Pyrolysis metals salts

Aerosol spray pyrolysis is another method used to control particle size by limiting the local environment around the particle nucleation sites. In aerosol spray pyrolysis, metal salt solutions are first aerosolized with a carrier gas and then heated in a high-temperature furnace to remove the solvent and form oxides. Heating metal salts to very high temperatures in air results in decomposition of the salts and subsequent formation of metal oxides. 

Thermolysis of 4-methyl(4-phenyl)isoxazolin-5-one produced a-cyanophenylacetic acid <67JHC533). The pyrolysis of 3-methylisoxazoline-4,5-dione 4-oxime generated fulminic acid, which was trapped in a liquid N2 cooled condenser for further study. Pyrolysis of metal salts such as Ag or Na produced the corresponding highly explosive salts of fulminic acid 79AG503). Treatment of the oxime with amines generated bis-a,/3-oximinopropionamides (Scheme 65) <68AC(R)189). 

Dihydro-2f/-pyran-2-one has been prepared by reductive cycliza-tion of 5-hydroxy-2-pentynoic acid [2-Pentynoic acid, 5-hydroxy-], which is obtained in two steps from acetylene [Ethyne] and ethylene oxide [Oxirane] 3 and by the reaction of dihydropyran [277-Pyran, 3,4-dihydro-] with singlet oxygen [Oxygen, singlet].4,5 2ff-Pyran-2-one has been prepared by pyrolysis of heavy metal salts of coumalic acid [2//-Pyran-5-carboxylic acid, 2-oxo-],8 by pyrolysis of a-pyrone-6-carboxylic acid [211 - Pyran-6-carboxyl ic acid, 2-oxo-] over copper,7 and by pyrolysis of coumalic acid over copper (66-70% yield).8... 

It is fairly stable as an ethereal solution, but the isolated acid is explosively unstable, and sensitive to heat, shock or friction [1], In a new method of preparation of the acid or its salts, pyrolysis of 4-oximato-3-substituted-isoxazol-5(4//)-ones or their metal salts must be conducted with extreme care under high vacuum to prevent explosive decomposition [2],... 

This can certainly be extended to other metal sulphides, using other complexes of sulphur (and also selenium). However, the complex and anion of the metal salt need to be chosen so that all the by-products of the pyrolysis reaction are volatile, otherwise the film will be contaminated with the nonvolatile by-products. For example, using cadmium nitrate and thiourea, all the by-products are volatile ... 

A number of complexes of isatin and metal salts have been reported.220,221 Isatin and N-substituted isatins react with dialkyl phosphites to give 56 and with trialkyl phosphites to give 57.222 The pyrolysis products of isatin have been studied,223 as have those of N-methylisatins.223a... 

Several examples of the synthesis of aryl alkyl ketones by the thermal decarboxylation of mixtures of carboxylic acids over heated metal salts are included under the preparation of aliphatic ketones (Expt 5.93). In this section the preparation of dibenzyl ketone (Expt 6.127) by the pyrolysis of the barium salt of phenylacetic acid, which proceeds in good yield, is included as a further example of this general type of synthesis. 

Spray pyrolysis An appropriate metal salt is sprayed from an atomizer onto a hot substrate where decomposition occurs yielding the metal oxide. There are advantages to be gained by electrically charging the droplets using an electrostatic atomizer Deposition rates are quite low, typically in the range 1-10 /unh-1. 

The various reagents may be created in several ways. They may be obtained by photolysis, pyrolysis or discharge of a suitable precursor. Refractory substances, such as metals and metal salts, can be produced in the gas phase by direct vaporisation or, more recently, by laser... 

Several thieno[3,2-6]thiophenes (67) are produced by pyrolysis of various 1,2-dithioles, including bi(l,2-dithiol-3-ylidenes) (20), alkali metal salts of l,2-dithiole-3-sulfonyI hydrazides (68) (75TL3473), and tetrahydrobenzo-l,2-dithiol-3-ones (69) (63BSF161). 

Owing to the slow rates of diffusion of the cations, the direct solid-state reaction of the oxides Cr2 03 and MO at an elevated temperature is not a good preparation of divalent metal chromium(III) oxides. They can be prepared by more elaborate methods, such as controlled reduction of dichromates MCr207,1 reaction of dichromium tungsten oxide Cr2W06 with a molten divalent metal fluoride2 at 1400°, pyrolysis of complexes,3 and pulverization of slurries containing Cr2 03 and a divalent metal salt.4... 

The pyrolysis of polymers of alkali emd alkaline earth metal salts of PMAA was studied by McNeill and Zulfigar [33]. The first psrolysis reaction is the elimination of water as in Figure 15.5. Then, two distinct processes may be discerned in the breakdown of the alkali metal salts of PMAA namely, chain scission and carbonate formation. Chain scission leads to monomer and metal isobutyrate. The metal carbonate formation occurs by intramolecular reaction of adjacent salt units in the chain, resulting in the elimination reaction of unstable four-membered ring structure species which undergo various transformations to cyclic or acrylic ketones. 

New routes to high quality colloidal NCs of varying compositions and shapes appear in the literature almost on a weekly basis. The most successful of these approaches to crystalline semiconductor NCs with excellent optical properties share the same basic premise of pyrolysis of metal-organic precursors in solutions of hot coordinating solvents. In contrast, the syntheses of noble metal NCs typically rely on the reduction of metal salts in the presence of citrate ions (e.g. An or Ag), in two-phase systems (e.g. An or Ag), or under high-temperature conditions in the presence of stabilizing... 

Pyrolysis of alkali-metal salts does not lead to simple decarboxylation but, instead, elimination of fluoride also occurs this is a useful S3mthetic method [36], commercialised in the synthesis of monomer for the manufacture of Nafion [37] (Figure 8.1) see Chapter 7, Section IIB for the preparation of fluoroalkenes. 

A number of reactions of metal salts can be rationalized in terms of the formation of a carbanion adjacent to the carboxylate. Dibasic metals such as calcium bring two carboxylate units close to each other so that the carbanion formed adjacent to one carboxylate may attack the carbonyl of the other. Thus pyrolysis of calcium acetate affords propanone (acetone) (Scheme 3.62). A similar reaction is found in the pyrolytic cyclization of some dicarboxylic acid anhydrides. Heating Cg and dicarboxylic acids gives cyclopentanones and cyclohexanones... 

Aryne formation by elimination of lithium fluoride limits the stability of 113 a polymer is formed, but attempts to trap the aryne (114) were unsuccessful.352 Decarboxylation of metal salts of tetrafluoroisonicotinic add occurs,357 giving the corresponding metal derivative, but pyrolysis of the disilver salt (115) appears to produce the aryne (114), since small amounts of diazabiphenylenes may be isolated from the reaction product.358 359... 

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