sample-practice-midterm

Part I (10 marks) - Multiple Choice (1 mark each) Place your
answers in the boxes on the answer sheet.

A. The structure of codeine, an alkaloid which is a derivative of
opium and a drug which has been used for centuries as a pain-
killer and sedative, is shown below. Questions 1 to 2 pertain to
this structure.

good
Y
↑
32
U
r

2
1. How many possible stereoisomers of codeine are there?
O
(a) 16 (b) 5 (c) 32 (d) 64 (e) 8

2. What is the configuration of the atom labeled “a” in the
codeine structure?
O
(a) R (b) S (c) E (d) Z (e) not a stereocenter


3. Which is the best nucleophile in methanol?


&
(a) Br
-

Not proti
&
(b) NH 3
-




(c) CH S 3
-



(d)
- CH O
(e) HO
&
3
-
-

ob
C

, 4. Rank the following in INCREASING acidity:


Sp2 Spa Spa




(a) A > B > C
(b) C > B > A
(c) B > A > C
(d) C > A > B
O (e) A > C > B

&
5. Which of the following statements is TRUE regarding the
reaction below?

&
-Nabiy
3



~I- The mixture of products formed is optically active.
-II-The stereoisomer shown is a meso compound.
~
WIII-The stereoisomer shown has a (1R, 2S) configuration.
~IV-The stereoisomers formed are diastereomers relative to each
other.
V-The stereoisomers are formed in a 50:50 ratio.

(a) I and IV only
(b) II, IV and V
(c) III, IV and V
(d) I, II, and IV
O
(e) I, III and IV

6. Which of the following mechanisms does NOT contain an
error?

-