The following 1H NMR absorptions were obtained on a spectrometer operating at 300 MHz

Into how many peaks would you expect the 1H NMR signals of the indicated protons to be split? (Green 5 Cl.)

How many absorptions would you expect the following compound to have in its 1H and 13C NMR spectra?

Sketch what you might expect the 1H and 13C NMR spectra of the following compound to look like (green 5 Cl):

How many electronically nonequivalent kinds of protons and how many kinds of carbons are present in the following compound? Dont forget that cyclohexane rings can ring-flip.

Identify the indicated protons in the following molecules as unrelated, homotopic, enantiotopic, or diastereotopic. Cysteine (a) (b)

The following 1H NMR absorptions were obtained on a spectrometer operating at 200 MHz and are given in hertz downfield from the TMS standard. Convert the absorptions to d units. (a) 436 Hz (b) 956 Hz (c) 1504 Hz

The following 1H NMR absorptions were obtained on a spectrometer operating at 300 MHz. Convert the chemical shifts from d units to hertz downfield from TMS. (a) 2.1 d (b) 3.45 d (c) 6.30 d (d) 7.70 d

When measured on a spectrometer operating at 200 MHz, chloroform (CHCl3) shows a single sharp absorption at 7.3 d. (a) How many parts per million downfield from TMS does chloroform absorb? (b) How many hertz downfield from TMS would chloroform absorb if the measurement were carried out on a spectrometer operating at 360 MHz? (c) What would be the position of the chloroform absorption in d units when measured on a 360 MHz spectrometer?

Why do you suppose accidental overlap of signals is much more common in 1H NMR than in 13C NMR?

Is a nucleus that absorbs at 6.50 d more shielded or less shielded than a nucleus that absorbs at 3.20 d? Does the nucleus that absorbs at 6.50 d require a stronger applied field or a weaker applied field to come into resonance than the nucleus that absorbs at 3.20 d?

How many types of nonequivalent protons are present in each of the following molecules? Naphthalene Ethyl acrylate

The following compounds all show a single line in their 1H NMR spectra. List them in expected order of increasing chemical shift: CH4, CH2Cl2, cyclohexane, CH3COCH3, H2CPCH2, benzene

How many signals would you expect each of the following molecules to have in its 1H and 13C spectra? CH3CCH3 O CH3 H3C CH3 (a) (d) (c) CC H3C CH3 (b) CH3 (e) (f) O 3C CCH 3C OH H3C OCH3 CH3 H3C CH3 CH3

Propose structures for compounds with the following formulas that show only one peak in their 1H NMR spectra: (a) C5H12 (b) C5H10 (c) C4H8O2

Predict the splitting pattern for each kind of hydrogen in the following molecules: (a) (CH3)3CH (b) CH3CH2CO2CH3 (c) trans-2-Butene

Predict the splitting pattern for each kind of hydrogen in isopropyl propanoate, CH3CH2CO2CH(CH3)2.

Identify the indicated sets of protons as unrelated, homotopic, enantiotopic, or diastereotopic: H (c) (b) H OH H (a) H H O H H H Cl

Identify the indicated sets of protons as unrelated, homotopic, enantiotopic, or diastereotopic: (a) (b) (c) H H H H H3C H3C CH2

The acid-catalyzed dehydration of 1-methylcyclohexanol yields a mixture of two alkenes. How could you use 1H NMR to help you decide which was which?

How could you use 1H NMR to distinguish between the following pairs of isomers? CHCH2CH3 H2C and CHCH2CH3 (a) CH3CH CH2 H2C (d) CH3CH2OCH2CH3 (b) CH3OCH2CH2CH3 and and CH3COCH2CH3 (c) O CH3CH2CCH3 O O O C(CH3 and CH3CH CHCCH3

Propose structures for compounds that fit the following 1H NMR data: (a) C5H10O (b) C3H5Br 0.95 d (6 H, doublet, J 5 7 Hz) 2.32 d (3 H, singlet) 2.10 d (3 H, singlet) 5.35 d (1 H, broad singlet) 2.43 d (1 H, multiplet) 5.54 d (1 H, broad singlet)

Propose structures for the two compounds whose 1H NMR spectra are shown. (a) C4H9Br Intensity 10 0123456789 ppm Chemical shift () TMS Chem. shift 1.05 1.97 3.31 Rel. area 6.00 1.00 2.00 (b) C4H8Cl2

How many 13C NMR absorptions would you expect for cis-1,3-dimethylcyclohexane? For trans-1,3-dimethylcyclohexane? Explain.

