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2014年化学竞赛——2005年第37届IChO预备试题答案(英文)13-18有机化学


Answer 13: Carbocation and Aromaticity
13-1 13-2 (CH3)3C SbF6
+ -

Spectrum I: (CH3)3CF in SbF5 6 π electrons yes (a) A singlet at δ 9.17

13-3 13-4

1

3-5 13-6

O OH O OH or O OH

O OH

O OH

O OH

O OH

O OH

13-7

D

O Fe O 3

Answer 14: Photochemical Ring Closure and Opening
14-1 (2E,4Z,6Z)-octatriene

14-2

E

14-3

F

95

H3C H3C H3C H HO H3C

CH3

14-4

I
O O O

14-5

No.

Answer 15: Stereochemistry
15-1 (2S,3S)

15-2 15-3

X= CH3, Y = PPh2 36% β

15-4 15-5

HO O HO HO OH OH

15-6
O H HO H H CH OH H OH OH CH2OH

15-7

none
96

15-8

99:1

15-9

0

Answer 16: Organic Synthesis
16-1
I A=

B=

HO

C=

16-2
D= Br

O E= Br

F=

Br

F G = C8H17O

F

97

Answer 17: Spectroscopy and Polymer Chemistry
17-1 C4H6O2 C=O group

17-2

17-3

A

H H H
17-4 B
In O

O O CH3

n O O O O O

In: initiator

17-5

Organic reactions that could transform acetate to alcohol such as acid or base hydrolysis, alcoholysis, or LiAlH4 reduction.

17-6

There are 100 units/molecule.
99

However, the last one does not contain chiral center,

therefore, there are 99 chiral centers and each of which would have R or S configuration. Totally there will be 2 stereoisomers, including enantiomers and diastereomers.
99

Therefore, the number of pairs of enantiomers is 2 /2 = 298. 17-7 C

H H H
17-8 E: CO2 G:
OH n

O O

CH3

F: (CH3)2C=CH2 H: (CH3)2CBr-CH2Br

17-9

I: (d)
98

Answer 18: Crown Ether and Molecular Recognition
18-1 B
O O O O O O

18-2

(c) To remove the tetrahydropyran group

18-3

C

D

O

O NH O

NH
O O Cl Cl O O

O O O

E

F

O

O

O O O

O O N O

NH

NH

N O O

O

O

18-4

(b) A high dilution condition is employed in order to inhibit polymer formation.

18-5

Curve I to I; Curve II to G; Curve III to H

99


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