bluuebunny/crossref_metadata_2025 huggingface dataset:
Ammonium compounds
Authors: Bailey Patrick D. , Morgan Keith M.
Published: September 2023

This chapter focuses on amines. Saturated amines are regarded as the simplest organonitrogen compound. The chapter highlights the importance of amines as they occur widely in nature and are used often as building blocks for more complex compounds and co-reagents in numerous organic reactions. The chapter notes nitrogen acting as nucleophile or base to facilitate the reactions on the nitrogen lone pair. Additionally, the chapter discusses the interplay between nucleophilicity and basicity alongside the reactions of amines. It concludes amines as bases that are readily protonated. Next, amines are also powerful nucleophiles following their reactivity with alkyl halides, carboxylic acid derivatives, aldehydes, ketones, and nitrous acid.
Compounds with N–N bonds
Authors: Bailey Patrick D. , Morgan Keith M.
Published: September 2023

This chapter looks into urethanes, ureas, imides, and diimides, which encompasses the most important remaining nitrogen-containing functional groups aside from those which have N-N or N-O bonds. It highlights the importance of urethanes as readily removable N-protective groups. Additionally, the chapter discusses the synthesis and reaction of urethanes, ureas, imides, and diimides. Urethanes are significant for protecting amines, while imides are useful for preparing primary amines. Diimides are one of the best types of reagent for the coupling of carboxylic acids to amines. Finally, the chapter lists other unsaturated nitrogen-containing groups such as amidines, imidines, guanidines, and imidate esters.
Photoelectron spectroscopy
Authors: Brown John M.
Published: September 2023

This chapter discusses photoionization, which is a process carried out in a gas phase that gives a large amount of energy to a molecule to make it ionize. It refers to the photoelectric effect in which radiation of a variable frequency is shone on the surface of an easily ionizable metal, such as an alkali. It also examines the energy required to ionize a hydrogen atom in a particular orbital and remove the electron from the influence of the Coulombic attraction of the nucleus. The chapter then clarifies how the ionization energy can be equated with the energy required to remove an electron from a particular molecular orbital of the molecule. It cites an experiment wherein the monochromatic radiation in the vacuum is focused onto a gaseous sample of molecules, which causes them to be ionized.
Retrosynthetic analysis III: Strategy and planning
Authors: Willis Christine L. , Wills Martin
Published: September 2023

This chapter offers some guidelines on devising synthetic routes to reasonably complex molecules. First, it is important to examine a number of possible retrosynthetic approaches to the target molecule before choosing an approach for which reagents are readily available and inexpensive and reactions which give a high yield of a single product at each stage. Second, one should try to divide the molecule into approximately equal halves; this will lead to a synthesis which is convergent. The third guideline is to aim for greatest simplification, giving straight chain fragments which are more likely to be commercially available or simply prepared. The fourth is to use any inherent symmetry in the target molecule. It is also important to introduce reactive functional groups at a late stage in a synthesis. Finally, one should introduce functional groups when and where required to facilitate bond-making.
Allylsilanes and acylsilanes
Authors: Thomas Susan E.
Published: September 2023

This chapter reviews some methods available for making allylsilanes. It focuses on the silylation of a metal-allyl species as the most direct method available for making them as well as the use of the Wittig reaction. Allylsilanes react with electrophiles at their γ carbon atom as attack at this position generates a carbocation β to silicon. Displacement of the silyl group subsequently produces a new alkene. The chapter then shifts to detail the method of synthesizing acylsilanes which involves deprotonation and silylation of the 1,3-derivative of an aldehyde. It considers how acylsilanes have been synthesized by several other approaches: a reverse Brook rearrangement (silyl-Wittig rearrangement) of allyltrimethylsilyl ether followed by oxidation and reductive cleavage of carbon-sulphur bonds in the silylenol ethers derived from thiol esters.
Feedback and control
Authors: Wayne Richard R
Published: September 2023

This chapter covers electronic signals which can be used to control a property, such as the position of a piece of equipment, the intensity of a light, or the temperature of a system. It discusses feedback as an example of the return of the measurement to the controlling device, wherein the control systems that incorporate a feedback loop can be regarded as types of servo system. It also mentions the position of an object that is set electrically by a motor or other output transducer and the feedback signal that is derived from a position-sensitive input transducer. The chapter describes an open loop situation that has no feedback, wherein the accuracy of the final response relies on the complete transfer function between initial input and ultimate output. It highlights the accuracy of the closed loop incorporating feedback which is determined by the calibration of the sensing transducer.
Electronic, magnetic and optical properties of inorganic materials
Authors: Weller Mark T.
Published: September 2023

