September 24th, 2007
Chemistry 251/261: Exam 1
Name:_________________________________________
Instructor(circle):
Celius
Myers
Zimmerman
12 or 1 PM
1. (28 pts) Match compounds labeled A thru J to the functional group contained in each. Use each letter
only once. You will not use all the letters. Use scratch paper to draw out the structures as needed.
O
I
___ 2° Alkyl halide
C 3° Alkyl halide
___
A. CH3C(O)OCH3
G. CH3CCH
O
NH
O
B. CH3(CH2)3CO2H
H.
H3C
OH
B Carboxylic acid
___
Cl
C. (CH3)2C(CH2CH3)Cl
CH3
Br
I. CH3CH2CHBrCH3
F Amide
___
G Alkyne
___
E Thiol
___
HO
S
D. CH3CH(SCH3)CH3
J. CH3CH(OH)CH3
SH
E. CH3(CH2)4SH
K. CH3CHCHCH3
O
H Imine
___
L. CH3CH2Cl
N
F. CH3CH2C(O)N(CH3)2
Cl
2. (12 pts) Provide the molecular formula for the following compounds.
Cl
CH3
OH
O
O
O
C10H8O
C9H16O
C4H7ClO2
C7H12
3. (12 pts) Give the atomic orbitals that make up each of the indicated bonds. Note, an example is provided.
H3C
O
[O(sp3)–C(sp3)]
[C(sp2)–C(sp3)]
[H(1s)–C(sp2)]
O
C
H
(π bond)
CH3
1
[C(py)–O(py)]
4. (12) Circle the structure in each group with the highest water solubility and put a star (*) next to the
compound in each group with the highest boiling point.
*
A
OH
B
OH
C
N
OH
O
*
OH
N
OH
N
*
5. (12) Draw the products in each acid-base reaction.
H
+
H
Conjugate Acid
CF3
Conjugate Base
H CH2CH2NH2CH3
H CH2CH2NHCH3
O
C C CH3
+
CH3
+
HCl
O
Conjugate Acid
CF3
+
Cl–
Conjugate Base
6. (3) Which of the indicated protons in the molecule is the most acidic (indicate by circling)?
H
OH
O
OH
2
7. (40 pts) For the following reactions:
a) Circle the acids and conjugate acids.
b) Estimate the pKa values for each. The table below may be of some help.
c) Use your pKa values to determine the direction of equilibrium. Indicate whether the reaction
is quantitatively to the left, mostly left, 50:50, mostly right or quantitatively to the right.
Quantitaive means >100:1.
H H
H
H
A
H
H
+
H
quant. left
+
CH3
Circle 1:
mostly left
50:50
H
pka = –10
pka = –10
mostly left
50:50
O
C
O
O Cl O
O
+
CH3
mostly right
O
+
quant. right
H
O
HO Cl O
O
quant. left
C
pka = 15.7
mostly right
OH
quant. right
OH
+
O
pka = 16
pka = 10
Circle 1:
NH4+
quant. left
+
mostly left
50:50
mostly right
NH3
O
quant. right
O
H
+
D
pka = 9
Circle 1:
H2O
H
Circle 1:
O
C
+
H
pka = 36
B
H
–OH
pka = –3
quant. left
mostly left
50:50
mostly right
quant. right
Acid
Conjugate Base
pKa
HClO4
ClO4–
–10
H
O
O
R
–10
R
H
HO
O
10
phenol
phenolate
R–CH2–CN
R–CH–CN
H
H
H
H
H
3
H
H
H
H
H
H
H
25
36
8. (33 pts) Using curly arrows, draw resonance structures of the following compounds to show distribution of
charge thoughout the structure (structural templates are provided for convenience). Finally, draw the
resonance hybrid indicating partial charges with δ– or δ+
H
H
H
H
H
δ+
δ+
δ+
H
resonance hybrid
O
Oδ
O
O
–
δ–
δ–
N
H3C
H
N
CH3
N
H3C
CH3
CH3
CH3
CH3
CH3
H
H3C
N
CH3
resonance hybrid
CH3
a
b
δ+
N
N
CH3
b
N
δ+
H
H3C
CH3
δ+
N
δ+
a
N
H3C
N
H3C
N
CH3
H
CH3
H
N
H3C
N
CH3
CH3
4
CH3
CH3
resonance hybrid
N
CH3
H
δ+
CH3
H