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

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.

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!

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?