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Arvin Moser
If there were an ideal NMR experiment for an unknown compound, many organic chemists would consider a 2D 13C-13C 1,1-INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment) to be it. The advantage of this experiment is the 1Jcc interaction that directly correlates a C atom to an adjacent C. The drawback is the long acquisition...

Arvin Moser
The warning flag for this puzzle is evident in the intensities of the signals. For an unknown compound, the TOF-ESI+ mass spectrum below shows the expanded region around four isotope clusters at m/z 300.336 ([M+H]+), 322.307 ([M+Na]+), 599.672 ([2M+H]+) and 621.611 ([2M+Na]+). The intensities of the 13C isotopes (i.e. the [M+1] signal) vary between 40...

Arvin Moser
A key element in data interpretation is to identify any warning flags. Warning flags can help a chemist differentiate good data from bad data. For an unknown compound, the TOF-ESI+ mass spectrum below shows the expanded region around four isotope clusters at m/z 300.336 ([M+H]+), 322.307 ([M+Na]+), 599.672 ([2M+H]+) and 621.611 ([2M+Na]+). Are the intensities...

Mikhail Elyashberg
Marine mollusks of the genus Siphonaria, commonly known as false limpets, are shelled, air-breathing herbivores that are believed to have a marine ancestry. When disturbed, siphonariid limpets secrete a sticky white mucus rich in polypropionate secondary metabolites. Specimens were steeped in acetone, and the acetone extract was subjected to extensive chromatography to afford three new polypropionate metabolites. Spectroscopic data of Polypropionate 1 (molecular formula C20H32O3) are used here to describe the structure elucidation of this compound using CASE techniques.

Arvin Moser
Many analytical data rely on common calculations. This solution shows the formula used in the calculations. NMR and MS data were collected on two unknown compounds. The TOF-MS data shows the [M+H]+ at m/z 300.0000 and 600.000 at an error of 0.001 Da. The 500 MHz 1H NMR spectrum shows two chemical shifts at 1500.00...

Mikhail Elyashberg
Le Goff et al reported the structural characterization of two novel alkylhydrazides produced by the bacterial strain Streptomyces sp. LMA-545. The structures were elucidated using 1D and 2D 1H and 13C NMR spectroscopic analysis and high-resolution mass spectrometry. 1H–15N NMR experiments were required for full structural elucidation. Here we investigate the structure elucidation of Geralcin A ( molecular formula C15H24N2O5), one of the three isolated novel compounds.

Arvin Moser
Many analytical data rely on common calculations. This puzzle covers one such common calculation. NMR and MS data were collected on two unknown compounds. The TOF-MS data shows the [M+H]+ at m/z 300.0000 and 600.000 at an error of 0.001 Da. The 500 MHz 1H NMR spectrum shows two chemical shifts at 1500.00 and 3000.00...

Mikhail Elyashberg
Lee et al have investigated the chemical constituents of the extracts obtained from cultures of the marine-derived fungus Aspergillus sp. SF-5044. This study led to the isolation of new natural products, particularly, an oxepin-containing diketopiperazine-type metabolite named Protuboxepins A (molecular formula C22H23N3O3).

Arvin Moser
On the surface, both good data and poor data offer information about an unknown compound. The challenge is to differentiate between what is good data and what is poor data. The purpose of this puzzle is to examine some poor data. From an LC-MS+ TOF dataset, an unknown compound elutes at 2.86 minutes and spans...

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