This chapter focuses on the electronic, magnetic, and optical properties of inorganic materials. The electronic properties exhibited by solids are crucial in a large number of inorganic materials applications. These unique electronic properties result from the extended structures adopted by many inorganic materials, where strong interactions between the atoms, ions, or molecules occur throughout the lattice. In terms of conductivity, behaviour ranges from insulating through semiconducting to metallic and superconducting. Similarly, the interaction between the unpaired electrons in inorganic material structures gives rise to magnetic properties characteristic of the whole solid rather than the individual atoms. Finally, the potential for concerted ion displacements in neighbouring unit cells produces ferroelectrics and optoelectric materials. The chapter also considers the band theory.
Atoms
Authors: Richards W.G. , Scott P.R.
Published: September 2023

This chapter addresses the question of whether light consists of waves or particles. This issue was resolved in the nineteenth century when it was shown that light could undergo interference and diffraction. The chapter reviews well-known properties and key features of wave motions that emphasize that a point illuminated by two sources of light can nevertheless be in darkness. It also looks at the measurements of diffraction experiments that allowed the wavelengths of different forms of light to be determined. The chapter explains how and why atoms come together to form molecules and illustrates the structure of the Periodic Table. It discusses electrons which are emitted from metal when the energy of the photon exceeds the work function, which implies that a single quantum of energy must be transferred to a single electron.
Reactions of dienes
Authors: Ward Robert S.
Published: September 2023

This chapter discusses allenes, wherein two carbon-carbon double bonds share a common carbon atom that is sp1 hybridized, and the molecular orbitals of the two double bonds are at right angles to one another. It clarifies that allenes are isomeric with alkynes, and the two classes of compounds can often be interconverted. It also highlights conjugated dienes as an important class of dienes that has two doubly bonded carbon atoms that are separated by a single bond. The chapter explains why the C2-C3 bond in 1,3-butadiene is slightly shorter than the carbon-carbon single bond in ethane by referring to the different hybridization of the orbitals involved. It describes the molecular orbital picture of conjugated dienes that is supported by their characteristic UV spectra.
Allyl compounds
Authors: Ward Robert S.
Published: September 2023

This chapter focuses on allyl alcohols, which are renowned for their ease of oxidation. It refers to manganese dioxide, which is highly effective for bringing about the oxidation of primary allylic alcohols to the αβ-unsaturated aldehydes. It also describes a highly-selective oxidation of allylic alcohols that involves epoxidation of the carbon-carbon double bond using tert-butyl hydroperoxide and a titanium or vanadium catalyst. The chapter analyses a valuable method of asymmetric synthesis known as Sharpless epoxidation, which involves treating the allylic alcohol with tert-butyl hydroperoxide in the presence of titanium tetraisopropoxide and a chiral ester of tartaric acid. This produces epoxy alcohols, which can be converted into a wide variety of other products by reduction or nucleophilic addition. The chapter also covers allyl ethers and allyl halides.
Alkene complexes
Authors: Bochmann Manfred
Published: September 2023

This chapter discusses alkene complexes. Alkene (olefin) complexes now exist of every transition metal and constitute one of the most important classes of coordination compounds. The development of the organometallic chemistry of olefins is closely connected with the rise of the petrochemical industry during the course of this century; olefins, in particular ethylene, are abundantly available from petrochemical feedstocks. The chapter then details the synthesis of alkene complexes and bonding of alkenes to transition metals. Olefins bind to transition metals via their π orbitals, by donating electron density into an empty metal d-orbital. However, since olefins are weak bases, the bond has to be stabilized by another bonding contribution: the donation of electron density from the metal to the olefin. Finally, the chapter explains the reactivity of alkene complexes.
Alkyne complexes
Authors: Bochmann Manfred
Published: September 2023

This chapter examines alkyne complexes. Alkynes (acetylenes) form complexes with transition metals in a similar way to alkenes, and similar bonding schemes can be applied. However, there are characteristic differences in the bonding of alkynes to metals compared to alkenes. Alkynes are stronger π-acceptors than alkenes; they have two orthogonal π-systems and can act as 2- as well as 4-electron donor ligands. Moreover, alkynes frequently undergo insertion reactions and are readily cyclotrimerized to give arenes. The chapter then studies the synthesis and bonding of alkyne complexes. Alkyne ligands can adopt a variety of coordination modes in mono and polynuclear complexes. The chapter also assesses the reactivity of alkynes. Alkynes, like alkenes, insert readily into metal–hydride bonds to give vinyl complexes.
Catalysis of organic reactions in solution by small molecules and ions
Authors: Maskill Howard
Published: September 2023

This chapter focuses on the catalysis of organic reactions in solution by small molecules and ions. Catalysis is the enhancement of the rate of a reaction by a compound (the catalyst) not generally present in the chemical equation which describes the reaction. Normally, a catalyst remains unchanged by the chemical reaction it catalyzes. It brings about the rate enhancement by providing a reaction pathway additional to the one which occurs in its absence. This additional pathway will have its own rate law, and the total rate of reaction in the presence of the catalyst is the sum of the catalysed and uncatalyzed pathways. The chapter then looks at electrophile catalysis, specific acid catalysis, general acid catalysis, nucleophile catalysis, specific base catalysis, and general base catalysis. It also considers the Brønsted equation.
Description and investigation of organic reaction mechanisms
Authors: Maskill Howard
Published: September 2023

