310_07_211nmr_data_sheet_postlab

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Northern Kentucky University *

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310L

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Chemistry

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Dec 6, 2023

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NMR DATA SHEET NAME: Section: Unknown number: Attach your 1 H NMR obtained using the benchtop NMR equipment. Now use the standard NMR obtained on 500 MHz equipment provided by your instructor to finish the NMR data analysis below: Draw the structure of your unknown below with all non-equivalent H’s labeled (a, b, etc.) for NMR identification. Redraw the structure and assignments directly on the 1 H NMR spectrum, making sure the assignments also match the table below. Label the peak(s) on the spectrum that corresponds to the NMR solvent used by writing the solvent above it (them). Complete the table below for the 1 H NMR spectrum. If necessary, use the expanded, online spectra for multiplicity and coupling constants. For Identification , use the same a, b, etc. that you used in your structure above. Do not include the solvent peak in your table.  (ppm) Multiplicity Coupling Constant J (Hz) Number of H’s Identification Sample calculations of chemical shift and coupling constant: 1 - NMR

Draw the structure of the unknown below with all non-equivalent C’s labeled (a, b, etc.) for NMR identification. Redraw the structure and assignments directly on the 13 C NMR spectrum, making sure the assignments match those in the table below. Label the peak(s) on the spectrum that corresponds to the NMR solvent used by writing the solvent above it (them). Complete the table below for the 13 C NMR Spectrum. For Identification , use the same a, b, etc. that you used in your structure above. Do not include the solvent peak in your table.  (ppm) Identification  (ppm) Identification Post-lab Questions: 1. The deuterated forms of the solvents below are common solvents for NMR. Commercially available deuterated solvents normally have 99.0 ~ 99.96% deuterium, meaning trace amounts of non-deuterated solvents are also present. What are the 1 H and 13 C chemical shifts produced by these residual solvents? Also, trace amounts of water are often found in 1 H spectra taken in CDCl 3 and d6-DMSO. What is the chemical shift of water in these solvents? Tables of these values can be found on line or in the lab. residual solvent 1 H  (ppm) 13 C  (ppm) Water in … 1 H  (ppm) CHCl 3 CHCl 3 DMSO DMSO CH 2 Cl 2 2 - NMR

2. Explain why all protons in a molecule do not absorb at the same radio frequency energy. In other words, why do non-equivalent protons have different chemical shifts? 3. The three 1 H NMR spectra shown below are collected using three different NMR instrument with the following magnetic field strengh: 60 MHz, 300 MHz and 600 MHz. Please write down the magnetic strength on its corresponding spectra. 4. Describe the effect of the magnet’s power, B 0 , on the separation of peaks arising from non-equivalent nuclei in the frequency (Hz) spectrum. Consider the nuclei in the absence of any spin-spin splitting. 5. Describe the effect of the magnet’s power, B 0 , on the chemical shift (  ; ppm spectrum)? Explain 3 - NMR

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6. Describe the effect of the magnet’s power, B 0 , on the separation of peaks arising from spin-spin splitting in the frequency (Hz) spectrum. 7. Describe the effect of the magnet’s power, B 0 , on the separation of peaks arising spin-spin splitting in the NMR (ppm) spectrum? Explain 8. You will find the 1 H and 13 C NMR spectra of nine additional compounds posted ( A-I ); each compound has one of the following formulas: C 2 H 3 Cl 3, C 4 H 10 O, C 4 H 8 O 2 , C 4 H 8 O, C 7 H 6 O 2 , C 9 H 8 . Prior to coming to lab, print out the post-lab spectra and calculate the degrees of unsaturation for the preceding formulae. You will turn in only one 1 H and 13 C spectrum for each compound. Use a spectrum that allows all of the peaks and assignments to be seen. For each spectrum ( A-I ) (1) Draw a structure consistent with each 1 H spectrum directly on the spectrum. - Use the a, b, c … system to label the sets of non-equivalent protons in your structure. - Place the letters over the corresponding peak(s) in the spectrum. - Label the peak(s) on the spectrum that corresponds to the NMR solvent used by writing the solvent above it (them). (2) Redraw the structure on the corresponding 13 C spectrum. - Use the a, b, c … system to label the sets of non-equivalent protons in your structure. - Place the letters over the corresponding peak(s) in the spectrum. - Label the peak(s) on the spectrum that corresponds to the NMR solvent used by writing the solvent above it (them). 4 - NMR