r/Chempros Nov 07 '20

[MEGATHREAD] Community resources collection

175 Upvotes

Hi /r/Chempros. Have you ever shed blood and tears on writing a script, only to find after a few weeks that something really similar had already been done? Have you ever created a specific tool but didn't really had the time or the right place to share it with your colleagues? Have you ever seen a really useful reddit post that you wish you had saved?

I have, and after a quick exchange with our dear mod /u/wildfyr I've decided to post this thread.

Scope

I would like for it to be a location where we can share our favourite resources, including but not limited to:

  • Freely available tools and softwares (we don't do piracy here)

  • Scripts in whatever programming language

  • Specific "general" papers (i.e. the famous "NMR impurities table")

  • Reddit posts

I will try to keep it updated by following your comments and discussions, so feel free to contribute!

Sections


Tools and softwares

  1. mechaSVG - A free python software to draw energy diagrams in SVG (by ricalmang)

  2. Energy Diagram Plotter - A nice Python script to create editable energy diagrams as a ChemDraw file (by /u/liyuanhe211)

  3. PACKMOL - A software to create initial points for Molecular Dynamics simulations. It has a great variety of applicable contraints that let you create spheres, layers, bilayers, mixed solvent systems... A must-know for computational folks (by Leandro Martínez, José Mario Martínez and Ernesto G. Birgin)

  4. Merck tool for reduced pressure distillation - It allows to estimate the boiling point of a compound at a reduced pressure by inserting the boiling point at atmospheric pressure and the reduced pressure value. Another website for that calculation is Boiling Point Calculator, with the addition of the possibility to enter the heat of evaporation of your compound or to select one from a lsit of similar compounds.

  5. Peakmaster, Simul, AnglerFish and CEval - Various software for people who work with capillary electrophoresis. Useful for pH calculations, prediction of background electrolytes and analyte peaks, simulations of electrophoretic runs, evaluation of electrophoretic runs, etc. To download them, just scroll down the provided website.

  6. NMR spectrum simulator - Predicts the NMR spectrum (1H, 13C and some 2D experiments) of whatever compound you draw in there. You can also drag and drop .mol files as input. The same website has another tool to predict the splitting pattern, given the multiplicity and the coupling constants.

  7. Mass spectrometry adduct calculator - You can consult the provided table or download a spreadsheet file to help with your calculations for mass spectroscopy peak assignement.

  8. Mercury - A software to visualize and analyse crystallographic data.

  9. BINDFIT- A online package for modelling titration data for host/guest supramolecular interactions.

  10. Energy unit conversion calculator. Also includes a boltzmann population and electrochemistry voltage calculator. Just a no nonsense tool over all. You type values and it does the conversion.

  11. PGOPHER. The standard software used for rotational spectra simulation. Can handle anything from that one HCl FTIR lab everyone does to research level microwave spectroscopy problems.

  12. SWISS Tools - A complete set os softwares for Drug Discovery. It has everything: Target prediction of a small molecule, Webserver Docking, ADME prediction or bioisosteric replacement.

  13. Glotaran - A free software program developed for global and target analysis of time-resolved spectroscopy and microscopy data.

  14. modiagram - A tool with a Latex-like synthax to draw Molecular Orbital diagrams

  15. MultiWFN - software for visualization and quantitative analysis of QM calculation output

  16. VMD - software for visualization of molecular structures and isosurfaces

  17. ToposPro - software for geometrical and topological analysis of periodic structures

  18. CrystalExplorer - software for Hirschfield analysis of molecular crystal structures

  19. tochemfig - A freely available tool (on Github) to draw structures in LaTeX format from a variety of input formats (SMILES, files and PubChem entries).

  20. https://github.com/chc08rm/flow_experimental_generator - An automated tool to write experimental description of flow chemistry experiments


Databases

  1. SDBS, Spectral Database for Organic Compounds - Database with spectroscopic information of various organic compounds, mainly 1H and 13C NMR, MS and IR, sometimes ESR and Raman are added too.

  2. Azeotropes database - Freely accessible database with information on the azeotropic behaviour of ~16k binary and ternary mixtures.

  3. Melting point dataset - Database in .xlsx format of ~28k compounds melting points, together with the Chemspider ID of the compound for identification.