This chapter discusses the terminology necessary for describing mechanisms of reactions of organic compounds. Each individual step of a complex reaction that is a proper chemical reaction in its own right is called an elementary reaction. As the concerted bonding of the nucleophile and unbonding of the nucleofuge, the molecular potential energy of the ion–molecule system increases until, at a certain stage, it reaches a maximum with both halogen atoms partially bonded to the carbon which is penta-coordinate. The chemical species corresponding to the molecular potential energy maximum is called the activated complex. The chapter then looks at molecularity, reaction coordinate, molecular potential energy reaction profile, and reaction maps. It also introduces the main techniques deployed in the investigation of organic reaction mechanisms, which can be divided into two groups: kinetics methods and non-kinetics methods.
Elimination reactions to give alkenes
Authors: Maskill Howard
Published: September 2023

This chapter focuses on elimination reactions to give alkenes. There are two principal alkene-forming reactions from alkyl halides which closely parallel SN2 and SN1 mechanisms. One is bimolecular and concerted, the other is stepwise with an initial unimolecular step. Both reactions overall involve a base and the elimination of HX from a molecule where X is either halogen or another nucleofuge bonded through a hetero-atom to the α-carbon. The chapter then looks at two other mechanisms for the elimination of HX. One is stepwise and involves a base, the other is a thermally induced single-step unimolecular mechanism which does not involve a base. Finally, the chapter considers briefly the mechanism of a nucleophile-induced reaction which yields alkenes though not by the elimination of HX, but X2.
Additions to carbon-carbon multiple bonds
Authors: Maskill Howard
Published: September 2023

This chapter studies the additions to carbon–carbon multiple bonds. In particular, it deals with additions of XY to double and triple carbon–carbon bonds to give products in which X and Y are separately bonded to the adjacent carbons of the original multiple bond. The simplest are reactions of diatomic molecules HX or X2 where X is a halogen, and these almost invariably have step-wise mechanisms. Such additions to alkenes or alkynes are the reverse of elimination reactions and two of the mechanisms are the E1 and E1cB in reverse. The chapter considers the mechanisms of addition in turn according to whether the initial step of the reaction of the unsaturated organic compound is with an electrophile, a nucleophile, or a radical. In electrophilic addition, the overall process is completed by the addition of a nucleophile and, in nucleophilic addition, completion involves addition of an electrophile.
Environmental and regulatory issues
Authors: Lee Stan , Robinson Graham
Published: September 2023

This chapter discusses how the escalating cost of developing a new drug or agrochemical product and the highly competitive nature of this area of business have led to greater pressure to reduce the time between discovery and marketing. It explains that fine chemical manufacturers are required to satisfy conditions imposed by environmental and regulatory authorities. It also emphasizes that process development chemists are required to consider all possible problems that could arise in this context when developing a route suitable for large-scale manufacture. The chapter includes information on the legislation that controls the movement of bulk chemicals within developed countries, based on which obtaining the permission to transport materials requires a notification involving the provision of toxicity data. It also mentions that chemical production plants are subject to stringent controls regarding pollution.
Development of a manufacturing route for cloprostenol sodium
Authors: Lee Stan , Robinson Graham
Published: September 2023

This chapter deals with cloprostenol sodium, the active ingredient in Estrumate, and a synthetic analogue of the naturally occurring prostaglandin F2α. It details the effectivity of cloprostenol sodium in the synchronization of oestrus, which led to its application in planned breeding in cattle. The chapter also talks about the innumerable synthetic routes to the prostaglandins and their analogues, considering the Corey route as one of the most versatile routes that allow for the preparation of side-chain variants. The chapter analyses the modification and improvement of the Corey route by ICI chemists so that cloprostenol sodium could be manufactured on a large scale, including how the chemical problems involved were solved. It cites the inherent problem with the Corey route, which is the tendency of the alkylated cyclopentadiene to isomerize.
Reactions of hydroxyl groups Part I
Authors: Davis Benjamin G. , Fairbanks Antony J.
Published: September 2023

This chapter describes the types of hydroxyl groups found in sugars and points out that carbohydrates exist in cyclic forms of hemiacetals. It highlights the importance of the reaction of the hydroxyl groups. This reaction allows for regioselective reactions of those groups left unprotected. The chapter also analyses the products of acetylations under different conditions and give examples of methods that are used to protect the c of a sugar. The chapter reviews the methods for forming and cleaving ether, such as benzyl, trityl, and silyl, and ester, such as acetate, benzoate, and sulfonate to protect groups. It talks about the difficulties associated with the substitution of sugar hydroxyl groups.
Inertness and lability to isomerism
Authors: Mingos D.M.P.
Published: September 2023

