Cyclopentanone carbon dioxide

CycHzation with loss of one carboxyl takes place in the presence of metal oxides, notably barium and thorium. Thus adipic acid yields cyclopentanone, carbon dioxide, and water (Dieckmaim reaction). 

Another example of the application of high pressure in the field of domino transformations has been revealed by Brinza and Fallis, representing a carbonylation/cy-clization procedure [4]. Thus, when hydrazones 10-12, bearing a bromine atom, are subjected to standard radical conditions under a high-pressure atmosphere of carbon dioxide, cyclopentanones 10-16 and 10-17 are smoothly produced in good yields (Scheme 10.3). 

The methyl ester has also been obtained by esterification of cyclopentanecarboxylic acid.8 The acid, in turn, has been prepared by the Favorskii rearrangement,6 7 9-11 by the reaction of cyclopentyl Grignard reagent with carbon dioxide,12 by the carbonylation of cyclopentyl alcohol with nickel carbonyl13 or with formic acid in the presence of sulfuric acid,14 and by the hydrogenation of cyclopentene-1-carboxylic acid prepared from ethyl cyclopentanone-2-carboxylate 15 or from cyclopentanone cyanohydrin.16... 

Scission near the end of a polymer chain would give the fragment —C0(CH2 )4C00H, which could also cyclize to form cyclopentanone, together with carbon dioxide. 

Ring size is crucial with adipic acid, for example, anhydride formation would produce a seven-membered ring, and does not take place. Instead, carbon dioxide is lost and cyclopentanone, a ketone with a five-membered ring, is formed. 

Ammonia and carbon dioxide result from decarboxylation and deamination following hydrolysis of the amide group. Dimers of cyclopentanone and the cyclic monomer of nylon-6,6, namely,... 

Glutaric acid loses water when slowly heated to 230-280°, giving its anhydride, m.p. 56-57°. Maleic anhydride can be obtained in 90% yield if the water liberated is removed by azeotropic distillation with tetrachloro-ethane.952 Fumaric acid rearranges when heated, giving maleic anhydride. Adipic acid requires boiling for several hours with acetic anhydride, then giving a polymeric anhydride that becomes converted into cyclopentanone with loss of carbon dioxide (see page 1005). 

Iq the case of pyrolysis under vacuum at 400°C of the mixed polyamide produced by polycondensation of caprolactam and hexamethylene-adipamide, as well as the mixed polyamide obtained from hexamethylene-adipamide, e-caprolactam, and hexamethylenesebacamide [15, 16], the following products were detected in the gas phase by mass spectroscopic analysis carbon monoxide, carbon dioxide, cyclopentanone, water, various hydrocarbons (methane, ethane, propane, butane, ethylene, butenes). Ammonia and other nitrogen compounds were not detected in the gas phase. All the nitrogen remains in the solid residue [15-18]. The... 

Hoberg H, Peres Y, Kruger C, Tsay Y-H (1987) A l-oxa-2-nickela-5-cyclopentanone fiom ethene and carbon dioxide preparation, structure, and reactivity. Angew Chem Int Ed Engl 26 771-773... 

Carbon dioxide has also been detected during the AIBN-initiated polymerization of MA. " Since the polymer suffers some decarboxylation at elevated temperatures, it was originally believed that carbon dioxide evolved from the polymer formed as a result of polymerization.Braun et suggested the analytical data support the concept that loss of CO2 occurs simultaneously with and as part of the polymerization process. Polymers formed under this assumption are presumed to contain units of succinic anhydride and cyclopentanone rings 10. 

The fast pyrolysis decomposition of cellulose starts at temperatures as low as 150°C. Pyrolysis of cellulose below 300°C results in the formation of carboxyl, carbonyl, and hydro peroxide groups, elimination of water and production of carbon monoxide and carbon dioxide as well as char residue (Evans and Milne, 1987). Therefore low pyrolysis temperatures will produce low yields of organic liquid yields. Fast pyrolysis of cellulose, above 300°C, results in liquid yields up to 80 wt.%. Cellulose initially decomposes to form activated cellulose (Bradbury et al., 1979). Activated cellulose has two parallel reaction pathways, depolymerization and fragmentation (ring scission). The main products from each reaction pathway are rather different as ring scission produces hydroxyacetaldehyde, linear carbonyls, linear alcohols, esters, and other related products (Bradbury et al., 1979 Zhu and Lu, 2010 Lin et al., 2009) and depolymerization produces monomeric anhydrosugars, furans, cyclopentanones, and pyrans and other related products (Bradbury et al., 1979 Zhu and Lu, 2010 Lin et al., 2009). Each reaction pathway is independent and is influenced by pyrolysis temperature and residence time (Bradbury et al., 1979). 

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