🇺🇦 nmr_spectroscopy / organic chemistry ⌬

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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🧲 ᗑ Multiplet of the Week. The interesting thing about this multiplet is that such small ³J couplings (1 Hz) are not typical for a small cyclopropane ring. Usually, ³J values are in the range of 5–10 Hz. The small ³J in this case is apparently a consequence of the presence of the heavy Br atom and two highly electronegative fluorine atoms.
#spin #coupling
Find this molecule at new.enaminestore.com | EN300-1600518

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

UPD ✅: The right answer was B. This is the only structure which has Methyl bonded to Oxygen (3,88ppm).

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The problem I’ve recently encountered in my NMR practice. ❓The question concerned the mutual positions of a Fluorine atom and an -O-R substituent. ☺️It turned out that a proton-decoupled Fluorine-19 spectrum is sufficient in this particular case. ☝️If the Fluorine is near a CF₃ group, a strong ⁴J coupling is observed, unlike in the other case.
#fluorine #proton #spin #coupling

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It’s #NMRweekend ⁉️🧲. This week’s challenge is about N- and O-alkylation, a common issue in organic chemistry synthesis. To solve the problem, an HSQC spectrum (one bond H-C correlation) was recorded. Use the quiz below 😊.
#nmrchallenge #chemistry #quiz

ANSWER:
The right answer was A
The key - ¹³C chemical shifts of CH₂- 43,5 ppm (bonded to N)
and CH₃- 55,7ppm (bonded to O)

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¹H NMR of Milk 🧲🥛: This is the Proton NMR spectrum of milk without any specific sample preparation. 🔍 However, with modern NMR techniques and methodologies, it is now possible to analyze dozens of metabolites in this product. Milk metabolomics represents a highly promising field of study with the potential to impact primary producers 👩‍🌾, the dairy industry 🧀, and consumers alike 🛒. Furthermore, studies focused on identifying milk metabolomes are crucial for advancing our understanding of mammary gland physiology, food science 🍽️, dairy research, and animal science 🧬. Through insights into mammary gland metabolic activity, milk composition, and quality, NMR-based metabolomics has provided evidence of the significant role milk metabolites play in relation to nutritional value 🥛, technological properties 🧑‍🔬, quality control ✅, and bioactivity 🌱.
👌🤝The spectrum was recorded by Andrii Sviatnenko
ℹ️ For more details find the publication by Sundekilde et al. Metabolites 2013, 3, 204-222
#products #milk #metabolomics

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It’s #NMRweekend ⁉️🧲. Use the quiz below 😊.
PS: In this series of posts, we’ll consider not only ¹H-related quizzes but a wide range of NMR experiments, so stay tuned 😉.
#nmrchallenge #quiz

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Look at this, the Eye of Sauron 😈 — Multiplet of the week. Once again, my software failed to analyze it, but apparently, this signal has four different couplings to each chemically inequivalent nucleus. Find this Building Block at the Enamine store. ID: EN300-1936715.
#spin #coupling

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❗️An interesting molecule I’ve recently encountered in my practice.
🔗The CF₃ groups appear to have both strong ‘through-space’ and more classical ‘through-bond’ spin-spin coupling pathways.
#spin #coupling

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🍀🧪The smallest cycloalkane, cyclopropane, is a basic structure element in a wide range of naturally occurring compounds.
💊Especially, the 1,2,3-trisubstituted cyclopropanes are found widely in natural products and biologically active molecules.
ℹ️🛒Check this 1,2,3-trisubstituted cyclopropane. More datails: https://new.enaminestore.com

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❗️ 5 interesting facts about Riboflavin (Vitamin B2):
1. 💡Fluorescence: Riboflavin glows yellow-green under UV light, making it stand out in biological samples. Its fluorescence comes from its conjugated ring system, which absorbs UV light.
2. ⚙️Cofactor Role: Riboflavin is a precursor for the coenzymes FMN and FAD, which play a key role in cellular energy production, especially in the Krebs cycle and the electron transport chain.
3. ☀️Light Sensitivity: Riboflavin breaks down quickly when exposed to light, particularly UV rays. That’s why foods like milk, rich in riboflavin, are stored in opaque containers to prevent degradation.
4. 🌈Natural Colorant: Riboflavin is a bright yellow compound used as a natural food dye (E101). Its vibrant color adds a yellow tint to many food products and supplements.
5. 🦠Essential for Growth: Riboflavin is vital for cell growth and development. It helps the body break down carbohydrates, proteins, and fats, and is especially important for maintaining healthy skin, eyes, and nervous system function.
#riboflavin #compound

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🧲 Multiplets of the week. Unfortunately, MestReNova failed to accurately analyze these multiplets. Each of the protons in this case has at least 4 strong couplings, plus some long-range ⁴J couplings.
#spin #coupling #proton #fluorine

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ℹ️ In 1D TOCSY, a single peak is selected, and the signal is transferred from it to all J-coupled protons in a stepwise process.
❗️This technique can be particularly useful for separating spectra in mixtures of compounds.
#TOCSY

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Recently, I encountered similar NMR problem in practice.
ℹ️ Found the answer in Breitmaier's book:
‼️Geminal couplings ²J(NH) distinguish the relative configurations of aldoximes/aldimines very clearly. Thus, anti-furan-2-aldoxime(a) shows a considerably larger ²J(NH) coupling than does the syn isomer b.
#nitrogen #coupling

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🧲‼️Reference deconvolution is a technique that able to remove some distortions that affect all peaks in a spectrum in the same (!) way, usually in the case of bad shimming.
🔑 The key idea is finding the distortion function of a reference signal (singlet) followed by the whole *.fid’s correction using this function.
ℹ️ The analysis was made using MNova software

#processing

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🧲☀️ Cinnamic acid derivatives are a good example of why it is necessary to protect your NMR samples from direct sunlight ☝️.
ℹ️ These NMR spectra illustrate the transformation of the trans isomer into the cis isomer when the sample is exposed to open light.
#uv #light

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