Post on 04-Jun-2018
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DETERMINACI N DE ESTRUCTURAS ORG NICAS(ORGANIC SPECTROSCOPY)
ESPECTROSCOPA INFRARROJA
Hermenegildo Garca GmezHermenegildo Garca GmezDepartamento de QumicaDepartamento de Qumica
Instituto de Tecnologa QumicaInstituto de Tecnologa Qumica
Universidad Politcnica de ValenciaUniversidad Politcnica de Valencia46022 Valencia46022 Valencia
EE--mail:mail: hgarcia@qim.upv.eshgarcia@qim.upv.es
Telephone: +34 96 387 7807 or ext. 78572/73441Telephone: +34 96 387 7807 or ext. 78572/73441Fax: + 34 96 387 7809Fax: + 34 96 387 7809
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ESPECTROSCOPA DE INFRARROJOS
- Niveles electrnicos- UV-Visible: transiciones de
electrones entre dos estados
electrnicos
- Niveles vibracionales dentrode un nivel electrnico
- Diferencia de energa muchomenor
- Hace falta onda con frecuenciams pequea
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FUNDAMENTAL VIBRATION MODES
- A molecule contains two or more atoms and several bonds- The position of each atom is indicated by three coordinates- If we have n atoms we need 3n coordinates- Three degrees of freedom are wasted in translation
- Degree of freedom for vibration: 3n-3
CzCy
Cx
C
BzB
yB
x
B
Az
AyA
x
A
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VIBRATION OF SINGLE BONDS AND GROUPS
1- A molecule may contain many atoms and bonds. In reality a vibration isnot located in a single bond or group of atoms, but
2- In a simplified model, the rest of the molecule can be considered ashaving infinite mass.
3- The conclusion of the previous point is that each covalent bond hasspecific absorptions irrespective of the rest of the molecule.
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TI POS DE VI BRACIONES
- Stretching: change in the atomic distance- Bending: changes in the bond angles
H2O
CO
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CH2
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1- All the covalent bond has a typical wavenumber irrespective of theconcentration at which the IR spectrum is recorded.
2- Except when there is a hydrogen bond
Hydrogen bonded to an electronegative element
|
HNR
HOR
HCl
HF
3- The intensity of the hydrogen bond depends on the difference of electronegativity
on other inductive effects
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FOTMETRO
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ALCANOS
A: CH2and CH3symmetric and asymmetric stretching
B: CH2bending. Sharp peak at 1370 cm-1corresponds to CH3;
C: rocket band
ALQUENOS
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ALQUENOS
A: CH2and CH3asymmetric and symmetric stretching
B: CH2bending. With several CH3at 1370 cm-1
A: C-H stretching. Above 3000 cm-1C-H (sp2); below 3000 cm-1C-H (sp3)
B: CH2=CH stretching vibration. Not visible in symmetric alkenes
C: CH2bending + CH3
D: CH2=C bending
ALQUINO
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ALQUINO
H IDROCARBURO AROMTICO (ORTOXIL ENO)
ALCOHOLES
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ALCOHOLES
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TER
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EJEMPLO DE I NTERACCIN POR PUENTES DE H IDRGENO
COMPUESTOS CARBONLICOS
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COMPUESTOS CARBONLICOS
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PROBLEMAS PROPUESTOS
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PPRROOBBLLEEMMAA11
PPRROOBBLLEEMMAA22
PPRROOBBLLEEMMAA33
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PP 33
PPRROOBBLLEEMMAA44
PPRROOBBLLEEMMAA55
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PP 55
PPRROOBBLLEEMMAA66
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PPRROOBBLLEEMMAA88
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PPRROOBBLLEEMMAA1100
PPRROOBBLLEEMMAA1111
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PPRROOBBLLEEMMAA1122
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PPRROOBBLLEEMMAA1177
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PPRROOBBLLEEMMAA1188
PPRROOBBLLEEMMAA1199
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PPRROOBBLLEEMMAA2200
PPRROOBBLLEEMMAA2211
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PPRROOBBLLEEMMAA2222
PPRROOBBLLEEMMAA2233
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PPRROOBBLLEEMMAA2244
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