Conjugated Dienes and U V Spectroscopy Some Dienes
- Slides: 77
Conjugated Dienes and U. V. Spectroscopy
Some Dienes
Some Conjugated Molecules
Prevents DNA from Unraveling
Orbital Depiction of Ethylene
Orbital Depiction
DHhydrogenation
Carbocation is Resonance Stabilized
Carbocation Stability
Conjugate Addition of HBr
1, 2 - vs. 1, 4 -Addition
Kinetic and Thermodynamic Products
Kinetic vs. Thermodynamic Control
2 Different 1, 4 - Products Form
Thermodynamic Products
Addition to 1, 3, 5 -Hexatriene
At 0 o. C 1, 2 -addition is favored
At 40 o. C, 1, 4 -addition is preferred
Form more stable carbocation
Allylic Bromination With NBS
Free Radical Mechanism
Mechanism involves the gradual generation of Br 2
Resonance stabilization leads to possibly several products
Diels-Alder Reaction a Pericyclic Reaction
Dienophiles Must be Electron Deficient
Stereochemistry
Bicyclic Adducts endo and exo
Endo Addition
Identify the Diene and Dienophile that gives the Adducts
Two Phosphatase Inhibitors
A Radiosensitizer
Synthesis of LS-5
1, 3 -Butadiene and Ethylene Molecular Orbitals
Proper Orbital Overlap
Overlap Must be Constructive
Unsymmetrical Diels-Alder Reactions
Lewis Acid catalysis in a Diels Alder Reaction
o 2 Intermediate is Preferred
Stereochemistry in endo Addition
Electrocyclic Reaction in Anti-Tumor Agent
Diradical Removes H atoms from Deoxyribose in Cancer Cell
Photochemical [2+2] Cycloaddition Need to Irradiate
Suprafacial – Allowed
Antarafacial - Forbidden
[4+2] is Suprafacial, hence Allowed
Cycloaddition Reactions can be Planned Based on the Number of Pairs of e-’s that Move
Formation of Cyclobutanes
Retro Diels-Alder, followed by Diels-Alder
Intramolecular photochemical [2+2] cycloaddion
Adjacent Thymines (T’s) in DNA • Susceptible to [2+2] cycloaddition in sunlight (UV-B, 290 -320 nm)
Ultraviolet Spectroscopy The absorption of a 171 -nm photon excites an electron from the p bonding MO of ethylene to the p* antibonding MO.
Conjugated Dienes Absorb Energy in UV Region
UV Spectrum of Isoprene lmax = 222 nm
Conjugation lowers the energy differences between the HOMO and LUMO energy levels, and so conjugated dienes absorb at longer wavelengths than isolated dienes, and trienes absorb at longer wavelengths than dienes, etc. Alkyl group substitution on double bonds also causes absorption to occur at longer wavelengths.
HOMO-LUMO Gap lessens with increased conjugation
Woodward-Fieser Rules for Predicting lmax Double bond extending conjugation Exocyclic double bond 30 nm Alkyl group 5 nm Cl, Br 5 nm OH, OR 6 nm SH, SR 30 nm NH 2, NHR, NR 2 60 nm 5 nm
Predict lmax in U. V. Spectrum
Determination of lmax
Determination of lmax
Determination of lmax
- Conjugated dienes
- Conjugated bilirubin vs unconjugated
- Bilirubin metabolism pathway
- Conjugated protein
- Fungi uses
- Economic importance of yeast
- Conjugated protein
- Conjugated bilirubin vs unconjugated
- Conjugated protein
- Cumulated diene
- Conjugate abrir
- Conjugated verbs examples
- Conjugated unsaturated systems
- Re conjugation
- Spanish verb
- Site:slidetodoc.com
- Svjetlana kalanj bognar
- 4:14 commenting on family members
- Jaundice introduction
- Conjugated hyperbilirubinemia
- Conjugated
- Contact and non contact forces
- Some trust in horses
- They say it only takes a little faith to move a mountain
- They say it only takes a little faith to move a mountain
- Ice cream is countable
- Fire and ice diamante poem
- Some say the world will end in fire some say in ice
- Contoh permainan bebas dienes
- Proposal alat peraga matematika
- Dienes
- Effetto dienes
- Konstruktivitás
- Selection rule for electronic transition
- Types of dienes
- Bloques de dienes
- Uv spectra of dienes
- Uv spectra of dienes
- Preparation of dienes
- Follicular conjunctivitis
- Dienes blocks examples
- Terahertz spectroscopy principles and applications
- Ir spectroscopy definition
- Difference between ir and raman spectroscopy
- Difference between ir and raman spectroscopy
- Advantages and disadvantages of spectroscopy
- Stretching and bending vibrations in ir spectroscopy
- Advantages and disadvantages of spectroscopy
- Spectroscopy and spectrophotometry
- Applications of uv spectroscopy
- What is spectroscopy
- Stretching and bending vibrations in ir spectroscopy
- Principle of atomic absorption
- Difference between atomic and molecular spectroscopy
- Erzeng
- Types of spectroscopy pdf
- What is spectroscopy
- Absorbance chemistry
- Ir sample preparation
- Prinsip kerja aas adalah
- Objectives of spectroscopy
- Beryllium pes
- Nir spectroscopy instrumentation
- Principal of mass spectroscopy
- Gross selection rules
- Draw a photoelectron spectrum for aluminum
- Dept nmr spectroscopy
- Raman spectroscopy basics
- Ortec renaissance
- Infrared spectroscopy
- Spectroscopy equations
- Nitro functional group ir spectrum
- Interferogram
- Advantages of flame emission spectroscopy
- Dispersive ir spectroscopy
- Nitro group ir peak
- Theory of atomic absorption spectroscopy
- Principle of fluorescence spectroscopy