HNMR & CNMR infirmation to identify a compound

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In summary, the conversation discusses a compound with the structure C7H10O2 and provides HNMR and 13C NMR data. The speaker identifies all functional groups in the compound and is now trying to put the structure together. They are having trouble distinguishing between a methyl ketone and an acetate group, and are missing some data for the compound.
  • #1
FARADAY JR
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I was given a structure C7H10O2 AND i WAS GIVEN THE FOLLOWING INFORMATION
HNMR:
1.16(3H,SINGLET) - RCH2R
2.21(2H,SINGLET)- RC=OCH3

13C NMR:
216.25(SINGLET)- R-C=O-R
52.57(SINGLET) -C-O
34.51 (TRIPLET) RCH2R
20.22 (QUARTET) RCH3

i identified all the functional groups in the compound but having a problem putting the structure together so any help I would truly appreciate it.
 
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I assume the 13C information is taken from an experiment without heteronuclear decoupling. Generally, 13C is performed with the proton decoupler on which gives only singlet type spectra. I also assume you've transposed the number of hydrogens in the 1H data you have given us.

You have a methyl group next to a carbonyl carbon which means you either have a methyl ketone or an acetate group in your structure (CH3C=OR, R=O- ). An aldehyde would require that your compound were the trivial compound ethanal which isn't right for the given empirical formula. How would you distinguish between a methyl ketone and an acetate? Where does the ketone carbonyl absorb in the 13C spectrum? How about acetate?

You have a C-O identified so is it an ether or part of the acetate group? Why wouldn't you observe a splitting pattern for this carbon? Is this carbon tertiary or was the splitting information left out for this bit of information? (I don't know the answer to that) You don't have all of the 1H data or all of the 13C data for this compound. Is the remaining data deliberately omitted to make this more of a challenge for you?
 

FAQ: HNMR & CNMR infirmation to identify a compound

What is HNMR and CNMR information used for in identifying a compound?

HNMR (proton nuclear magnetic resonance) and CNMR (carbon nuclear magnetic resonance) information is used to determine the structure and composition of a compound by analyzing the different chemical shifts and integrations of its protons and carbon atoms.

2. How does HNMR and CNMR information help distinguish between different compounds?

HNMR and CNMR information can help distinguish between different compounds by providing unique chemical shifts and integrations for each proton and carbon atom in the compound, allowing for comparison to known spectra and identification of functional groups.

3. What factors can affect the HNMR and CNMR spectra of a compound?

The HNMR and CNMR spectra of a compound can be affected by factors such as solvent used, temperature, concentration, and impurities.

4. How can HNMR and CNMR information be used to determine the purity of a compound?

If the HNMR and CNMR spectra of a sample match the expected spectra for a pure compound, it can be concluded that the sample is pure. Any discrepancies or additional peaks may indicate the presence of impurities.

5. Are there any limitations to using HNMR and CNMR information for compound identification?

While HNMR and CNMR information can provide valuable insights into the structure and composition of a compound, it is not always sufficient for complete identification. Other analytical techniques, such as mass spectrometry and infrared spectroscopy, may also be necessary for a comprehensive analysis.

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