The document provides an overview of basic principles of photochemistry. It discusses key concepts like photochemical processes, importance of photochemistry, terminology used in photochemistry including charge transfer transitions, multiplicity, internal conversion and more. It also explains photochemical reaction processes like dissociation, direct reactions, isomerization, energy transfer and quenching. Laws of photochemistry, quantum yield, Jablonski diagram, Franck-Condon principle, electronic transitions, mechanisms of photosensitization and applications of photosensitization are summarized.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors such as the solvent, substituents on the carbonyl compound or alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize various natural products and allows formation of oxetane rings, which are present in several biologically active compounds.
Thermal reactions involve absorption or evolution of heat, while photochemical reactions require light to occur. Thermochemical reactions can take place in dark conditions, while photochemical reactions only occur in the presence of light. Temperature significantly affects thermochemical reaction rates, while light intensity mainly influences photochemical reaction rates. The free energy change of a thermochemical reaction is always negative, but a photochemical reaction's free energy change may not be negative. Photochemical reactions involve electronic excitation from light absorption. Excited states can undergo chemical reactions or transfer energy through intersystem crossing to more stable triplet states. Photochemical reactions include photoreduction, photoaddition, and photo-rearrangement reactions of carbonyl compounds and alkenes.
Photoelectron spectroscopy
- a single photon in/ electron out process
• X-ray Photoelectron Spectroscopy (XPS)
- using soft x-ray (200-2000 eV) radiation to
examine core-levels.
• Ultraviolet Photoelectron Spectroscopy (UPS)
- using vacuum UV (10-45 eV) radiation to
examine valence levels.
Photochemistry of alkenes can produce various reaction types upon irradiation with light, including isomerization, cyclization, and rearrangement. Isomerization reactions can involve direct cis-trans isomerization of alkenes or can be sensitized using triplet photosensitizers. Cyclization reactions are either concerted or proceed through a biradical intermediate. Rearrangement reactions of 1,4-dienes follow a D-π-methane rearrangement through a concerted 1,2-shift, while 1,5-dienes undergo a stereospecific [3,3] sigmatropic Cope rearrangement through a cyclic transition state.
Photochemistry is the study of chemical reactions initiated by light. Light provides the energy needed for photochemical reactions. There are several types of photochemical reactions including photo-oxidation, photo-addition, and photo-fragmentation. Photochemical reactions have specific characteristics - each molecule absorbs only one photon, the rate depends on light intensity, and the change in free energy may be positive or negative. Photochemistry is important for processes like vision, vitamin D formation, photosynthesis, and polymerization.
The video lecture for this presentation is available at the following link on YouTube
https://youtu.be/3sxal579RNM
The presenation will be useful for Ug/PG (Chemistry) students
The document discusses various photooxidation and photoreduction reactions in organic synthesis. It begins by introducing photochemistry and defining related terms. It then provides examples of photoreduction of ketones and aromatic hydrocarbons. Examples of photooxidation reactions include the conversion of trans-stilbene to phenanthrene and the synthesis of benzoic acids via aerobic photooxidation. The document also describes the mechanism and advantages of using a CdIn2S4 photocatalyst for selective photosynthesis of organic aromatic compounds under visible light.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors such as the solvent, substituents on the carbonyl compound or alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize various natural products and allows formation of oxetane rings, which are present in several biologically active compounds.
Thermal reactions involve absorption or evolution of heat, while photochemical reactions require light to occur. Thermochemical reactions can take place in dark conditions, while photochemical reactions only occur in the presence of light. Temperature significantly affects thermochemical reaction rates, while light intensity mainly influences photochemical reaction rates. The free energy change of a thermochemical reaction is always negative, but a photochemical reaction's free energy change may not be negative. Photochemical reactions involve electronic excitation from light absorption. Excited states can undergo chemical reactions or transfer energy through intersystem crossing to more stable triplet states. Photochemical reactions include photoreduction, photoaddition, and photo-rearrangement reactions of carbonyl compounds and alkenes.
Photoelectron spectroscopy
- a single photon in/ electron out process
• X-ray Photoelectron Spectroscopy (XPS)
- using soft x-ray (200-2000 eV) radiation to
examine core-levels.
• Ultraviolet Photoelectron Spectroscopy (UPS)
- using vacuum UV (10-45 eV) radiation to
examine valence levels.
Photochemistry of alkenes can produce various reaction types upon irradiation with light, including isomerization, cyclization, and rearrangement. Isomerization reactions can involve direct cis-trans isomerization of alkenes or can be sensitized using triplet photosensitizers. Cyclization reactions are either concerted or proceed through a biradical intermediate. Rearrangement reactions of 1,4-dienes follow a D-π-methane rearrangement through a concerted 1,2-shift, while 1,5-dienes undergo a stereospecific [3,3] sigmatropic Cope rearrangement through a cyclic transition state.
Photochemistry is the study of chemical reactions initiated by light. Light provides the energy needed for photochemical reactions. There are several types of photochemical reactions including photo-oxidation, photo-addition, and photo-fragmentation. Photochemical reactions have specific characteristics - each molecule absorbs only one photon, the rate depends on light intensity, and the change in free energy may be positive or negative. Photochemistry is important for processes like vision, vitamin D formation, photosynthesis, and polymerization.
The video lecture for this presentation is available at the following link on YouTube
https://youtu.be/3sxal579RNM
The presenation will be useful for Ug/PG (Chemistry) students
The document discusses various photooxidation and photoreduction reactions in organic synthesis. It begins by introducing photochemistry and defining related terms. It then provides examples of photoreduction of ketones and aromatic hydrocarbons. Examples of photooxidation reactions include the conversion of trans-stilbene to phenanthrene and the synthesis of benzoic acids via aerobic photooxidation. The document also describes the mechanism and advantages of using a CdIn2S4 photocatalyst for selective photosynthesis of organic aromatic compounds under visible light.
