Molecular Oxygen Reactions（PDFファイル）

Molecular Oxygen Reactions
2014,11,15
D3 Masafumi Ando
Contents
Photochemical Reaction
σ
π
E
LUMO
HOMO
σ
π
Photochemical Reaction
σ∗ 2p
π∗ 2p
π 2p
E
σ 2p
σ∗ 2s
σ 2s
σ∗ 1s
σ 1s
3Σ -O
g 2
1Δ O
g 2
1 Σ +O
g
2
Ameta, S. C.; Punjabi, P. B.; Chobisa, C. S.; Mangal, N.; Bhardwaj, R. Asian J. Chem. Rev. 1990, 1, 106–124.
Potential Energy (kcal)
Photochemical Reaction
Internuclear Distance (Å)
Derosa, M. C.; Crutchley, R. J. Coord. Chem. Rev. 2002, 233–234, 351–371.
Photochemical Reaction
S2
T2
internal conversion
internal conversion
S1
intersystem crossing
T1
phosphorescene
fluorescene
S0
S:
0:
1, 2 :
, T:
Photochemical Reaction
Substrate
Type I
P(S 1 )
radicals
or
radical ions
intersystem crossing
P(T1)
Type II
fluorescene
phosphorescene
3O
2
P(S 0)
P : Photosensitizer
S:
, T:
0:
1, 2 :
Ethirajan, M.; Chen, Y.; Joshi, P.; Pandey, R. K. Chem. Soc. Rev. 2011, 40, 340–362.
1O
2
Photochemical Reaction
Dye
Triplet energy E T
(kcal/mol)
Rose bengal
Fluorescein
Eosin blue
Methylene blue
Erythrosin blue
I
-O
42.0
47.2
45.5
32.0
-O
O
I
I
I
-O
H 2O
0.76
0.75
0.03
0.52
O
ΦΔ (EtOH)
ΦΔ (CH3OH)
0.68
0.03
0.37
0.52
0.69
0.76
0.1
0.5
Br
O
-O
Br
O
O
O2N
COO -
COO Cl
Rose Bengal
D 2O
0.63
I
O
ΦΔ (aqueous)
NO 2
COO -
I
O
O
I
I
COO -
Erythrosin B
Fluorescein
Eosin Blue
Me 2N
S
N
Methylene Blue
NMe 2
Singlet Oxygen Reactions
OOH
1O
2
allylic hydroperoxide
1O
O
2
O
endoperoxide
EtO
EtO
1O
OEt
O
2
O
EtO
Δ
H
O
EtO
1,2-dioxetane
Schenck, G. O.; Ziegler, K. Naturwissenschaften. 1944, 32, 157.
Denny, R. W.; Nickon, A.; Org. React. 1973, 20, 133.
Frimer, A. A. Chem. Rev. 1979, 79, 359–387.
Triplet Oxygen Reactions
1O
k = 4.7•10 9
(M-1s-1)
O
O
2
helianthrene
(HEL)
I shows the reaction spectrum of the dark reaction of HEL in
air-saturated toluene:
(a) spectrum of HEL at t = 0
(b) spectrum of the solution after t ≈ 2 weeks
heliannthrene endoperoxide
(HELPO)
II shows the reaction spectrum of the self-sensitized photooxygenation of
HEL in air-saturated toluene leading to HELPO formation:
(a) before irradiation with visible light (HEL spectrum), ε563 = 22000 M-1
cm-1
(b) after complete bleaching of the solution (HELPO spectrum)
Seip, M.; Brauer, H.-D. J. Am. Chem. Soc. 1992, 114, 4486–4490.
Triplet Oxygen Reactions
k diff
HEL + 3O2
k-diff
3
HEL••• 3O2
(3C)
4
k diff
HEL•••1O2
(1C)
HEL + 1O2
k-diff
15
5
6
7
16
9
HEL-O-O
(3D)
HEL(T1 ) +
3O
kET
2
10
12
{HEL(S0):1O2}
11
1HELPO
8
HEL-O-O
(1Z)
HEL(S 0) + 1O2
13
(80%)
14
HELPO
TME (tetramethylethylene) は1O2捕捉剤
TME過剰の条件下でも反応速度は影響なし
→1O2は反応に関与していない
（[HEL] = 8 × 10–5 M, [TME] = 0.1 M, kTME = 5 × 107 M–1 s–1）
(20%)
Triplet Oxygen Reactions
k diff
HEL + 3O2
k-diff
3
HEL••• 3O2
(3C)
4
k diff
HEL•••1O2
(1C)
HEL + 1O2
k-diff
15
5
6
7
16
9
HEL-O-O
(3D)
10
HEL-O-O
(1Z)
13
12
11
8
1HELPO
14
TME (tetramethylethylene) は1O2捕捉剤
TME過剰の条件下でも反応速度は影響なし
→1O2は反応に関与していない
（[HEL] = 8 × 10–5 M, [TME] = 0.1 M, kTME = 5 × 107 M–1 s–1）
O
DPBF，TPを1O2捕捉剤として用いる検討
（DPBF，TPの酸化体は反応条件下安定）
酸化物は観測されない
→HELPOの熱分解によって1O2は生成していない
1,3-Diphenylisobenzofuran
Triplet Oxygen Reactions
k diff
HEL + 3O2
k-diff
3
HEL••• 3O2
(3C)
k diff
HEL•••1O2
(1C)
4
k-diff
15
5
6
7
16
9
HEL-O-O
(3D)
HEL-O-O
(1Z)
10
13
12
11
8
1HELPO
14
2,6-di-tert-Butyl-4-methylphenolをラジカル捕捉剤として添加
→ 反応速度は影響なし
→ •HEL-O-O•のようなoxygen biradicalは律速段階に含まれない
k2
HEL + 3O2
HELPO
k-2
k2 = 1.4 × 10-3 (in CH3CN)，0.5 × 10-3 (in toluene)
→ HELPOは極性の高い遷移状態を経由することが示唆される
HEL + 1O2
Triplet Oxygen Reactions
溶媒をtolueneからiodobenzeneに変更
→k2 は5.3倍に増加
（external heavy atom effect: intersystem crossingが加速）
→spinの反転がHELPO生成の律速段階に含まれる
Plot of the rate constant k2 for the thermal HELPO formation as
a function of iodobenzene concentration (v/v) in air- saturated
toluene-iodobenzene mixture (T = 298 K).
Triplet Oxygen Reactions
HEL
HELPO
HELの歪んだ構造により3O2との反応が進行（1O2とも反応が進行）
Triplet Oxygen Reactions
k diff
HEL + 3O2
k-diff
3
HEL••• 3O2
(3C)
4
k diff
HEL•••1O2
(1C)
15
5
6
7
16
9
HEL-O-O
(3D)
10
11
HEL-O-O
(1Z)
13
12
1HELPO
8
14
k-diff
HEL + 1O2
Triplet Oxygen Reactions
O
O
OH
O
O
OH
OH
CH3CN
or CD3CN
O2
(balloon)
CH3CN, rt
O
O
O
OOH
P(OR) 3
EtOH, rt
Riahi, A.; Muzart, J.; Abe M.; Hoffmann, N. New J. Chem. 2013, 37, 2245.
OH
Triplet Oxygen Reactions
H
O
O
O
mol -1
ΔG298 in kcal
(in acetonitrile)
at (U)B3LYP/6-31G(d)
27.4 (27.0)
TS1
26.7 (26.3)
H
H
O
H
O
O
O
O
O
ISC
O
O
O
0
T-DR
OH
S-DR
–13.3 (–14.9)
O
+ O2
one-center
spin-flip
HO
O
Summary

Download Report