Polymer intermediates production

Production operation (1700 kg h" ) of a microstructured mixer-reactor for high-value polymer intermediate product (FZK works) [17]... 

Production Operation for High-value Polymer Intermediate Product (DSM Linz/Austria + FZK)... 

Urea - formaldehyde polymers. Formalin and urea (usually in the molecular proportions of 3 2) condense in the presence of ammonia, pyridine or hexamine to give urea - formaldehyde polymers, known commercially as Bedle or Plaskon, and are widely used as moulding powdens. It is believed that the intermediate products in the condensation are methylol-urea and dimethylol-urea ... 

Several early interpretations of the polymerization mechanism have been proposed (1,17,29—31). Because of the complexity of this polymerization and insoluble character of the products, key intermediates have not ordinarily been isolated, nor have the products been characterized. Later work, however, on the resinification of furfural (32,33) has provided a new insight on the polymerization mechanism, particularly with respect to thermal reaction at 100—250°C in the absence of air. Based on the isolation and characterization of two intermediate products (9) and (10), stmcture (11) was proposed for the final resin. This work also explains the color produced during resinification, which always is a characteristic of the final polymer (33). The resinification chemistry is discussed in a recent review (5). 

In 1991, over 1 x 10 t sulfonic acids were produced in the United States (24). The materials, for the most part, were used as intermediates for the manufacture of sulfonates in the detergent market, dye manufacture, dispersing agents, catalysts, polymers, etc. Production of dodecjlbenzenesulfonic acids derivatives dominated the sulfonic acid market (Table 2). These had a 38% overall share. The differences between the production tons and the tons sold is accounted for by in-plant use by various manufacturers verses merchant market production. 

Example 4. Glycolysis of Polyurethanes with Propylene Oxide after Pretreatment with a Mixture of Diethanolamine and Potassium Hydroxide.57 Polyurethane scrap was treated with a mixture of diethanolamine and potassium hydroxide at a temperature between about 80 and 140° C with stirring to form an intermediate product. The weight ratio of the scrap PUR polymer to the mixture of diethanolamine and potassium hydroxide was from about 15 1 to 30 1. The intermediate product was reacted with propylene oxide at a temperature of from about 100 to 120°C in a closed reaction vessel to form a polyol. The propylene oxide was added at a rate to maintain a pressure of from about 2 to 5 atm (29-73 psi). The progress of the reaction was followed by following the change of pressure with time. When the pressure remained constant, the reaction of the intermediate product with propylene oxide was considered to be complete. The crude polyol obtained was treated with 10 mol % excess of dodecylbenzene sulfonic acid to remove the potassium hydroxide. 

There appear to be three types of product, a low molecular weight product appearing to be small ring compounds (PI), an intermediate product (PII), and the usually desired high molecular weight polymer (PHI). Previous studies have concentrated only on PHI,... 

Pyrrolidones fit well into the bio-refinery concept since they may be produced in a scheme beginning with the fermentation of a portion of the bio-refineiy s sugar product into succinate. Pyrrolidones are a class of industrially important chemicals with a variety of uses including polymer intermediates, cleaners, and green solvents which can replace hazardous chlorinated compounds. 

This reaction mechanism has already been reported.23,24 The mechanism is actually quite significant for the economics and efficiency of the preparative chemistry. The fact that an S 2 mechanism is not in effect here means that only a slight stoichiometric excess of the fluorocarbon reagent is required for good yields of the intermediate products. Also, the action of an S 2 mechanism would make the desired product itself susceptible to a second nucleophilic attack on the terminal -CF2Br, resulting primarily in the production of polymer from this reaction instead of the observed product. 

In grafting reactions initiated by redox processes, there is an interaction of the intermediate products with the substrate polymer chains. There may also be a chain transfer reaction involved. It is sometimes difficult to make a clear distinction between a direct redox reaction and a chain transfer process. Three redox systems have been studied extensively in grafting onto cellulose persulfate ions 1, hydroperoxide/ferrous ions 2> 3 and cerium (IV) ions. ... 

