Pyrolysis prepared

The information in Part II is from Burning Tires for Fuel and Tire Pyrolysis, prepared by Charlotte Clark, Kenneth Meardon, and Dexter Russell of Pacific Environmental Services for the U.S. Environmental Protection Agency, December 1991. 

Osaka A, Mima Y, Takeuchi K, Asada M, Takahashi K (1991) Calcium apatite prepared from calcium hydroxide and orthophosphoric acid. J Mater Sci Mater in Med 2 51-55 Osaka A, Tsura K, lida H, Ohtsnki C, Hayakawa S, Miura Y (1997) Spray pyrolysis preparation of apatite-composite particles for biological application. J Sol-Gel Sci Technol 8 655-61 Otsuka M, Matsuda Y, Suwa Y, Fox JL, Higuchi W1 (1995) Effect of particle size of metastable calcium phosphates on mechanical strength of a novel self-setting bioactive calcium phosphate cement. J Biomed Mater Res 29 25-32... 

Frequently, samples like paint flakes present a problem to the analytical lab because they are small, non-volatile and opaque with inorganic pigments. Since pyrolysis prepares a volatile organic sample from a polymer or composite, it offers the ability to introduce these organics to an analytical instrument... 

Cyanogen fluoride, FCN. Colourless gas (b.p. — 46 C) prepared by pyrolysis of cyanuric fluoride. Polymerizes to (FCN), cyanuric fluoride, at room temperature. 

B.p. — 29X. Monomer used to form polymers (only under rather drastic conditions) or copolymers with C2F4 and vinylidene fluoride, CH2 = CF2. Hexafluoropropene may be prepared by thermal decomposition of CF3CF2CF2C02Na or is prepared commercially by low pressure pyrolysis of C2F4. 

Some of these compounds are used as potential intermediates for the preparation of 4,7-dioxo-4,5,6,7-tetrahydrothiazolo[4,5d]pyridazines (78). The diesters (77) are hydrolyzed under appropriate conditions to free acids (79), whose monopotassium salts (80) yield the cyclic anhydrides (81) under the influence of thionylchloride. Pyrolysis of 79, Rj = a-thienyl, results in its decarboxylation to 82. 

Fig. 4.24 Heat of immersion of a carbon (prepared by pyrolysis of Saran Polymer A) in different liquids at 300 K. The liquids for points 1-6 were (I) methanol (2) benzene (3) n-hexane (4) 3-methyl benzene (5) 2,2-dimethyl butane (6) 2,2,4-trimethyl pentane. The abscissae represent the molar volumes of the liquids. (Redrawn from the original diagram of Barton, Beswick and Harrison. " )...

Manufacture. Furan is produced commercially by decarbonylation of furfural in the presence of a noble metal catalyst (97—100). Nickel or cobalt catalysts have also been reported (101—103) as weU as noncatalytic pyrolysis at high temperature. Furan can also be prepared by decarboxylation of 2-furoic acid this method is usually considered a laboratory procedure. 

Fluoronaphthalene [323-09-1] is prepared in 54—67% yield from 2-naphthylamine by the Balz-Schiemann reaction or in 51% yield by pyrolysis of indene and chlorofluoromethane at 600°C (77). 

Preparation. The manufacture of tetrafluoroethylene [116-14-3] (TEE) involves the following steps (2—9). The pyrolysis is often conducted at a PTFE manufacturing site because of the difficulty of handling TFE. 

Vlayl fluoride [75-02-5] (VF) (fluoroethene) is a colorless gas at ambient conditions. It was first prepared by reaction of l,l-difluoro-2-bromoethane [359-07-9] with ziac (1). Most approaches to vinyl fluoride synthesis have employed reactions of acetylene [74-86-2] with hydrogen fluoride (HF) either directly (2—5) or utilizing catalysts (3,6—10). Other routes have iavolved ethylene [74-85-1] and HF (11), pyrolysis of 1,1-difluoroethane [624-72-6] (12,13) and fluorochloroethanes (14—18), reaction of 1,1-difluoroethane with acetylene (19,20), and halogen exchange of vinyl chloride [75-01-4] with HF (21—23). Physical properties of vinyl fluoride are given ia Table 1. 

The lower molecular weight oils, waxes, and greases of PCTFE can be prepared direcdy by telomerization of the monomer or by pyrolysis of the higher molecular weight polymer (45—54). 