The document discusses charge transfer complexes and the different types of charge transfer that can cause color in transition metal complexes. It explains that ligand to metal charge transfer and metal to ligand charge transfer can produce color when pi donor or accepting ligands are present with metals lacking or having low oxidation state d-electrons, respectively. As an example, it describes the metal to ligand charge transfer observed in the spectra of the tris(bipyridine)ruthenium(II) dichloride complex.
This document provides an overview of the topic of photochemistry. It discusses key concepts like quantum yield, which is a measure of reaction efficiency, and how it is experimentally determined. Diagrams like the Jablonski diagram are also mentioned. Specific photochemical processes covered include fluorescence, phosphorescence, chemiluminescence, and bioluminescence. Finally, some applications of photochemistry are listed, along with a bibliography for further reading.
This document discusses theories of unimolecular reaction kinetics, including the Lindemann-Christiansen theory, Hinshelwood theory, RRK theory, and RRKM theory. It notes limitations of earlier theories in explaining experimental data. The RRKM theory, developed by Marcus in 1951-1952, redefined the RRK treatment and addressed prior limitations. RRKM theory is now widely used to interpret thermal and photochemical reactions and allows calculating reaction rates from known vibrational frequencies of molecules.
An overview of the use of the Marcus Theory to calculate the energies of transition states.
Contributed by: Elizabeth Greenhalgh, Amanda Bischoff, and Matthew Sigman, University of Utah, 2015
Pericyclic reactions involve the formation and breaking of bonds in a concerted cyclic transition state. They can be classified as cycloadditions, electrocyclic reactions, sigmatropic rearrangements, cheletropic reactions, or group transfers. Examples of important pericyclic reactions discussed include the Diels-Alder reaction, 1,3-dipolar cycloadditions, Claisen rearrangement, and electrocyclic ring openings and closings. These reactions are useful in synthesis and occur in biological systems.
Electronic spectra of metal complexes-1SANTHANAM V
This document discusses electronic spectra of metal complexes. It begins by relating the observed color of complexes to the light absorbed and corresponding wavelength ranges. It then discusses the use of electronic spectra to determine d-d transition energies and the factors that affect d orbital energies. Key terms like states, microstates, and quantum numbers are introduced. Configuration, inter-electronic repulsions described by Racah parameters, nephelauxetic effect, and spin-orbit coupling are explained as factors that determine the splitting of energy levels. Russell-Saunders and j-j coupling are outlined as approaches to describe spin-orbit interactions in light and heavy elements respectively.
Alkenes by absorption of light activated to higher energy singlet & triplet state and undergoes chemical reaction. These reactions are mainly:- 1. Cis - trans isomerization
2. Dimerization
3. Cycloaddition
The document summarizes the dienone-phenol rearrangement, which is the acid- or base-catalyzed migration of alkyl groups in cyclohexadienones, resulting in highly substituted phenols. It was first described in 1893 for the rearrangement of santonin to desmotroposantonin under acidic conditions, but was more fully characterized in 1930. The rearrangement requires only moderately strong acids and is exothermic. It proceeds by a [1,3] sigmatropic migration of C-C bonds, which actually occurs through two subsequent [1,2] alkyl shifts. Depending on the migrating group, other rearrangements such as [1,2], [1,3], [
1. Reaction mechanisms can be determined through various methods like identifying products, detecting intermediates through isolation, trapping or labeling studies, studying the effects of catalysts and acids, and performing kinetic studies.
2. Isotope labeling and crossover experiments involve using isotopically labeled reactants to determine whether reaction pathways are intra- or intermolecular. Kinetic isotope effects also provide information about which bonds are broken or formed in the rate-determining step.
3. Acid and base catalysis can indicate whether proton transfer is involved in the rate-determining step. General acid catalysis means proton transfer is rate-determining while specific catalysis means it is not.
This document presents information on the Tanabe-Sugano diagram, which is used in coordination chemistry to predict absorptions in the UV-visible and IR spectra of coordination compounds. It was developed by Yukito Tanabe and Satoru Sugano in 1954 to explain the absorption spectra of octahedral complex ions. The diagram plots orbital energy as a function of the Racah parameter B versus the ligand field splitting parameter Δo/B. It can be used to determine the ordering of electronic states and predict possible electronic transitions based on parameters like Δo, Racah parameters B and C, symmetry rules, and term symbols of electronic configurations. The diagram has advantages over earlier Orgel diagrams in that it can be applied to
Photo-oxidation involves the oxidation of materials under the influence of light or radiant energy. It requires a photosensitizer that absorbs light strongly and can transfer energy to reactants. Main steps include initiation by excitation of the photosensitizer, propagation by reaction of radicals formed with oxygen, and termination. Specific photo-oxidation reactions include the formation of peroxy compounds, cyclic peroxides from conjugated dienes, oxidative coupling of aromatics, and formation of polycyclic compounds and changes to polymers.
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
photo redox reactions
Wilkinson's catalyst, chlorotris(triphenylphosphine)rhodium(I), is an organometallic catalyst that is very effective for the homogeneous hydrogenation of unsaturated compounds at room temperature and atmospheric pressure. Its mechanism involves five steps - ligand dissociation, oxidative addition of hydrogen, alkene coordination, migratory insertion, and reductive elimination - known as Tolman's catalytic cycle. This cycle allows the catalyst intermediates to shuttle between 18 and 16 electron configurations, making the electron shifts energetically favored.
IR spectroscopy . P.K.Mani, BCKV, West Bengal, IndiaP.K. Mani
This document provides an introduction to infrared (IR) spectroscopy, including:
1. IR spectra originate from the vibrational and rotational motions of molecules, which can absorb IR radiation if there is a change in dipole moment.
2. Molecules absorb specific frequencies that correspond to their natural vibrational frequencies. Stretching and bending vibrations within different functional groups absorb in characteristic regions of the IR spectrum.
3. IR spectroscopy can be used to identify molecules based on their absorption fingerprints between 400-1300 cm-1, which are influenced by the whole molecular structure.
