bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fractionation of polymers
Authors: Koningsveld R , Stockmayer W H , Nies E 
Published: November 2023

Abstract
Fractionations of polymers are carried out for two different purposes. One of these entails the analytical determination of the molar-mass distribution (MMD). The other refers to the preparation of fractions large enough in size to permit study of their properties. In analytical fractionations the amount of initial polymer is usually small; the fractions do not need to be separated and are often characterized on-line in automated fractional dissolution procedures. Some column techniques are in use that are based on thermodynamic equilibrium principles and may make use of either liquid/liquid or liquid/solid phase separations. In preparative polymer fractionation, scaling-up problems are the main issue, because the necessary amount of initial polymer increases considerably when purity requirements of the fractions are raised. It is usually necessary to resort to pilot-plant operations if relatively pure fractions of 100-gram size are required.
Many-Body Theory of Monolayers
Authors: Bruch L W , Cole Milton W , Zaremba Eugene 
Published: November 2023

Abstract
In this chapter we develop the theory of interacting monolayers, following a division into two classes: (1) those in which the substrate imposes such a strong lattice structure on the adsorbate that lattice gas approximations capture much of the essential physics and (2) those in which the continuous character of the configurations is dominant and for which an analogue of the theory of 3D rare gas solids is implemented. Section 5.1 treats the lattice gas models and results of the renormalization group theory of phase transitions (Domb and Green 1972, 1976). The concept of universality applies here and critical point exponents are expected to be insensitive to several parameters in the models. Section 5.2 treats the continuum systems, using methods applied to rare gas solids and liquids (Pollack 1964; Klein and Venables 1976, 1977). This is ‘nonuniversal theory’ and the goals are to account generically for the observations and to reach a quantitative understanding for a few systems. We emphasize the formulation of the theory and illustrate it with a few physical examples. Our aim is to highlight the considerations from which the theory begins and to show the relations among the different approximation methods. In Chapter 6 we give a more thorough account of a few series of adsorbates, covering the range from the initial monolayer condensation to the multilayer regime and contrasting the behavior to the 3D bulk phases of the adsorbate.
Residue-specific considerations
Authors: Jones John 
Published: November 2023

Abstract
Specific peptide bond formation with the α-amino group of lysine requires prior blockade of the ε-amino group. The necessary differentiation can be achieved by using the fact that the side-chain amino group is the more basic and nucleophilic because there is an electron-withdrawing group next to the α-amino group (Scheme 6.1), or by taking advantage of the fact that the two functionalities can engage in chelate formation (Scheme 6.2).
Solution peptide synthesis
Authors: Jones John 
Published: November 2023

Abstract
Hundreds of oligopeptides have been synthesized by the so-called ‘classical’ solution approach to peptide synthesis. The designation ‘classical’ is a little misleading, however. We deal here not with an elegant anachronism, but with a continuously evolving and lively art. That it operates to an increasing extent in the shadow of the solid phase approach has more to do with the expansion of the latter than with the contraction of the former. The flexibility of the solution approach makes it impossible to convey its full scope with a few examples, and we must content ourselves with four historically important and spectacular successes.
Dehydration reactions
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
Ureas and urethanes dissociate on heating into two components; isocyanates and amines, and isocyanates and alcohols, respectively (eqn (2.1)). Analysis of the rate of these thermal dissociation reactions allows us to conclude that ureas and urethanes dissociate via a ‘termolecular’ reaction mechanism.1 After all, ureas and urethanes can be viewed as addition products of isocyanates with amines and with alcohols, respectively. One of their analogues is a class of amides having an electron-withdrawing substituent at the a-carbon of their carbamoyl group. On heating, these amides are also expected to dissociate into their components in a manner similar to ureas and urethanes (eqn (2.2)).
Pyrolysis
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
Dehydration of hydroxamic acid gives isocyanates by a rearrangement reaction. Although this process was well known as the Lassen rearrangement, it was often difficult to isolate the resultant isocyanates when common dehydrating agents were used. Among numerous such reagents, only phosgene, thionyl chloride, etc. allowed isolation of isocyanates from the reaction mixture. However, I still thought that it would be possible to isolate them by reaction with some of the dehydration agents noted in Chapter 2, e.g. alkoxyacetylene or ketene acetal as illustrated in eqns (3.1) and (3.2), and therefore we started to investigate this problem. To our satisfaction, various isocyanates were prepared and isolated with the aid of these reagents, since only a carboxylic ester, which is unreactive to isocyanates, was formed as a side-product of the reaction.
Phosphorylation
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
Among the dehydrations described in Chapter 2, intramolecular dehydration by the use of polyphosphoric esters proceeded along with hydrolysis of pyrophosphoric bonds, which are involved in polyphosphoric esters. Turning our attention to this point, I discussed with the members of my laboratory a possible extension to intermolecular dehydration and decided to start a study on phosphorylation, which is important for the synthesis of nucleotides, oligonucleotides, and coenzymes.
Deoxygenation reactions: oxidationreduction condensation
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
Through our further discussions on the development of dehydration reactions using organic dehydrating agents, such as isocyanates, vinyl ethers, and imidoyl phosphate (see Chapter 2), we visualized that a dehydrating agent is characterized by its high reactivity toward water. For instance, phosphorus trichloride is usually kept sealed in an ampoule in the laboratory, and when exposed to air it reacts with moisture to form a white mist.
Oxidation-reduction condensation: the synthesis of peptides and nucleotides
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
Phosphorylation of bromocyanoacetamide with phosphonate proceeds through the initial formation of an enol phosphate of the amide via a phosphonium salt, which is a reactive species responsible for the reaction with an alcohol to produce the corresponding phosphate along with a stable carboxamide.
Synthetic reactions with the onium salts of aza-arenes
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
As mentioned in preceding chapters, the dehydration reaction has been a major subject of interest over the years as it is one of the most fundamental organic reactions. The importance of this reaction is apparent when one considers the wide variety of biological substances, such as peptides and oligonuclcotides, which arc formed mostly by intermolecular dehydration.
The selective aldol reaction and Michael reaction
Authors: Mukaiyama Teruaki 
Published: November 2023