How many absorptions would you expect to observe in the 13C NMR spectra of the following compounds? (a) 1,1-Dimethylcyclohexane (b) CH3CH2OCH3 (c) tert-Butylcyclohexane (d) 3-Methyl-1-pentyne (e) cis-1,2-Dimethylcyclohexane (f ) Cyclohexanone

Suppose you ran a DEPT-135 spectrum for each substance in Problem 13.47. Which carbon atoms in each molecule would show positive peaks, and which would show negative peaks?

How could you use 1H and 13C NMR to help you distinguish among the following isomeric compounds of formula C4H8? CH3C CH2 CH2 CH2 H2C CHCH2CH3 CH3CH CHCH3 CH2 CH2 CH3

How could you use 1H NMR, 13C NMR, and IR spectroscopy to help you distinguish between the following structures? 3-Methyl-2-cyclohexenone 3-Cyclopentenyl methyl ketone

Assign as many of the resonances as you can to specific carbon atoms in the 13C NMR spectrum of ethyl benzoate.

Assume that you have a compound with formula C3H6O. (a) How many double bonds and/or rings does your compound contain? (b) Propose as many structures as you can that fit the molecular formula. (c) If your compound shows an infrared absorption peak at 1715 cm21, what functional group does it have? (d) If your compound shows a single 1H NMR absorption peak at 2.1 d, what is its structure?

The compound whose 1H NMR spectrum is shown has the molecular formula C3H6Br2. Propose a structure.

The compound whose 1H NMR spectrum is shown has the molecular formula C4H7O2Cl and has an infrared absorption peak at 1740 cm21. Propose a structure.

Propose structures for compounds that fit the following 1H NMR data: (a) C4H6Cl2 (b) C10H14 2.18 d (3 H, singlet) 1.30 d (9 H, singlet) 4.16 d (2 H, doublet, J 5 7 Hz) 7.30 d (5 H, singlet) 5.71 d (1 H, triplet, J 5 7 Hz) (c) C4H7BrO (d) C9H11Br 2.11 d (3 H, singlet) 2.15 d (2 H, quintet, J 5 7 Hz) 3.52 d (2 H, triplet, J 5 6 Hz) 2.75 d (2 H, triplet, J 5 7 Hz) 4.40 d (2 H, triplet, J 5 6 Hz) 3.38 d (2 H, triplet, J 5 7 Hz) 7.22 d (5 H, singlet)

Long-range coupling between protons more than two carbon atoms apart is sometimes observed when p bonds intervene. An example is found in 1-methoxy-1-buten-3-yne. Not only does the acetylenic proton, Ha, couple with the vinylic proton Hb, it also couples with the vinylic proton Hc, four carbon atoms away. The data are: Ha (3.08 ) Hb (4.52 ) Hc (6.35 ) Ja-b = 3 Hz Ja-c = 1 Hz Jb-c = 7 Hz 1-Methoxy-1-buten-3-yne Ha Hb C C CH3O C C Hc Construct tree diagrams that account for the observed splitting patterns of Ha, Hb, and Hc.

The 1H and 13C NMR spectra of compound A, C8H9Br, are shown. Propose a structure for A, and assign peaks in the spectra to your structure.

Propose structures for the three compounds whose 1H NMR spectra are shown. (a) C5H10O

The mass spectrum and 13C NMR spectrum of a hydrocarbon are shown. Propose a structure for this hydrocarbon, and explain the spectral data.

