Pyrolysis condensation products

Fig. 2. Overall schematic of solid fuel combustion (1). Reaction sequence is A, heating and drying B, solid particle pyrolysis C, oxidation and D, post-combustion. In the oxidation sequence, left and center comprise the gas-phase region, tight is the gas—solids region. Noncondensible volatiles include CO, CO2, CH4, NH, H2O condensible volatiles are C-6—C-20 compounds oxidation products are CO2, H2O, O2, N2, NO, gaseous organic compounds are CO, hydrocarbons, and polyaromatic hydrocarbons (PAHs) and particulates are inerts, condensation products, and solid carbon products.

J. Douda and V.A. Basiuk, Pyrolysis of ammino acids, recovery of starting materials and yields of condensation products, J. Anal. Appl. Pyrol., 56, 113 121 (2000). 

The condensation product (358) from 1,2-dimethyl-3-formylindole and Meldrum s acid gave 2-hydroxy-9-methylcarbazole on flash vacuum pyrolysis at 500°C, probably via 359. ... 

Condensation of formyl-pyrroles and -indoles with a wide range of other activated methylene compounds has been reported. These include, for example, hydantoin, which provides a useful synthetic route to tryptophane and j8- (pyrrolyl)alanines, thiohydantoin, rhodanine and AT-substituted barbituric acids (B-77MI30505, 79HC(25-3)357). Flash pyrolysis of the condensation product derived from 3-formyl-2,5-dimethylpyrrole with Meldrum s acid produces 6-hydroxy-2-methylindole, (440) — (441) (74AJC2605), whilst the analogous... 

Treatment of the ( -lactam 1 with N -methylhydroxylamine gave the expected condensation product, pyrolysis of which in toluene at 110°C led to formation of the isomers 2 in 72% yield. 

At higher temperatures, the intermediates, including levoglucosan and the condensation products further pyrolyze to give various products by fission of the carbohydrate units and rearrangement of the intermediate products. Table III shows the products obtained from the pyrolysis of cellulose and treated cellulose at 600° (8). The significant increase in the yields of water and char and decrease in the yield of tar in the acid treated cellulose verifies the previously mentioned promotion of dehydration and charring reactions by acidic additives. 

The addition of a Lewis acid, i.e., ZnC significantly decreases the production of tar and enhances the production of char due to the enhanced dehydration reactions. At higher temperatures the glycosyl units and the random condensation products are further degraded to a variety of volatile products, as shown in Table V (9). Comparison of this table with the high temperature pyrolysis products listed for cellulose in Table III shows that the products of both fractions are basically similar. The significant increase in the yields of 2-furaldehyde, water and char and decrease in the yield of tar by the addition of ZnCl verifies the enhanced dehydration and is similar to observed effects in cellulose pyrolysis. 

Figure 21.5 Cumulative yield of condensable products for the microwave pyrolysis of HOPE pellets pyrolysis at (A) 500°C and (B) 600°C [85]. (Reproduced by permission of the American Chemical Society)...

In terms of the individual compounds found in the condensable products, as with conventional pyrolysis, a-alkenes alkanes and dialkenes were the most abundant compounds. A large number of other aliphatic and aromatic compounds ranging from C3 to approximately 55 were also found, including methylcyclopentene, benzene, cyclohexene, toluene, ethylbenzene, xylene, propylbenzene and methyl-ethylbenzene. The analysis also showed that the condensables obtained at 500 and 700°C, although possessing similar levels of cleavage, showed important differences in the individual compounds present [85],... 

In this connection, the information about the formation of the main olatilc condensable products during the pyrolysis process is of interest. Tliis information is presented in Figures 3, 4 and 5. 

Derivation (1) From cracked products of heavy petroleum oils (2) dehydrogenation of isopentene (3) pyrolysis of methyl pentene or of isobutylenefor-maldehyde condensation products (4) dehydration of methyl butenol. 

Nitrogen Systems. - Monoaza-Compounds. Gas-phase pyrolysis of the condensation product (532) of pyrrole-2-aldehyde with Meldrum s acid gives pyrrolizin-3-one (533). The acid chloride (535) is produced by the action of phosphorus pentachloride on the pyrrole derivative (534). Treatment of the enamine (536) with dimethyl acetylenedicarboxylate in methanol yields, inter alia, the diester (537). A -Dehydropyrrolizidine undergoes dimerization to yield mainly compound (538), The pyrroloindoloquinone (540) is produced by irradiation of the benzoquinone derivative (539). ° ... 

Generation of the phenolic hydroxyl group via a reactive ketene intermediate is shown in the pyrolysis of the condensation product of... 

An interesting procedure to obtain 5-oxopyrrolo[l,2-a]imidazole (41) has been described, by pyrolysis, in the gas phase, of compound (M), a condensation product of Meldrum s acid and imidazole-2-carbaldehyde (Equation (5)) <87JCS(P1)653,87JCS(Pi)657>. 

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