Abstract
In the first half of the 1970s, we investigated the characteristics of alkylthioboranes based on the concept of ‘elements in combination’ as described in Chapter 7,1 and we explored new reactions of significant interest. Further extension of research to investigate new characteristics of alkylthioboranes seemed quite promising, because the combination of two different elements in this particular case could create an unexpected and novel reactivity. In fact, we found that an aldol product was formed smoothly in the reaction of alkylthioborane, ketene, and aldehyde. One example, shown in eqn (13.1), is the formation of [3-hydroxy thioester by the reaction of dibutyl-S-butylthioborane, aldehyde, and ketene. We then started an investigation of the mechanism of this reaction.
Oscillations In A Closed Isothermal System: Ma Them A Ti Cal Analysis
Authors: Gray Peter , Scott Stephen K 
Published: November 2023

Abstract
The previous chapter has provided some indication of the behaviour which can be exhibited by the simple cubic autocatalysis model. In order to make a full analysis, it is convenient both for algebraic manipulation and as an aid to clarity to recast the rate equations in dimensionless terms. This is meant to be a painless procedure (and beloved of chemical engineers even though traditionally mistrusted by chemists). We aim wherever possible to make use of symbols which can be quickly identified with their most important constituents: thus for the dimensionless concentration of A we have a, with /3 for the dimensionless concentration of B.
Thermokinetic Oscillations In A Closed System
Authors: Gray Peter , Scott Stephen K 
Published: November 2023

Abstract
This chapter and chapter 5 study the prototypical thermokinetic oscillator. Thermal feedback replaces autocatalysis, and the Arrhenius temperature dependence of rate coefficients supplies non-linearity in the scheme
In the preceding chapters we investigated the basic patterns of behaviour which might be exhibited by a reaction scheme which involved a certain form of chemical feedback under isothermal conditions. Here we make a similar analysis for systems with purely first-order chemical reactions but under conditions in which the heat produced by the natural exothermicity can lead to departures from isothermal operation. Feedback is then provided from thermal coupling as the increase in temperature of the reacting mixture leads to an increase in the local value of the reaction rate constant.
Reaction In A Non-Isothermal Cstr: Stationary States And Singularity Theory
Authors: Gray Peter , Scott Stephen K 
Published: November 2023

Abstract
Chapter 6 considered isothermal autocatalysis in an open system; here we study a classic case of thermal feedback. A rich variety of stationary-state patterns (bifurcation diagrams) are generated and considered here alongside those of the previous isothermal example. Flow diagrams are again illuminating and singularity theory provides a systematic approach. After study a reader should be able to:
Chemical Diffusion Pattern Formation (Turing Structures)
Authors: Gray Peter , Scott Stephen K 
Published: November 2023

Abstract
In this chapter we investigate some of the ways in which spatial patterns can arise in closed chemical systems. Coloured patterns can arise when a reaction is carried out in thin layers, in a petri dish for instance, corresponding to spatial variations in chemical concentrations. Thus in the BelousovZhabotinskii reaction, blue concentric circles indicating local regions of high Ce4+ concentration travel through a red background of Ce3+ to form target patterns. The latter are moving in time, i.e. they are a form of travelling wave, about which we will say more in the next chapter. Here we are interested in the possible spontaneous formation of stationary patterns.
Manipulation of Nuclear Spin Hamiltonians
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander 
Published: November 2023