Compound A, a hydrocarbon with M1 5 96 in its mass spectrum, has the 13C spectral data given below. On reaction with BH3 followed by treatment with basic H2O2, A is converted into B, whose 13C spectral data are also given below. Propose structures for A and B. Compound A Broadband-decoupled 13C NMR: 26.8, 28.7, 35.7, 106.9, 149.7 d DEPT-90: no peaks DEPT-135: no positive peaks; negative peaks at 26.8, 28.7, 35.7, 106.9 d Compound B Broadband-decoupled 13C NMR: 26.1, 26.9, 29.9, 40.5, 68.2 d DEPT-90: 40.5 d DEPT-135: positive peak at 40.5 d; negative peaks at 26.1, 26.9, 29.9, 68.2 d

Propose a structure for compound C, which has M1 5 86 in its mass spectrum, an IR absorption at 3400 cm21, and the following 13C NMR spectral data: Compound C Broadband-decoupled 13C NMR: 30.2, 31.9, 61.8, 114.7, 138.4 d DEPT-90: 138.4 d DEPT-135: positive peak at 138.4 d; negative peaks at 30.2, 31.9, 61.8, 114.7

Compound D is isomeric with compound C (Problem 13.61) and has the following 13C NMR spectral data. Propose a structure. Compound D Broadband-decoupled 13C NMR: 9.7, 29.9, 74.4, 114.4, 141.4 d DEPT-90: 74.4, 141.4 d DEPT-135: positive peaks at 9.7, 74.4, 141.4 d; negative peaks at 29.9, 114.4 d

Propose a structure for compound E, C7H12O2, which has the following 13C NMR spectral data: Compound E Broadband-decoupled 13C NMR: 19.1, 28.0, 70.5, 129.0, 129.8, 165.8 d DEPT-90: 28.0, 129.8 d DEPT-135: positive peaks at 19.1, 28.0, 129.8 d; negative peaks at 70.5, 129.0 d

Compound F, a hydrocarbon with M1 5 96 in its mass spectrum, undergoes reaction with HBr to yield compound G. Propose structures for F and G, whose 13C NMR spectral data are given below. Compound F Broadband-decoupled 13C NMR: 27.6, 29.3, 32.2, 132.4 d DEPT-90: 132.4 d DEPT-135: positive peak at 132.4 d; negative peaks at 27.6, 29.3, 32.2 d Compound G Broadband-decoupled 13C NMR: 25.1, 27.7, 39.9, 56.0 d DEPT-90: 56.0 d DEPT-135: positive peak at 56.0 d; negative peaks at 25.1, 27.7, 39.9 d

3-Methyl-2-butanol has five signals in its 13C NMR spectrum at 17.90, 18.15, 20.00, 35.05, and 72.75 d. Why are the two methyl groups attached to C3 nonequivalent? Making a molecular model should be helpful. CH3CHCHCH3 H3C OH 34 2 1 3-Methyl-2-butanol

A 13C NMR spectrum of commercially available 2,4-pentanediol, shows five peaks at 23.3, 23.9, 46.5, 64.8, and 68.1 d. Explain. CH3CHCH2CHCH3 OH OH 2,4-Pentanediol

Carboxylic acids (RCO2H) react with alcohols (ROH) in the presence of an acid catalyst. The reaction product of propanoic acid with methanol has the following spectroscopic properties. Propose a structure. Propanoic acid CH3CH2COH ? O H+ catalyst CH3OH MS: M1 5 88 IR: 1735 cm21 1H NMR: 1.11 d (3 H, triplet, J 5 7 Hz); 2.32 d (2 H, quartet, J 5 7 Hz); 3.65 d (3 H, singlet) 13C NMR: 9.3, 27.6, 51.4, 174.6 d

Nitriles (RCqN) react with Grignard reagents (RMgBr). The reaction product from 2-methylpropanenitrile with methylmagnesium bromide has the following spectroscopic properties. Propose a structure. 2-Methylpropanenitrile ? 1. CH3MgBr 2. H3O+ CH3CHC N CH3 MS: M1 5 86 IR: 1715 cm21 1H NMR: 1.05 d (6 H, doublet, J 5 7 Hz); 2.12 d (3 H, singlet); 2.67 d (1 H, septet, J 5 7 Hz) 13C NMR: 18.2, 27.2, 41.6, 211.2 d