化学工程与工艺概论.doc

0 Introduction to Fine Chemicals Selected from Industrial Chemicals and Introduction to Organic Laboratory Techniques July，2008 1 Contents Chapter 1 Classifications of Chemicals 1 Chapter 2 Formulations 20 Chapter 3 Surface active materials and Emulsion 43 Chapter 4 ESSAY 4.1 Aspirin 63 ESSAY 4.2 Ethanol and Fermentation Chemistry 69 ESSAY 4.3 Esters-Flavors and Fragrances 77 ESSAY 4.4 Fats and Oils 83 ESSAY 4.5 Petroleum 88 ESSAY 4.6 Polymers and Plastics 99 ESSAY 4.7 Carbohydrates 108 ESSAY 4.8 Proteins and Amino Acids 117 2 Chapter 1 Classifications of Chemicals Order is a lovely thing: On disarray it lays its wing . Teaching simplicity to sing. “The Monk in the Kitchen” Anna Hempstead Branch CLASSIFICATION OF CHEMICALSWHAT FOR? In 1990, the Chemical Abstracts Service registered the 10 millionth compound in its registry system. (It was cis-(+)-4,6,7,8,8a,8b-hexahydro-6,6,8b-trimethyl-3H-naphtho 1,8-bcfuran). About one percent of these, a hundred thousand chemicals, are on the marketplace 1. These chemicals have approximately 350,000 common names. How are they listed? How are they categorized? Such a population needs order. We shall try and make some. The obvious way of listing chemicals, a way accepted by researchers is alphabetically by the name of the chemicals, without any classification. But what name? And how does one deal with those materials having very complex names? Then again, should Chemical Abstracts names be used? Or generic names? Or common names? And how is it possible to classify materials that are not pure, like washing powder? And materials that are better known by their tradenames (e.g. Teflon)? Such an alphabetical list will not include all possible materials. and is necessarily limited. Grouping chemicals in the “real world” is difficult: the boundaries are unclear, there is much room for overlapping and duplication, and different parameters are needed for classification. The question is, of course, what purpose dose the classification serve? Different types of chemicals mean different types of businesses. The differences cross the lines of all activities dealing with chemicals: technological, marketing, management and financial characteristics vary widely from one group of chemicals to another. These differences may be very great. Due to such “incompatibility”, the Union Carbide Corp was split in 1992, and the industrial gases business has been spun off the 3 other chemical businesses. We would also like to consider the point of view of the user who looks for a chemical, when this user may be positioned anywhere along the line starting with research and ending with application. Accordingly, we shall discuss the major types of classifications beginning with the chemically-based mode and ending with the chemically-based mode and ending with the commercially-based mode: (i) organic/inorganic chemical listing, (ii) classification by price and (iii) Classification by application. If we examine a specific chemical within each of the three lists, we find that different types of information are hidden behind the name (Table 2.1). We shall discuss all these modes of classification in detail. TABLE 2.1 INFORMATION IMPLIED BY THE VARIOUS CLASSIFICATION METHODS FOR CHEMICALS Type of ClassificationInformation Organic/inorganic listing Listing by priceListing by Application Chemical identity and structure + Price-+- Volume in market-+- Practical use-+ Nature of production equipment -+ LISTING BY CHEMICAL NATUREORGANIC/INORGANIC CHEMICALS From the chemical point of view this is, of course, an entirely clear definition. Nevertheless, for daily use we often find it necessary to deviate from this framework. Polymers, for instance, are frequently presented as a separate group, as are industrial gases. Products which are mixtures (i.e. toothpaste, paint, etc.) cannot be included in such a classification as they contain both organic and inorganic materials. The inorganic group of materials found in commercial catalogs may, on the one hand, include low priced mineral products such as potash, and expensive chemicals for electronic use in semiconductors such as gallium arsenide on the other. Similarly, in the organic group one can find the inexpensive ethylene alongside the highly priced atenolol (a beta-blocker drug). This method of classifying is used by the customs authorities for listing chemicals. 4 In the customs classification, until recently known as the Bruxelles Tariff Number system (BTN) and lately as the Harmonized System (HS), Section 28 is dedicated to inorganic chemicals, whereas Section 29 deals with organic materials. The groups are determined by the products chemical nature. For example, the group 29.21 deals with the “compounds possessing amino group”. Subgroup 1000 of this group (i.e.29.21.1000) represents acyclic monoamines, their salts and their derivatives. This group includes in particular methylamine, dimethyl and trimethylamine, and diethylamine. All the other acyclic amines are not specified here, but are grouped together under Section “29.21- 1990/6Others”. When the molecule contains tow different functional groups, the decision regarding the correct customs section for that material becomes more complicated. p-Chloroaniline can, for example, be placed in Section “29.03.6900Halogen derivatives of aromatic hydrocarbonsOthers” or in Section “29.21.4290Compounds having amino functional group Aromatic monoamines and their derivativesAniline and its SaltsOthers”. It is worth noting that organic and inorganic chemicals are included in two chapters. However, the customs classification for chemical materials includes 14 additional chapters(!)mostly dedicated to formulations(functional mixtures of materials). Among the other chapters we find: Pharmaceutical