Multiple ChoiceWhich compound possesses a hydrogen with the highest chemical shift for its 1H NMR signal? 686views3rank3comments
Multiple Choice Which of the following chemical shift values could plausibly correspond to the protons in divinyl ether (CH2=CH–O–CH=CH2)305views
Textbook QuestionPredict the approximate chemical shifts of the protons in the following compounds. (c) CH3-O-CH2CH2CH2Cl (d) CH3CH2-C=C-H750views
Textbook QuestionThe NMR spectrum of toluene (methylbenzene) was shown in Figure 13-11. (a) How many different kinds of protons are there in toluene? (b) Explain why the aromatic region around d7.2 is broad, with more than one sharp absorption.3022views
Textbook QuestionPredict the chemical shifts of the protons in the following compounds. (a) (b) 1335views
Textbook QuestionIn a 300-MHz spectrometer, the protons in iodomethane absorb at a position 650 Hz downfield from TMS. (a) What is the chemical shift of these protons? (b) What is the chemical shift of the iodomethane protons in a 60-MHz spectrometer? (c) How many hertz downfield from TMS would they absorb at 60 MHz?598views
Textbook QuestionWithout referring to Table 14.1, label the proton or set of protons in each compound that gives the signal at the lowest frequency a, at the next lowest b, and so on. h. 443views
Textbook QuestionWithout referring to Table 14.1, label the proton or set of protons in each compound that gives the signal at the lowest frequency a, at the next lowest b, and so on. e. 389views
Textbook QuestionLabel each set of chemically equivalent protons, using a for the set that will be at the lowest frequency in the 1H NMR spectrum, b for the next lowest, and so on. Indicate the multiplicity of each signal. a. 603views
Textbook QuestionExplain the relative chemical shifts of the benzene ring protons in Figure 14.18.536views
Textbook QuestionWithout referring to Table 14.1, label the proton or set of protons in each compound that gives the signal at the lowest frequency a, at the next lowest b, and so on. c. 481views
Textbook QuestionExplain why the chemical shift of the OH proton of a carboxylic acid is at a higher frequency than the chemical shift of an OH proton of an alcohol.423views
Textbook QuestionWhich underlined proton (or sets of protons) has the greater chemical shift (that is, the higher frequency signal)? a. b. 481views
Textbook QuestionWhich underlined proton (or sets of protons) has the greater chemical shift (that is, the higher frequency signal)? c. d. 526views
Textbook QuestionThe methyl hydrogens in propane appear at a chemical shift of 0.9 ppm, whereas the methyl hydrogens of propene appear around 2.5 ppm. Explain.391views
Textbook QuestionAlkene hydrogens usually appear at similar chemical shifts between 5 and 6 ppm. The alkene hydrogens in the structure shown are very different. Rationalize the difference in chemical shifts between Hₐ and H₆ in the structure shown.325views
Textbook Question(•) For the following molecules, give the chemical shift for each indicated hydrogen. (d)338views
Textbook Question(•) For the following molecules, give the chemical shift for each indicated hydrogen. (e)373views
Textbook Question(•) For the following molecules, give the chemical shift for each indicated hydrogen. (b)311views
Textbook QuestionCompound A with molecular formula C6H10 has two peaks in its 1H NMR spectrum, both of which are singlets (with ratio 9 : 1). Compound A reacts with an acidic aqueous solution containing mercuric sulfate to form compound B, which gives a positive iodoform test (Problem 58) and has an 1H NMR spectrum that shows two singlets (with ratio 3 : 1). Identify A and B.561views
Textbook QuestionThe 1H NMR chemical shifts of nitromethane, dinitromethane, and trinitromethane are at d 6.10, d 4.33, and d 7.52. Match each chemical shift with the compound. Explain how chemical shift correlates with pKa.641views
Textbook QuestionWhich set of underlined hydrogens has its 1H NMR signal at a higher frequency? a. CH3CH2CH3 or CH3OCH2CH3 b. CH3CH=CH2 or CH3OCH=CH2391views
Textbook QuestionHow would you expect the IR and ¹H NMR spectra for propanamide and N,N-diethylpropanamide to differ?402views
Textbook QuestionThe chemical shifts of the C-2 hydrogen in the spectra of pyrrole, pyridine, and pyrrolidine are 2.82 ppm, 6.42 ppm, and 8.50 ppm. Match each heterocycle with its chemical shift.548views
Textbook Question[18]-Annulene shows two signals in its 1H NMR spectrum: one at 9.25 ppm and the other to the right of the TMS signal at -2.88 ppm. What hydrogens are responsible for each of the signals? (Hint: Look at the direction of the induced magnetic field outside and inside the benzene ring in Figure 14.6.)554views1rank
Textbook QuestionAn unknown compound (C₇H₆O) gives the IR spectrum shown here. At what chemical shifts would you expect to see signals in the ¹H NMR spectrum?358views
Textbook QuestionPredict the theoretical number of different NMR signals produced by each compound, and give approximate chemical shifts. Point out any diastereotopic relationships. (c) Ph—CHBr—CH2Br (d) vinyl chloride460views
Textbook QuestionPredict the theoretical number of different NMR signals produced by each compound, and give approximate chemical shifts. Point out any diastereotopic relationships. (a) 2-bromobutane (b) cyclopentanol551views