reactions in critical water
TRANSCRIPT
1
Organic Reactions in Critical water
ByKARTHIK NOONEY
M.S. (Pharm.)III Semester
Dept. of Medicinal Chemistry
Contents
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Phase Diagram of Water Properties of Super/Near Critical water Organic reactions in Super/Near Critical water
Alkylation reactions Nazarov cyclisation Disproportionation reactions Organometallic reactions Rupe rearrangement Decomposition reactions
Conclusions
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374 � C
221.2 bar
Chem. Rev. 2007, 107, 2786-2820
Phase diagram of water
4Chem. Rev. 2007, 107, 2786-2820
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Superheated waterSub critical waterPressurized hot water
Under Pressure and Temperature between 100 �C to 374 �C
Near Critical water Above 300 �C
Super Critical water Above 374 �C
Tetrahedron 2012 , 68, 949-958
6Angew. Chem. Int. Ed. 2005, 44, 2672-2694
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Angew. Chem. Int. Ed. 2005, 44, 2672-2694
PROPERTIES
Density(0.32 g/cm3)
Dielectric constant
(5)
Ionization constant
Heat capacity
Anti aqueous property
Medium
Accelerator
Miscibility
Oxidation(99.9%)
8Li, C. J.; Chan, T. H. Comprehensive Organic Reactions in Aqueous Media. John Wiley & Sons: 2007; pp 1-12
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Pressure influence
SCW reactor
New reaction pathways
Ecologically benign solvent
Extraction
Chemical reactions
Tetrahedron 2012 , 68, 949-958
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Alkylation ReactionsOH
OH
OH OH
H2O
50 h, 275 oC
O. O
H.
O
H OOR
ROO.
AIChE J 1998, 44, 2080-2087
OH
ROO.O.
ROOH
Antioxidant mechanism of sterically hindered phenols
Reaction of phenoxy radical from antioxidant mechanism with a second free radical
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NAZAROV CYCLISATIONO O
R2R1
O
R1
R2
R1 R2
H+ (or)
2 3
R1
O
R2R1
OH
R2
HO R2
R1
O R2
R1
HO R2
R1
H2O R2
R1
R2
R1
R2
R1
H+
1. -H+
2.isomerization
1. ROH2. -H+
OR
1. isomerization
2. H+H2O
R2
R1
isomerization
-R+
deprotonation ordeacylation
OR OR
OO
1 45 2
6 7 8
93
R
J. Org. Process Res. Dev. 2005, 9, 629-633
Mechanism
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Disproportionation reactions
Tetrahedron Lett. 2002, 43, 5859–5861
Ph Ph
OH
Ph Ph Ph Ph
O Ph
PhO
Ph
Ph
H2O
Ar1a 2a 3a 4a
13Tetrahedron Lett. 2002, 43, 5859–5861
Ar1 Ar2
XAr1 Ar2 Ar1 Ar2
OSupercritical water
X=OH, NH2
435 oC, 0.30g/cm3, 90min, Ar
Ph
PhO
Ph
PhPh Ph Ph Ph
OSupercritical water
435 oC, 0.30g/cm3, 90min, Ar
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R SiMe2X R HSupercritical Water
C-Si BOND CLEAVAGER= aryl, alkenyl, allyl, and alkylX=OH, Cl, OEt, OSiR'3, SiMe3, Me
Organometallic reactions
R
SiMe3
R
HSupercritical Water
390 OC, 27 MPa30 min
1 (R=H)2 (R=Bu) R = H:72% yield
R = Bu: 91% yield
C10H21 - n SiMe3
Supercritical Water
390 OC, 27 MPa5 min67% yield
C10H21 - n
other dodecenes
Supercritical Water
390OC, 27 MPa3 h
73% yield
C10H21 - n
other dodecenes
C9H19 - n SiMe3
J. Am. Chem. Soc, 2003, 125, 6058-6059
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Rupe Rearrangement
45% yield
Near critical waterOH O
OH OH2
H
H
H
OH
H
H
O
H+ -H20
dehydration
-H+
protonationH+
H2O..
H+
Tautomerization
Tetrahedron 2012 , 68, 949-958Jie Jack Li. Name Reactions. Springer: 2005; pp 346
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Decomposition Reactions
OHHO OH OHSCW
J. Org. Chem. 2004, 69, 4724-4731Tetrahedron 2012 , 68, 949-958
PVC CO2 + H2O + HCl (NaCl)(O2, NaOH)
SCW
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B
OHO
HO
O
OHHO
BH+
O O
OH
HO
BH+0
1
2
3
4
5
IPP
BPAPhenol
QM
J. Org. Chem. 2004, 69, 4724-4731
General Base- Catalysed Mechanism for BPA Cleavage in HTW
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AH
OH2HOHO
OHHO
OH2
HOBPA
OH
IPP
Phenol
A
A
J. Org. Chem. 2004, 69, 4724-4731
General Acid- Catalysed Mechanism for BPA Cleavage in HTW via Protonation of the
Hydroxyl Group
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Conclusions
High temperature waterUnique solvent that has gained much attention as a medium of conductance
Because physicochemical properties are dramatically different
For instance, decrease in the relative permittivity and degree of hydrogen bonding
Small organic molecules achieve water solubility The ionic product Kw is upto 3 order of magnitude greater than that of 20 ˚C water
Simultaneous decrease in pH and pOH
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Thank You
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Questions?
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Given the following reactionsa. Cannizaro reactionb. Rupe rearrangementc. Wurtz reactiond. Benzidine rearrangemente. Tischenko reactionf. Nazarov cyclization
Q. Out of the following given options find the one which corresponds to a set of being strictly not a disproportionation reaction
1. a&b2. c&d3. f&b4. c&f5. a&e