This chapter explores inertness and lability. The ability to isolate molecules depends not only on their thermodynamic stability, but also on the activation energies for decomposition pathways. Inert (kinetically stable) compounds have high activation energies associated with their possible decomposition pathways, while labile compounds have low energy pathways and react rapidly to form the thermodynamically favoured products. These qualitative ideas may be placed on a more quantitative basis using half-lives derived from kinetic data. The chapter then looks at inert gases and the inert pair effect, inorganic reactions, intermolecular forces, ionic bonds, ionization energy, isoelectronic molecules, and isomerism. Structural isomerism arises from a different bonding arrangement of atoms.
Magnetism to molecular orbital theory
Authors: Mingos D.M.P.
Published: September 2023

This chapter explains magnetism, differentiating between diamagnetism and paramagnetism. Diamagnetism is the magnetic property of a material as a result of the circulation of closed (complete) shells of electrons. Meanwhile, paramagnetism is the magnetic property arising from the unbalanced spin of electrons around the nuclei in molecules possessing unpaired electrons. The chapter then looks at metals and metalloids, before considering metallic bonding. It also examines mixed valence compounds and molecular orbital theory. In molecular orbital theory, the electron is described by a wavefunction that spreads throughout the molecule and is not localized on a specific atom. Molecular orbitals are constructed by taking a linear combination of atomic orbitals (LCAOs).
Radii to resonance
Authors: Mingos D.M.P.
Published: September 2023

This chapter looks at radii, defining covalent, ionic, metallic, and van der Waals radii. It also explains radius ratios. For ions which are really hard, incompressible spheres, it is possible to calculate the radius ratios of cation and anion which achieve optimal packing. Optimal packing means that the cation at the centre of the co-ordination polyhedron touches all the anions surrounding it and all the anions which make up the co-ordination polyhedron are also touching. The chapter then considers resonance. In valence bond theory, resonance denotes the superposition of wavefunctions to produce a better approximation to the actual wavefunction of the molecule.
Introduction and definitions
Authors: Housecraft Catherine E.
Published: September 2023

This chapter focuses on compounds in which metal atoms are within bonding contact, citing some examples of metal-metal bonded dimers. It concentrates on clusters with π-acceptor ligands and looks at a three-dimensional metal core in the molecule or ion that suggests that cluster is an appropriate descriptive term. It also mentions compounds in which the metal core consists of triangular units that share common edges, and the overall metal framework is approximately planar. The chapter talks about the modes by which ligands bind to metal centres that are indicated in compound formulae by the use of the Greek letters μ and η. It includes species with triangular metal-units but excludes compounds with linear or bent M3-units.
Binary metal carbonyls: synthesis, structures and localized bonding schemes
Authors: Housecraft Catherine E.
Published: September 2023

This chapter analyzes the low oxidation state transition metal associated with π-acceptor ligands. This tends to obey the 18-electron rule. The chapter illustrates an example of a dimer in which the metal-metal interaction is supported by bridging carbonyl ligands. It also mentions Raman spectroscopy. This is used as a means of probing for direct metal-metal bonding in dimetallic species. The chapter considers the strength of M-M bonds in the bulk state, which can be estimated from standard enthalpies of atomization as the structures of transitions metals vary. It talks about the partitioning of a moral enthalpy of atomization into bond dissociation enthalpies which is considered structure dependent.
The approach, and background topics
Authors: G. Denis Meakins
Published: September 2023

This chapter provides some background information on the functional groups and the methods for interconverting them. It includes some aromatic compounds which exhibit similar behaviour to aliphatic and aromatic compounds. This is the result of them having a common structural feature. It also describes the properties of a functional group, which are influenced by the nature of the α carbon atom. The chapter explains the concept of resonance, which is the concept invoked when the properties of a compound cannot be represented satisfactorily by one conventional formula. It covers two types of acids: Bronsted acids, which give an H+ to the substrate, and Lewis acids, which coordinate with an unshared electron pair in the substrate.
Organometallic compounds
Authors: G. Denis Meakins
Published: September 2023

This chapter covers the most useful organometallic compounds R-M with M = Li, Mg, or Cd, including Zn compounds and lithium cuprates. It illustrates the main features of R-Mg-Hal as reagents in synthetic work and reactions that produce Mg derivatives from which the products are liberated by a treatment with dilute acid. It also discusses the reactions with esters that result in ketones or aldehydes, which cannot be isolated under standard conditions. The chapter refers to the instability of intermediates, which is are not readily predicted by organic theory and stems from the decrease of free energy associated with their decompositions. It highlights the formation of the tertiary alcohol in high yield by R-Li, which provides a sharp contrast and exemplifies the modern trends towards the use of reagents.
Alkenes
Authors: G. Denis Meakins
Published: September 2023

This chapter considers the relations between alkanes, alkenes, and alkynes, noting that the first general characteristic of alkenes and alkynes is their tendency to be attacked by electrophiles. It mentions that the spherical s orbital of C may be regarded as near to the positive nucleus, while the pear-shaped p orbital may be considered as farther away. It also emphasizes that as the s characteristic of an orbital increases the orbital becomes effectively nearer the nucleus. The chapter illustrates how an electron in an orbital becomes more strongly attracted by the positive nucleus as the orbital goes from sp3 to sp2 to sp. It refers to the tendency for additional reactions as the second characteristic of alkenes and alkynes, implying that additions to multiple bonds are more favourable.
Amines
Authors: G. Denis Meakins
Published: September 2023

