Nature of chemical products

There exists a body of knowledge for chemical processes. Clearly, there should be a similar one for chemical products. To improve our knowledge of chemical products, it would help to have some kind of classification which guides its development and teaching. Thus, the main aim of this chapter is to examine the nature of chemical products. This subject encompasses a wide spectrum of issues. I would like to share my thinking on these issues with you. 

The challenge of this chapter then is to clarify the nature of chemical products, give the basic definitions related to a chemical product and see how these definitions can be useful for the classification, study and design of chemical products. 

While the principal value of the book is for the professional chemist or student of chemistry, it should also be of value to many people not especially educated as chemists. Workers in the natural sciences—physicists, mineralogists, biologists, pharmacists, engineers, patent attorneys, and librarians—are often called upon to solve problems dealing with the properties of chemical products or materials of construction. Eor such needs this compilation supplies helpful information and will serve not only as an economical substitute for the costly accumulation of a large library of monographs on specialized subjects, but also as a means of conserving the time required to search for... 

The physical characteristics of a fat or oil for imitation dairy products are not necessarily dictated by the fat being replaced, but by the composition, processiag methods, and conditions of use of the substitute product. Thus, the selection of the fat or oil is generally developed experimentally. The chemical and physical nature of the components of the system, order of addition, shear iaput, and processiag temperature dictate the final iateractions and the nature of the product. A comparison of the characteristics of milk fat and three different fats that are used ia satisfactory filled and imitation milks are listed ia Table 1 and those that comprise whipped toppiag, ia Table 2. 

Careful attention should be paid to processing and storage equipment to assure that certain future uses will not be contraindicated based upon the nature of the products. For example, it would not be wise to allow storage of food or food chain materials in vessels that once contained agricultural chemicals, even if the vessels were first cleaned. In the event the toller will not assure appropriate future use of the equipment, the client may consider purchasing the equipment for future use elsewhere. 

There is a wide range of conversion levels. The term maximum conversion type has no precise definition but is often used to describe a level of conversion, where there is no net fuel oil manufactured. A fuel products refinery with specialities may manufacture lubricating oils, asphalts, greases, solvents, waxes and chemical feed stocks in addition to the primary fuel products. The number and diversity of products will naturally vary from one refinery to another. Refineries produce chemical feed stocks for sale to the chemical affiliates and do not have responsibility for the manufacture of chemical products directly. Both operations may be carried out at the same physical location but the corporate product responsibilities are usually separate. 

It has been known for many years that microbial contaminants may effect the spoilage of pharmaceutical products through chemical, ply sical or aesthetic changes in the nature of the product, thereby rendering it unfit for use (see Chapter 18). Active drug constituents may be metabolized to less potent or chemically inactive forms. Physical changes commonly seen are the breakdown of emulsions, visible surface growth on solids and the formahon of slimes, pellicles or sediments in hquids, sometimes... 

Dynamic Changes to Process Conditions. Because of the dynamic nature of chemical processes, conditions change over time as a result of changes in production rates, quality targets, feed compositions, and equipment conditions. This in turn changes how certain process information may be interpreted. Thus, adaptive interpretation ability is often required. 

Petrochemical plant. Over 90 % of chemical products are based on natural oil that is mostly "cracked" to give simple products, which are laboriously separated by distillation. Of the 4 billion tons of natural oil consumed worldwide every year, only 7 % is used by the chemical industry. 

The mechanism of combustion of blackpowder is extremely complex and only an outline can be given here. It will be convenient to consider first the initial chemical reactions in ignition, then the reactions which occur during the main combustion and finally the nature of the products. 

The mechanisms by which coal is converted to soluble or liquid form and the nature of the products of such reactions have been the subjects of a great deal of effort throughout the world. In the last two sections, researchers from Australia, Japan, South Africa, and the United States describe their findings in these areas. The reader will note that no unanimous agreement exists on the chemical mode by which coal is converted although kinetic descriptions are often similar. 

Three of the most important parameters that affect the hydrogenation of coal and the products obtained are the catalyst, the temperature and the residence time. The effects of these parameters on the chemical nature of the products are still not fully understood. 

Also, by the very nature of chemical transformations, there are almost always unused chemicals remaining. These chemical leftovers include contaminants in the raw materials, incompletely converted raw materials, unavoidable coproducts, unselective reaction by-products, spent catalysts, and solvents. There have long been efforts to minimize the production of such waste products, and to recover and reuse those that cannot be eliminated. For those that cannot be reused, some different use has been sought, and as a last resort, efforts have been made to safely dispose of whatever remains. The same efforts apply to any leftovers from the production of the energy from the fuels produced or consumed by the processing industries. Of particular immediate and increasing concern are the potential detrimental effects of carbon dioxide emissions to the atmosphere from fossil fuel combustion, as discussed further in Chapters 9 and 10. 

Companies who to date have decided in favor of the quant-based combinatorial optimization approach, are collectively characterized by a complex and multi-step supply chain whose scheduling requires the consideration of multiple constraints. By nature of their production processes, many of these companies come from the chemical or pharmaceutical industry. 

The catalyst does not affect the chemical nature of the products. This must be qualified if more than one reaction (set of products) is possible, because the catalyst usually affects the selectivity of reaction. 

The technique is currently not used as widely as UV, visible and infrared spectrometry partly due to the high cost of instrumentation. However, it is a powerful technique for the characterization of a wide range of natural products, raw materials, intermediates and manufactured items especially if used in conjunction with other spectrometric methods. Its ability to identify major molecular structural features is useful in following synthetic routes and to help establish the nature of competitive products, especially for manufacturers of polymers, paints, organic chemicals and pharmaceuticals. An important clinical application is NMR imaging where a three-dimensional picture of the whole or parts of a patient s body can be built up through the accumulation of proton spectra recorded over many different angles. The technique involves costly instrumentation but is preferable to... 

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