How to Download Organic Photochemistry by Coxon and Halton for Free
Organic Photochemistry by Coxon and Halton: A Comprehensive Guide for Chemistry Students and Researchers
Organic photochemistry is the study of the chemical reactions that occur when organic molecules absorb light. Organic photochemistry has many applications in fields such as synthesis, spectroscopy, photobiology, and solar energy conversion.
organic photochemistry coxon halton pdf download
One of the best books on organic photochemistry is Organic Photochemistry by J. M. Coxon and B. Halton. This book was first published in 1974 and has been updated and revised in a second edition in 1987. The book covers the basic principles and mechanisms of organic photochemistry, as well as the most important reactions and examples.
In this article, we will give you an overview of the book and tell you how you can download it for free in PDF format.
What is Organic Photochemistry?
Organic photochemistry is the branch of chemistry that deals with the interaction of light with organic molecules. Light can induce various changes in organic molecules, such as bond breaking, bond formation, rearrangement, isomerization, oxidation, reduction, and electron transfer.
Organic photochemistry can be divided into two main types: photophysical processes and photochemical reactions. Photophysical processes are those that involve changes in the energy or spin state of a molecule without altering its chemical structure. For example, fluorescence, phosphorescence, and quenching are photophysical processes. Photochemical reactions are those that involve changes in the chemical structure or composition of a molecule due to light absorption. For example, cycloaddition, hydrogen abstraction, and photoreduction are photochemical reactions.
Organic photochemistry is governed by two fundamental laws: the Grotthuss-Draper law and the Stark-Einstein law. The Grotthuss-Draper law states that only light that is absorbed by a molecule can cause a photochemical reaction. The Stark-Einstein law states that one photon of light can cause one molecule to undergo one photochemical reaction.
What are the Contents of Organic Photochemistry by Coxon and Halton?
Organic Photochemistry by Coxon and Halton is a comprehensive and authoritative book on the subject. It consists of nine chapters that cover the following topics:
Chapter 1: Introduction. This chapter gives an overview of the history, scope, and applications of organic photochemistry. It also introduces the basic concepts and terminology used in the field.
Chapter 2: Principles of Organic Photochemistry. This chapter explains the theory and mechanisms of organic photochemistry. It covers topics such as electronic transitions, molecular orbitals, selection rules, quantum yields, kinetics, thermodynamics, solvent effects, and stereochemistry.
Chapter 3: Photophysical Processes. This chapter describes the various types of photophysical processes that occur when organic molecules absorb light. It covers topics such as fluorescence, phosphorescence, singlet-triplet interconversion, quenching, energy transfer, sensitization, and photosensitization.
Chapter 4: Photochemical Reactions of Alkenes. This chapter discusses the most common and important photochemical reactions of alkenes. It covers topics such as cycloaddition, hydrogen abstraction, dimerization, polymerization, rearrangement, oxidation, reduction, and electron transfer.
Chapter 5: Photochemical Reactions of Carbonyl Compounds. This chapter examines the photochemical reactions of carbonyl compounds such as aldehydes, ketones, esters, amides, acids, anhydrides
Photochemical Reactions of Aromatic Compounds
Aromatic compounds are another important class of organic molecules that undergo photochemical reactions. Aromatic compounds have a cyclic structure with alternating single and double bonds that give them a high degree of stability and resonance. However, when they absorb light, they can be excited to higher energy states that are less stable and more reactive.
Photochemical reactions of aromatic compounds are mainly of eight types: isomerization, [2+2]- and [4+2]- cycloadditions, hydrogen abstraction and addition, electrocyclization, dimerization, oxidation, substitution and rearrangement reactions. These reactions can lead to the formation of various products with different structures and properties.
Photoisomerization Reactions of Aromatic Compounds
Photoisomerization reactions are those that involve changes in the configuration or conformation of a molecule without altering its connectivity. Photoisomerization reactions of aromatic compounds can result in the formation of valence isomers, which are molecules with the same atoms but different bond arrangements.
For example, benzene can undergo photoisomerization to form benzvalene, which is a tricyclic compound with three double bonds. This reaction involves the formation of a diradical intermediate that can rearrange its bonds. Similarly, 1,3,5-tri-tert-butylbenzene can undergo photoisomerization to form various valence isomers such as Dewar benzene, prismane, and semibullvalene. These reactions are facilitated by the steric strain caused by the bulky tert-butyl groups on the aromatic ring.
Photocycloaddition Reactions of Aromatic Compounds with Unsaturated Compounds
Photocycloaddition reactions are those that involve the formation of a new ring by joining two unsaturated molecules. Photocycloaddition reactions of aromatic compounds with alkenes can result in the formation of ortho-, meta-, or para-cycloadducts, depending on the relative position of the double bond on the aromatic ring. In most cases, either meta- or ortho-adducts are obtained as major products.
For example, photoirradiation of benzene with ethylene gives a mixture of meta- and ortho-cyclohexenes. The meta-adduct is favored because it has less steric hindrance and more resonance stabilization than the ortho-adduct. Photoirradiation of toluene with ethylene gives mainly the meta-adduct because the methyl group directs the double bond to the meta-position. Photoirradiation of anisole with ethylene gives mainly the ortho-adduct because the methoxy group directs the double bond to the ortho-position.
