Exam Organic Chemistry II
@
TUM Asia 2016
Initials:__________
p.
1
Exam „Organic Chemistry II“ - 2016 / II
Name:
Student Nr.:
Rules: You have 90 minutes of time for writing. Use separate, empty sheets for drafts, but write the final solution
on the exam sheet. 50% of the points are needed for passing the exam.
Problem
1
2
3
4
5
6
7
8
9
10
11
Total
Points
6
3
4
3
5
8
4
8
3
6
6
56
achieved
Problem 1. [6 P] a) Order the following compounds according to acid strength by writing No. 1, 2 and 3 into the
boxes (the strongest acid gets No. 1, the weakest gets No. 3).
COOEt
Br
NO2
Cl
F
COOH
HI
COOH
H
COOH
HCl
HBr
O
EtOOC
SH
COOEt
OH
NH 2
Problem 2. Please draw...
[3 P]
b) ... a weaker nucleophile than is
more acidic than methane thiolate
(MeS–).
c) ... a better leaving group than
bromide (Br–);
d) ... an oxygen base, which is more
basic than ethoxide (–OEt).
Problem 3. Which are the products of acidic hydrolysis (H+/H2O/120 °C) of the following compounds?
H2O
MeO
Me
H2O
OEt
Me C N
+
H+
EtO
+
H+
O
H2O
Me
+
H+
OEt
[4 P]
N
Me
H2O
H
+
H+
Problem 4. Which substances have a carbon (•, if unclear) at the oxidation level (OL = 1) of an alcohol? [3 P]
A
B
C
H
CHCl3
H
E
O
H
H
D
MeO
F
H
OMe
Cl
H
Answer (write 1 letter into each box):
OMe
G
H
O
O
O
SMe
I
OMe
OMe
OMe
K
N
Exam Organic Chemistry II
@
TUM Asia 2016
Initials:__________
Problem 5. Energy diagram: give (only) one solution out of A–G (reactions can go forward/backwards)
p.
2
[5 P]
This is a transition state:
This is a reactive intermediate:
This ist the most stable species:
This is the most inert species:
This is the most labile species:
reaction coordinate
Problem 6. Recognize which reaction should occur: give the structure of the major organic product.
a)
NaI
Br
acetone, 56 °C
b)
S
H2N
Br
NH2
EtOH, 78 °C
c)
O
BocHN
NaOCl, KBr
TEMPO (cat.)
OtBu
CH2Cl2/H2O,
20 °C
OH
d)
O
NHCBz
PhMe,
120 °C
CF3
e)
Me
O
O
Me
f)
Cl
O
(hint: an oxidation)
Al(Oi-Pr)3,
i-PrOH
F3C
O
(it is a salt with Br– as anion)
(hint: catalyzed hydrogen transfer reaction)
MeNH2·HCl (6.0)
NaCNBH3 (1.6)
MeOH
HCl (aq) up to pH 6
(hint: "reductive amination")
Pd/C (cat.), H2 (1 bar)
catalyst poison
THF, 25 °C
(hint: catalytic hydrogenation with "poisoned catalyst")
g)
Br
1. Mg, Et2O
2. CO2 (g)
3. HCl (aq)
h)
O
(hint: organometallic intermediate)
NaCN
NH4Cl
MeOH, H2O
25 °C
(hint: three components are condensing)
[8 P]
Exam Organic Chemistry II
@
TUM Asia 2016
Initials:__________
Problem 7. a) This is the name we give to trivalent, carbon-centered cations:
p.
3
[total 4 P]
_____________________________________________ [1 P]
b) Trivalent carbon-centered cations can undergo three fundamental types of follow-up reactions:
Reaction type 1 (Name)
Problem 8. Carbonyl chemistry:
Reaction type 2 (Name)
[3 P]
Reaction Type 3 (Name)
[8 P]
a) Give two examples for carbonyl compounds, which form stable hydrates (geminal diols) (stable =can be filled
into bottles). (Draw the structures and give names, if you know them. [2 P]
b) Acetone (propanone) is reacted with propane-1,3-dithiol in the presence of an acidic catalyst (e.g., p-TsOH).
Draw a reaction scheme with all starting materials and products! (No mechanism required). [2 P]
c) What happens if we mix aniline (PhNH2) with benzaldehyde (PhCHO)? Draw a reaction scheme with all starting
materials and products! (No mechanism required). [2 P]
d) Which organic compound is formed when heating piperidine [= (CH2)5NH ] with cyclohexanone in the
presence of an acidic catalyst (such as p-TsOH)? Draw a reaction scheme with all starting materials and products!
(No mechanism required). [2 P]
Exam Organic Chemistry II
@
TUM Asia 2016
Initials:__________
p.
4
Problem 9. Draw the intermediates for the following reaction mechanism into the boxes (only one limiting
structure per intermediate required).
[3 P]
O
Ph
Li-CH3
OMe
Li-CH3
H+
H2O
+ 2 Li-CH3
OH
CH3
Ph
CH3
Problem 10. Addition reactions: draw structures of products, starting materials or reagents into the boxes.
HBr
1.
[6]
R
H B
R
2. NaOH (aq), H2O2
organic major product
Br2
O
(Reagent? give structure)
stereochemistry?
O
O
I2
H2O2, MeOH
O
NaHCO3
H2O
NaOH (cat.)
I
Problem 11. [6 P] a) The radical initiators dibenzoyl peroxide (left) and AIBN (right) decompose to give a radical
and a stable product; draw them into the box
[4 P]
CN
O
Ph
O
Ph
O
N
CN
heat
O
heat
N
2
2
2
1
b) Give the expected (constitutional) isomers (not: stereoisomers) for the following radical reaction.
Me
Me
O
Br
N
O
+
AIBN
Note: Check that you have 4 pages and 11 problems on your exam sheets
[2 P]