Download packet 1, 2325 key

Organic Chemistry II
CHEM 2325
Packet #1
1.
Benzyl alcohol (MW = 108 g/mol) was reacted under different conditions to generate
products A-C. The IRs are shown for products A-C. The value of the molecular ion peak is
given along with the intensity ratio (relative to the parent peak) of the M+2 peak. Indicate the
structure of each product.
?
OH
a.
Product A (M = 106, M+2 ratio = 0%)
Lost 2 hydrogens, and have aldehyde carbonyl due to C=O stretch and two aldehyde C-H stretch
at 2700-2800 cm-1.
O
H
b.
Product B (M = 170, M+2 ratio = 97.6%)
No alcohol or carbonyl stretch, MS indicates bromine present due to M/M+2 ~ 1/1
Br
c.
Product C (M = 150, M+2 ratio = 0%)
Have ester carbonyl (see stretch at ~1740 cm-1). MS indicates need to add acetyl group.
O
O
d.
Indicate reagents that can convert benzyl alcohol into products A-C.
O
OH
OH
PDC
H
OH
PBr3
Br
CH3MgBr
O
O
OH
CH3MgBr
Cl
O
CH3MgBr
OH
OH
e.
What organic products are obtained if products A-C are reacted with methyl magnesium
bromide?
See above
2.
Four alcohol isomers with molecular formula C4H10O1 (MW = 74 g/mol) are shown
below. Also shown are the MS for these four isomers, but the individual spectra are not labeled.
HO
HO
OH
OH
a.
Assign structure to appropriate MS. (see below)
b.
What fragment structure corresponds to the most intense peak in each spectrum? (The
most intense peak starting from top right and going clockwise about the spectrum are: 56, 43,
45, and 59 m/z)
O
O
HO
O
NR
HO
CrO3
CrO3
CrO3
OH
HO
CrO3
OH
HO
OH
56
43
45
OH
59
Most intense peak indicates type of alcohol needed to obtain the fragment in high yield.
c.
Indicate products obtained if each compound is reacted with CrO3. (see above)
1˚ alcohols will react to acids, 2˚ alcohols to ketones and 3˚ alcohols will not react.