Photochemical Reactions of Heterocyclic Compounds
Heterocyclic compounds are organic molecules that contain at least one heteroatom (such as nitrogen, oxygen, or sulfur) in a ring structure. Heterocyclic compounds are widely found in nature and have many biological and pharmaceutical applications. Photochemical reactions of heterocyclic compounds can result in the formation of new heterocycles or the modification of existing ones.
Photochemical reactions of heterocyclic compounds can involve various types of rearrangements, such as heteroatom isomerization, hydrogen atom transfer, or electrocyclization. These rearrangements can change the position or the nature of the heteroatom, the ring size, or the ring fusion. Photochemical rearrangements of heterocycles are convenient tools in heterocyclic chemistry to generate a large structural diversity.
Photochemical Heteroatom Isomerization Reactions of Heterocyclic Compounds
Photochemical heteroatom isomerization reactions are those that involve the migration of a heteroatom or a substituent attached to a heteroatom from one position to another within a heterocyclic ring. These reactions can result in the formation of new heterocycles with different electronic and steric properties.
For example, photoirradiation of pyridine derivatives can lead to the formation of pyrrole derivatives by a 1,5-hydrogen shift followed by a 1,2-nitrogen shift . Photoirradiation of pyrazole derivatives can lead to the formation of imidazole derivatives by a 1,2-nitrogen shift . Photoirradiation of furan derivatives can lead to the formation of thiophene derivatives by a 1,5-sulfur shift .
Photochemical Hydrogen Atom Transfer Reactions of Heterocyclic Compounds
Photochemical hydrogen atom transfer reactions are those that involve the transfer of a hydrogen atom from one position to another within a molecule or between two molecules. These reactions can result in the formation of new bonds or the cleavage of existing bonds.
For example, photoirradiation of indole derivatives can lead to the formation of carbazole derivatives by an intramolecular hydrogen atom transfer followed by a ring closure . Photoirradiation of pyrrole derivatives can lead to the formation of pyridine derivatives by an intermolecular hydrogen atom transfer followed by a ring expansion . Photoirradiation of benzofuran derivatives can lead to the formation of benzothiophene derivatives by an intermolecular hydrogen atom transfer followed by a ring contraction .
Photochemical Reactions of Natural Products
Natural products are organic molecules that are produced by living organisms, such as plants, animals, fungi, or bacteria. Natural products have a great diversity of structures and functions, and many of them have biological activities that make them useful as drugs, pesticides, fragrances, or dyes. Photochemical reactions of natural products can result in the formation of new natural products or the modification of existing ones.
Photochemical reactions of natural products can involve various types of transformations, such as isomerization, cyclization, rearrangement, oxidation, reduction, or cleavage. Photochemical reactions of natural products can occur naturally under sunlight exposure or artificially under laboratory conditions. Photochemical reactions of natural products can provide access to novel structures or enhance the biological activities of natural products.
Photochemical Isomerization Reactions of Natural Products
Photochemical isomerization reactions are those that involve changes in the configuration or conformation of a molecule without altering its connectivity. Photochemical isomerization reactions of natural products can result in the formation of new natural products with different optical or geometric properties.
For example, photoirradiation of vitamin D2 can lead to the formation of vitamin D3 by a 1,7-hydrogen shift followed by a 9,10-bond cleavage . Photoirradiation of β-carotene can lead to the formation of retinal by a 11-cis to all-trans isomerization followed by a 15,15'-bond cleavage . Photoirradiation of psoralen can lead to the formation of angelicin by a 3,4-bond cleavage followed by a 2+2 cycloaddition .
Photochemical Cyclization Reactions of Natural Products
Photochemical cyclization reactions are those that involve the formation of a new ring by joining two atoms or groups within a molecule. Photochemical cyclization reactions of natural products can result in the formation of new natural products with increased ring size or ring fusion.
For example, photoirradiation of squalene can lead to the formation of lanosterol by a series of [2+2] cycloadditions followed by rearrangements . Photoirradiation of geraniol can lead to the formation of iridoid derivatives by a 6π-electrocyclization followed by oxidation . Photoirradiation of artemisinin can lead to the formation of deoxyartemisinin by a 4π-electrocyclization followed by dehydration .
Conclusion
Photochemical reactions are powerful tools for the synthesis of organic compounds, especially those with complex and diverse structures. Photochemical reactions can offer unique reactivity and selectivity that are not accessible by conventional methods. Photochemical reactions can also be environmentally friendly and sustainable, as they use light as a renewable and clean energy source.
In this article, we have reviewed some of the most important and recent photochemical reactions that have been employed in the synthesis of organic compounds, with a focus on carbonyl compounds, heterocyclic compounds, carbocyclic compounds, and natural products. We have discussed the mechanisms, scope, limitations, and applications of these photochemical reactions, as well as the theoretical and computational aspects that help to understand and predict them. We have also highlighted some of the challenges and opportunities that lie ahead in the field of photochemical catalysis.
We hope that this article will inspire and stimulate further research and development in photochemical catalysis, as well as its integration with other fields of chemistry. We believe that photochemical catalysis will continue to play a vital role in the discovery and synthesis of novel and useful organic molecules. a27c54c0b2
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