Commercial uses

The first commercially manufactured fluorosurfactants were the PFAAs, PFOS, [11, 55] and PFOA [56-58] made by ECF. Their unique properties led to use in a plethora of industrial and consumer applications. Here we highlight the major 

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While hopes are high, heterogeneous photochemical systems seem not yet to have found major practical application. The photovoltaic cell or solar cell is the only system with important (although specialized) commercial use (see Ref. 343). 

Europium oxide is now widely used as a phospor activator and europium-activated yttrium vanadate is in commercial use as the red phosphor in color TV tubes. Europium-doped plastic has been used as a laser material. With the development of ion-exchange techniques and special processes, the cost of the metal has been greatly reduced in recent years. 

Others would include the addition of materials aimed at increa sing the bioavailabiUty of the contaminant to the degrading organisms. The most studied compounds are surfactants, but cations have been reported to increase the bioavailabiUty of some organic compounds, and sorbents and clays are also considered. The dispersion of spilled oil on water by the appHcation of dispersants is perhaps the major commercial use of this idea. 

Furfural—acetone resins have been used to form resin-aggregate mixtures referred to as organic concretes. Despite the reportedly excellent properties, there has been virtually no commercial use of such resins outside the former Soviet Union. The stmctures and polymerization mechanisms of these furfural—aldehyde—ketone polymers are discussed in a review (6). 

Photopolymerization and Plasma Polymerization. The use of ultraviolet light alone (14) as well as the use of electrically excited plasmas or glow discharges to generate monomers capable of undergoing VDP have been explored. The products of these two processes, called plasma polymers, continue to receive considerable scientific attention. Interest in these approaches is enhanced by the fact that the feedstock material from which the monomer capable of VDP is generated is often inexpensive and readily available. In spite of these widespread scientific efforts, however, commercial use of the technologies is quite limited. 

Manufacture. For the commercial production of DPXN (di-/)-xylylene) (3), two principal synthetic routes have been used the direct pyrolysis of -xylene (4, X = Y = H) and the 1,6-Hofmaim elimination of ammonium (HNR3 ) from a quaternary ammonium hydroxide (4, X = H, Y = NR3 ). Most of the routes to DPX share a common strategy PX is generated at a controlled rate in a dilute medium, so that its conversion to dimer is favored over the conversion to polymer. The polymer by-product is of no value because it can neither be recycled nor processed into a commercially useful form. Its formation is minimised by careful attention to process engineering. The chemistry of the direct pyrolysis route is shown in equation 1 ... 

The details of the commercial preparation of acetal homo- and copolymers are discussed later. One aspect of the polymerisation so pervades the chemistry of the resulting polymers that familiarity with it is a prerequisite for understanding the chemistry of the polymers, the often subde differences between homo- and copolymers, and the difficulties which had to be overcome to make the polymers commercially useful. The ionic polymerisations of formaldehyde and trioxane are equiUbrium reactions. Unless suitable measures are taken, polymer will begin to revert to monomeric formaldehyde at processing temperatures by depolymerisation (called unsipping) which begins at chain ends. 

Polymerization. In the absence of inhibitors, acrolein polymerizes readily in the presence of anionic, cationic, or free-radical agents. The resulting polymer is an insoluble, highly cross-linked soHd with no known commercial use. 

Acetylene-Based Routes. Walter Reppe, the father of modem acetylene chemistry, discovered the reaction of nickel carbonyl with acetylene and water or alcohols to give acryUc acid or esters (75,76). This discovery led to several processes which have been in commercial use. The original Reppe reaction requires a stoichiometric ratio of nickel carbonyl to acetylene. The Rohm and Haas modified or semicatalytic process provides 60—80% of the carbon monoxide from a separate carbon monoxide feed and the remainder from nickel carbonyl (77—78). The reactions for the synthesis of ethyl acrylate are... 

Principal Adsorbent Types. Commercially useful adsorbents can be classified by the nature of their stmcture (amorphous or crystalline), by the sizes of their pores (micropores, mesopores, and macropores), by the nature of their surfaces (polar, nonpolar, or intermediate), or by their chemical composition. AH of these characteristics are important in the selection of the best adsorbent for any particular appHcation. 