This document provides an overview of 2D NMR spectroscopy techniques, specifically HETCOR. It discusses the principles behind 2D NMR, describing how it plots data in two frequency axes rather than one, providing more information about a molecule's structure. It then explains the four periods that occur in a 2D NMR experiment: preparation, evolution, mixing, and detection. The document focuses on HETCOR, describing it as a heteronuclear experiment that provides correlations between different nuclei like protons and carbons. Examples of HETCOR spectra are provided to show how they indicate couplings between protons and the carbons they are attached to. Related techniques like HSQC and HMBC are also briefly described.
Photochemistry
ELECTROMAGNETIC SPECTRUM
LAW GOVERNING ABSORPTION OF LIGHT
LAW OF PHOTOCHEMISTRY
Grotthurs-Drapper law.
Einstein Stark law of photochemical equivalence
ELECTRONIC TRANSITIONS
Jablonski Diagram
QUANTUM YIELD
Use Of Photochemistry
Chemistry of vision
Photosynthesis in plant
Formation of Vitamin D
Fluorescent dyes in traffic
Photodynamic therapy
Spectroscopy for Pharmaceutical Analysis and Instrumental Method of Analysis....Yunesalsayadi
This document discusses electronic spectroscopy and molecular spectroscopy. It begins by explaining that electronic spectroscopy relies on quantized energy states of electrons and involves electronic transitions between principal quantum states when electrons absorb enough energy. It then discusses different regions of the electromagnetic spectrum and how spectrometers are used to analyze absorption and emission spectra. The rest of the document discusses molecular spectroscopy, deviations from Beer's law, and applications of using spectrophotometry and Beer's law to determine equilibrium constants.
Fluorescence spectroscopy is based on the principle of fluorescence emission that occurs when a molecule absorbs light and is excited to a higher electronic state. The excited molecule then relaxes to the ground state via vibrational relaxation and emission of a photon. The emitted light has a longer wavelength than the absorbed light due to energy losses in vibrational relaxation, following Stokes' rule. Fluorescence spectroscopy can provide information about molecular structure and interactions through analysis of fluorescence emission spectra.
The document discusses charge transfer complexes and the different types of charge transfer that can cause color in transition metal complexes. It explains that ligand to metal charge transfer and metal to ligand charge transfer can produce color when pi donor or accepting ligands are present with metals lacking or having low oxidation state d-electrons, respectively. As an example, it describes the metal to ligand charge transfer observed in the spectra of the tris(bipyridine)ruthenium(II) dichloride complex.
This document provides an overview of the topic of photochemistry. It discusses key concepts like quantum yield, which is a measure of reaction efficiency, and how it is experimentally determined. Diagrams like the Jablonski diagram are also mentioned. Specific photochemical processes covered include fluorescence, phosphorescence, chemiluminescence, and bioluminescence. Finally, some applications of photochemistry are listed, along with a bibliography for further reading.
This document discusses theories of unimolecular reaction kinetics, including the Lindemann-Christiansen theory, Hinshelwood theory, RRK theory, and RRKM theory. It notes limitations of earlier theories in explaining experimental data. The RRKM theory, developed by Marcus in 1951-1952, redefined the RRK treatment and addressed prior limitations. RRKM theory is now widely used to interpret thermal and photochemical reactions and allows calculating reaction rates from known vibrational frequencies of molecules.
An overview of the use of the Marcus Theory to calculate the energies of transition states.
Contributed by: Elizabeth Greenhalgh, Amanda Bischoff, and Matthew Sigman, University of Utah, 2015
Pericyclic reactions involve the formation and breaking of bonds in a concerted cyclic transition state. They can be classified as cycloadditions, electrocyclic reactions, sigmatropic rearrangements, cheletropic reactions, or group transfers. Examples of important pericyclic reactions discussed include the Diels-Alder reaction, 1,3-dipolar cycloadditions, Claisen rearrangement, and electrocyclic ring openings and closings. These reactions are useful in synthesis and occur in biological systems.
Electronic spectra of metal complexes-1SANTHANAM V
This document discusses electronic spectra of metal complexes. It begins by relating the observed color of complexes to the light absorbed and corresponding wavelength ranges. It then discusses the use of electronic spectra to determine d-d transition energies and the factors that affect d orbital energies. Key terms like states, microstates, and quantum numbers are introduced. Configuration, inter-electronic repulsions described by Racah parameters, nephelauxetic effect, and spin-orbit coupling are explained as factors that determine the splitting of energy levels. Russell-Saunders and j-j coupling are outlined as approaches to describe spin-orbit interactions in light and heavy elements respectively.
Alkenes by absorption of light activated to higher energy singlet & triplet state and undergoes chemical reaction. These reactions are mainly:- 1. Cis - trans isomerization
2. Dimerization
3. Cycloaddition
The document summarizes the dienone-phenol rearrangement, which is the acid- or base-catalyzed migration of alkyl groups in cyclohexadienones, resulting in highly substituted phenols. It was first described in 1893 for the rearrangement of santonin to desmotroposantonin under acidic conditions, but was more fully characterized in 1930. The rearrangement requires only moderately strong acids and is exothermic. It proceeds by a [1,3] sigmatropic migration of C-C bonds, which actually occurs through two subsequent [1,2] alkyl shifts. Depending on the migrating group, other rearrangements such as [1,2], [1,3], [
1. Reaction mechanisms can be determined through various methods like identifying products, detecting intermediates through isolation, trapping or labeling studies, studying the effects of catalysts and acids, and performing kinetic studies.
2. Isotope labeling and crossover experiments involve using isotopically labeled reactants to determine whether reaction pathways are intra- or intermolecular. Kinetic isotope effects also provide information about which bonds are broken or formed in the rate-determining step.
3. Acid and base catalysis can indicate whether proton transfer is involved in the rate-determining step. General acid catalysis means proton transfer is rate-determining while specific catalysis means it is not.
