Question on Mass Spec/IR/NMR to identify compound

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In summary: Without knowing anything else about the molecule, it's impossible to say for certain how many carbons are present.
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Protools
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Homework Statement


im given c13 nmr, h1 nmr, IR spec and mass spec without any chemical formula


Homework Equations


-none


The Attempt at a Solution


- i tried to start with mass spec, trying to count the highest peak to find out the total weight but i don't think that works
- also tried to find the largest peak on the IR. there are a bunch of large peaks near the 1500-1600 and one peak at around 500 cm-1
- h1 NMR integrates to give 7 H
- aproxx 10 carbons
 
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  • #2
This problem is essentially impossible to answer without more information about the spectra you've been given. Here's my best shot.
Protools said:
- i tried to start with mass spec, trying to count the highest peak to find out the total weight but i don't think that works
Depending on the method used to ionize species for the mass spec, the parent mass peak is not always present. You can look at differences between peaks to get an idea of what groups are attached to the molecule (for instance, loss of successive 14 m/z units usually corresponds to loss of successive CH2 groups in an alkyl chain, or loss of 44 and 45 m/z units generally corresponds to the loss of a carboxyl group).

Protools said:
- also tried to find the largest peak on the IR. there are a bunch of large peaks near the 1500-1600 and one peak at around 500 cm-1
Peaks in this range can be C=C double bonds, phenyl rings, or C=O stretches, among other things. The 500cm-1 peak honestly gives very little information. Low frequency modes like this are usually complicated and involve many atoms.

Protools said:
h1 NMR integrates to give 7 H
With no other information, you can only say that the HNMR integrates to a multiple of 7.

Protools said:
- aproxx 10 carbons
I'm assuming this comes from the number of peaks in the C13 spectrum.
 

FAQ: Question on Mass Spec/IR/NMR to identify compound

1. What is mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance used for?

Mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance are analytical techniques used to identify and characterize chemical compounds. These techniques are commonly used in fields such as chemistry, biochemistry, and forensics to determine the molecular structure and composition of a compound.

2. How does mass spectrometry work?

Mass spectrometry works by ionizing a sample and then separating the ions based on their mass-to-charge ratio. The separated ions are then detected and recorded, producing a mass spectrum that can be used to identify the compounds present in the sample.

3. What information can be obtained from an infrared spectrum?

An infrared spectrum provides information about the functional groups present in a compound, as different types of chemical bonds absorb infrared radiation at specific frequencies. This can help identify the types of bonds present in the compound, as well as its overall molecular structure.

4. What types of compounds can be analyzed using nuclear magnetic resonance?

Nuclear magnetic resonance (NMR) is primarily used to analyze compounds containing hydrogen, carbon, or phosphorus. This includes organic compounds, such as proteins and nucleic acids, as well as inorganic compounds like metal complexes. However, NMR cannot be used to analyze compounds containing only light elements, such as hydrogen, helium, and lithium.

5. How do mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance complement each other in compound identification?

Mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance are often used together in a technique called "hyphenated spectroscopy". This allows for a more comprehensive analysis of a compound, as each technique provides different types of information. For example, mass spectrometry can provide the molecular weight of a compound, while infrared spectroscopy can identify functional groups, and nuclear magnetic resonance can determine the molecular structure.

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