Typical nonsieve, polar adsorbents are siUca gel and activated alumina. Kquilihrium data have been pubUshed on many systems (11—16,46,47). The order of affinity for various chemical species is saturated hydrocarbons < aromatic hydrocarbons = halogenated hydrocarbons < ethers = esters = ketones < amines = alcohols < carboxylic acids. In general, the selectivities are parallel to those obtained by the use of selective polar solvents in hydrocarbon systems, even the magnitudes are similar. Consequendy, the commercial use of these adsorbents must compete with solvent-extraction techniques. 

There are currently two medicinally valuable alkaloids of commercial import obtained from ergot. Commercial production involves generation parasiticaHy on rye in the field or production in culture because a commercially useful synthesis is unavailable. The common technique today (65) is to grow the fungus in submerged culture. Clavicepspaspali (Stevens and Hall) is said to be more productive than C. purpurea (Fries). In this way, ergotamine (100,... 

The only other petrochemical feedstock of significant commercial use is methane (natural gas) which is used primarily to produce ammonia and methanol. Consumption factors are about 28 GJ and 31 GJ per metric ton, respectively (58,300 and 64,700 BTU/lb) (8). Approximately... 

An organic Hquid extractant is used to remove the HCl and to shift the reaction in the desired direction. After concentration, the by-product hydrochloric acid is suitable for commercial use. 

Acrylonitrile and its comonomers can be polymerized by any of the weU-known free-radical methods. Bulk polymerization is the most fundamental of these, but its commercial use is limited by its autocatalytic nature. Aqueous dispersion polymerization is the most common commercial method, whereas solution polymerization is used ia cases where the spinning dope can be prepared directly from the polymerization reaction product. Emulsion polymerization is used primarily for modacryhc compositions where a high level of a water-iasoluble monomer is used or where the monomer mixture is relatively slow reacting. 

Vegetable fibers are classified according to their source ia plants as follows (/) the bast or stem fibers, which form the fibrous bundles ia the inner bark (phloem or bast) of the plant stems, are often referred to as soft fibers for textile use (2) the leaf fibers, which mn lengthwise through the leaves of monocotyledonous plants, are also referred to as hard fibers and (J) the seed-hair fibers, the source of cotton (qv), are the most important vegetable fiber. There are over 250,000 species of higher plants however, only a very limited number of species have been exploited for commercial uses (less than 0.1%). The commercially important fibers are given ia Table 1 (1,2). 

Sisal. The tme sisal fiber Fora Agave sisalana is the most important of the leaf fibers ia terms of quahty and commercial use. Originating ia the tropical western hemisphere, sisal has beea transplanted to East Africa, Indonesia, and the Philippines. It is named after the port ia the Yucatan from which it was first exported. 

Red Phosphorus. This aHotropic form of phosphoms is relatively nontoxic and, unlike white phosphoms, is not spontaneously flammable. Red phosphoms is, however, easily ignited. It is a polymeric form of phosphoms having thermal stabiUty up to ca 450°C. In finely divided form it has been found to be a powerful flame-retardant additive (26,45—47). In Europe, it has found commercial use ia molded nylon electrical parts ia a coated and stabilized form. Handling hazards and color have deterred broad usage. The development of a series of masterbatches by Albright Wilson should facihtate further use. 

Aryl Phosphates. Aryl phosphates were introduced into commercial use early in the twentieth century for flammable plastics such as cellulose nitrate and later for cellulose acetate. CeUulosics are a significant area of use but are exceeded now by plastici2ed vinyls (93—95). Principal appHcations are in wire and cable insulation, coimectors, automotive interiors, vinyl moisture barriers, plastic greenhouses (Japan), furniture upholstery, conveyer belts (especially in mining), and vinyl foams. 

A number of commercial phosphoms-containing polyols have been made by the reaction of propylene oxide and phosphoric or polyphosphoric acid. Some have seen commercial use but tend to have hydrolytic stabiHty limitations and are relatively low in phosphoms content. BASF s Pluracol 684 is a high functionahty polyol containing 4.5% P, sold for Class 11 rigid foam use. 

Oligomeric Phosphate—Phosphonate. A commercially used reactive oligomeric alcohol, Akzo s Eyrol 51 [70715-06-9] has a stmcture approximately represented by (110) ... 

Two ammoniation processes, ie, the THPOH—NH and the precondensate—NH processes, have seen considerable commercial use. 

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