NMR_ExamProblems_key - Some NMR problems from previous...

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November 14, 2013 Some NMR problems from previous exams Calculate the resonance frequency of a proton in a NMR spectrometer with a magnetic field of 10.5T. a. 342 MHz b. 405 MHz c. 447 MHz d. 495 MHz ! = " B 2 # = 1 2 # (26.75 ! 10 7 T " 1 s " 1 )(10.5 T ) = 4.90 ! 10 8 s " 1 = 447 MHz Calculate the resonance frequency of a proton in a NMR spectrometer with a magnetic field of 9.5T. a. 342 MHz b. 405 MHz c. 447 MHz d. 495 MHz ! = " B 2 # = 1 2 # (26.75 ! 10 7 T " 1 s " 1 )(9.5 T ) = 4.90 ! 10 8 s " 1 = 405 MHz Suppose someone comes to you and states that they had found a new amino acid. You say that you will identify the amino acid using NMR. The observed 2D NMR spectrum is below. Determine the structure of the new amino acid. Be sure to label all of the peaks, and include an explanation of why you believe this would be the spectrum.
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Unformatted text preview: Start at the highest chemical shift, peak , assign this point to the alpha carbon. This carbon in bonded to one carbon, assign peak 2 to the beta carbon. The beta carbon has two bonds, assign peaks 3 and 4 to gamma1 and gamma2. The gamma1 carbon (peak 3) has one bond to peak 9 that has a small chemical shift, assign peak 9 to a methyl carbon, delta1. The gamma2 carbon (peak 4) has two bonds to peaks 5 and 6, assign these peaks to carbons delta2 and delta3. The delta2 carbon (peak 5) has one bond to peak 8, assign peak 8 to methyl carbon, epsilon1. The delta3 carbon (peak 6) has one bond to peak 7, assign peak 7 to methyl carbon, epsilon2....
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  • Spring '14
  • Nuclear magnetic resonance, MHz

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