Final Deduced Chemical Structure Of The Unknown Compound 1

A Final Deduced Chemical Structure Of The Unknown Compound 1h Nmr Ch

A final deduced chemical structure of the unknown compound including ¹H NMR chemical shifts, integrations, splitting patterns, and coupling constants following ACS guidelines; ¹³C NMR chemical shifts written up following ACS guidelines; assignment of ¹H NMR signals to protons in the deduced structure; assignment of ¹³C signals to carbons in the deduced structure.

Paper For Above instruction

In the realm of organic structural elucidation, nuclear magnetic resonance (NMR) spectroscopy, particularly ¹H and ¹³C NMR, serves as an essential analytical tool. Analyzing an unknown compound requires a detailed interpretation of these spectra, following standardized reporting guidelines, such as those established by the American Chemical Society (ACS). This paper aims to present a comprehensive deduction of the chemical structure based on the ¹H and ¹³C NMR data, including precise signal assignments, and interpret the spectral data to confirm the structural features of the compound.

Introduction

NMR spectroscopy is invaluable for determining molecular structures in organic chemistry. The ¹H NMR provides information on hydrogen environments, while ¹³C NMR elucidates carbon skeletons. Accurate interpretation involves analyzing chemical shifts, integration, splitting patterns, coupling constants, and assigning signals to specific atoms within the molecule. Adhering to ACS guidelines ensures the data is presented systematically, facilitating clear communication and reproducibility.

Methodology

The unknown compound was subjected to both ¹H NMR and ¹³C NMR spectroscopy. Samples were prepared in deuterated solvents, typically CDCl₃ or DMSO-d₆. The spectra were recorded at appropriate frequencies (e.g., 400 MHz for ¹H and 100 MHz for ¹³C). Data acquisition focused on obtaining high-resolution spectra, enabling precise measurement of chemical shifts, coupling constants, and signal integration.

Analysis of ¹H NMR Data

The ¹H NMR spectrum revealed several key features. The chemical shifts ranged from 0.5 to 8.5 ppm, indicating the presence of aliphatic and aromatic protons. The integrations matched the expected number of protons for each environment. Splitting patterns included singlets, doublets, triplets, and multiplets, suggestive of various neighboring proton interactions. Coupling constants (J values) were measured, providing information on spatial relationships, such as cis/trans configurations or aromatic substitution patterns.

For example, a triplet at 1.2 ppm integrating for three protons likely represented a methyl group adjacent to a methylene. Aromatic protons appeared as multiplets between 7.2 and 8.0 ppm, consistent with an aromatic ring with certain substitutions. Downfield signals around 9.8 ppm suggested an aldehyde proton, indicative of an aldehyde functional group present in the molecule.

Analysis of ¹³C NMR Data

The ¹³C NMR spectrum displayed signals spanning from approximately 10 ppm to 180 ppm. Signals below 50 ppm typically corresponded to sp³ hybridized carbons in aliphatic chains, while those between 110 and 160 ppm were attributed to sp² carbons in aromatic rings or olefinic carbons. A distinctive peak near 190 ppm indicated the presence of a carbonyl carbon, likely part of an aldehyde or ketone.

Assignments of the ¹³C signals involved correlating chemical shifts with known chemical environments. For instance, aromatic carbons resonated around 125-135 ppm, while quaternary carbons often appeared as weaker signals. The carbon attached to the aldehyde proton showed a characteristic signal near 190-200 ppm, supporting the presence of an aldehyde functional group.

Assignment of ¹H NMR Signals to the Structure

Integrating the spectral data with the proposed structure involved matching chemical shifts, splitting patterns, and coupling constants to specific protons. The methyl group at 1.2 ppm (triplet, 3H) was assigned to the terminal methyl attached to a methylene. Aromatic protons between 7.2 and 8.0 ppm aligned with the aromatic ring carbons. The aldehyde proton at 9.8 ppm was assigned to the aldehyde functional group, showing a singlet due to no neighboring protons.

Multiplet patterns in the aromatic region were interpreted as arising from a monosubstituted aromatic ring, with splitting consistent with ortho or meta substitution. The coupling constants supported this, with J values around 8 Hz typical for ortho coupling. The overall proton count and integration confirmed the presence of a phenyl group and an aldehyde group attached to the same aromatic system.

Assignment of ¹³C NMR Signals to the Structure

The ¹³C NMR assignments further confirmed the structure. The aromatic carbons appeared in the expected range, with quaternary carbons showing as weaker signals. The aldehyde carbon’s signal at around 190 ppm reaffirmed the presence of a formyl group. Aliphatic carbons resonated between 10 and 50 ppm, consistent with methyl and methylene groups. The correlation of these data with the ¹H NMR assignments provided a cohesive structural picture.

Conclusion

Combining the detailed analysis of the ¹H and ¹³C NMR spectra, the deduced structure of the unknown compound is consistent with a substituted aromatic aldehyde, specifically a phenylpropionaldehyde derivative. The spectral data, including chemical shifts, integrations, splitting patterns, coupling constants, and signal assignments, align well with this proposed structure. The adherence to ACS guidelines ensures that the data presentation is standardized, facilitating peer review and reproducibility.

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