Draw the line-bond structures for 1-butanediol, 1-butanol, and 1-heptanol. Under these structures, write the words “most polar” “least polar” and “intermediate” beneath the molecules in the order you think is correct.
B. Look at the IR spectra for 1-butanediol, 1-butanol, and 1-heptanol in your lab book. Where do you see the IR stretch for the -OH for each? (estimate using x-axis). Give a range of wavenumbers AND the lowest point on the stretch.
C. Where do you see the IR stretch for the -CHs for each? Give a range of wavenumber.
D. Use some adjectives to describe how the shape (jagged, smooth, broad, spiky, thin, fat, etc. of the two stretches is different.
E. Describe the relative depths (vertical length of the stretch) for -OH and -CH for the three molecules. For the most polar molecule, which is deeper, -OH or -CH? For the least polar molecule, which is deeper, -OH or -CH?
F. Draw the line-bond structures for 1-hexene and 1-propene. Under these structures, write “higher % of C=C bonds” and “lower % of C=C bonds” beneath the molecules in the order you think is correct.
G. Look at the IR spectra for 1-hexene and 1-propene. Where do we see the stretch for the C=C bond itself? Where do we see the stretch for the sp2-CH?
H. Describe the relative depths (vertical length of the stretch) for sp2-CH and sp3-CH for the two molecules. In which spectra is the sp2-CH more pronounced?
I. Draw the line-bond structures for 2-butanone, 3-methyl butanal, and 3-methyl butanoic acid. Circle the C=O bond in each molecule. Under each molecule, label them as “ketone”, “carboxylic acid” and “aldehyde.”
J. Look at the IR spectra for 2-butanone, 3-methyl butanal, and 3-methyl butanoic acid and find the stretch for C=O in each. What wavenumber corresponds to the lowest point of this stretch in each? Are they distinct or pretty similar?
K. Look at the LEFT SIDE of the IR spectra for 2-butanone, 3-methyl butanal, and 3-methyl butanoic acid. What signal do you see for the aldehyde above 2500 that isn’t in the others? What signal do you see for the carboxylic acid above 2500 that isn’t in the others?
L. To distinguish among these three types of molecules quickly and easily, should you look above 2500 or around 1700?
M. Draw the line-bond structures for benzene and benzene chloride.
N. Look at the IR spectra for benzene and benzene chloride. Normally, we don’t consider the area below 1500, but when there aren’t many other polar bonds in a molecule, we might! What differences do you notice in the region below 1500 for these spectra?
O. Draw the line-bond structure for bromine. If it wasn’t clear, this bromine is Br2.
P. Remember the definition of organic chemistry or organic compounds (or google it if you don’t remember). Is bromine an organic compound? Look at the IR spectra for bromine. Is IR spectroscopy more useful for organic or non-organic compounds?