1. Which of the following species would you expect show up in electron impact ma
ID: 563364 • Letter: 1
Question
1. Which of the following species would you expect show up in electron impact mass spectrometry? Circle the appropriate answer(s). (2 points) ONH2 CH3 C CH3 H-CEC-H CH3 H3C CH3 NH2 2. Which of the following molecules would have an odd-numbered molecular ion peak? Circle the appropriate answer(s). (2 pts) NH2 CH NO2 3. For the following, which fragmentation procss (A or B) would be favored? Provide an explanation for your answer. (2 points) CH3 CH2-CH2 CH3 3C3H9 819 pathway A CH2CH3 CTH7 CH2":--CH2-CH3 pathway BExplanation / Answer
Solution:-
1) Except tertiary butyl radical and acetylene, all ion species including cation radical wold be observed in electron impact mass spectroscopy. THis is because radicals are not detected.
2) Molecules B and D would have an odd numbered molecular ion peak.
This is because according to "Nitrogen Rule" if a molecular ion has an odd mass it must have an odd number of nitrogens and that a molecular ion with an even mass must either lack nitrogen atoms or contain an even number of them. Thus,Molecules B and D have one nitrogen each which is odd number.
3) For the fragmentation of this molecules, the fragmentation process through pathway B would be favoured. This is because after fragmentation benzylic cation is formed which is converted into tropylium ion, a stable and aromatic group,
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