This chapter points out that ethers are ideal solvents for many reactions, but only special types of ethers can be regarded as reagents, such as the atmospheric O2 that reacts slowly with ethers by a radical mechanism to give highly explosive peroxides. It highlights that splitting simple ethers, two primary alkyl groups, requires vigorous treatment with the strongly nucleophilic hydroiodic acid. The nucleophilic attack occurs at the C which is less hindered and less negative. The chapter explains that the alternative ring opening occurs with protonated oxiran. It describes a method that has been widely used in carbohydrate chemistry for methylating primary and secondary alcohols
Photochemical kinetics
Authors: Wayne Carol E. , Wayne Richard P.
Published: September 2023

This chapter evaluates photochemical kinetics. It shows how an analysis of information about the rates of reactions can lead to a better and more quantitative understanding of photochemical processes. Reaction kinetics is the part of chemistry that deals with reaction rates, and photochemical kinetics affords valuable insights into the mechanisms of photochemical reactions and even into the detailed nature of individual elementary reactionary steps. The kinetic approach is also a valuable adjunct to studies of absorption spectra, fluorescence, and many other optical and photochemical phenomena. Its use has been implicit in much of the discussion of previous chapters, and this chapter also provides a more specific account of the relation between kinetics and photochemistry.
Stereoelectronic Effects
Authors: Kirby A.J
Published: September 2023

Stereoelectronic Effects provides an introduction to this important topic in the study of chemistry. Stereoelectronic effects control the way molecules are put together and especially for the 'rules of engagement' which operate when they meet and react. Understanding them can give us a 'feel' or intuition for what molecules are and what they are capable of. The treatment in this text is deliberately non-mathematical and this unifying treatment shows how to build up a powerful but simple way of thinking about chemistry. Chapters examine the electronic basis of stereoelectronic effects and the effects on conformation and on reactivity. The text also considers substitutions at saturated centres. It also looks at additions and eliminations, rearrangements and fragmentations, and radical reactions.
Potential energy surfaces
Authors: Brouard M.
Published: September 2023

This chapter discusses potential energy surfaces. A prerequisite for calculating a reaction cross-section or rate coefficient is a knowledge of the forces acting on the nuclei. Such information is usually derived from a potential energy function, known as a potential energy surface. The word 'surface' emphasizes that the potential energy function depends on the relative positions of all the nuclei involved in a reaction, and is, therefore, generally a function of more than one parameter. It is the adiabatic separation of electronic and nuclear motion, known as the Born–Oppenheimer approximation, which allows chemists to view reactions in terms of the motions of nuclei over single electronic potential energy surfaces. The chapter then looks at different types of potential energy surfaces. It also considers experimental probes of potential energy surfaces and the motion of the nuclei over the potential energy surface.
Molecular vibrations (non-degenerate modes)
Authors: Ogden J.S
Published: September 2023

This chapter deals with the symmetry aspects of vibrational spectroscopy by using a fuller treatment that includes bending modes and a stretches-only approach based on internal coordinates. It outlines the role of symmetry in molecular vibrations by considering the 3n degrees of freedom of motion in a molecule in terms of a present symmetry element. It also highlights the three degrees of freedom of an isolated atom, which are represented by translational displacements in mutually perpendicular directions. The chapter describes the in-phase displacements of atoms along the Cartesian directions that result in net translations of a whole molecule. It shows the result of out-of-phase motion along the x direction.
Vibrational spectroscopy— degenerate vibrations
Authors: Ogden J.S
Published: September 2023

This chapter discusses the role of symmetry in infrared and Raman vibrational spectroscopy. It examines the relationship between vibrational symmetry and spectroscopic methods of characterization, which is considered one of the main purposes behind identifying the symmetries of different molecular vibrations. It also explains how the link between molecular symmetry and spectroscopic observations relies on the number and type of vibrational energy levels that exist for a molecule. The chapter outlines the spectroscopic selection rules that dictate the transitions between the energy levels, which are expected to be observed depending on molecular symmetry. It covers basic symmetry selection rules that determine whether a particular vibration can be detected using infrared or Raman spectroscopy.
Appendix II
Authors: Ogden J.S
Published: September 2023

Character tables for selected point groups
The wave properties of matter
Authors: Cox P. A.
Published: September 2023