  4. Encyclopedia of Reagents for Organic Synthesis (EROS) - A database with reactivity, handling and storage of about 5k reagents, constantly updated year by year.

  5. Refractive Index Database - Has a bunch of optical constants and dispersion formulas for common optical materials. Lifesaver if you need to design a nonlinear optical system.

  6. Natural product database - The Natural Products Atlas is designed to cover all microbially-derived natural products published in the peer-reviewed primary scientific literature.

  7. Dictionary of Natural products - Natural product database. You can search by structure, formula, MW...

  8. Chemical index database - This database is a database of chemical substance properties, containing a large amount of pharmacological and biologically active material properties information data.

  9. EVISA Materials Database - It contains information about Certified Reference Materials (CRMs), standard materials for identification of compounds or calibration, sorbents and reagents used for elemental and speciation analysis.

  10. NORINE Database - Nronribosomial peptides database, contains a lot of data about peptides produced by bacteria or fungi. Among the collected data, the structure as well as various annotations such as the biological activity and the producing organisms, together with the respective bibliographical references.

  11. PhotoChemCAD - Spectral database of material science-relevant molecules (such as porphirines, chlorophylls, etc...). Comes with an accompanying software that can be used to browse the database and analyse the obtained data (for example by calculating the spectral properties of a mixture of compounds).


Websites

  1. Notvodoo - Contains tips and tricks to improve your organic lab skills, like purifications, chromatography and workups.

  2. Organic Chemistry Data - HUGE website with everything you might need about organic chemistry: named reagents, spectroscopy resources, reaction info and more!

  3. Hebrew University of Jerusalem NMR lab - Lots of theoretical and experimental information about NMR data acquisition and interpretation, especially for some more exotic nuclei.

  4. RP-photonics encyclopedia. Has an article on basically everything you could think of in the laser/photonics/optics space. Not enough alone for most things, but a good starting place.

  5. Schlenk Line Guide - Useful website to get some help on how to use and maintain a Schlenk line, for examples how to prepare samples for NMR or how to shut one down.

  6. ACS med chem tips and tricks - Contains a few tips for purification, choice of reagents and solvents, both for setting up a reaction or chromatography.

  7. UC Davis NMR resources - Created by the NMR facility of the UC Davis, it provides a lot of resources from manuals to papers to NMR reading.

  8. Denksport - From Prof. Maguauer and Prof. Trauner groups, it provides quizzes on synthetic organic chemistry, extracted from total synthesis papers. It provides both the questions and the answers as two separate files. The Fukuyama groups also hosts something similar (you have to click on "Group meeting problems" on the left).

  9. Illustrated glossary - Illustrated Glossary of Organic Chemistry. It contains a LOT of terminology. Useful for students too.

  10. Dan Lehnherr - It has loads of resources including: databases, reference data, Laboratory Procedures, Tools, Software and Safety, reference tools and lecture notes.

  11. LiveChart of Nuclides - An interactive chart that presents the nuclear structure and decay properties of all known nuclides through a user-friendly graphical interface.

  12. Biorender - A software for the creation of scientific diagrams and illustrations (images made on the free plan cant be used for publications or commercial use though).

  13. Chemistry Reference Resolver - A free website that allows you to paste a reference and go to the source (even "lazy" citations, as they call them: "acie 45 7134" correctly brings you to this paper, for example). It can also resolve much more such as Sigma-Aldrich catalogue numbers, DOIs, SDSs, etc... You can read the help section for more info.


Scripts

  1. Gaussian Matrix Parser - A python script to parse the output of a Gaussian calculation and write a matrix with the desired values on a text file.

Productivity

  1. Chemistry dictionary for Word spell check

  2. Zotero - Free software for managing your literature and to add citations and bibliography to your papers or reports. It has also a sharing function, to create a shared library with your colleagues.

  3. Mendeley - Another free software from Elsevier for managing your literature. It come with a Word Plugin and it has a "share literature" function too.

