Test 3 CHEM 2511 Summer 2018 13) Which of the following mass spectra shows the presence of bromine in a compound? m/e 14) Which one of the following compounds is consistent with the following spectra below?
Solution
Answer 13: Bromine has twi isotopes: 79 Br and 81 Br. The isotopic abundance of both isotopes are almost equal i.e about 1:1.
So, a compound having a Bromine group shows M + as well as (M+2) + peak. The given spectras show that option (D) is having M + as well as (M+2) + peak. Further, the molecular ion peak must have value greater than the molecular weight of Bromine (79) so, answer is (D).
Answer 14: The correct answer is (C).
Since in (c) the three H of benzene rings are equivalent while in other options they are not equivalent. Moreover in (d) there are five protons.
Overall, structure (c) justifies the 9 (METHYL protons) and 3 (AROMATIC potons).
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Test 3 CHEM 2511 Summer 2018 13) Which of the following mass spectra s.docx
1. Test 3 CHEM 2511 Summer 2018 13) Which of the following mass spectra shows the presence
of bromine in a compound? m/e 14) Which one of the following compounds is consistent with
the following spectra below?
Solution
Answer 13: Bromine has twi isotopes: 79
Br and 81
Br. The isotopic abundance of both isotopes
are almost equal i.e about 1:1.
So, a compound having a Bromine group shows M +
as well as (M+2) +
peak. The given spectras
show that option (D) is having M +
as well as (M+2) +
peak. Further, the molecular ion peak must
have value greater than the molecular weight of Bromine (79) so, answer is (D).
Answer 14: The correct answer is (C).
Since in (c) the three H of benzene rings are equivalent while in other options they are not
equivalent. Moreover in (d) there are five protons.
Overall, structure (c) justifies the 9 (METHYL protons) and 3 (AROMATIC potons).
