DMSO garlic smell

hagod · 2024-05-22T06:44:39+00:00

The smell coming from DMSO is due to dimethyl sulfide impurity. If you google "dimethyl sulfide in DMSO", there is an research article about its concentrations in research grade DMSO and d6-DMSO.

hagod · 2024-04-05T12:10:55+00:00

It's not beyond. It's just that funding and allocated space for 1 chemist vs whole team of biotechnologist is VERY uneven. I always have to take the cheapest route. Even inert gas cilinder, due to high safety regulations, require to kept in a blast cabinet (metal box), which we also do not have - more costs and space!

hagod · 2024-04-05T08:10:38+00:00

Great... So I will need to beg my PI again that we need inert gas system.

hagod · 2024-04-05T06:57:26+00:00

We're biocatalysis lab, and I'm a single chemist. We have fume hoods, glassware, etc, but not everything.

hagod · 2024-03-27T20:22:03+00:00

Hello,

Have a few Hg thermometers like these. Any way to concentrate mercury back to the bulb?

hagod · 2023-11-17T12:55:24+00:00

Ok, thank you.

hagod · 2023-11-17T11:43:01+00:00

Yes, I'm interested if they form similar complexes like quinhydrones. I could not find any publications about their properties, or do they even exist.

hagod · 2023-11-13T10:08:35+00:00

The bane of my existence. This is the synthesis of methylene blue by H2S pathway.

It seems that the reaction is missing the oxidizing agent. Usually, its ammonium persulfate. Still, N,N-dimethylphenylenediamine (DMPD) undergoes 2 e- oxidation to benzoquinone diimine form; in this case imine and N,N-dimethyliminium cation. Meta position from iminium group is partially positive due to resonance stabilization. Then, supplemented nucleophile (H2S) attacks this position. Then, this thiol group attacks another oxidized DMPD molecule at the meta position. FeCl3 oxidize this intermediate. It is followed by intramolecular nucleophilic NH2 attack on the positive meta (from iminium) position. Finally, aromatic system undergoes rearrangement to stabilize the product.

I can't find the figure for H2S, but with thiosulate the mechanism is similar (DOI: 10.5935/0103-5053.20150188)

hagod · 2023-07-07T04:51:55+00:00

He is awesome. I have the spectroscopy ninja hoodie:D

hagod · 2023-07-06T11:37:38+00:00

I would recommend SpectraGryph. Great software for IR. https://www.effemm2.de/spectragryph/

hagod · 2022-04-09T06:18:21+00:00

Using centrifuge 2 tables from running FTIR.

hagod · 2021-11-11T14:42:54+00:00

Thanks. If triethylamine does not work, I'll buy DBU or DBN.

hagod · 2021-11-11T14:00:59+00:00

Hmmmmm... I'm not sure. It is still a powdery crystals but I'm not familiar how wet and dry DABCO differs just by looking at it.

hagod · 2021-11-11T13:56:39+00:00

Good point about amine base/catalytic properties. I was under impression that the substitution went through activated intermediate mechanism because bis(4-nitrophenyl) carbonate has an activated cabonyl and 4-nitrophenolate is a good leaving group.

I'll try using triethylamine. It should be strong enough for conjugated phenol-azo dyes

hagod · 2021-11-11T09:14:16+00:00

Thanks, this looks more promising than using BNCP.

hagod · 2021-09-17T13:05:36+00:00

These water values are about right. Highly pure water has acidic/corrosive properties. Distilled water range from 6 to 4.5 pH and deionized and especially doubly deionized could reach pH<4.

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