This document presents information on the Tanabe-Sugano diagram, which is used in coordination chemistry to predict absorptions in the UV-visible and IR spectra of coordination compounds. It was developed by Yukito Tanabe and Satoru Sugano in 1954 to explain the absorption spectra of octahedral complex ions. The diagram plots orbital energy as a function of the Racah parameter B versus the ligand field splitting parameter Δo/B. It can be used to determine the ordering of electronic states and predict possible electronic transitions based on parameters like Δo, Racah parameters B and C, symmetry rules, and term symbols of electronic configurations. The diagram has advantages over earlier Orgel diagrams in that it can be applied to
Photo-oxidation involves the oxidation of materials under the influence of light or radiant energy. It requires a photosensitizer that absorbs light strongly and can transfer energy to reactants. Main steps include initiation by excitation of the photosensitizer, propagation by reaction of radicals formed with oxygen, and termination. Specific photo-oxidation reactions include the formation of peroxy compounds, cyclic peroxides from conjugated dienes, oxidative coupling of aromatics, and formation of polycyclic compounds and changes to polymers.
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
photo redox reactions
Wilkinson's catalyst, chlorotris(triphenylphosphine)rhodium(I), is an organometallic catalyst that is very effective for the homogeneous hydrogenation of unsaturated compounds at room temperature and atmospheric pressure. Its mechanism involves five steps - ligand dissociation, oxidative addition of hydrogen, alkene coordination, migratory insertion, and reductive elimination - known as Tolman's catalytic cycle. This cycle allows the catalyst intermediates to shuttle between 18 and 16 electron configurations, making the electron shifts energetically favored.
IR spectroscopy . P.K.Mani, BCKV, West Bengal, IndiaP.K. Mani
This document provides an introduction to infrared (IR) spectroscopy, including:
1. IR spectra originate from the vibrational and rotational motions of molecules, which can absorb IR radiation if there is a change in dipole moment.
2. Molecules absorb specific frequencies that correspond to their natural vibrational frequencies. Stretching and bending vibrations within different functional groups absorb in characteristic regions of the IR spectrum.
3. IR spectroscopy can be used to identify molecules based on their absorption fingerprints between 400-1300 cm-1, which are influenced by the whole molecular structure.
This document provides an overview of 2D NMR spectroscopy techniques, specifically HETCOR. It discusses the principles behind 2D NMR, describing how it plots data in two frequency axes rather than one, providing more information about a molecule's structure. It then explains the four periods that occur in a 2D NMR experiment: preparation, evolution, mixing, and detection. The document focuses on HETCOR, describing it as a heteronuclear experiment that provides correlations between different nuclei like protons and carbons. Examples of HETCOR spectra are provided to show how they indicate couplings between protons and the carbons they are attached to. Related techniques like HSQC and HMBC are also briefly described.
Photochemistry
ELECTROMAGNETIC SPECTRUM
LAW GOVERNING ABSORPTION OF LIGHT
LAW OF PHOTOCHEMISTRY
Grotthurs-Drapper law.
Einstein Stark law of photochemical equivalence
ELECTRONIC TRANSITIONS
Jablonski Diagram
QUANTUM YIELD
Use Of Photochemistry
Chemistry of vision
Photosynthesis in plant
Formation of Vitamin D
Fluorescent dyes in traffic
Photodynamic therapy
Spectroscopy for Pharmaceutical Analysis and Instrumental Method of Analysis....Yunesalsayadi
This document discusses electronic spectroscopy and molecular spectroscopy. It begins by explaining that electronic spectroscopy relies on quantized energy states of electrons and involves electronic transitions between principal quantum states when electrons absorb enough energy. It then discusses different regions of the electromagnetic spectrum and how spectrometers are used to analyze absorption and emission spectra. The rest of the document discusses molecular spectroscopy, deviations from Beer's law, and applications of using spectrophotometry and Beer's law to determine equilibrium constants.
Fluorescence spectroscopy is based on the principle of fluorescence emission that occurs when a molecule absorbs light and is excited to a higher electronic state. The excited molecule then relaxes to the ground state via vibrational relaxation and emission of a photon. The emitted light has a longer wavelength than the absorbed light due to energy losses in vibrational relaxation, following Stokes' rule. Fluorescence spectroscopy can provide information about molecular structure and interactions through analysis of fluorescence emission spectra.
1. Photochemistry involves using light as a chemical reagent to promote molecules to electronically excited states or as a chemical product when excited states return to the ground state.
2. Fluorescence occurs when a molecule in an excited singlet state returns to the ground state and emits light. It is a spin-allowed process that results in emission at a longer wavelength than the absorbed light.
3. The excitation and fluorescence emission spectra of a compound are often approximately mirror images of each other, though there are exceptions when the excited and ground states differ in geometry.
Ultraviolet spetroscopy by Dr. Monika Singh part-1 as per PCI syllabusMonika Singh
UV Visible spectroscopy as per PCI syllabus: Electronic transitions, chromophores, auxochromes, spectral shifts, solvent effect on absorption spectra, Beer and Lambert’s law, Derivation and deviations.
Fluorimetry.pptx by Saloni Kadam Nanded talukauser621767
The document discusses fluorimetry and provides details about:
- Luminescence processes including fluorescence and phosphorescence
- Factors that affect fluorescence like pH, temperature, and concentration
- Instrumentation used for fluorimetry including radiation sources, monochromators, sample holders, and photomultiplier tube detectors
- Quenching processes that can decrease fluorescence intensity
Photochemistry is the branch of chemistry concerned with chemical reactions caused by light absorption. Photochemical reactions proceed differently than thermal reactions and can form thermodynamically disfavored products or overcome large activation barriers. When a molecule absorbs light, it is elevated to an excited state. The Grotthuss–Draper law states that light must be absorbed for a photochemical reaction to occur. Absorbed light can excite a molecule to different singlet or triplet states, which can then relax through radiationless or radiative processes like fluorescence or phosphorescence. Experimental factors like light sources, reactors, solvents, and wavelength selection influence photochemical reactions.
