<br><h3> Chapter One </h3> <b>Chemistry and Chemical Technology <p> Contents <p> 1.</b> Introduction 2 <b>2.</b> Organic chemistry 3 <b>2.1.</b> The chemical bond 3 <b>2.2.</b> Bonding in carbon-based systems 4 <b>3.</b> Chemical engineering 7 <b>3.1.</b> Conservation of mass 8 <b>3.2.</b> Conservation of energy 9 <b>3.3.</b> Conservation of momentum 9 <b>4.</b> Chemical technology 9 <b>4.1.</b> Historical aspects 10 <b>4.2.</b> Technology and human culture 11 <b>5.</b> Hydrocarbons 13 <b>5.1.</b> Bonding in hydrocarbons 15 <b>5.2.</b> Nomenclature of hydrocarbons 16 <i>5.2.1. Alkanes</i> 16 <i>5.2.2. Alkenes</i> 18 <i>5.2.3. Alkynes</i> 19 <i>5.2.4.</i> Cycloalkanes 19 <i>5.2.5.</i> Aromatic hydrocarbons 20 <b>5.3.</b> Isomers 24 <b>6.</b> Non-hydrocarbons 25 <b>6.1.</b> Alcohols 26 <b>6.2.</b> Ethers 27 <b>6.3.</b> Aldehydes 27 <b>6.4.</b> Ketones 28 <b>6.5.</b> Organic acids 28 <b>6.6.</b> Esters 28 <b>6.7.</b> Amines 29 <b>6.8.</b> Alkyl halides 30 <b>6.9.</b> Amides 30 <b>7.</b> Properties of hydrocarbons 31 <b>7.1.</b> Density 33 <b>7.2.</b> Heat of combustion (energy content) 34 <b>7.3.</b> Volatility, flammability, and explosive properties 35 <b>7.4.</b> Behavior 37 <b>7.5.</b> Liquefied natural gas 38 <b>7.6.</b> Environmental properties 39 References 41 <p> <p> <b>1. INTRODUCTION</b> <p> Chemistry (from the Arabic <i>al khymia</i>) is the science of matter and is concerned with the composition, behavior, structure, and properties of matter, as well as the changes matter undergoes during chemical reactions. Chemistry is a physical science and is used for the investigation of atoms, molecules, crystals, and other assemblages of matter, whether in isolation or combination, which incorporates the concepts of energy and entropy in relation to the spontaneity or initiation of chemical reactions or chemical processes. <p> Disciplines within chemistry are traditionally grouped by the type of matter being studied or the kind of study and include (alphabetically): (1) analytical chemistry, which is the analysis of material samples to gain an understanding of their chemical composition and structure; (2) biochemistry, which is the study of substances found in biological organisms; (3) inorganic chemistry, which is the study of inorganic matter (inorganic chemicals, such as minerals); (4) organic chemistry, which is the study of organic matter (organic chemicals, such as hydrocarbons); and (5) physical chemistry, which is the study of the energy relations of chemical systems at macro, molecular and sub-molecular scales. <p> In fact, the history of human culture can be viewed as the progressive development of chemical technology through evolution of the scientific and engineering disciplines in which chemistry and chemical engineering have played major roles in producing a wide variety of industrial chemicals, especially industrial organic chemicals (<b>Ali et al., 2005</b>). Chemical technology, in the context of the present book, relies on chemical bonds of hydrocarbons. Nature has favored the storage of solar energy in the hydrocarbon bonds of plants and animals, and the evolution of chemical technology has exploited this hydrocarbon energy profitably. <p> The focus of this book is hydrocarbons and the chemistry associated with hydrocarbons in organic chemistry, which will be used to explain the aspects of hydrocarbon properties, structure, and manufacture. <p> The book will provide information relating to the structure and properties of hydrocarbons and their production through process chemistry and chemical technology to their conversion into commercial products. <p> <p> <b>2. ORGANIC CHEMISTRY</b> <p> <i>Organic chemistry</i> is a discipline within chemistry that involves study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of carbon-based compounds (in this context – hydrocarbons). <p> On the other hand, <i>inorganic chemistry</i> is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad of carbon-based compounds, such as the hydrocarbons, which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, and there is much overlap, most importantly in the sub-discipline of <i>organometallic chemistry</i> in which organic compounds and metals form distinct and stable products. An example is tetraethyl lead, which was formerly used in gasoline (until it was banned by various national environmental agencies) as an octane enhancer to prevent engine <i>knocking</i> or <i>pinging</i> during operation. <p> Other than this clarification and brief mention here, neither <i>inorganic chemistry</i> nor <i>organometallic chemistry</i> will be described further in this text. <p> Organic compounds are structurally diverse, and the range of applications of organic compounds is enormous. In addition, organic compounds may contain any number of other elements, including nitrogen, oxygen, sulfur, halogens, phosphorus, and silicon. They form the basis of, or are important constituents of, many products (such as plastics, drugs, petrochemicals, food, explosives, and paints) and, with very few exceptions, they form the basis of all life processes and many industrial processes. <p> <p> <b>2.1. The chemical bond</b> <p> The most basic concept in all of chemistry is the chemical bond. The chemical bond is essentially the sharing of electrons between two atoms, a sharing which holds or bonds the atoms together. <p> Atoms have three components: protons, neutrons, and electrons. Protons have a positive charge of +1, neutrons have 0 charge, and electrons have a negative charge of –1. The protons and neutrons occupy the center of the atom as a piece of solid matter called the