Using Chemicals

A minor chemical use for many of the commoner alkaloids is the resolution of racemic compounds (often acids) into their optically active enantiomorphs. 

Urea is largely used as a fertilizer (ISy ), and as a non-protein feed supplement for sheep and cattle. The most important chemical use, which however accounts for only a small part of urea production, is in the manufacture of urea-formaldehyde resins. U is also used in the manufacture of adhesives, pharmaceuticals, dyes and various other materials. U.S. production 1981 7 0 megatonnes urea resins 1983 6 megatonnes. 

Epichlorohydnn is the common name of an industrial chemical used as a component in epoxy cement The molecular formula of epichlorohydnn is C3H5CIO Epichlorohydnn has an epoxide functional group it does not have a methyl group Write a structural formula for epichloro hydrin... 

Among the chemicals used by insects to communicate with one another esters occur frequently... 

Fertilization of ponds to increase productivity is the next level of intensity with respect to fish culture, followed by provision of supplemental feeds. Supplemental feeds are those that provide some additional nutrition but caimot be depended upon to supply all the required nutrients. Provision of complete feeds, those that do provide all of the nutrients required by the fish, translates to another increase in intensity. Associated with one or more of the stages described might be the appHcation of techniques that lead to the maintenance of good water quaUty. Examples are continuous water exchange, mechanical aeration, and the use of various chemicals used to adjust such factors as pH, alkalinity, and hardness. 

Use both as a solvent and in production of aldol chemicals used as solvents. 

Propylene requirements for acrylates remain small compared to other chemical uses (polypropylene, acrylonitrile, propylene oxide, 2-propanol, and cumene for acetone and phenol). Hence, cost and availabihty are expected to remain attractive and new acrylate capacity should continue to be propylene-based until after the turn of the century. 

Using estimates of proven reserves and commitments to energy and chemical uses of gas resources, the net surplus of natural gas in a number of different countries that might be available for major fuel methanol projects has been determined. These are more than adequate to support methanol as a motor fuel. 

There are thousands of breweries worldwide. However, the number of companies using fermentation to produce therapeutic substances and/or fine chemicals number well over 150, and those that grow microorganisms for food and feed number nearly 100. Lists of representative fermentation products produced commercially and the corresponding companies are available (1). Numerous other companies practice fermentation in some small capacity because it is often the only route to synthesize biochemical intermediates, enzymes, and many fine chemicals used in minor quantities. The large volume of L-phenylalanine is mainly used in the manufacture of the artificial dipeptide sweetener known as aspartame [22389-47-0]. Prior to the early 1980s there was httle demand for L-phenyl alanine, most of which was obtained by extraction from human hair and other nonmicrobiological sources. 

Secondary and Micronutrients in Fertilizers The great majority of farm fertilizers are produced, marketed, and appHed with regard only to the primary plant nutrient content. The natural supply of secondary and micronutrients in the majority of soils is usually sufficient for optimum growth of most principal crops. There are, however, many identified geographical areas and crop—soil combinations for which soil appHcation of secondary and/or micronutrient sources is beneficial or even essential. The fertilizer industry accepts the responsibiHty for providing these secondary and micronutrients, most often as an additive or adjunct to primary nutrient fertilizers. However, the source chemicals used to provide the secondary and micronutrient elements are usually procured from outside the fertilizer industry, for example from mineral processors. The responsibiHties of the fertilizer producer include procurement of an acceptable source material and incorporation in a manner that does not decrease the chemical or physical acceptabiHty of the fertilizer product and provides uniform appHcation of the added elements on the field. 

Quality Control. Because fine chemicals are sold according to specifications, adherence to constant and strict specifications, at risk because of the batchwise production and the use of the same equipment for different products ia multipurpose plants, is a necessity for fine chemical companies. For the majority of the fine chemicals, the degree of attention devoted to quahty control (qv) is not at the discretion of the iadividual company. This is particularly the case for fine chemicals used as active iagredients ia dmgs and foodstuffs (see Fine chemicals, standards). Standards for dmgs are pubHshed ia the United States Pharmacopeia (USP) ia the United States (6) and the European Pharmacopeia ia Europe (7). 

Fine chemicals are generally considered chemicals that are manufactured to high and weU-defined standards of purity, as opposed to heavy chemicals made in large amounts to technical levels of purity. Fine chemicals usually are thought of as being produced on a small scale and the production of some fine chemicals is in tens or hundreds of kilograms per year. The production of others, especially fine chemicals used as dmgs or food additives (qv), is, however, in thousands of metric tons (see Pharmaceuticals). For example, the 1990 U.S. production of aspirin [50-78-2] and acetaminophen [103-90-2] was on the order of 20,500 t and 15,000 t, respectively. 

Chemicals used in the manufacture of integrated circuits (qv) need to be controlled to even mote stringent levels of purity than either USP or ACS grades. 

The Food Chemicals Codex defines food-grade quaUty for the identity and purity of chemicals used in food products. In the United States, the FDA adopts many of the Food Chemicals Codex specifications as the legal basis for food-grade quaUty of flavor and food chemicals. 