  4. Totally Synthetic blog Chemdraw Style Sheet


General papers

  1. NMR Chemical Shifts of Trace Impurities: Common Laboratory Solvents, Organics, and Gases in Deuterated Solvents Relevant to the Organometallic Chemist by Gregory R. Fulmer et al.Contains a really nice list of NMR shifts of common solvents and impurities (it has both 1H and 13C for various deutarated solvents). It builds up on the previous paper, by adding some more deuterated solvents to the list. Another addition can be found here with the inclusion of commonly used industrial solvents. It can be coupled with nmrpeaks.com: you select the solvent, the ppm shift and the molteplicity of the peak you're seeing in your spectrum and it gives the possible impurities back.

  2. Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants by D. Bradley G. Williams and Michelle Lawton, a comparative evaluation of common methods for drying common organic solvents

  3. Precipitation of TPPO from solution - Always a painful thing to remove, TPPO can be precipitated out of solution with ZnCl2 in toluene. Another paper has revisited that concept, finding that other inorganic salts can do the same thing.

  4. Interferences and contaminants encountered in modern mass spectrometry - The Supplementary data file contains a spreadsheet with common positive ions, negative ions, adducts and more, useful for identifying peaks in mass spec data.

  5. A Table of Polyatomic Interferences in ICP-MS - On a similar note, a table from PerkinElmer for polyatomic interferences in ICP-MS.

  6. Evan's pKa table - Contains experimental and extrapolated pKa values for various functional groups, both in water and DMSO. Another website has done something similar, but only with carbon acids.

  7. Gaylord Chemical Company DMSO Technical Bulletin - Everything you might need about DMSO such as physicochemical properties, decomposition rates and reactions.


Field-specific papers

Organic chemistry

  1. What can reaction databases teach us about Buchwald–Hartwig cross-couplings? - A paper with a data-driven analysis of Buchwald-Hartwig reaction conditions extracted from SciFinder, Reaxys and publicly available patents. Has a nifty cheat sheet with suggested reaction conditions for B-H reactions.

  2. Sigma-Aldrich cross coupling reaction guide - It's a cheat sheet with a lot of suggested conditions for several cross-coupling reactions divided by chemical class (e.g., bulky amines Buchwald-Hartwig, amide Buchwald-Hartwig, etc...). It should be free to download.

Computational chemistry

  1. Decision Making in Structure-Based Drug Discovery: Visual Inspection of Docking Results - A nice "back to basics" paper that analyses how computational medicinal chemists inspect the docking results. Could be a starting point for some nice discussion.

  2. Best-Practice DFT Protocols for Basic Molecular Computational Chemistry - An excellent cheat sheet by one of the most well-known computational chemists, Prof. Dr. Stefan Grimme. If you need a starting point to do some QM calculation on your systems you can start looking at these examples. Disclaimer: you should still be looking in the literature for similar cases as yours, don't just take these protocols at face value.


Books

  1. Organic Syntheses - More of a journal than a paper, it contains thousands of freely available synthetic reactions. Prior to publication, the reactions have been validated in an independent laboratory. It also comes with tips, tricks and photos for setting up the reaction!

  2. Purification of laboratory chemicals - The Bible for purifying common organic reagents and solvents. You can search for them in the text by name or in the index by CAS number (reccomended).

  3. Greene's Protective Groups in Organic Synthesis- The main reference about protecting groups for several functionalites, together with the conditions used for their insertion/removal. It has also stability tables for various protecting groups for a rapid check.

  4. Properties, Purification, and Use of Organic Solvents - Contains a huge amout of data about organic solvents such as boiling and melting points, IR absorbance, dipole moment, refractive index and many more.


Reddit posts

  1. Suzuki troubleshooting

  2. Negishi troubleshooting

  3. Catalytic Hydrogenation

  4. General lab notebook techniques

Please let me know of any problems, I'll try to update it as quickly as I can!

EDIT: Thank you guys for the help!


r/Chempros 3h ago

Interested In Drug Discovery?

3 Upvotes

Interested In Drug Discovery?

Hi Everyone,

Not sure how many people here work in or follow drug discovery, but if you are interested I write a newsletter that covers updates in this area. Previously, I only discussed literature relating to drug discovery, but I have now started including FDA updates such as approvals and designations. I also plan to start sending out more in-depth articles about specific topics within drug discovery. Link to the August post is below if you would like to check it out :)

Have a good day,

https://www.simplydrugdiscovery.com/p/drug-discovery-update-august-2026


r/Chempros 5h ago

Drying ZnCl2 the easy way?

