作者yutsao (一包)
看板LifeSci_100
标题[有机] Fischer's Proof of D-Glucose
时间Thu Jun 7 12:04:47 2012
下课不少同学来问我这个部分，打个（或许）比较好懂的整理给大家。
期末考加油。
Part I. Reactions used in Fischer's proof
1. Nitric acid oxidation
CHO COOH
| HNO3 |
(CHOH)n --------> (CHOH)n
| |
CH2OH COOH
aldose aldonic acid
2. Kiliani-Fischer synthesis
CN CN
CHO | |
| HCN H-C-OH HO-C-H
(CHOH)N --------> | + |
| (CHOH)n (CHOH)n
CH2OH | |
CH2OH CH2OH
3. Ruff degradation
CHO
| CHO
CHOH ------> |
| ------> (CHOH)n + CO2
(CHOH)n |
| CH2OH
CH2OH
==============================================================================
Part II. Fischer's proof of the configuration of D-(+)-glucose
1. It's a D-sugar, so there are 8 (= 2^3) possibilities:
1 2 3 4 5 6 7 8
CHO CHO CHO CHO CHO CHO CHO CHO
| | | | | | | |
H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH HO-C-H
| | | | | | | |
H-C-OH H-C-OH HO-C-H HO-C-H H-C-OH H-C-OH HO-C-H HO-C-H
| | | | | | | |
H-C-OH H-C-OH H-C-OH H-C-OH HO-C-H HO-C-H HO-C-H HO-C-H
| | | | | | | |
H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH
| | | | | | | |
CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH
2. After adding HNO3, it should be an optically active compound.
X X
1 2 3 4 5 6 7 8
CHO CHO CHO CHO CHO CHO CHO CHO
| | | | | | | |
H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH HO-C-H
| | | | | | | |
H-C-OH H-C-OH HO-C-H HO-C-H H-C-OH H-C-OH HO-C-H HO-C-H
| | | | | | | |
H-C-OH H-C-OH H-C-OH H-C-OH HO-C-H HO-C-H HO-C-H HO-C-H
| | | | | | | |
H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH
| | | | | | | |
CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH
3. We get an optically active acid after degradation followed by HNO3
X
X X X X
1 2 3 4 5 6 7 8
CHO CHO CHO CHO CHO CHO CHO CHO
| | | | | | | |
H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH HO-C-H
| | | | | | | |
H-C-OH H-C-OH HO-C-H HO-C-H H-C-OH H-C-OH HO-C-H HO-C-H
| | | | | | | |
H-C-OH H-C-OH H-C-OH H-C-OH HO-C-H HO-C-H HO-C-H HO-C-H
| | | | | | | |
H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH H-C-OH
| | | | | | | |
CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH
HCN
4. (-)-Arabinose -----> Glucose + Mannose
No.3 and
No.4 might be glucose and mannose.
or
No.7 and
No.8 might be glucose and mannose
HNO3
5. Glucose + Mannose ------> Both are optically active
HNO3
No.7 ------> Optically inactive
So No.3 and No.4 are glucose and mannose
6. L-glucose + HNO3 ------> Glucaric acid ┐
├ The same
D-glucose + HNO3 ------> Glucaric acid ┘
It turns out that No.3 is glucose and No.4 is mannose.
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