🇺🇦 nmr_spectroscopy / organic chemistry ⌬

It’s #NMRweekend ⁉️🧲 Use the poll below 😊. Note: This is an experimental spectrum. The explanation for the challenge will be published in a few days 😉.
#nmrchallenge #quiz

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Among all the CH and CH₂ protons in menthol, this one is the simplest 😬.
#spin #coupling

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The last #NMRWeekend question requires a detailed answer 😉.
‘A’ is ruled out because of the chemical shift of the Me group. OMe should appear at ~3.5 ppm.
‘B’ is excluded due to the presence of a proton with δ 9.09 ppm, showing only two couplings: 2.3 Hz (⁴J) and 0.9 Hz (⁵J). If it were ‘B,’ each proton would exhibit a ³J coupling with a minimum value of ~4 Hz for an alpha pyridine proton.
The correct answer is ‘C’. Details are provided in the picture.
#nmrchallenge

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It’s #NMRweekend ⁉️🧲 Use the poll below 👌😊. Note: This is an experimental spectrum. The answer will be published here in a few days 😉.
#nmrchallenge

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Another informative example of the solvent effect on ¹H NMR. As you can see, only in D₂O are all 8 aliphatic signals completely resolved, which was the key to solving the cis/trans problem. NOTE: both ¹R and ²R are groups without aliphatic protons.

#nmrtricks #solvent

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It’s #NMRweekend ⁉️🧲 Use the quiz below 😊. Note: This is an experimental spectrum. The explanation for the challenge will be published in a few days 😉.

✅ UPD: The correct answer was B: it’s the only molecule that is chiral and has all four CH₃ groups, as well as CH and CH₂ protons, chemically inequivalent.


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5 interesting facts about Menthol ❗️:
1. Cooling Sensation Mechanism ❄️: Menthol activates the TRPM8 receptor, giving a cooling effect without actually lowering temperature. That’s why it feels so refreshing on the skin and in the mouth!
2. Natural Occurrence and Sources 🌿: Found in peppermint and other mint plants, menthol makes up about 50-60% of peppermint oil, making it a primary natural source.
3. Stereochemistry 🔬: Menthol has multiple stereoisomers, but only one, (-)-menthol, delivers that distinct cooling sensation. Its unique structure is key to how it interacts with our senses.
4. Antimicrobial Properties 🦠: Menthol’s antimicrobial and antifungal qualities make it popular in oral care and hygiene products. It disrupts bacterial growth by penetrating cell membranes.
5. Role in Medicine 💊: Beyond its cool feel, menthol has analgesic effects, making it a go-to ingredient in pain-relief balms. It helps by desensitizing pain receptors on the skin.
#menthol #naturalproducts

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The multiplet of the week!
🧲You may notice the slight broadening of each component of this multiplet. The reason of it ⁴J to Ph protons.

#spin #coupling

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It’s #NMRweekend ⁉️🧲 Use the poll below 😊. Note: This is an experimental spectrum. The explanation for the challenge and the DOI of the original article will be published in a few days 😉.
#nmrchallenge #quiz

✅ UPD: The correct answer is ‘B.’
🔴 In ‘A,’ CH₂ would appear as a singlet, and CH would have a higher chemical shift.
🔴 In ‘C,’ the two CH₃ groups would be chemically inequivalent.
🟢 ‘B’ completely matches the spectrum: CH₂ at a relatively high ppm, CH at a lower ppm, and chemically equivalent CH₃ groups.
(Those are not all differences in spectra)
The DOI of the original article: 10.1002/adsc.201500912


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Happy halloween to everyone! 🎃👻
Here is a WET spectrum (CD₃OD, 600MHz) of methanol extract of pumpkin pulp. As you can see, all regions of the spectrum are fairly crowded with signals. To find out what substances are in pumpkins - visit https://www.compoundchem.com/2016/10/24/pumpkins/
#halloween #pumpkin

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It’s #NMRweekend ⁉️🧲 Today, you’ll use proton-decoupled ¹⁹F data to distinguish the compounds 🫢. Use the quiz below 👇 😊.
#nmrchallenge #quiz

UPD. ‼️The correct answer is “B.”
🔴A: Achiral molecule. Both fluorines appear as a singlet because they are chemically equivalent.
🔴C: Chiral molecule, but since there is a CF₃ group, all three fluorines are homotopic and appear as a singlet.
🟢B: Chiral molecule, which makes both fluorines chemically inequivalent, with a ²J coupling constant of approximately 279 Hz.


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A small, hard-to-synthesize spirocyclic amine developed by Enamine Ltd. chemists, with an elegant 🤌 ¹H NMR spectrum.
#enaminecompany

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Tobacco in the NMR Spotlight 🚬🔬🧲

Check out this ¹H NMR spectrum of a tobacco sample in DMSO-d6! 🎉
The spectrum is packed with signals, including nicotine 🧪, which is easily detected thanks to its characteristic peaks. But it’s not just nicotine—tobacco contains a variety of other organic compounds like alkaloids, sugars, and even small organic acids.

So, how can NMR help in quality control of tobacco products? 📊 It provides a molecular fingerprint of the sample, ensuring product consistency, monitoring for contaminants, and checking for the authenticity of the natural components. 🔍 In this spectrum, every peak tells a story about the different molecules present!

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It’s #NMRweekend ⁉️🧲. Use the quiz below 😊.
#nmrchallenge #quiz

✅ UPD. The correct answer was “C.” Key points:

1. Acidic signals at 9.9 ppm, indicating the presence of a COOH group.
2. Two inequivalent triazole protons, as the molecule is not symmetrical.

P.S. Many were surprised by the chemical shift of the N-bonded CH₂ group (4.40 ppm), but it’s actually quite typical for such methylene groups in triazoles, pyrazoles, and tetrazoles.

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