Photochemistry is the branch of chemistry concerned with chemical reactions caused by light absorption. Photochemical reactions proceed differently than thermal reactions and can form thermodynamically disfavored products or overcome large activation barriers. When a molecule absorbs light, it is elevated to an excited state. The Grotthuss–Draper law states that light must be absorbed for a photochemical reaction to occur. Absorbed light can excite a molecule to different singlet or triplet states, which can then relax through radiationless or radiative processes like fluorescence or phosphorescence. Experimental factors like light sources, reactors, solvents, and wavelength selection influence photochemical reactions.
Photoluminescence is light emission from matter after absorbing photons. Following photon absorption, various relaxation processes occur where photons are re-emitted. Photoluminescence can be classified by excitation energy relative to emission energy. Resonant excitation involves equivalent absorption and emission photon energies, while fluorescence involves energy loss so emitted photons have lower energy. Phosphorescence also involves energy loss but through a spin-forbidden transition, making it a slower process. Photoluminescence is used to measure semiconductor purity and disorder.
Ultraviolet and visible (UV-Vis) absorption spectroscopy measures the attenuation of light passing through or reflected from a sample. When light energy matches an electronic transition in a molecule, some light is absorbed, promoting electrons to higher orbitals. The resulting absorbance spectrum shows absorbance versus wavelength. Fluorescence spectroscopy involves excitation of molecules to higher electronic singlet states followed by emission of light as they relax to ground states. Quantum yield is the ratio of emitted to absorbed photons. Both techniques are useful in characterizing biological systems like proteins, DNA, and fluorophores.
This document provides an overview of organic photochemistry. It discusses fundamentals such as the laws of absorption and mechanisms behind photochemical reactions. It also covers practical considerations for running photochemical experiments including the effects of impurities, oxygen, and temperature. Additionally, it examines photochemistry as a key step in organic synthesis, focusing on [2+2] cycloadditions between α,β-unsaturated ketones/esters and olefins. Topics discussed include reaction mechanisms, regioselectivity issues influenced by electronic and steric factors, and stereoselectivity considerations regarding alkene geometry preservation.
This document provides an overview of various spectroscopy techniques including UV-Vis, IR, and NMR spectroscopy. It discusses key concepts like electromagnetic radiation, photon energy, and the electromagnetic spectrum. It describes the interactions between electromagnetic radiation and matter that are measured in different spectroscopy methods. It also provides examples of spectra for organic compounds and explanations of spectral features.
Introduction, electromagnetic radiation, units, electromagnetic and absorption spectra, Lambert’s and Beer’s laws, deviations from Lambert’s–Beer’s law, chromophores and auxochromes, absorption and intensity shift, types of electronic transition, effects of solvents,
electronic transition in polyenes, instrumentation, colorimetry, Woodward-Fieser rules for
calculating absorption maximum, analysis of mixtures, applications of ultraviolet and visible
spectroscopy in quantitative analysis of drugs, use of ultra violet and visible spectroscopy in
structural analysis.
Fluorescence and phosphorescence are forms of luminescence that involve the emission of light from a substance that has absorbed radiation or light. Fluorescence involves emission of light from singlet excited states, while phosphorescence involves emission from triplet excited states. Factors like temperature, concentration, and molecular structure can influence the intensity of fluorescence. Fluorescence and phosphorescence find applications in areas like analytical chemistry, microscopy, lighting, and more. Instrumentation used to study these phenomena include filter fluorimeters and modern fluorescence spectrophotometers.
This document provides an overview of photochemistry presented by Dr. Satish Kola. It begins with definitions of photochemistry as chemical reactions caused by light absorption. It then discusses characteristics of light as waves and particles. Key aspects of photochemistry covered include absorbance and color of materials, photochemical reaction mechanisms, quantum yield calculations, and photosensitized reactions where a sensitizer transfers energy to start a reaction. Photochemistry examples discussed are atmospheric reactions, photosynthesis, and determination of absorbed light intensity using spectrophotometry.
The document summarizes infrared (IR) spectroscopy, including its principle, instrumentation, applications, and interpretation of spectra. IR spectroscopy works by detecting the vibrational and rotational absorption frequencies of molecules when exposed to IR radiation. The spectrum produced provides information on molecular structure and bonding. Key regions of the IR spectrum correspond to common functional groups like C=O, N-H, and O-H. Analysis of peak positions and relative intensities allows identification of compounds and detection of impurities.
Spectroscopic techniques involve measuring the interaction of electromagnetic radiation with matter. There are various types of spectroscopy depending on the type of radiation used. Infrared (IR) spectroscopy analyzes infrared light interacting with molecules and is based on absorption spectroscopy. IR spectroscopy is useful for qualitative and quantitative analysis, detecting impurities, and characterizing organic compounds. Molecular vibrations that can be analyzed include stretching vibrations, which change bond lengths, and bending vibrations, which change bond angles. Selection rules determine which vibrations are IR active based on whether they induce a change in the molecule's dipole moment.
This document provides an overview of UV-Visible spectroscopy. It discusses how UV radiation causes electronic transitions in molecules, which can be observed via absorption spectroscopy. The instrumentation used includes sources of UV and visible light, a monochromator to select wavelengths, and a detector. Samples are dissolved and placed in transparent cuvettes for analysis. Spectra are recorded as absorbances and show absorption bands corresponding to electronic transitions. UV-Vis is useful for structure elucidation and quantitative analysis.
Spectroscopy is the study of the interaction between electromagnetic radiation and matter. It involves using different types of radiation to excite the energy levels of atoms and molecules and analyze the absorbed and emitted radiation. Common techniques include absorption, emission, and scattering spectroscopy which are used in fields like chemistry, physics, astronomy, and forensic analysis. Spectrometers are devices used to measure spectra that provide information to identify substances.
