And now the interesting part realted to DEPT. P5.9: Match the 1H-NMR spectra 19-24 below to their corresponding structures S-X. For more information contact us at info@libretexts.org or check out our status page at https://status.libretexts.org. Notify me of followup comments via e-mail. b) Suggest a 1H-NMR experiment that could be used to determine what percent of starting material (1) got turned into product (2A and 2B). In the example on the left below (blue box), cyclohexane and 2,3-dimethyl-2-butene both give a single sharp resonance signal in the proton nmr spectrum (the former at δ 1.43 ppm and the latter at 1.64 ppm). There are names given to a signal based on the number of peaks present: What is the resonance frequency (again expressed in Hz) of this sub-peak?). They treated 4'-acylpyridine (1) with living yeast, and isolated the alcohol product(s) (some combination of 2A and 2B). https://www.khanacademy.org/.../proton-nmr/v/proton-nmr-practice-1 P5.14: You obtain the following data for an unknown sample. What is the chemical shift, expressed to the nearest 0.1 Hz, of the furthest downfield sub-peak in the quartet? You can also subscribe without commenting. 13C-NMR data is given for the molecules shown below. C5.1: All of the 13C-NMR spectra shown in this chapter include a signal due to CDCl3, the solvent used in each case. However, you suspect that the bottle might be contaminated with 2-bromopropane. P5.8: Match the 1H-NMR spectra 13-18 below to their corresponding structures M-R . Have questions or comments? Do this for: a) a spectrum obtained on a 300 MHz instrument, b) a spectrum obtained on a 100 MHz instrument, P5.4: Consider a quartet signal in an 1H-NMR spectrum obtained on a 300 MHz instrument. Does this pattern indicate ortho, meta, or para substitution? b) Suggest a 1H-NMR experiment that could be used to determine what percent of starting material (1) got turned into product (2A and 2B). Specifically, what percent of the molecules in the bottle are 2-bromopropane? All it does (and that’s a lot and very handy) is it differentiates the carbons based on the number of hydrogens it is bonded to. Do this for: a) a spectrum obtained on a 300 MHz instrument, b) a spectrum obtained on a 100 MHz instrument, P5.4: Consider a quartet signal in an 1H-NMR spectrum obtained on a 300 MHz instrument. However, you suspect that the bottle might be contaminated with 2-bromopropane. 13C-NMR data is given for the molecules shown below. P5.2: For each of the 20 common amino acids, predict the number of signals in the proton-decoupled 13C-NMR spectrum. d) Explain, very specifically, how the researchers could use 1H-NMR to determine the relative amounts of 2A and 2B formed in the reaction catalyzed by yeast enzyme. Therefore, the compound has a double bond or a ring. At times solving an NMR problem leads to two or more plausible structures satisfying the given data. Watch the recordings here on Youtube! Let’s how do we get this information in DEPT? Assume that diastereotopic groups are non-equivalent. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. We have seen that 13C NMR is usually decoupled and therefore there is no splitting of signals which limits the information we can get as to how many hydrogens are connected to a carbon atom.

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