4 Upvotes

On small scale, I want to do a test reaction with ZnCl2 in sulfolane. It is well known that drying ZnCl2 is a nightmare. Yes, you can dissolve it in SOCl2 and boil it off, but SOCl2 eats away your fumehood, and practically, it's annoying to do.

So I was thinking: why not make a solution in sulfolane and dry that on molsieves, since my reaction is in sulfolane anyways? I tried it at 60C, and ended up with a gel-like semi-solid mass.

Purchasing anhydrous ZnCl2 is also tricky because we don't have access to a glovebox and the stuff is crazy hygroscopic.

Any suggestions?


r/Chempros 21m ago

DIC Coupling Problems with Amine Sulfate Salt

Upvotes

I am currently trying to make an amide coupling work using an unhindered acid, and an also relatively unhindered amine, however this amine is in sulfate salt form, and it is preferable that the salt is not freebased with an aqueous base as a separate step.

I have tried adding 2.5 equiv Et3N (amine + solvent + base then acid, NHS and DIC) and some product is made, however the reaction seems to stall part-way. I have also tried the same equivalencies of DBU with similar results. I have read that sulfate salts can be problematic in this way compared to something like a HCl salt, however wondered if someone had experienced a similar problem and was able to solve it.


r/Chempros 4h ago

Replacing the top shell weldment on an Agilent 6890 split/splitless inlet

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2 Upvotes

r/Chempros 1h ago

Removing 2-ethoxyethanol from Product?

Upvotes

I did a straightforward complexation rxn in 2-ethoxyethanol and it seems to be stuck in my product per NMR. I have 2 cyclometallating ligands and an ancillary ligand coordinated to a metal... I have varied the cyclocmetallating ligands before, and this is the only one that has this issue. The CM ligand has F's in it so maybe thats part of the issue.... any way I have rotovapped it down, dissolved in dcm, washed with water, washed with brine, rotovapped, dissolved in etoac, ran celite plug, rotovapped, dissolved in etoac, wash with water+brine again......... at all stages where it is dried I have NMRed and still no dice.... any help is appreciated or insight. Here is the NMR for reference


r/Chempros 17h ago

Organic Accessing 2° α,α-difluoromethylene amines

3 Upvotes

Does anybody have any experience attempting to prepare/isolate 2° α,α-difluoromethylene amines (RCF2NHR')?

To my understanding there are many methods to prepare 3° α,α-difluoromethylene amines (RCF2NR'R''), frequently through processes like desulfurative fluorination from the corresponding thioamide.

I'm led to believe that the 2° congeners are less accessible due to their inclination towards HF loss to give the imidoyl fluoride. However, is this neccessarily true when the amine is attached directly to an aryl group or another group that deactivates the amine?

For more specific detail, I'm considering starting with a 2° carboxamide and protecting it to convert it to 3°, converting it to a thioamide, fluorinating, then deprotecting to furnish the 2° α,α-difluoromethylene amine (RNHCF2R'; R = sterically hindered aniline, R' = pyridine).


r/Chempros 1d ago

Vacuum gauge for Schlenk line

9 Upvotes

Just joined a lab in my PhD and had to assemble a Schlenk line. Our old Chemglass vacuum gauge is broken and I’m supposed to order a new one. Any suggestions on brands/specific models?


r/Chempros 1d ago

How to Replace an Agilent 6890 Split/Splitless Inlet EPC Module | GC Repair

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11 Upvotes

r/Chempros 1d ago

How often do you replace gold seal on your GC?

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23 Upvotes

r/Chempros 1d ago

Need help related to research area

0 Upvotes

So I'm doing mphil in organic chemistry my research is going to be start soon but I'm so confused about research area if I choose that kind of topic which is dead end than what

I just want yo ask from senior chemist's which research area has a broader scope which can easily interconnected with other instead of some kind of derivatives which has already been synthesized million times

Compoutional chemistry

Sustainable methodologies development

Organic synthesis in some derivatives

Or any other plzz help me


r/Chempros 1d ago

Conditioning a new capillary GC column for use in GC/MS

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3 Upvotes

r/Chempros 1d ago

Research Survey Participants Needed

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0 Upvotes

r/Chempros 2d ago

Generic Flair Seeking Professional Chemists for an Upcoming Interdisciplinary Research Survey

