2 (b) In the following reaction, compounds B or C might be formed. HCI or в с (i) By using the 'H NMR spectra, explain the difference in these two products. (ii) In a mass spectrum of compound B, identify the m/z for the molecular ion peak(s). (iii) Explain the intensity of the molecular ion peak(s) observed in (ii). (iv) For compound C, propose a cation structure at m/z 71.

2 (b) In the following reaction, compounds B or C might be formed. HCI or в с (i) By using the 'H NMR spectra, explain the difference in these two products. (ii) In a mass spectrum of compound B, identify the m/z for the molecular ion peak(s). (iii) Explain the intensity of the molecular ion peak(s) observed in (ii). (iv) For compound C, propose a cation structure at m/z 71.

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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2,3-Dimethylbutane and 2,2-dimethylbutane have the same molecular ion in the mass spectrum, but only one of these isomers gives a significant fragment at m/z = 57. (a) Which isomer shows an intense peak at m/z = 57? (b) Propose a structure for the ion that gives rise to this peak. (c) The base peak in the mass spectrum of the other isomer occurs at m/z = 43. What ion gives rise to this peak?
2 (a) In the following reaction, PCC A (i) Draw the structure of compound A. (ii) Explain using the IR spectra to confirm that the reaction is completed. (iii) Identify the molecular ion peak for compound A. (iv) Fragmentation of A shows a peak at m/z 111. Draw the possible cation for this peak. (v) Determine the resonance structure of this cation.
2 (a) In the following reaction, OH РСС A (i) Draw the structure of compound A. (ii) Explain using the IR spectra to confirm that the reaction is completed. (iii) Identify the molecular ion peak for compound A. (iv) Fragmentation of A shows a peak at m/z 111. Draw the possible cation for this peak. (v) Determine the resonance structure of this cation.
How could 1H NMR spectroscopy be used to distinguish among isomers A, B, and C?
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4. (a) Chemical shift (8) value of CH and CH3 proton in [Al(acac)3] are 1.99 and 5.47 ppm, respectively whereas in [Fe(acac)3] the 8 values of CH and CH3 proton are shifted to more downfield region i.e, 2.18 and 5.52 ppm, respectively where 'acac' denotes acetylacetonate anion. Explain the observation.
The mass spectrum of the following compound shows fragments at m/z= 127, 113, and 85. Propose structures for the ions that give rise to thesepeaks.
Butanal and methylpropanal give slightly different mass spectra. Both give a molecular ion peak at m/z = 72, but butanal gives four other peaks whereas methylpropanal only gives three. State the species responsible for the four other peaks in the mass spectrum of butanal and write equations to show their formation from the molecular ion.
You are given two compounds, dimethylamine (CH3)2NH and ethanamide, CH3CONH2. a) b) c) Which compound is more basic? Explain your answer. How do you distinguish them by infrared spectroscopy? Outline an extraction method to separate a mixture of these two compounds.
9. (a) A compound with chemical formula C₂H₂CIBr shows the proton NMR spectrum consisting of two doublets with J-7.3 Hz. What is the molecular structure of this compound? (b) The proton chemical shifts of the two doublets from the previous question differ by 0.3 ppm. Can you consider the proton spectrum as the first order one?
(b) The proton decoupled compound A (COH1202) còntain three peaks-13, 40, 60, 130-138 (4 peaks), 13 C spectrum of 172 n proton coupled C ppm. In spectrum the peaks at 13 ppm. 40 and 60 ppm split into quartret, triplet and triplet respectively. Suggest a`structure. for the compound A. Explain your deduction. If you take a DEPT-135 spectrum, then what will be the nature of these peaks? What 13C proton coupling constant (' J) would you expect for the peak at 13 and 40 ppm?
The mass spectrum of compound B is shown below. 100 180 80 181 77 В 182 20 104 25 50 75 100 125 150 175 200 m/z (i) Identify the molecular ion peak of compound B. (ii) Explain the peak at m/z 182 in terms of intensity. (iii) Explain the formation of the other labelled fragments (m/z 180, 104 and 77). Relative Intensity