products. Fertilizers. Tannin and its derivatives; coloring materials; ink. Oil extracts; cosmetics. Soap; organic surfactants; lubricants. Albumins; starches; adhesives; enzymes. Explosives; pyrotechnical products; matches. Photographic or cinematographic goods. Miscellaneous chemical products. CLASSIFICATION BY PRICE Classification of chemicals by price is an effective method. It involves a certain paradox, however. We classify chemical products and then claim that chemical classification is awkward, and that economic classification based on price, might be more useful The justification for this is twofold: firstly, the purpose of the sorting and classifying is to allow the manufacturers and the consumers to deal with those materials which they need clearly an economical aspect. Secondly, it will be shown that prices 5 of chemicals also indicate chemical and technological characteristics in addition to the marketing and economic aspects. Here too (as was the former case) it is easier to suggest the basis for definition, then to carry out the actual listing. We find that terms which are commonly used to define subgroups are vague, overlapping and confusing. Terms such as the following: Commodities Bulk chemicals Specialty chemicals Chemical specialties Intermediates Fin chemicals Branded chemicals Composition chemicals are used as sub-definitions in an attempt to avoid duplication and confusion. Generally, it will be found that bulk chemicals (or commodities) are referred to on one end of the scale, fine chemicals on the other end, and all the rest in between. In many instances this classification tends to correlate with the degree of the chemical “complexity” of the product which increases from bulk materials to fine chemicals: high complexity is expressed by the increasing number of production stages, as well as by the greater number of atoms in the molecule (except for polymers, of course). We chose somewhat arbitrarily the following sub-division: (1) Bulk chemicals or commodities characterized by large quantities and relatively low prices (up to $1/kg). (2) Intermediates/specialtiesaverage quantities, with a price range from $1 to $50/kg. (3) Fine chemicals small quantities ranging in price from $50 to $1,000/kg. Before attempting to develop this approach, the question of stability or instability of the prices in the chemical marketplace must be addressed. The common market forces play their usual role. The entrance of new producers, from developing countries for example, pushes prices down. Such is also the case when governmental subsidization of production enables the reduction of prices. As a result, old, inefficient, large plants are shut down. Customers try to avoid shortages by building up inventories, and prices rise. These cyclic price fluctuations are common in the field of chemical commodities. 6 Sodium cyanide is used extensively for extracting gold from ore. During the 1970s and early 1980s, the price of sodium cyanide was $1.00-$1.20/kg. For various reasons, the demand for gold has increased, and a shortage of cyanide was felt. Prices of sodium cyanide have doubled. Most of the major cyanide producers responded by increasing production capacity, and towards the end of the 1980s, prices started to decrease. On a long-term basis prices have risen during these last decades. But allowing for monetary devaluation, they seem to be quite steady. For example, ethylene glycol was sold during the 1950s at $0.30/kg, and in 1992at $0.50/kg. Commodities prices, as will be described later, are quite sensitive to political changes, which often affect prices of oil and minerals. (The oil crisis in 1973, the Iranian revolution in 1979, the Gulf War in 1991, etc.). A considerable reduction of prices of more complex molecule chemicals occurs, for instance, when a patent expires and the product ceases to be proprietary and becomes generic. Nevertheless, despite all these changes, the above classification of commodities, intermediates/specialties and fine chemicals remains valid. Bulk Chemicals Bulk chemicals commodities, basic chemicals, industrial chemicalsare all different titles for the same group of chemicals. They are basic materials, relatively simple in terms of their chemical structure, i.e. one-step chemical processing is generally required to produce them from their natural sources. They are consumed in very large quantities, their price is relatively low（up to $1/kg, according to our definition）, and their degree of purity is usually “technical”. Minerals are our primary source of chemicals. The commodities generally result from the first stage of chemical conversion performed on the natural sources: Inorganic materials are derived from minerals, organic materials from petroleum and coal. For example, phosphate is derived from phosphate rock, and methanol form petroleum fraction. The number of the basic materials that are classified as commodities can be counted in tens or hundreds! This number is surprisingly low when we consider the ten million known chemicals and even the 115,000 different chemicals sold in the United States. A few examples are: Ethylene, PVC from petroleum 7 Phosphates, chlorine/soda from minerals Phenol, phenolic resins from charcoal Ammonia from air Potash from sea water The quantities by which such commodities are sold are demonstrated by the following two examples of consumption in the United States（1986）: Vinyl chloride (raw material for PVC): 3.8million tons$290 million p.a. Soda ash (for various industries): 6.7million tons$670 million p.a. Reference to “large quantities” vis-vis commodities, means a scale of millions of tons and hundreds of millions of dollars per annum. Assuming the group of commodities comprises some 100 products, we can calculate that 100200 kilograms