Esters. The monoisobutyrate ester of 2,2,4-trimethyl-1,3-pentanediol is prepared from isobutyraldehyde ia a Tishchenko reaction (58,59). Diesters, such as trimethylpentane dipelargonate (2,2,4-trimethylpentane 1,3-dinonanoate), are prepared by the reaction of 2 mol of the monocarboxyhc acid with 1 mol of the glycol at 150—200°C (60,61). The lower aUphatic carboxyHc acid diesters of trimethylpentanediol undergo pyrolysis to the corresponding ester of 2,2,4-trimethyl-3-penten-l-ol (62). These unsaturated esters reportedly can be epoxidized by peroxyacetic acid (63). 

Pyrolysis approaches can also be used to prepare substituted isocyanates which caimot be prepared using other methods. For example, A[,A[(A[ -trichlorocyanuric acid [87-90-1] thermally dissociates to yield chloroisocyanate [13858-09-8] and carbonyl diisocyanate [6498-10-8]. The carbonyl isocyanate is unstable and polymerizes (8,94). Table 3 Hsts specialty isocyanates. 

From the time that isoprene was isolated from the pyrolysis products of natural mbber (1), scientific researchers have been attempting to reverse the process. In 1879, Bouchardat prepared a synthetic mbbery product by treating isoprene with hydrochloric acid (2). It was not until 1954—1955 that methods were found to prepare a high i i -polyisoprene which dupHcates the stmcture of natural mbber. In one method (3,4) a Ziegler-type catalyst of tri alkyl aluminum and titanium tetrachloride was used to polymerize isoprene in an air-free, moisture-free hydrocarbon solvent to an all i7j -l,4-polyisoprene. A polyisoprene with 90% 1,4-units was synthesized with lithium catalysts as early as 1949 (5). 

The production of ketene by this method has no significant environmental impact. The off-gases from the ketene furnace are either circulated to the furnace and burned to save energy or led to a flare system. The reaction can also be carried out at 350—550°C in the presence of alkaH-exchanged zeoHte catalysts (54). Small quantities of ketene are prepared by pyrolysis of acetone [67-64-1] at 500—700°C in a commercially available ketene lamp (55,56). 

Thioketenes can be prepared in several ways, from carboxyHc acid chlorides by thionation with phosphoms pentasulfide [1314-80-3] 2 5 ketene dithioacetals by -elimination, from l,2,3-thiadia2oles with flash pyrolysis, and from alkynyl sulfides (thioacetylenes). The dimeri2ation of thioketenes to 2,4-bis(alkyHdene)-l,3-dithietane compounds occurs quickly. They can be cleaved back pyrolyticaHy (63). For a review see Reference 18. 

Sample preparation for the modified Fischer assay technique, a standard method to determine the Hquid yields from pyrolysis of oil shale, is necessary to achieve reproducible results. A 100-g sample of >230 fim (65 mesh) of oil shale is heated in a Fischer assay retort through a prescribed temperature range, eg, ca 25.5—500°C, for 50 min and then soaked for 20 min. The organic Hquid which is collected is the Fischer assay yield (7). The Fischer assay is not an absolute method, but a quaHtative assessment of the oil that may be produced from a given sample of oil shale (8). Retorting yields of greater than 100% of Fischer assay are possible. 

Carbon—Carbon Composites. Above 300°C, even such polymers as phenoHcs and polyimides are not stable as binders for carbon-fiber composites. Carbon—carbon composites are used at elevated temperatures and are prepared by impregnating the fibers with pitch or synthetic resin, foUowed by carbonization, further impregnation, and pyrolysis (91). 

A hquid-phase reaction in which TiCl is reacted with hquid ammonia at —35 C to form an adduct that is subsequendy calcined at 1000°C has also been proposed (35). Preparation of titanium nitride and titanium carbonitride by the pyrolysis of titanium-containing polymer precursors has also been reported (36). 

Titanoxanes can also be prepared by pyrolysis of tetraalkyl titanates at 200—250°C. Higher temperatures, however, can lead to thermal decomp o sition. 

A/-Vinylamides and /V-vinylimides can be prepared by reaction of amides and imides with acetjiene (3), by dehydration of hydroxyethyl derivatives (4), by pyrolysis of ethyUdenebisamides (5), or by vinyl exchange (6), among other methods the monomers are stable when properly stored. 

Penta.bora.ne(9), Pentaborane(9) and can be prepared by gas-phase pyrolysis of B2H under different conditions. Pentaborane(9) is a... 

G in the presence of a catalytic amount of a Lewis base such as dimethylether, (GH2)20. In addition to the gas-phase pyrolysis of diborane, can be prepared by a solution-phase process developed at Union Garbide Gorp. Decaborane is a key intermediate in the preparation of many carboranes and metaHa derivatives. As of this writing, this important compound is not manufactured on a large scale in the western world and is in short supply. Prices for decaborane in 1991 were up to 10,000/kg. 

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