Infrared spectroscopy involves measuring the absorption of infrared radiation by a sample. The infrared spectrum produced provides information about the chemical bonds and molecular structure in the sample. Common methods to obtain an infrared spectrum include measuring absorption, emission, or reflection of infrared radiation. Infrared spectroscopy is widely used to analyze organic materials and some inorganic compounds.
Video lecture is available on YouTube on the link:https://youtu.be/xrBnxxN-RUw
For UG students of All Engineering Branches, Chemistry, Food Science, Polymer Science, Chemical Engg. etc.
This document discusses the Maillard reaction, also known as non-enzymatic browning, which is responsible for pleasant flavors in foods like bread, coffee, and chocolate. It produces primary products through the condensation of reducing sugars and amino acids, which then undergo additional reactions to form secondary products that contribute flavor. These secondary products include carbonyls, pyrroles, pyrazines, oxazoles, thiazoles, pyridines, and imidazoles. The document outlines the specific chemical reactions that form several classes of these compounds, such as Strecker degradation producing carbonyls and pyrazines. It also discusses the formation of furanones, pyranones, pyrrolines
The Fritsch–Buttenberg–Wiechell (FBW) rearrangement involves the rearrangement of a 1,1-diaryl-2-bromo-alkene to a 1,2-diaryl-alkyne using a strong base through an anionic 1,2-sigmatropic rearrangement. However, this route is forbidden by the Woodward–Hoffmann rules. Extensive experimentation and analysis of isotopic labeling, cis-trans isomerization, and solvent effects showed that the reaction occurs through a stepwise migration of the vinyl group rather than a concerted mechanism. The FBW rearrangement has been modified and applied to the synthesis of novel polyynes and steroidal
The document discusses 1,3-dipolar cycloaddition reactions, which involve a 1,3-dipole reacting with a dipolarophile to form a 5-membered heterocyclic ring. Key points include:
- 1,3-dipoles are classified into three types based on their electronic structure. Common examples are azides, nitrones, and carbonyl ylides.
- The reaction typically proceeds by a concerted pericyclic mechanism through a six-electron transition state, though some exceptions involve a stepwise mechanism.
- Frontier molecular orbital theory can be used to classify dipoles as HOMO-controlled, LUMO-controlled, or ambiphilic based
The document discusses electrocyclic reactions, which involve the conversion of a conjugated polyene to an unsaturated cyclic compound with one less carbon-carbon double bond. It notes that these reactions can occur thermally or photochemically, and with high stereoselectivity. It provides examples of electrocyclic reactions involving butadiene and hexatriene, and discusses the correlation between molecular orbital symmetry and the conrotatory or disrotatory nature of the reaction. It also addresses electrocyclic reactions involving reactants with an odd number of atoms, such as cations and anions, as well as photochemical cyclizations.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors like the solvent, substituents on the carbonyl and alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize biologically active oxetane-containing compounds and to construct more complex carbocyclic and heterocyclic ring systems.
Main Java[All of the Base Concepts}.docxadhitya5119
This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
Thinking of getting a dog? Be aware that breeds like Pit Bulls, Rottweilers, and German Shepherds can be loyal and dangerous. Proper training and socialization are crucial to preventing aggressive behaviors. Ensure safety by understanding their needs and always supervising interactions. Stay safe, and enjoy your furry friends!
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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How to Add Chatter in the odoo 17 ERP ModuleCeline George
In Odoo, the chatter is like a chat tool that helps you work together on records. You can leave notes and track things, making it easier to talk with your team and partners. Inside chatter, all communication history, activity, and changes will be displayed.
Assessment and Planning in Educational technology.pptxKavitha Krishnan
In an education system, it is understood that assessment is only for the students, but on the other hand, the Assessment of teachers is also an important aspect of the education system that ensures teachers are providing high-quality instruction to students. The assessment process can be used to provide feedback and support for professional development, to inform decisions about teacher retention or promotion, or to evaluate teacher effectiveness for accountability purposes.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Physiology and chemistry of skin and pigmentation, hairs, scalp, lips and nail, Cleansing cream, Lotions, Face powders, Face packs, Lipsticks, Bath products, soaps and baby product,
Preparation and standardization of the following : Tonic, Bleaches, Dentifrices and Mouth washes & Tooth Pastes, Cosmetics for Nails.
2. Introduction
The photochemistry is the interaction of light with matter.
IUPAC has defined it as, “The branch of chemistry concerned
with the chemical effects of light (far UV to IR)”.
2
The simplest photochemical process
is seen with the absorption and
subsequent emission of a photon by a
gas phase atom such as sodium.
When the sodium atom absorbs a
photon it is said to be excited. After
a short period of time, the excited
state sodium atom emits a photon of
589 nm light and falls back to the
ground state
3. Importance
The photochemistry is very important as life itself depends on
photochemical processes like photosynthesis. Photochemistry
also determines the composition of Earth’s atmosphere supports
life and shields us from damaging UV radiation. Further,
photochemistry is a central branch from which many other
processes find applications.
3
4. Terminology
❏ CHARGE-TRANSFER (CT) TRANSITION: An electronic transition in which a
large fraction of an electron charge is transferred from one region of a molecular
entity, called the electron donor, to another, called the electron acceptor
(intramolecular CT) or from one molecular entity to another (intermolecular
CT).
❏ MULTIPLICITY (Spin Multiplicity): The number of possible orientations,
calculated as 2S + 1, of the spin angular momentum corresponding to a
given total spin quantum number (S), for the same spatial electronic wave-
function. A state of singlet multiplicity has S = 0 and 2S + 1 = 1. A doublet state
has S = ½ and 2S + 1 = 2.
❏ ELECTRONIC ENERGY MIGRATION (or Hopping): The movement of
electronic excitation energy from one molecular entity to another of the
same species, or from one part of a molecular entity to another part of the
same entity. The migration can happen via radiative or radiationless processes
4
5. Terminology
HUND’s RULES
❏ Of the different multiplets resulting from different configurations of
electrons in degenerate orbitals of an atom those with greatest
multiplicity have the lowest energy (multiplicity rule).