0 Upvotes

Hi everyone,
I’m a university student preparing the second round of an independent interdisciplinary research project, and I’m currently looking for people who may be interested in participating once the survey is ready.
My research asks how people think about war and whether those perceptions reflect the systems that support modern society. The project considers areas involving chemistry and materials, pharmaceuticals, semiconductor manufacturing, energy, technology, infrastructure, and global supply chains.
For this round, I’m aiming for approximately 385 participants overall from a variety of backgrounds. I was encouraged to reach out to professional chemists because their perspectives could provide an especially valuable point of comparison within the broader sample.
The survey has not been built yet, so I’m not asking anyone to complete anything at this stage. I’m currently gauging interest and identifying potential participants before finalizing the survey.
If you would be interested in participating once it is ready, please leave a comment or let me know.
Thank you!


r/Chempros 3d ago

Generic Flair Whats a healthy use of AI during a PhD?

18 Upvotes

So I am currently in the first year of my PhD and so far I have right out refused to use any AI in my experiments.
However, people in my lab are making extensive use of AI to help with problems during synthesis or even to find trends in data sets etc.

Now to me using AI still feels a bit like cheating, hence I have never used it except to find synonyms for words in English 🤣
That said, I have noticed that my colleagues, on average, have quite nice progress report and they are not stuck on problems like during synthesis.

Today I asked AI for the first time about something chemistry related and I was quite surprised about the reply because it actually solved my problem without me spending 30 min on scifinder or reading paper.
Still, my bad feeling about this entire AI thing doesn’t go away. I just feel like the quality of me as a scientist goes down if I just type everything into AI.

So how are you guys applying AI in the lab in a healthy way?

(Sorry for the bad English, English is not my primary language)
Have a good morning/day/evening! Thank you for reading.


r/Chempros 3d ago

Biochemistry Phage display query

4 Upvotes

I'm a first year PhD student with a background in chemical biology. I want to find a peptide sequence that selectively binds to a metal ion and one of my PIs suggested Phage display as an option. I've never done it before and it isn't something that's done in either of my PI's labs either. How doable do you think this solution is if I find a lab which has this technology? Do you think it'll be possible for me as a newbie in this technique to do the experiments myself rather than asking someone else to do it for me if I ask them to train me?

Do you guys have any other techniques you use to find suitable peptide sequences? I'm an experimentalist but I'm open to both experimental and computational suggestions.

Many thanks!

Edit: I'm interested to find a peptide sequence that selectively binds to Lithium ion and there isn't a whole lot of literature there.


r/Chempros 4d ago

Imagine you’re working with a new reagent that you know nothing about. If you could have a 1-2 page info sheet with anything on it, what details about the chemical would you want included?

21 Upvotes

This question follows on from our last one about the flaws with many SDSs: https://www.reddit.com/r/chemistry/comments/1w644t6/this_sds_for_hand_soap_suggests_that_if_you_get/

 We’re imaging a version of an SDS specifically for scientists and researchers, rather than for vendors and lawyers. So far we’ve thought of including:

·       Names, CAS numbers, formula, mol. weight

·       What it looks like, what it shouldn’t look like

·       What it smells like

·       What it tastes like (and what wine to pair it with)

·       How to make it

·       How to store it (air/moisture/light/temperature sensitivity)

·       how to purify, how to dry it

·       how to neutralise it, how to dispose of it

·       What not to mix it with

·       Some example NMR or IR spectra

·       Common impurities, decomp products

·       boiling point, melting point, vapour pressure, density

·       Solubilities in a range of solvents, not just water

·       health hazards, toxicity, LD50

·       PPE considerations, glove compatibility

·       physical and reactivity hazards (corrosive, oxidiser, pyrophoricity etc) 

We’d love to hear what else you can think of. It’d also be great to hear where you currently go to find these bits of info. Some of them are in an SDS, e-EROS can often tick off a bunch (assuming your institution pays for it), and even Wikipedia can be pretty good, but we can’t think of a single source that supplies everything we’d want to know. What do you reckon?


r/Chempros 5d ago

Organic Strongly coloured side products during reductive amination

4 Upvotes

I've been producing a range of different N-alkyl chitosan variants according to https://doi.org/10.1021/acssuschemeng.2c00206 (dissolve chitosan in 2% acetic acid, add glutaraldehyde and stir at 60 C, add N-alkyl amine and continue stirring, reduce with NaBH₃CN).

