Pyrolysis Structure

Condensation reactions Organic pyrolysis Structural rearrangement... 

Pyrolysis. Structural units of the organic matter split off under fast heating in an inert atmosphere, and lower molecular weight fragments evolve (termed the pyrolysis products). 

The pyrolysis thresholds of this series of compounds show that the thiazole structure is thermostable, decomposition temperatures being generally between 450 and 510°C. Other observations that can be made are ... 

Diels-Alder reactions, 4, 842 flash vapour phase pyrolysis, 4, 846 reactions with 6-dimethylaminofuKenov, 4, 844 reactions with JV,n-diphenylnitrone, 4, 841 reactions with mesitonitrile oxide, 4, 841 structure, 4, 715, 725 synthesis, 4, 725, 767-769, 930 theoretical methods, 4, 3 tricarbonyl iron complexes, 4, 847 dipole moments, 4, 716 n-directing effect, 4, 44 2,5-disubstituted synthesis, 4, 116-117 from l,3-dithiolylium-4-olates, 6, 826 electrocyclization, 4, 748-750 electron bombardment, 4, 739 electronic deformation, 4, 722-723 electronic structure, 4, 715 electrophilic substitution, 4, 43, 44, 717-719, 751 directing effects, 4, 752-753 fluorescence spectra, 4, 735-736 fluorinated derivatives, 4, 679 H NMR, 4, 731 Friedel-Crafts acylation, 4, 777 with fused six-membered heterocyclic rings, 4, 973-1036 fused small rings structure, 4, 720-721 gas phase UV spectrum, 4, 734 H NMR, 4, 7, 728-731, 939 solvent effects, 4, 730 substituent constants, 4, 731 halo... 

Several methods ean be employed to eonvert eoal into liquids, with or without the addition of a solvent or vehiele. Those methods which rely on simple pyrolysis or carbonization produce some liquids, but the mam produet is eoke or char Extraction yields can be dramatically increased by heating the coal over 350°C in heavy solvents sueh as anthraeene or eoal-tar oils, sometimes with applied hydrogen pressure, or the addition of a eatalyst Solvent eomponents whieh are espeeially benefieial to the dissolution and stability of the produets eontain saturated aromatic structures, for example, as found in 1,2,3,4 tctrahydronaphthalene Ilydroaromatie eompounds are known to transfer hydrogen atoms to the coal molecules and, thus, prevent polymerization... 

As can be noted in Figure 21.7.2, steam and ediane are mi.xed before entering die reactor tubes where pyrolysis reacdons take place. All feed and product lines must be equipped with appropriate control devices to ensure safe operation. The FTA flow chart breaks down a TOP event (see descripdon of fault tree in Unit II) into all possible basic causes. Aldiough, diis mediod is more structured than a PHA, it addresses only one individual event at a dine. To use an FTA for a complete liazard analysis, all possible TOP events must be identified and investigated this would be extremely time consuming and perhaps urmecessary in a preliminary design. 

The structural analogy with the dicarbaborane C2B3H5 (56) is obvious. Likewise, pyrolysis of a mixture of B2CI4 and PCI3 yields [closo-... 

HgO exists in a red and a yellow variety. The former is obtained by pyrolysis of Hg(N03)2 or by heating the metal in O2 at about 350°C the latter by cold methods such as precipitation from aqueous solutions of Hg" by addition of alkali (Hg(OH)2 is not known). The difference in colour is entirely due to particle size, both forms having the same structure which consists of zigzag chains of virtually linear O-Hg-O units with Hg-O 205pm and angle Hg-O-Hg 107°. The shortest Hg - O distance between chains is 282 pm. 

Ring fusion seems to occur in the quinoxaline derivative (28), which has been stated to exist in red and blue-black forms. Other derivatives of type 28 are reported. Attempts to prepare 5,6-furo-xanobenzofuroxan by pyrolysis of the azide (29) met with no success. An early example in the literature of such a linear fused structure was shortly afterward revised to the angularly fused type (17). 

Thus, the hydrogenation of isomeric l-ethynyl-3-methyl- and l-ethynyl-5-methylpyrazoles by hydrogen with 10% Pd/C in l-ethyl-3-methyl- and 1-ethyl-5-methylpyrazoles was used to prove the structure of iV-ethynylpyrazoles formed from pyrolysis of the corresponding iV-propynoylazoles (94AJC991) (Scheme 79). 

This structure rationalizes (a) the formation of mono- and, under more vigorous conditions, tetra-acetyl derivatives, (b) the methyla-tion to a dimethyl derivative still containing two active hydrogens, (c) the pyrolysis back to monomeric indole, (d) the formation of a benzylidene derivative containing the Ph CH=N— Ar ehromophore, (e) the failure to form a simple nitroso derivative, (f) the Zn/AcOH reduction of the dimethyl trimer to base C18H20N2, shown to be identical with the dihydro derivative of (26). 

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