The same questions about the safety of organic flocculants have been raised ia other countries. The most drastic response has occurred ia Japan (7,77) and Swit2edand (77) where the use of any synthetic polymers for drinking water treatment is not permitted. Alum and PAC are the principal chemicals used ia Japan (7). Chitin, a biopolymer derived from marine animals, has been used ia Japan (80,81). Maximum allowed polymer doses have been set ia Prance and Germany (77). 

Table 5. Inorganic Chemicals Used as Auxiliary Reagents...

Tranquilizers. Fluphena2ine hydrochloride [146-56-5] triduopera2ine hydrochloride [440-17-5], and triduproma2ine [146-54-3] are all triduoromethyl substituted phenothia2ine chemicals useful in the management of psychotic disorders. 

CgHgO, diacetyl [431-03-8], and benzaldehyde [100-52-7], C H O, are aroma chemicals used by the food industry (53). 

Chemical Use. Both natural gas and natural gas Hquids are used as feedstocks in the chemical industry. The largest chemical use of methane is through its reactions with steam to produce mixtures of carbon monoxide and hydrogen (qv). This overall endothermic reaction is represented as... 

Off-Shoot-O. The methyl esters of the Cg—C 2 fatty acids (40) are collectively sold under the name Off-Shoot-O and are closely related to 1-decanol, the fatty alcohol sold to control axillary shoots in tobacco. The material is a contact-type chemical used to pinch ornamental plants such as a2aleas, cotoneaster, juniper Juniperus sp. privet, rhamnus, and taxus (Taxus sp. sp.). As a result of treatment the shmbs become bushier. The mode of action is by plasmolysis of the young, sensitive tissues. Therefore, appHcation timing may be critical. 

Acetylene is used primarily as a raw material for the synthesis of a variety of organic chemicals (see AcETYLENE-DERiVED CHEMICALS). In the United States, this accounts for about 80% of acetylene usage and most of the remainder is used for metal welding or cutting. The chemical markets for acetylene are shrinking as ways are found to substitute lower cost olefins and paraffins for the acetylene, with some products now completely derived from olefinic starting materials. Metalworking appHcations, however, have held up better than chemical uses. 

Chemical Uses. In Europe, products such as ethylene, acetaldehyde, acetic acid, acetone, butadiene, and isoprene have been manufactured from acetylene at one time. Wartime shortages or raw material restrictions were the basis for the choice of process. Coking coal was readily available in Europe and acetylene was easily accessible via calcium carbide. 

Japan and China. During the 1980s, acetylene demand in Japan suffered a significant decline. Chemical use declined from over 100,000 to 42,000 t, acetylene black production declined from 20,000 to less than 10,000 t, and industrial use went from 42,000 to 30,000 t. Thus, based on 1990 estimates, Japan has an excess capacity for acetylene production with capabiUties for 247, 000 t/yr and a demand of only 82,000 t. 

Ma.leic Anhydride. The largest chemical use for / -butane is as feedstock for maleic anhydride. A dilute air—butane mixture is passed over a vanadium—phosphoms catalyst 400—500°C to produce maleic anhydride [108-31-6] in good yield. Formerly benzene was used as feedstock, but in the last few years nearly all maleic anhydride in the United States, and an increasing proportion worldwide, is made from butane. 

Production of maleic anhydride by oxidation of / -butane represents one of butane s largest markets. Butane and LPG are also used as feedstocks for ethylene production by thermal cracking. A relatively new use for butane of growing importance is isomerization to isobutane, followed by dehydrogenation to isobutylene for use in MTBE synthesis. Smaller chemical uses include production of acetic acid and by-products. Methyl ethyl ketone (MEK) is the principal by-product, though small amounts of formic, propionic, and butyric acid are also produced. / -Butane is also used as a solvent in Hquid—Hquid extraction of heavy oils in a deasphalting process. 

The hydroxybenzaldehydes are used primarily as chemical intermediates for a variety of products. The largest single use of sahcylaldehyde is in the manufacture of coumarin. Coumarin is an important commercial chemical used in soaps, flavors and fragrances, and electroplating (see Coumarin). Other significant uses of both sahcylaldehyde and -hydroxybenzaldehyde are as follows. 

Industrial antimicrobial agents are chemicals used to prevent the adverse consequences of microbiological activity in processes and products. Some are unique to this segment and others are drawn from the antimicrobial agents used in medicine, agriculture, and sanitary appHcations. Industrial antimicrobials are selected where process or stricdy physical conditions, such as irradiation or heat, are impractical or ineffective in controlling microbiological activity. 

Miscellaneous, New, and Developmental Antimicrobial Agents. Table 11 shows some of the antimicrobials that do not neady fit into the principal families. Acrolein (qv) is a unique chemical used for secondary oil recovery (43). Biobor has become the antimicrobial addition of choice for aviation fuels (44). Cbloropbtbalonil (tetrachloroisophthalnitrile [1897-45-6]) is a significant agricultural fungicide, in addition to being one of the most important latex paint film preservatives (producer, ISK). 

E. Y. Spencer, Guide to the Chemicals Used in Crop Protection, 7th ed.. Research Branch Agriculture, Ontario, Canada, 1980. 

Separate ketdes and backwash towers are frequendy used to convert ion-exchange resins from one ionic form to another prior to packaging, and to cleanse the resin of chemicals used in the functionalization reactions. Excess water is removed from the resin prior to packaging by a vacuum drain. Both straight line filters and towers or columns are used for this purpose. 

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