❏ Among multiplets having the same multiplicity, the lowest-energy one
is that with the largest total orbital angular momentum (angular
momentum rule) (valid if the total orbital angular momentum is a constant
of motion).
❏ In configurations containing shells less than half full of electrons, the
term having the lowest total angular momentum J lies lowest in energy,
whereas in those with shells more than half filled, the term having the
largest value of J lies lowest (fine structure rule).
5
6. Terminology
❏ INTERNAL CONVERSION: A photo-physical process. Iso-energetic radiation-
less transition between two electronic states of the same multiplicity. When the
transition results in a vibrationally excited molecular entity in the lower
electronic state, this usually undergoes deactivation to its lowest vibrational
level, provided the final state is not unstable to dissociation
❏ QUENCHING: The deactivation of an excited molecular entity intermolecularly
by an external environmental influence (such as a quencher) or intramolecularly
by a substituent through a non-radiative process.
❏ SELECTION RULE: A selection rule states whether a given transition is allowed
or forbidden, on the basis of the symmetry or spin of the wave-functions of the
initial and final states.
6
7. Laws of Photochemistry
Grothus-Draper Law (Ist Law of Photochemistry)
“When light is incident on a cell containing a reaction mixture, some portion
of the light is absorbed while the other remaining part is transmitted.
The photochemical reaction is produced by the absorbed light and
transmitted light is not effective in any way for the photochemical
transformation.
Stark-Einstein law (2nd Law of Photochemistry)
It states that each molecule involved in a photochemical reaction absorbs
only one quantum of the radiation that causes the reaction
7
8. Quantum Yield (ჶ)
As per IUPAC, quantum yield is the number of defined events which occur
per photon absorbed by the system. The integral quantum yield is:
(ჶ) = (number of events)/ (number of photons absorbed)
For a photochemical reaction, quantum yield can be defined as the
number of molecules of the reactant consumed or number of molecules of
the product formed per quantum of light absorbed. It is denoted by ჶ and
is also known as quantum efficiency. The value of quantum efficiency of a
reaction may vary from about zero to 106 depending upon the reaction.
8
9. Jablonski Diagram
9
Jablonski diagrams are frequently
used and are actually state diagrams
in which molecular electronic states,
represented by horizontal lines
displaced vertically to indicate
relative energies, are grouped
according to multiplicity into
horizontally displaced columns.
Excitation and relaxation processes
that interconvert states are indicated
in the diagram by arrows. Radiative
transitions are generally indicated
with straight arrows, while
radiationless transitions are
generally indicated with wavy
arrows.
10. Jablonski Diagram
10
Relaxation Mechanism for Excited State Molecules
Once a molecule has absorbed energy in the form of electromagnetic
radiation it goes to higher energy level (excited state) from ground state
as arrow upward pointing S0 S1. There are a number of routes by
which it can return to ground state.
If the photon emission (S1 S0) occurs between states of the same spin
state this is termed as fluorescence.
If the spin state of the initial and final energy levels is different (T1 S0),
the emission (loss of energy) is called phosphorescence.
11. Franck-Condon Principle
11
The nuclei are enormously heavy as
compared to the electrons so, during light
absorption (which occurs in femtoseconds)
electrons can move, not the nuclei. The
much heavier atomic nuclei have no time to
readjust themselves during the absorption
act, but have to do it after it is over, and this
readjustment brings them into vibrations.
Hence, Franck-Condon principle states that,
“As electrons move much more rapidly as
compared to the nuclei, so it is approximated
that in an electronic transition, the nuclei do
not change their position”.
12. Franck-Condon Principle
12
Fluorescence, originates from near the bottom of the upper potential curve, until it
strikes the lower potential curve. Again, it does not hit it in its deepest point, so that
some excitation energy becomes converted into vibrational energy. The
absorption-emission cycle therefore contains two periods of energy dissipation.
Because of this, the fluorescence arrow (F) is always shorter (that is, the fluorescence
frequency is lower) than that of absorption (A). In other words, the wavelengths of the
fluorescence band are longer than of the absorption band. This displacement of
fluorescence bands towards the longer wavelengths compared to the absorption bands
is called as Stokes' shift. The Stokes shift is thus displacement of fluorescence band
compared to the absorption band of a molecule.
13. Photochemical
Energy
13
❏ The energy of photons is dependent upon the wavelength of the light.
❏ Longer wavelength light has low energy and shorter wavelength
light has high energy.
❏ Photochemistry involves radiation between 2000 nm (near
infrared) and <100 nm (soft x-ray).
❏ The most important regions for photochemistry are:
700-400 nm (visible),
400-200 nm (Ultraviolet)
200-100 nm (Ultraviolet- visible)
❏ The energy range for photochemical dissociation (~ 170-1200 kJ
mol-1)
15. Chemistry of Photochemical Excitation
15
In photochemistry, the light is absorbed in the wavelength range of 200-800 nm
of the spectrum. Such a spectrum measures amount of incident light by the
molecule as a function of wavelength.
Lambert’s law states that when a monochromatic beam of light is allowed to pass
through a transparent medium, the rate of decrease in intensity with the thickness
of the medium is directly proportional to the intensity of the incident light.
Beer’s Law states that when a monochromatic light is passed through a solution
the rate of decrease in intensity with the thickness of the solution is directly
proportional to the intensity of the incident light as well as the concentration of the
solution.
16. Chemistry of Photochemical Excitation
16
The expression in the following equation is termed as mathematical
statement for Beer-Lambert’s law,
The quantity log (I0/It) is called as absorbance (A). The following is the
relation between absorbance (A), transmittance (T) and molar absorption
coefficient (e):
.
17. Electronic Transitions
17
The absorption of UV or visible radiation
corresponds to the excitation of outer electrons.