nucleus. The electrons exist in <i>orbitals</i> surrounding the nucleus. In reality, it is impossible to tell the precise trajectory of an electron and the best that can be achieved is to describe the probability of locating the electron in a region of space. <p> The simplest case is when the nucleus is surrounded by just one electron (for example, the hydrogen atom). In this case, the probability of finding an electron in its lowest energy, or most stable, state is distributed in a spherically symmetric way around the nucleus. The probability of finding the electron is highest at the nucleus and decreases as the distance from the nucleus increases. <p> This lowest energy, spherically symmetric orbital is called the <i>1s orbital</i>, which is the lowest energy orbital that an electron can occupy, but several higher energy orbitals are significant in organic chemistry. The next lowest energy orbital that an electron can occupy is the <i>2s orbital</i>, which looks much like the 1s orbital except that the electron is more likely to be found farther from the nucleus. The third lowest energy orbital is the <i>2p orbital</i>. The major and highly important difference between a <i>p orbital</i> and an <i>s orbital</i> is that the <i>p orbital</i> is not spherically symmetric and is oriented along a specific axis in space. There are three p orbitals, which are oriented along the x, y, and z axes. <p> <p> <b>2.2. Bonding in carbon-based systems</b> <p> A chemical bond is essentially the sharing of electrons between two atoms. Since electrons are negatively charged and exert an attractive force on nuclei, they serve to hold the atoms together if they are located between two nuclei. <p> When two atoms approach each other, their <i>atomic orbitals</i> overlap. The overlapped atomic orbitals can add together to form a <i>molecular orbital (linear combination of atomic orbitals</i>, LCAO). The area of greatest overlap between the original atomic orbitals represents the chemical bond that is formed between them. Since the sharing of electrons is the basis of the chemical bond, the molecular orbitals formed represent chemical bonds. <p> For example, in the case of hydrogen, the two 1s orbitals gradually come closer together until there is a good deal of overlap between them. At this point, the area in space of greatest electron density will be between the two nuclei, which themselves were at the center of the original atomic orbitals. This electron density, now part of a new molecular orbital, represents the chemical bond. When the area of greatest overlap occurs directly between the two nuclei on an axis containing the nuclei of both atoms <i>(internuclear axis)</i>, the bond is a <i>sigma bond (σ bond)</i> (<b>Figure 1.1</b>). <p> More than one atomic orbital from a single atom can be used to form new molecular orbitals. For example, a 2s orbital and a 2p orbital from one atom might add together and overlap with one or more orbitals from a second atom to form new molecular orbitals. Second, parts of orbitals can possess a sign (+ or –). The s orbital has the same sign throughout, while in the p orbitals, one lobe is þ and the other lobe is –. Signs do not matter with respect to electron density, but they must be taken into account when orbitals are added or subtracted. If two orbitals of the same sign are added, electron density will increase, while if two orbitals of opposite signs are added, the shared electron density will cancel out. <p> Carbon has six electrons – only two electrons can occupy an s orbital at a time. The first two electrons in carbon occupy the 1s orbital and the next two occupy the higher-energy, but similarly shaped 2s orbital while the final two electrons occupy the 2p orbitals. <p> In carbon, the electrons in the 1s orbital are too low in energy to form bonds. Thus, electrons used to form bonds must come from the 2s and 2p orbitals. Carbon very often makes four bonds by redistribution of the 2p electrons: <p> [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] <p> When it does so, these bonds are arranged so that they are as far away from each other as possible. This arrangement is referred to as a <i>tetrahedral bond</i> (<b>Figure 1.2</b>). <p> The individual 2s orbital and the 2p orbital cannot form bonds in this arrangement due to their geometry. The 2s orbital is completely symmetric, while the 2p orbitals are aligned along specific axes. None of these orbitals is well-equipped to form bonds in the tetrahedral geometry alone. <p> Since a chemical bond does not have to be formed from individual atomic orbitals, but can be formed from a combination of several atomic orbitals from the same atom, each bond that is made in the tetrahedral geometry, a part of the 2s and a part of each of the 2p orbitals will contribute, resulting in a tetrahedral arrangement and there is a 109.5 angle between each of the bonds (<b>Figure 1.2</b>). To achieve this geometry, both the 2s and all three of the 2p orbitals (2px, 2py, and 2pz) must contribute. The new bonds that are formed are called <i>sp</i><sup>3</sup> <i>bonds</i>, since one s orbital and 3 p orbitals were used to form the bonds. <p> [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] <p> <i>(Continues...)</i> <p> <!-- copyright notice --> <br></pre> <blockquote><hr noshade size='1'><font size='-2'> Excerpted from <b>Handbook of INDUSTRIAL HYDROCARBON PROCESSES</b> by <b>JAMES G. SPEIGHT </b> Copyright © 2011 by Elsevier Inc. . Excerpted by permission of Gulf Professional Publishing. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.<br>Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.