This chapter examines the wave properties of matter. Early attempts to extend the quantum ideas to the theory of matter had some limited success, but did not progress very far. Another radical idea was required before a satisfactory theory could be developed. As light has both wave and particle properties, perhaps the same is true of 'ordinary' particles such as electrons. This bold suggestion was made by Louis de Broglie in 1923, and within a few years it had been confirmed experimentally. De Broglie's wave hypothesis formed the basis for Schrödinger's equation, which was found capable of predicting the allowed energy levels in atoms and molecules, and must be regarded as one of the most important mathematical equations of modern science. Before discussing these ideas, the chapter begins by considering the classical mechanics of particles, reviewing some simple concepts that form an essential background to the quantum theory of matter.
Applications of Schrödinger’s equation
Authors: Cox P. A.
Published: September 2023

This chapter deals with some solutions of Schrödinger's equation in situations that are relatively simple, but which nevertheless have important applications in chemistry. Most of these deal with the quantization of energy. However, there is another remarkable prediction of quantum mechanics, known as tunnelling. In classical physics, kinetic energy cannot be negative; in other words, the total energy cannot be less than the potential energy. Schrödinger's equation can, however, be solved when this is the case. In some situations, these solutions are physically significant. The chapter then looks at the harmonic oscillator, which is one of the most important elementary models in mechanics, and is especially relevant in chemistry in connection with the vibration of molecules. It also considers rotations and angular momentum.
Organometallic chemistry and catalysis
Authors: Whyman Robin
Published: September 2023

This chapter provides a background on the vital role that catalysis plays in the production of fuels, commodity chemicals, fine chemicals, and pharmaceuticals, including as a means for strengthening environmental safeguards all over the world. It mentions the rapid development of organometallic chemistry and applications in catalytic processes, including technology based on organometallic catalysis such as olefin polymerization. It also discusses heterogenous catalysts which are used for the production of large-scale commodity chemicals, such as methanol and ammonia, and in the production of high-octane gasoline from petroleum. The chapter talks about the significance of homogeneous catalysts in the manufacture of both commodity and fine chemicals in high purity. It gives a comparison between homogeneous and heterogeneous catalysis.
Essentials of Inorganic Chemistry 2
Authors: Mingos D.M.P.
Published: September 2023

Essentials of Inorganic Chemistry 2 begins by looking at agostic interactions and angular overlap models. It moves on to band theory, crystal defects, and the Dewar–Chaff–Duncanson bonding model. Next, the text considers Group Theory, the isolobal analogy, ligand substitution reactions, and multiple metal-metal bonds. Then, it looks at redox reactions, stereochemical non-rigidity, superconductors, and symmetry. Finally, it considers synergic bonding, the tolman cone angle, and zintl isoelectronic relationships.
Group theory
Authors: Mingos D.M.P.
Published: September 2023

This chapter focuses on Group Theory. The interrelationships between the symmetry properties and the observable properties are defined using a mathematical formalism described as Group Theory. The properties of a molecule of interest to a chemist such as its total energy, the number of infrared vibrational modes, and the number of electronic transitions, must be invariant to the symmetry operations. The solution of a Schrödinger equation for the hydrogen atom leads to sets of degenerate orbitals, which are crucial to chemists because their number, shape, and energies not only determine the form of the Periodic Table but also the number and type of bonds in molecules. The chapter then looks at the derivation of qualitative molecular orbital diagrams; direct products; π orbitals in coordination and polyhedral molecules; stretching and bending modes; and symmetry analysis of stretching modes.
Isolobal analogy
Authors: Mingos D.M.P.
Published: September 2023

This chapter assesses the isolobal analogy, which provides a very useful methodology for rationalizing the structures of polyhedral molecules having both main group and transition metal fragments. It highlights that the metal carbonyl fragments of the later transition metals, the dδorbitals, are not used. Therefore, they form a maximum of three out-pointing hybrids, which makes them analogous to the main group fragments. It also notes that the total number of valence electrons in these isolobal fragments differ by 10. Finally, the chapter explains that, since the isolobal analogy is clearly linked to the Effective Atomic Number Rule, it has to be modified and indeed in some cases abandoned for classes of complexes where the rule is inapplicable.
Zintl isoelectronic relationships
Authors: Mingos D.M.P.
Published: September 2023

This chapter examines Zintl isoelectronic relationships. The chapter starts by noting how many binary compounds are formed between the Group 1 and 2 elements and Groups 13–15. The Zintl concept utilizes isoelectronic relationships in order to provide some insight into the solid state structures adopted by such compounds. The chapter highlights that the electronegativity differences between the atoms are sufficiently large in these compounds that, to a first approximation, an ionic formulation is reasonable. The isoelectronic relationship is then used as a basis for rationalizing the manner in which the Group 13–15 elements aggregate in the solid state. Next, the chapter explains that many of the anionic species observed in Zintl phases in the solid state are not observed as stable solution species. This is because their large negative charges make them very nucleophilic and therefore sensitive to the slightest traces of moisture.
Inorganic Spectroscopic Methods
Authors: Brisdon Alan K.
Published: September 2023