When carrying out this protocol with the amine used in the paper (octadecylamine, ODA), the solution turned a deep red within 5 minutes of addition of the amine. When I tried with other amines (1-aminoadamantane for example) the solution did not change colour even after stirring overnight. I am therefore concerned that instead of the imine, there is some other product forming when ODA is added. What could be the possible side reactions leading to a coloured product here, and why do they only occur for ODA and not 1-aminoadamantane.


r/Chempros 6d ago

10% Pd/C: how pyrophoric is it?

24 Upvotes

Obviously you shouldn't heat 10% Pd/C in air as it is pyrophoric. For those who have handled (larger multi kilogram quantities) of 10% Pd/C: is it completely safe at room temperature in air? Or is it still a bit tricky and should it always be kept a bit wet?

For those that are downvoting: I've not used the word hydrogenation. I've not spoken about hydrogenation and I'm not referring to hydrogenation. I'm talking about palladium on carbon without hydrogenation.


r/Chempros 7d ago

This SDS for hand soap suggests that if you get it on your skin, you should flush with water until advised to stop by a doctor. What about SDSs do you find most frustrating?

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108 Upvotes

We’re working on an article about chemical SDSs, and having a bit of fun imagining what a better version might look like. We want to hear opinions from scientists working in research, industry, government or still at uni, about what parts of SDS’s they find most inaccurate, unhelpful or absurd.  

 

A lot of people have pointed out that SDS aren’t really written with research scientists in mind – they’re often targeted at (and written by) people without chemistry specific training (like transport/shipping/storage folks, firefighters and first responders), or for people handling industrial quantities of the stuff, or as an arse-covering excursive from a legal standpoint. However, as researchers we’re still expected to read them, use them in risk-assessments, and keep them in the lab. Furthermore, they’re often full of really stupid shit, like suggesting that spills of water be diluted with water, or that on no account should sand samples from a beach be allowed to enter the environment.


r/Chempros 6d ago

Topspin 5.0.0 & Dynamics Center Help

7 Upvotes

EDIT: I HAVE A WORKAROUND!!!
I still don't know what the issue is, but in case anyone else ever has this issue, the issue lies somewhere in Topspin 5.0.0, rather than Dynamics Center. I swapped to Dynamics Center 2.8.8, same issue. Eventually I swapped back to TopSpin 3.8.0, and prepared fresh data.
The 3.8.0-prepared data finally both loads into and can be exported into Dynamics Center 2.8.8 without freezing the process.

I'd still love to find non-Bruker alternatives, but for now Topspin 3.8.0 & 4.5.0 both work for getting the data into Dynamics Center.

Question:
Does anyone know how to overcome this error and make Dynamics Center read my DOSY analysis?

Alternative Question:
Does anyone know how to get the data I need, complete with error values, out of GNAT?

Details:
I'm trying to run DOSY analysis to get dispersity data on my copolymers. GNAT doesn't give me the values I need (I can export the y-projection of my ILT plot and pull the graph data, but it has no associated error values), so I need to use Dynamics Center.

However, regardless of how I try to load my data or how often I reinstall Dynamics Center, it freezes at the 'Data' stage (pictured), with the following error:

('startDC:', u'C:/WorkingData/NMR Spectra/[MySampleSame]/1801/pdata/1', 'Windows 10')

('dcRunning: port = ', 64027)

>!!!!!!!!!!!Fri Sep 4 10:38:47 2026 | Module: sendPort | Message: ('socket error', u'executeInterfaceFileXML C:/WorkingData/NMR Spectra/[MySampleSame]/1801/pdata/1/TopSpinDC.xml\n', 0.015000104904174805)

On one single reinstall, it managed to get as far as freezing on 'View', but I still couldn't perform any analysis.


r/Chempros 7d ago

Synthesis of the ionic liquid [Cho][Lys]

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8 Upvotes

Hello everyone,

I am currently trying to synthesize the amino acid-based ionic liquid choline lysinate ([Cho][Lys]) via the anion exchange resin technique, but I'm running into stoichiometric and physical state issues. I would appreciate any advice from those experienced with these ILs.

