Plants, polymers from

Vinyl acetate (ethenyl acetate) is produced in the vapor-phase reaction at 180—200°C of acetylene and acetic acid over a cadmium, 2inc, or mercury acetate catalyst. However, the palladium-cataly2ed reaction of ethylene and acetic acid has displaced most of the commercial acetylene-based units (see Acetylene-DERIVED chemicals Vinyl polymers). Current production is dependent on the use of low cost by-product acetylene from ethylene plants or from low cost hydrocarbon feeds. 

There has been only one major use for ozone today in the field of chemical synthesis the ozonation of oleic acid to produce azelaic acid. Oleic acid is obtained from either tallow, a by-product of meat-packing plants, or from tall oil, a byproduct of making paper from wood. Oleic acid is dissolved in about half its weight of pelargonic acid and is ozonized continuously in a reactor with approximately 2 percent ozone in oxygen it is oxidized for several hours. The pelargonic and azelaic acids are recovered by vacuum distillation. The acids are then esterified to yield a plasticizer for vinyl compounds or for the production of lubricants. Azelaic acid is also a starting material in the production of a nylon type of polymer. 

As mentioned in the introduction, various reviews over the last ten years show that many plants contain bioactive polysaccharides. Most of the plants studied were chosen due to their traditional use for different kinds of illnesses where the immune system could be involved. The following section will describe the pectic type polymers from the plants most studied for their structure, and activities related to the structure where possible. 

Figure 9 from Paulsen BS (ed) Bioactive Carbohydrate Polymers. Yamada H (2000) Bioactive plant polysaccharides from Japanese and Chinese traditional herbal medicines , p 15-p24. Kluwer Academic Publishers, with permission from Springer. 

The ability to control the polymer from the design of the catalyst, coupled with high catalytic efficiency has led to an explosion of commercial and academic interest in these catalysts. Exxon started up a 30 million lb/5rr ethylene copol3rmer demonstration plant in 1991 using a bis-cyclopentadienyl zirconium catalyst of structure 1. The Dow Chemical Company (Dow) began operating a 125 million Ib/yr ethylene/l-octene copolymer plant in 1993 and has since expanded production capacity to 375 million Ib/yr. This paper will focus on the structure / property relationships of the catalysts used by Dow to produce single-site ethylene a-olefin copolymers. 

Other US companies chose to await expiration of the Whinfield and Dickson patent before entering the market. One of the earliest to become involved was Celanese Corporation, whose joint venture with ICI, named Fiber Industries Inc. (FII Fortrel), began construction of its first PET plant in 1959. Beaunit (Vycron) was also an early entrant, initially with a copolymer fibre that was arguably not covered by the basic patent, using polymer from Goodyear. 

Primary organics are emitted to the atmosphere by industrial sources (oil refineries, chemical plants, producers and users of solvents and plasticizers), vehicles (as a result of incomplete fuel combustion, oxygenated degradation products of lubricating oil, polymers from tires), and agricultural activities (use of pesticides). An exhaustive literature survey is beyond the scope of this section, but can be found in Air Quaiity Criteria for Particulate Matter many useful references are also available. 

Plant In plants, the A-methyl group may be subject to oxidation or hydroxylation (Kuhr, 1968). The presence of pinolene (P-pinene polymer) in carbaryl formulations increases the amount of time carbaiyl residues remain on tomato leaves and decreases the rate of decomposition. The half-life in plants range from 1.3 to 29.5 d (Blazquez et al., 1970). 

There are at least five types of phenylpropanoid related reactions which appear to occur in plant cell walls. Two are UV-mediated photochemical reactions, and hence may be restricted only to the first few layers of cells under the plant surface due to poor penetrability of the light (3). The other reactions appear to be enzymatically mediated, and result in the formation of dimers or polymers from the corresponding monomeric units. 

Suberized Cell Walls. An analogous set of CPMAS experiments is presented for suberin in Figure 6. Because this polymer is an integral part of the plant cell wall, the 13C NMR spectrum had contributions from both polysaccharide and polyester components. Chemical-shift assignments, summarized in Table IV, demonstrated the feasibility of identifying major polyester and sugar moieties despite serious spectral overlap. Semiquantitative estimates for the various carbon types indicated that, as compared with cutin, the suberin polyester had dramatically fewer aliphatic and more aromatic residues. A similar observation was made previously for the soluble depolymerization products of these plant polymers (1,8,11). 

Butenes can also be alkylated in the form of various polymers, such as the by-product diisobutene polymers from butadiene plants. In this operation, each octene molecule appears to react as two individual butene molecules, and the high alkylate quality and low catalyst consumption characteristic of butene alkylation are obtained. For the most part, polymers have been alkylated only as supplemental feed stocks from external sources in periods of high aviation gasoline demand. 

The search for a lightweight, nonbreakable, moldable material began with the invention of vulcanized rubber. This material is derived from natural rubber, which is a semisolid, elastic, natural polymer. The fundamental chemical unit of natural rubber is polyisoprene, which plants produce from isoprene molecules, as shown in Figure 18.5. In the 1700s, natural rubber was noted for its ability to rub off pencil marks, which is the origin of the term rubber. Natural rubber has few other uses, however, because it turns gooey at warm temperatures and brittle at cold temperatures. 

One of the anticipated growth areas for industrial uses of plants is in development of non-brittle, durable polymers from renewable plant feedstocks (in both biodegradable and non-biodegradable forms). Starch and sugars are currently used commercially as feedstocks for polyester production utilising microbial monomer and polymer fermentation systems (see Chapter 5 for more information). 

NatureWorks LLC has set up a 300 million plant at Blair, NE, which is capable of producing about 140,000-tons/year of poly-lactide polymers from com sugar. It employs a fermentation process to produce two chiral isomers of lactic acid from glucose, which are then cracked to form three lactide isomers. The isomers are subsequently polymerized to polylactide. 

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