2301 Chemistry In-Class Exercise: IR Spectroscopy and MS Fragmentation Patterns
Friday, May 1
Cladosporium resinae, sometimes called fuel fungus, colonizes aircraft fuel lines in wet climates. To use aircraft fuel as food, the fungus must first oxidize the fuels component hydrocarbons. To better understand this process, C. resinae was grown on n-pentane and oxygen, and initial metabolites were collected and analyzed by IR and MS. In this problem, you will try to determine the structure of one metabolite from IR and mass spectra. a. The IR spectrum of one pentane metabolite is shown below.
100
Transmittance (%)
50
0 4000
3000
2000
1500
1000
500
Wavenumbers (cm-1) Hydrocarbon oxidation could presumably generate any of the functional groups shown below. Based on the IR spectrum, which would you predict to find in this metabolite? Circle all answers that apply.
H (sp) C H C(sp 2)
H C(sp 3)
O C
H O C C
b. Lets assume that the metabolite still has the linear, five-carbon skeleton of npentane. Given your answers to part (a), what are some possible structures for the molecule?
c. The mass spectrum of the metabolite is shown below.
100 80 60 40 20 0 10 20 30 40 50 60 70 80 90 100 88 73 45
Relative Intensity
m/z
Lets assume that the parent mass for [M+] has m/z = 88. Is this consistent with any of the structures you drew in part (b)? (Do any of them have mass 88 amu?)
d...