CHM 201
Roadmap Problems
1. An unknown compound (A) has a formula of C7H8. Treatment of A with H2 on
Lindlar's catalyst gives compound B (C7H12). Treatment of A with H2/Pd on carbon
(standard hydrogenation) gives compound C (C7H16). Ozonolysis of B followed by a
Zn/acetic work-up gives pentanedial and 2 equivalents of formaldehyde.
Propose structures for A, B, and C that are consistent with these data.
2. An unknown compound (A) has a formula of C8H12. Treatment of A with H2/Pd-
carbon gives B (C8H16). Treatment of A with H2 on a Lindlar catalyst gives no reaction.
Ozonolysis of A followed by workup with Zn, HOAc affords 2,4-pentanedione and
propanedial shown below.
a) How many double bonds does A have? __________
b) How many triple bonds does A have? __________
c) How many rings does A have? __________
d) Propose structures for both A and B that are consistent with these data.
A B
A (C
7
H
8
)
H
2
on Lindlar's cat. B(C
7
H
12
)
H
2
, Pd on C C (C
7
H
16
)
1) O
3
2) Zn, HOAc
HCCH
2
CH
2
CH
2
CH
OO
HCH
O
2 eq. +
A
H
2
/ Pd on carbo
n
B
C
8
H
12
C
8
H
16
H
2
/ Lindlar's cat. no rxn
1) O
3
2) Zn, HOAc
OO
OO
HH
+