Inorganic Spectroscopic Methods provides an introduction to common spectroscopic techniques and interpretation of spectra, and their application to inorganic-based systems. The approach taken is aimed at the application of the techniques and interpretation of the spectra obtained. Beginning with an introductory description of electromagnetic radiation and its interaction with matter, each subsequent chapter covers the physical basis of related spectroscopic methods (vibrational, resonance, UV-visible spectroscopy, mass spectrometry) and their applications typical in inorganic compounds. The final chapter offers an integrated approach to the identification of unknown materials—putting together the techniques discussed.
Reactions of enolates
Authors: Procter Garry
Published: September 2023

This chapter investigates the reactions of enolates. The reaction of enolates with electrophilic species, often referred to as α-substitution of carbonyl compounds, is a very important reaction in organic chemistry. One reason for this is that the carbonyl group can be converted easily into many other functional groups. The carbonyl group can even be removed completely by reduction to a methylene group. This means that one can use α-substitution to a carbonyl group to introduce a new substituent, and then convert to carbonyl group into another functional group. Stereoelectronic restrictions apply to the deprotonation step to form the enolate and its reaction with an electrophile. The chapter then looks at the reactions of chiral enolates, chiral auxiliaries, chiral reagents, and enantioselective catalysis.
Aldol reactions
Authors: Procter Garry
Published: September 2023

This chapter evaluates aldol reactions, which occupy a particularly important position in organic synthesis. It is a very general method for forming a new C–C bond and, at the same time, two new stereocentres. Many aldol reactions take place through a highly ordered transition state, which appears to possess a predictable stereochemistry. This is often called the Zimmerman–Traxler transition state. In this, the counter ion of the enolate, usually a metal, is bonded to the oxygen of the enolate and coordinated to the oxygen of the aldehyde. Following this ‘complexation’, the bond forming and bond breaking take place. The chapter then considers the stereochemical aspects of aldol reactions; the control of enolate geometry, diastereoselective reactions involving prochiral substrates and chiral enolates, and chiral reagents and catalysts.
The reactive interface
Authors: Bowker Michael
Published: September 2023

This chapter provides a background of catalysis, which is an extremely important phenomenon for the modern industrial economy. It is a process whereby a reaction occurs faster than the uncatalysed reaction, the reaction being accelerated by the presence of a catalyst. Industrial catalysis can be divided into two broad types: heterogeneous and homogeneous. Most large-scale, industrially catalysed processes are of the former type, and the widespread recent application of catalysis to car emission control uses such solid catalysts in contact with the gas phase exhaust stream. For these kinds of reaction, the nature of the interface is crucial for the efficiency of the process. The nature of the top layer of atoms determines how fast a catalytic reaction takes place and small amounts of additives can reduce or enhance the reaction. The chapter then details the catalytic cycle and the adsorption on surfaces.
Catalysis for the future
Authors: Bowker Michael
Published: September 2023

This chapter studies the use of catalysis in the future. The main areas of importance here are threefold: new routes to fuels; new routes to commodity chemicals from alternative feedstocks; and new areas of the application of catalysis to environmental protection. The chapter begins by considering how the process of catalytic invention and development will change as we advance into the 21st century. Over recent years, the importance of the application of computer technology to the field of chemistry has been realised. Catalysis has been rather backward in this area, but in the 21st century it will mature from a 'black art' to a truly predictive scientific discipline by the use of computer-based 'expert systems'. The chapter then looks at catalytic hydrogen production, fuel cells, and the reduction of indoor pollution.
Reactions of amino compounds with aldehydes and ketones
Authors: Jones John
Published: September 2023

This chapter investigates the reactions of amino compounds with aldehydes and ketones. Amino nucleophiles ~NH2 react reversibly with aldehydes and ketones. The reversible reaction of ~NH2 with an aldehyde or ketone is very similar to that of water, involving as it does nucleophilic addition followed by dehydration. Secondary amines R2NH are intrinsically just as nucleophilic as primary amines RNH2. They react with aldehydes and ketones similarly, except that the final stage is blocked because there is no proton to discard, so iminium ions are generated. The chapter then looks at classical aldehyde and ketone derivatization, as well as reactions of ammonia and primary amines with aldehydes and ketones. It also considers enamines, the Wolf–Kishner reaction, and transamination.
Heat exchange between grey surfaces
Authors: Jones H. R. N.
Published: September 2023

This chapter examines the radiation exchange between non-black surfaces, which has the additional complication of reflection of incident radiation as the radiation leaving the surface is composed of emission plus reflection. It considers two opaque or grey surfaces and the radiative fluxes associated with one of those surfaces. It also mentions the contrasts with black surfaces, where radiative transfer depends on the difference between the emissive power of each surface as the transfer rate is dependent on the difference between the radiosity of each surface. The chapter illustrates additional complexities associated with non-black systems in the simplest system involving just two surfaces. It reviews the analysis of systems involving non-black surfaces that invariably requires solving a set of equations to obtain radiosities, from which heat transfer rates can be determined.
Emission and absorption by gases
Authors: Jones H. R. N.
Published: September 2023

