Summary: Identification Of Unknown Organic Compounds
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Identification of Unknown Organic Compounds
September 24th, 2015
Introduction: In this three-week experiment my partners and I were given two samples, one solid and one liquid and told to determine what compound we were given. Our unknowns will contain a functional group which should help us determine our compound. In order to determine our compounds, we will be using infrared spectroscopy and NMR. We will also find a melting point as well as a boiling point.
How to use the IR Machine:
• Double click on spectrum on the desktop
• Login as Admin
• Click Background on dialog box
• Click yes, (the top plate is clean and in position)
• A background will be run, it will take 30 seconds
• Use a clean…show more content… Analyze the spectrum of each of the unknowns. Identify the major functional group(s) in each of the unknowns. Provide the wavenumber(s) for all the diagnostic peaks outside the fingerprint region that support your claim.
1. a) What is the theory of Nuclear Magnetic Resonance? b) What is the magnetic shielding of electrons? Describe the results of its effect on the NMR spectrum. c) What is a chemical shift? d) What does the intensity of the NMR signals imply? e) What is the information provided by the splitting of the NMR signals? Nuclear Magnetic Resonance results from the interaction of magnetic moments involving nuclei in a compound. Magnetic shielding depends on the structure of a compound, to reach the nucleus of the compound a magnetic field has to pass through the electron cloud that is surrounding the nucleus. By the time the magnetic field reaches the nucleus the effects will be reduced. The greater the electron density around the nucleus the more shielded the nucleus is. The shielding effects the chemical shift of the NMR scan. A chemical shift is defined as the difference between the frequency of a nuclear spin flip of the nucleus in question and the nuclear spin flip of a reference molecule divided by the operating frequency of the NMR spectrometer. The peak intensity is related to the number of hydrogen's that the peak is representing. A split shows the number of neighboring hydrogen atoms in the…show more content… Interpret the IR spectra for each of the unknowns and classify each unknown in the appropriate functional group. At this point you can use the melting point and the boiling point to narrow down your choices. The IR spectrum for our unknown liquid has a very strong peak at 2253 which means a nitrile is present in the compound. There is also a peak at 2988 that is a little broad but sharp at the end which could be an alkane.
The spectrum for the unknown solid has two weak peaks in the 3000 region. One is at 3010 that seems to be insignificant while the other is at 3335 which could either indicate that an alkyne or an amine is present in the structure.
2. Provide detailed analysis of 1H- and 13C-NMR spectra for each of the unknowns. This analysis must list the chemical shift values for all signals in each NMR spectrum, multiplicity and intensity of the 1H-NMR signals, and values of coupling constants if possible. Interpret the spectra and propose the molecular structure of each