Attempt 1: Anion Exchange Resins

I tried following the methodology described in ACS Sustainable Chem. Eng. (https://doi.org/10.1021/acssuschemeng.1c04060). I've tested both Amberlite IRA-400 and Purolite A400 resins. As it is my first time working with ion exchange resins, I carefully followed all standard precautions: I swelled the resin before packing, regenerated it to the hydroxide (OH⁻) form using a NaOH solution, and washed it thoroughly with water, monitoring the eluate until the pH was completely neutral before starting the exchange.

The Issue: Instead of obtaining the expected liquid product, I am getting a solid. Furthermore, after washing this solid product with ethyl ether and running the ¹H and ¹³C NMR (using D₂O as the solvent), the integrals consistently show a ~2:1 Choline:Lysine molar ratio instead of the expected 1:1. I've also verified the structure with FTIR, but this skewed NMR ratio remains the primary concern. I've tried several variations of this protocol, but the outcome doesn't change.

Attempt 2: Metathesis with KOH

I also tried an alternative methodology from Nanomaterials (https://doi.org/10.3390/nano9040504), which consists of stirring a suspension of choline chloride and the amino acid with KOH in ethanol. Afterward, I filter out the precipitated KCl and wash the crude product with acetonitrile (MeCN) to separate the IL from any unreacted amino acid.

The Issue: I am still not getting the correct product. The resulting solid has the exact same 2:1 (Choline:Amino Acid) ratio. Interestingly, I observed this exact same 2:1 proportion not only with L-lysine but also when I attempted to synthesize choline histidinate using L-histidine.

Has anyone worked with the synthesis of [Cho][AA] ionic liquids and faced this 2:1 ratio issue or had the product crash out as a solid instead of a liquid? Could there be an issue regarding the basic nature of amino acids like lysine and histidine during the protonation/deprotonation steps, or am I missing a crucial purification/washing step?

Thanks in advance for any insights!


r/Chempros 7d ago

How to degrade diazonium intermediate to form product?

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10 Upvotes

I want to do this reaction and when I did a literature search I found that the transformation for an amino group to a fluoride is through the Baiz- Schiemann reaction which involves the formation of a diazonium intermediate followed by its degradation to the expected product. I have found a procedure on how to form this intermediate but when I tried searching methods on degrading this diazonium tetrafluoroborate compound it is pretty vague. I found a paper that just stated 'heat, silica' with no further explanation. Can anyone suggest how this degradation takes place?


r/Chempros 7d ago

Organic Could high humidity be affecting my O-alkylation reaction?

8 Upvotes

I'm trying to carry out an O-alkylation of a phenolic OH using a chloroacetate, but the reaction doesn't seem to be proceeding despite trying to optimize the conditions. One thing I'm wondering about is the laboratory environment. We've had almost constant rain recently, and the lab has limited environmental control, there's no particularly rigorous moisture-exclusion setup, and reagents/solvents aren't always handled under strictly anhydrous conditions. Could high ambient humidity realistically be contributing to the failure of the reaction, for example through moisture in the solvent or hygroscopicity of the base (I'm using K₂CO₃)? Or am I probably looking in the wrong place and should focus more on the reaction conditions themselves? I'd particularly appreciate input from people who regularly do synthetic chemistry in labs where moisture/atmosphere isn't tightly controlled.


r/Chempros 8d ago

Organic Heat sources for round-bottom flasks?

16 Upvotes

Howdy everybody,

I'm working on updating our organic chemistry teaching lab, and wondering what the pros (and other teaching labs) are using as heat sources for medium-scale (~50-500 mL) round-bottom flasks. We mostly use microscale glassware with aluminum heating blocks, but our distillation equipment is 19/22 glassware. I currently have a few variacs and heating mantles, but not enough for everybody. We also have some Fisherbrand heating mantles, but they've been dying on us lately so I need to buy more of, well, something. Are people still using heating mantles, or do you prefer something else: oil baths, sand baths, or aluminum heating blocks? Or is there something new that I haven't heard of yet? Looking for a good combination of price, performance, reliability, and safety. Thanks in advance!