Below is the mass spectrum of an unknown hydrocarbon. In ...

[kshipps]

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm¹ in its IR spectrum. Give the structure of this unknown.
 
   
 
   (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Question 2

Instructions: Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s).
 
   
 
   (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

  Refer to instructions. Propose structures for fragment ions at m/z = 57, 43, and 29

Question 3

Instructions: Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s).
 
   

[Ashley I]

Answer to Question 1

The formula weight of 54 corresponds to a molecular formula of C₄H₆, which has two degrees of unsaturation. Possible structures for this formula are:



The IR data is consistent with an internal alkyne, so the compound is but-2-yne.

Answer to Question 2

m/z
structure
57

43

29


Answer to Question 3

The peak at m/z = 43 is the base peak.

Answer to Question 4

The peak at m/z = 72 represents M⁺.

Answer to Question 5

This compound has the formula C₉H₂₀O and a mass of 144. Dehydration will result in the loss of H₂O producing a charged fragment at m/z = 126, 18 mass units less than M⁺.

Answer to Question 6

This compound, phenylacetone, has the formula C₉H₁₀O and a nominal mass of 134. Alpha cleavage will result in charged fragments at m/z = 43 and m/z = 119.

Answer to Question 7

Since the molecular ions are even numbers, loratidine must have an even number of nitrogen atoms. Therefore, the minimum number of nitrogen atoms in loratidine is two.

Answer to Question 8

e

[kshipps]

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[tuate]

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