Abstract
A major advantage of NMR in comparison with other forms of spectroscopy is the possibility of manipulating and modifying the nuclear spin Hamiltonian at will, almost without any restriction, and to adapt it to the special needs of the problem to be solved. Many infra-red and ultraviolet spectra cannot be interpreted because of the enormous complexity of incompletely resolved signal patterns. In NMR, however, it is very often possible to simplify complex spectra by modifying the Hamiltonian to an extent which permits a successful analysis. The ease of manipulation of nuclear spin Hamiltonians is unique for purely practical reasons. Because nuclear interactions are weak, it is possible to introduce competitive perturbations of sufficient strength to override certain interactions. In optical spectroscopy, the relevant interactions are of much higher energy, and similar manipulations are virtually impossible.
Two-Dimensional Fourier Spectroscopy
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander 
Published: November 2023

Abstract
The extension of spectroscopy to two and more dimensions stems from the recognition that the properties of a molecular system cannot be fully characterized by a conventional one-dimensional (ID) spectrum. Even an ensemble of one-spin systems is a non-linear system, as mentioned in Chapter 4, and is only incompletely characterized by its impulse response or transfer function. This holds even more so for coupled spin systems. Many ambiguities remain in ID spectra, such as the assignment of multiplets and the identification of connected transitions. Two dimensional (2D) spectroscopy is a general concept which makes it possible to acquire more detailed information about the system under investigation. Since the first proposal in 1971 (6.1) and the first experimental realization in 1974 (6.2—6.5) an astonishing number of powerful 2D techniques have been invented, tested, and applied to problems in physics, chemistry, biology, and medicine.
Two-Dimensional Separation ofof Interactions
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander 
Published: November 2023

Abstract
The interpretation of NMR spectra in liquid or solid phases is often impeded by the complexity of overlapping resonances. When the Hamiltonian is composed of terms of different physical origin, such as chemical shifts or dipolar or scalar couplings, it is often possible to render spectra more intelligible by separating various interactions in orthogonal frequency domains. Two-dimensional separation is preferable to decoupling techniques, since there is no loss of information. In the course of 2D separation, the number of peaks is conserved. The primary advantage lies in the fact that overlapping resonances are unravelled. The separation of interactions by 2D spectroscopy can be compared with two-dimensional chromatography. In a one-dimensional thin layer or paper chromatogram, the separation of the constituents by elution with a given solvent is often incomplete. Elution with a second solvent in a perpendicular direction may then achieve full separation.
Nonequilibrium Phenomena in Polyatomic Gases
Authors: Mccourt Frederick R W , Beenakker Jan J M , Kohler Walter E , Kuscer Ivan 
Published: November 2023

Abstract
Properties of the effective cross sections which have been utilized in the expressions for nonequilibrium phenomena in dilute polyatomic gases are discussed, and interrelationships amongst them elucidated. Then, the evaluation of such effective cross sections from molecular scattering theory is outlined. The temperature dependence of the effective cross sections as determined experimentally is discussed, and for molecular hydrogen, compared with the results of full quantum scattering calculations. Transport phenomena in rarefied gases, the modelling of the surface scattering operator and the derivation of boundary-layer effects (with and without magnetic fields present) are covered in four chapters. Aspects of the collisionless gas regime are then dealt with in a separate chapter. The penultimate chapter covers relevant mathematical material, and the final chapter provides tables of experimental data and effective cross sections deducted from these data wherever possible. This book completes this major two-volume work on Non-equilibrium phenomena in polyatomic gases, and stands as a definitive treatise in this area of chemical physics. Volume 1, on dilute gases, was published in August 1990.
Molecular Scattering Theory
Authors: Mccourt Frederick R W , Beenakker Jan J M , Kohler Walter E , Kuscer Ivan 
Published: November 2023

Abstract
Since the scattering of particles is usually analyzed quantum mechanically, the greater part of this chapter will be devoted to quantum mechanical scattering theory. However, as will be shown in the last section, classical theory based upon the evaluation of trajectories can also provide useful approximations, except for the very lightest molecules. The analysis leads to scattering amplitudes, S -matrix elements, and differential scattering cross sections, which provide the raw material for the evaluation of effective cross sections - the ultimate goal from the viewpoint of this book. Recipes for such evaluation were given in the preceding chapter. Although there are persistent discrepancies between quantum mechanical and classical evaluations of differential cross sections for small scattering angles and low energies, such differences are largely washed out in the calculation of effective cross sections and consequently cheaper classical calculations can often be employed.
Introduction
Authors: Scott Stephen K 
Published: November 2023

