.

Some Notes
Pour silica, shake, and run the column inside a fume hood.

Wetting silica is exothermic and volatile solvents will build real pressure, so when stoppering and shaking, vent frequently by taking the stopper off, and point the column away from yourself and others while you do.

The dry load is usually prepared by adding an appropriate (I usually eyeball but ~2x the mass of the crude) amount of Celite (I should probably start using silica though, to be honest) to the crude, adding enough DCM to make a slurry, and finally removing the DCM by rotary evaporation. Always ensure it is completely dry (residual DCM can smear the bands).

In our lab we pretty much exclusively use columns with a sintered layer. Use cotton wool or glass wool and a layer of sand if you don’t have sintered columns.

Finally, don’t be afraid to ask a more experienced lab mate for advice if you’re unsure. You’ll pick things up much faster, and you’ll avoid mistakes that are easy to avoid once someone has pointed them out.

Hi everyone,

I need to use deuterated TfOH for NMR of my samples. How to safely handle TfOH, does it smoke in the air a lot, will the NMR cap be fine or will it get eaten (do I need to get special caps?). Is it better to order 5x 1g or 5g (how to store it?)

Thank you for your answers!

I need to prepare the acid chloride from my carboxylic acid and then perform a coupling reaction with glycine to synthesize the corresponding hippuric acid derivative. I am looking for the simplest and most reliable method that can be successfully carried out in a laboratory.

Hi guys, I'm a newbie at this, please help if you can! We need to lyophilize a water-soluble compound, basically, we mixed it into a second liquid compound so the first compound would be encapsulated and give better results for our purposes. What I need to know: we have to freeze this before it goes into the lyophilization machine, but we were told to freeze it first in a normal freezer, then move it to a -80°C freezer, and only then send it to the lyophilizer. Is this accurate? If so, how long should it stay in the normal freezer before going to -80°C, and how long should it stay at -80°C before going to the lyophilization machine? Is there some kind of protocol for this? I tried to find something and couldn't find an exact one. Thank you!!

Hey everyone. I’m in a kinda dilema and would appreciate any advice from pharmacists especially those with more experience in the field in the US.

I’m considering applying for graduate school; MS pharmaceutical sciences( Med Chem, Pharmaceutics or Pharmacology). However, I’m not quite sure which track to pick that would guarantee me a better future career wise. I’m good with clinical work and my pharmacology knowledge is upto date and most of the things I do are around pharmacology. However, pharmaceutics from My small research seems to offer a better path both in industry and academia/research while med chem path solely lies on academia and research.

So which one would you choose based on market trends?

Thank you

Hello. I am trying to make transparent polyglycerol with minimal free glycerol in it. I am an industrial chemist.

I am running a base-catalyzed polyetherification. I have 3% w/w NaOH cooking with free glycerol under a nitrogen sparge and blanket at 240C. The Dean
\-Stark apparatus collects the water of polymerization separately.

The solution is amber in colour after about 8h. On neutralisation with sulphuric acid, the colour is lightened but it’s very much there. Filtering the material with a 10-micron cloth is also quite difficult because the material is quite viscous.

Bleach the solution with hydrogen peroxide results in a lot of foaming. It helps colour but the solution is clearly a pale yellow.

My BIG question is this: how do I save the colour of polyglycerol? Are there methods I don’t know that can keep the solution clear?

My smaller question is this: how do I filter the solids out of a viscous fluid efficiently?

I would hugely appreciate the insight of someone with some experience with this. AI dump doesn’t help any in lab.

I have been following the method presented in this paper and according to it, since I have a very lipophilic compound I should follow procedure 1b or 3. I am trying to replicate 1b but I have a few questions regarding the meaning of the dilutions and the Vw / Vo ratio. For example, If I want to do a trial with a Vw / Vo ratio, which procedure would be correct, 1ml of water and 9ml of octanol, or 1ml of water and 10ml of octanol?. If I do the second one, my total volume would be 11ml and if I also want to do a Vw / Vo ratio of 1 and a Vw / Vo ratio of 10, should I aim for a total volume of 11 as well? or could I do 10 ml for the ratio of 1 (5 and 5 ml each) and then again 11ml for the ratio of 10 (10 and 1 ml respectively?.

Additionally, I have a stock solution in DMSO that I can dilute in PBS as the water phase, when the procedure asks for a 100x dilution, is that considering only the water phase volume as the final volume? or is it considerinf the total volume as the water phase + octanol volumes together? Since the water to octanol ratio changes, if I dilute my sample in PBS (water phase) for the Vw / Vo ratio of 1, the amount of sample would be different than the ratio of 0.1 with less water phase and different than the ratio of 10 with more water phase present. On the other hand, If I take the 100x dilution as related to the total volume of water + octanol, also the amount of compound would be different depending on the trial because some will have a total volume of 11ml and other of 10ml.

In summary, what should I keep consistent? total water+octanol volume? sample concentration? niether? Help please.

Hey everyone!

I have noticed that Grignard reactions often use either THF or Et2O, but why the reactivity changes so much?

I know THF is string Lewis base but is it really just about basicity ? Or is it more about solubility, aggregation state, and shifting the Schlenk equilibrium?

Curious how folks who do a lot of organometallic work think about this, and if anyone has a solid reference that dives into the details. Thanks !

I was taught that 'chiral centers' shouldn't be used in writing because chiral is a quality of the whole molecular, not the carbon. This was twenty years ago. Has the use of 'chiral centers' become more acceptable in the field?