This chapter discusses the extent to which gases emit or absorb radiation. This features a molecule that must change as its dipole moment vibrates to emit or absorb infra-red radiation. It explains how radiation in gases occurs at very specific wavelengths as emission or absorption can be strong at some wavelengths but be effectively zero at others. It also describes when radiation passes through a gas which is either transmitted, absorbed, or scattered, noting that gas emission and absorption is a volumetric phenomenon that depends on the thickness of the gas. The chapter talks about how a beam will be attenuated as it passes though the medium by an amount which will be proportional to the intensity of the beam. It cites an example that shows two parallel plates with two beams of radiation originating from the same point on one plate and travelling to the opposite plate.
Radiative heat transfer in furnaces
Authors: Jones H. R. N.
Published: September 2023

This chapter focuses on the notion of the high temperature furnace, which is considered an important application of radiation heat transfer where radiation is generally the dominant mechanism of heat transfer. It clarifies the object of any furnace, which is to heat some material using a high temperature heat source, such as combustion gases or an electrically heated panel. It also describes the correct design and sizing of a furnace that depends on the accurate modelling of radiation heat transfer within the furnace. The chapter considers two aspects of radiative heat transfer calculations that are pertinent to furnaces, covering the non-isothermal nature of most furnaces. It addresses the question of time dependence, wherein furnace designers are frequently concerned with the heating time required for a given material to reach a target temperature.
Radiation from flames
Authors: Jones H. R. N.
Published: September 2023

This chapter deals with radiation heat transfer in combustion systems, particularly the combustion gases present in such systems. It analyses the main complication that arise when combustion gases are often laden with particles, which plays a significant role in the heat transfer processes. It also discusses particles which give a flame its luminosity. This is a major contributor to heat transfer from flame gases to the surroundings. The chapter emphasizes the importance of understanding the heat transfer processes in the development of the modelling of high temperature systems. It highlights the gaseous phase in combustion gases which contain a mixture of carbon dioxide, water vapour, unused oxygen, nitrogen, and unburnt fuel, including traces of carbon monoxide and nitrogen oxides that have a negligible effect on radiation.
Multiple reactions
Authors: Metcalfe Ian S.
Published: September 2023

This chapter evaluates how the design process must be modified when more than one reaction is occurring. It considers parallel reactions. Treatment must be different when there are reactions of mixed reaction rate orders proceeding at the same time, and the local or instantaneous selectivity depends upon the concentration of reactant. In such a case, the choice of reactor will influence the overall selectivity. For a continuous stirred tank reactor (CSTR), the overall selectivity is equal to the local selectivity as the local selectivity is a constant because of the lack of concentration gradients. Hence, calculation of the product distribution is straightforward. For a plug flow reactor (PFR) or batch reactor, it is more complex to evaluate the overall product distribution as the local selectivity or instantaneous selectivity will vary with position or time.
Diatomic molecules
Authors: Winter Mark J.
Published: September 2023

This chapter evaluates diatomic molecules. Atomic orbitals of the correct symmetry on adjoining atoms interact to form a bonding combination orbital and an antibonding combination orbital. Molecular orbitals that display cylindrical symmetry when viewed along the bond axis are called σ orbitals. Atomic s-orbitals on adjoining atoms combine to form σ and σ*orbitals (the * denotes antibonding). Meanwhile, atomic p-orbitals on adjoining atoms combine by sideways overlap to form π and π*orbitals. The bond order is a number calculated by subtracting the number of antibonding electrons from the number of bonding electrons, and dividing by 2. Ultimately, molecular orbital energy level diagrams of homodiatomic molecules are symmetrical, but molecular orbital energy level diagrams of heterodiatomic molecules are asymmetric because the energy levels of the more electronegative atom are lower.
An ionic model of metal complexes
Authors: Mark J. Winter
Published: September 2023

This chapter analyses the model of the nature of the metal–ligand bonding in d block complexes that is either ionic or covalent. It distinguishes crystal field theory, which is a useful ionic treatment, from molecular orbital theory, which provides a covalent bonding model. The chapter also reviews the underlying assumption behind the crystal field model, noting that the metal complex here is represented as a point positive charge surrounded by a set of point negative charges. The chapter describes the crystal field model of metal complex bonding, which is represented as a point positive charge surrounded by a set of point negative charges. The chapter refers to the bulk of the bonding within the crystal field model of metal complex that is electrostatic.
Consequences of d orbital splitting
Authors: Mark J. Winter
Published: September 2023

This chapter describes properties, such as colour and unusual magnetic properties, of d-block metal complexes. It points out that if a compound contains an electron in the lower of two energy levels, then irradiation of that compound with light whose energy is equal to the energy gap between the two levels. The chapter also reviews orbitals that possess a centre of symmetry when a molecule possesses a centre of symmetry that are gerade (g). The chapter talks about photochemically induced d–d transitions that are governed by the Laporte symmetry selection rule and by the spin selection rule. It discusses Jahn–Teller distortions that arise when the electron occupancy of a degenerate set of energy levels is asymmetric.