Abstract
This quantitative interpretation of experimental results from chemical systems is frequently based on the construction and subsequent analysis of kinetic mechanisms or models. This process can work in two directions. If we can confidently predict the chemistry, in terms of the individual reactions which are likely to occur between all the possible chemical species in the system, we can then write down the reaction rate equations based on the law of mass action. The reaction rate equations specify the rates at which the species concentrations change with time, and how these rates depend upon those concentrations. The idea here is to break the overall reaction up into a number of component or elementary steps.
Mappings
Authors: Scott Stephen K 
Published: November 2023

Abstract
The idea of a mapping in a dynamical system can be treated at various levels. At its simplest it can be accepted as a ‘game’. Even in this form it is instructive and has the advantage of requiring nothing more than a non-programmable calculator for the reader to participate. Later, we will see that the lessons learnt are of surprising relevance to the behaviour in chemical reactions.
Flows I. Two-variable systems
Authors: Scott Stephen K 
Published: November 2023

Abstract
In the previous chapter we investigated the behaviour of simple mappings. These showed ‘stationary states’ and bifurcations to periodicity, aperiodicity, and periodic windows. Even if we cannot claim to have completely understood these responses, a number of patterns with some definite structure have clearly emerged. Now we turn to models described by differential equations. In order to bring out the relevant features most clearly, we will employ the simplest of the model chemical schemes: the cubic autocatalator (Merkin et al. 1986, 1987a,h; Gray and Scott 1986, 1990a,b).
Flows II: Three-variable systems
Authors: Scott Stephen K 
Published: November 2023

Abstract
The previous chapter revealed a great deal about the behaviour of two variable chemical systems. Despite the variety of bifurcation phenomena, only two structurally-stable responses were found: stationary-state operation or simple period-I limit cycles. More complex patterns, such as oscillations that repeat every other excursion (period-2), are forbidden with only two variables by the restriction that trajectories may not, in general, cross on the phase plane (which is a two-dimensional surface). If we consider models or systems with more than two variables, the phase space becomes at least three dimensional.
Forced systems
Authors: Scott Stephen K 
Published: November 2023

Abstract
In the previous chapter we have considered models that have distinct variables, such as concentrations or local temperature, and parameters. The parameters are under our control and stay fixed when we want them to-only varying should we wish so. Thus the inflow concentrations or ambient temperature are fixed in time. In this chapter we investigate the types of behaviour possible when one or more of the parameters is varied in time (or does so of its own volition in spite of our wishes). Specifically we will be interested in the case where this time variation is periodic and in situations where the system without this additional periodicity can abo oscillate or show multistability. Again. this chapter will deal mainly with models and theory: practical aspects and real experimental systems come where appropriate in Chapters 8 to 12.
Experimental methods
Authors: Scott Stephen K 
Published: November 2023

Abstract
This chapter sets out to link the various theoretical methods described in the previous chapters to their application in experimental situations. In the latter case we must learn to cope with the ‘real world’ limitations on the availability and precision of our data. The theoretician or computer modeller is generally in an atypically privileged position in this respect. In principle, all species concentrations can be made available at any fixed time interval or other choice of sampling condition. The data can be obtained, and the parameters maintained constant, to almost arbitrary precision (within the confines of a computing budget). Such control over the raw data allows further manipulation such as constructing limit cycles or other attractors. Poincare sections, etc. to be made with relative ease.
Heterogeneous catalysis
Authors: Scott Stephen K 
Published: November 2023

Abstract
Heterogeneous catalytic systems have seemed a natural and fertile field for non-linear behaviour and only solution-phase reactions have been more widely studied. The oxidation of carbon monoxide over many metal surfaces in particular seems to have been the subject of deep investigations perhaps because of its technological as well as fundamental significance. Heterogeneous catalysis is widely applied in the chemical industry as a whole-the petrochemical industry in particular-and so there has been both motivation and support for any increase in understanding and control of such reactions. It might also be added that many theoreticians have also taken advantage of the ‘grey areas’ of uncertainty in the form of appropriate reaction rate laws, using putative surface reactions (and their enzyme equivalents) as an excuse for almost any otherwise unbelievable but convenient polynomial or transcendental form.
Quantum Description Of Nmr
Authors: Goldman Maurice 
Published: November 2023

Abstract
We are now equipped with the necessary mathematical background to analyse NMR in quantum-mechanical terms. In this chapter, the analysis is restricted to standard NMR, essentially the free-induction decay following a single r.f. pulse. The first section deals with the case when the only interaction experienced by the spins is the Zeeman interaction with an external field. It illustrates the way in which quantum mechanics is used in practice and its main result is a quantum justification of the equation of motion of the magnetization derived in Chapter 1 by a purely classical approach. The second section is a simplified description of chemical shifts and indirect interactions and of their influence on the NMR spectra. For such a simple problem, it will already become apparent that the formal machinery developed in the previous chapters is far superior to the classical or naive quantum methods, as regards the ease and the simplicity with which quantitative results are obtained.