These macromolecule-based purification methods isolate polymer-bound products from soluble impurities, but do not generally purify the product from other polymer-bound byproducts. Such byproducts arise from incomplete reactions or side reactions and in classical solution chemistry, similar byproducts are removed during product purification at each step of a multi-step synthesis. Support-based methodologies, while removing the multiple, laborious purification steps of a classical synthesis, generally do not provide a method for the purification of intermediates. Instead, these methodologies demand that reaction conditions be optimized such that reactions are driven to completion to avoid a complicated final mixture of products. However, some developed liquid-phase methods achieve high purity of products without quantitative reaction yields [21-26]. 

Polymerization, or conjugation, is the process in which toxic organic molecules undergo microbially mediated transformation by oxidative coupling reactions. In this case, a contaminant or its intermediate product(s) combines with itself or other organic molecules (e.g., xenobiotic residues, naturally occurring compounds) to form larger molecular polymers that can be incorporated in subsurface humic substances. 

Radioactivation analysis has been used to measure bromine in polymers (37—39) and recently a novel technique for trace oxygen has been reported (40). Any polymer or other material (e.g. metal alkyl) which is miscible with butyl lithium solutions may be analysed since the procedure involves the intermediate production of triton particles by the nuclear reaction 6Li (n, a) t. The tritons then act as nuclear projectiles for the activation of oxygen 0 (t, n) 18F and the radioactivity due to fluorine-18 is measured. A sensitivity of 1 x 10 g in a 0.5 g sample is claimed. 

The important polymer intermediate bis-phenol A [2,2-bis-(4-hydroxy-phenyI)propane] used, among other things, in epoxy resins, is made by an acid-induced condensation of 2-propanone and benzenol. Write a stepwise mechanism for this reaction that is consistent with the nature of the reactants and the products. 

Polymer analogue reactions tend to give poor yields of the desired products. Furthermore, where several synthetic steps are required to introduce the azo functions then at least some of all the intermediate products will be present in the final product. Such reactions should be avoided when possible. 

Chemistry - or chemicals - lies at the heart of everything fibers for new textiles, catalysts for a clean environment, colors that gleam in the sun, polymer electrolyte diaphragms for fuel cells, chemicals for chip production, or fertilizers that help plants grow, ensuring global food production. The chemical industry develops the intermediate products that other industries use, and often develops new processes and products itself, or in conjunction with customers. 

As in the carbon series, this photolytic rearrangement involved a nitrene intermediate. Indeed, in the case of thio phospho-razides, beside the formation of dimers 3 and polymers, the product was characterized and arises from hydrogen abstraction from the solvent by the nitrene intermediate. 

A different approach but still in the frame of the chlorosilane method was adopted by Tsiang for the synthesis of (A-b-B)B3 miktoarm star copolymers, where A is PS and B is PB [29]. Living PB chains were reacted with SiCl4 in a molar ratio 3 1, followed by the addition of the living diblock PS-b-PBLi. The key step of the method is the succesfull synthesis of the (PB)3SiCl intermediate product. The reduced steric hindrance of the PBLi chain end poses questions about the purity of this polymer, since several byproducts, such as (PB)2SiCl2, (PB)4Si, PBSiCl3 can be formed in the first step of the synthesis. SEC analysis was performed to monitor the reaction sequence. 

The demand for nitrogen in a chemically fixed form (as opposed to elemental nitrogen gas) drives a huge international industry that encompasses the production of seven key chemical nitrogen products ammonia, urea, nitric acid, ammonium nitrate, nitrogen solutions, ammonium sulfate and ammonium phosphates. Such nitrogen products had a total worldwide annual commercial value of about US 50 billion in 1996. The cornerstone of this industry is ammonia. Virtually all ammonia is produced in anhydrous form via the Haber process (as described in Chapter 2). Anhydrous ammonia is the basic raw material in a host of applications and in the manufacture of fertilizers, livestock feeds, commercial and military explosives, polymer intermediates, and miscellaneous chemicals35. 

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