There are 3 types of electronic transition which
can be considered;
(i) Transitions involving 𝝅, 𝛔, and n electrons
(ii) Transitions involving charge-transfer electrons
(iii) Transitions involving d and f electrons
When an atom or molecule absorbs energy,
electrons are promoted from their ground state to
an excited state. In a molecule, the atoms can
rotate and vibrate with respect to each other.
These vibrations and rotations also have
discrete energy levels, which can be considered
as being packed on top of each electronic level .
18. Electronic Transitions
18
The Absorption of ultraviolet and visible radiation in organic molecules is
restricted to certain functional groups (chromophores) that contain valence
electrons of low excitation energy. The electronic transition is involved in
promotion of an electron from one of three ground states ( 𝝅, 𝛔 or n) to one of the
antibonding ( 𝝅*, 𝛔*) molecular orbital. Organic molecules show four important
types of transitions:
19. Electronic Transitions
19
Most absorption spectroscopy of organic compounds is based on transitions
of n or 𝝅 electrons to the 𝝅 * excited state. This is because the absorption
peaks for these transitions fall in an experimentally convenient region of
the spectrum (200 - 700 nm). These transitions need an unsaturated group
in the molecule to provide the 𝝅 electrons.
21. Photochemical Reaction Processes
21
Dissociation: The excited state species may fragment to a pair of
radicals (halogens) or, in the case of nitrogen dioxide to nitric oxide
and oxene.
2- Pentanone Propanone
22. Photochemical Reaction Processes
22
Direct Reaction: The photo-excited state may undergo reactions
unavailable to the ground state species. E.g., a photo-excited ketone can
undergo a [2+2] cycloaddition with an alkene to give an oxetane, a
Paterno-Büchi reaction .
23. Photochemical Reaction Processes
23
Isomerization: Photo-excited species may undergo isomerization.
E.g. trans-stilbene can be photo-excited to a state that allows free rotation
around the alkene double bond. This photo-excited species is able to relax
back to the ground state to give cis-stilbene.
24. Photochemical Reaction Processes
24
Energy transfer: An excited state species can transfer energy to another
ground state species. This process is used to produce singlet oxygen and energy
transfer in such cases is intermolecular. A dye, usually rose bengal, is photo-
excited with UV light to transfer energy to triplet oxygen, which is converted to
singlet oxygen.
Intramolecular Energy Transfer
Intermolecular Energy Transfer
25. Photochemical Reaction Processes
25
Quenching: In the liquid state, the
excited state species may be quenched
in which the energy of the excited state
species is converted into vibrational
energy (heat). The quenching is
generally affected with solvents .
Photoionization: These processes
are of great importance high in the
atmosphere where pressures are low
and short wavelength UV radiation
from the sun has a high flux. E.g., photo-
ionization of nitric oxide by photon
having wavelength 134.3 nm.
26. Selection Rules for Electronic Transitions
26
Spin Based Selection Rules Symmetry Based Selection
Rules
Transitions between electronic states
of same spin multiplicity are
ALLOWED.
Singlet Singlet
Triplet Triplet
Transitions between electronic states
of different spin multiplicity are
FORBIDDEN.
Singlet Triplet
Triplet Singlet
Transitions between orbitals of same
symmetry are ALLOWED.
= ALLOWED transition
Transitions between orbitals of different
symmetry are FORBIDDEN.
=
FORBIDDEN transition
27. Primary Photochemical Reactions
27
Reactions initiated by 𝛑 𝛑 * state
[S1 state]
Reactions involving Carbocations
Reactions involving Carbanions
Concerted Pericyclic reactions
Electron Transfer reactions
Cis-trans Isomerization reactions
Homolytic Fragmentation
Hydrogen atom Abstraction
Addition to Unsaturated Bonds
Rearrangement of stable carbon
centred radicals
Reactions initiated by n 𝛑 * state
[T1 state]
28. Photosensitized Reactions
28
Reactants in some chemical reactions do not absorb light and no product
is formed on exposure of such reactants to radiations. However, if with
the addition of another substance, which can absorb radiations, these
reactants are converted into products. In actual the substance added
absorbs light and becomes excited and then passes this energy to one of
the reactants, which gets activated to react with the other reactant(s) to
give products. The substance which when added to a reaction mixture to
help in initiating a photochemical reaction without undergoing any
chemical change is called a photo-sensitizer and these types of reactions are
called photosensitization reactions. The process is called as
photosensitization. The most commonly used photosensitizers include
mercury, cadmium, benzophenone and sulphur dioxide.
29. Mechanism of Photosensitization
29
A general donor-acceptor system in which donor
(sensitizer) absorbs the incident light and becomes
excited. The triple state of the donor is higher than the
triple state of the acceptor that is reactant. On
absorption of photon donor changes to singlet excited
state and then it changes to triplet excited state by
intersystem crossing (ISC). This triplet state then collides
with acceptor producing triplet excited state of acceptor (T1)
and ground state of donor, when triplet state of acceptor
gives the desired product then the mechanism is called
photosensitization. The triplet excited state of sensitizer
must be higher in energy than triplet excited state of the
reactant so the energy available is sufficient to raise the
reactant molecule to its triplet excited state.
.
30. Applications of Photosensitization
30
Isomerization of but-2-ene:
SO2 acts as photosensitizer in this
isomerization reaction. The cis-but-2-ene
and SO2 vapour are irradiated with light
of 𝞴 = 254 nm leading to the formation of
trans-but-2-ene
Dimerization of Cyclohexane:
Hg is used as photosensitizer in this
reaction. The mixture of cyclohexane and
mercury vapour are irradiated with light
of 𝞴=254 nm to give dimerized products
31. 31
References
❏ Chemistry For Engineers, Harish Kumar and Anupama
Parmar, ISBN No. 978-81-8487-545-4 (2016), Published by
Narosa Publishing House Pvt. Ltd., New Delhi. .
❏ NPTEL Lectures & Videos
❏ Internet sources