are produced per capita, worldwide, every year! Production plants for bulk chemicals are located generally close to the natural sources. They are characterized as follows: Large plants. Plants are dedicated to the process; shifting from product to product is not possible. The process is generally continuous and not in batches. The energy required for production is high. High dependence on complex conveying and transportation systems. In the production of these chemicals there is an advantage to the large size. Small production plants are not economically feasible. Examples of the typical capital investment required for the production of commodities are cited in Table 2.2. From the marketing point of view, the ability to maintain a market segment depends first and foremost on the price of the product. In addition, the political and economic atmosphere in the marketplace has a certain influence. These factors, and others, frequently cause price fluctuation. We often hear, for example, that a factory producing phosphates “suffered a loss due to lower phosphate prices in the world market”as though from an “omnipotent power”. On the other hand, sales are usually made to a limited clientele, and in large quantities; therefore, sales costs are relatively low. 8 TABLE 2.2 EXAMPLES FOR CAPITAL INVESTMENT FOR PLANTS PRODUCING COMMODITIES ProductInvestment （million $） Volume （tons/ year） Turnover （million $） Phenol150300,000400 Sulfur30200,000 25 Polypropylene10050,00050 Mineral oil400250,000125 Ethanol2530,00025 A dominant factor in the costing of commodities is transportation: Due to their large quantities, commodities are usually not delivered in drums, bags, etc. but often in bulk, using transport trailers, cargo vessels, and in direct pipelines to the consumer plant. In fact, transport costs for bulk chemicals can account for as much as 50% of the products price to the consume! The life cycle of commodities is generally highdecades, if not longer. Data for production costs of phenol, as quoted by Jones 2 illustrates certain characteristics of commodities production（Table 2.3）. Points worth emphasizing are: The energy factor is about 20% of total costs.（In the production of chlorine, the energy cost represents more than 50% of the cost of production.） The transportation factor is about 13% of total costs. Labor costs are very low (approximately 0.5%). Marketing costs (except transportation) are low (about 5%). Increasing the plants capacity from 20,000 to 80,000 tons per year decreases costs significantlyby 7%. Specialties: Composition and Performance Chemicals This group of chemicals includes mainly organic materials of medium complexity, whose prices ranges from $1 to $50/kg. It is a very complex, multi-product group. To try and make some order within this class, we must introduce a subdivision which is classification by use. The purpose of all this becomes clearer after discussing the class of commodities: If we know to which group an industrial chemical belongsit tells us a lot 9 about its chemical nature, production equipment and scale, role in the marketplace, price range, use, etc. TABLE 2.3 PRODUCTION COSTS OF PHENOL2 Production capacity20000 tones/year80000 tones/year Cost/ton of totalCost/ton of total Production Costs Raw materials27.348.727.352.3 Energy (steam, electricity, fuel) 10.819.310.820.7 Labor0.6 Maintenance3.8 Plant overhead3.5 Sales Costs Transportation7.012.57.013.4 Technical services1.01.81.01.9 Sales expenses2.03.62.03.8 TotalTotal 56.0100.052.2100.0 CLASSIFICATION BY USE Basic chemical as defined earlier, and fine chemicals that will be discussed later are used almost without exception by various industries as raw materials and not by end users as consumer products. The intermediary group specialties/intermediates is differently characterized. Listing some collective titles for chemicals in this group will indicate this difference, and suggest the sub-classification by use: Speciality chemicals Chemical specialties Performance chemicals Functional chemicals Branded chemicals Composition chemicals A closer look at the nature of the market reveals that a certain material of defined chemical structure can be used by different industries. For example, phenol can be used for disinfectants, or as a major raw material for resins and adhesives. Ethylene glycol is 10 used for polymerization process as well as an anti-freeze agent in car cooling systems. On the other hand, when a particular industrial requirement is defined (say, cleaning milk lines in a dairy), many materials may be used, probably very different from one another in terms of their chemical structure and consequently in their production processes. There are materials geared for highly specific single use (as specific as, for example, the control of certain tapeworms in dogs). On the other hand, there are materials which are multi-functional (e.g. certain antioxidants are broadly used in plastics, rubber, food, and cosmetics). At this point we might already feel somewhat confused. Will it be of any consolation to know that we share this feeling with experts and specialists? Throughout this chapter we are searching for clear definitions but these simply do not exist. A few excerpts from the professional literature illustrates this: European Chemical News wrote on 24 October 1983 3: “In any discussion of smaller volume chemicals, it is important to define some terms. Specialties is a description which is used to cover a wide variety of products and means different things to different people. One of the difficulties with establishing definitions and having tidy categories (like true commodities, fine chemicals and specialties) is that products can move from one category to another during their life cycle.” Chemical Business wrote in