Xylenes decomposition

In the single field study (Cozzarelliera/., 1990) where Fe(III) likely functioned as the predominant terminal electron acceptor, o-toluic acid was speculated to be an oxidized product of o-xylene decomposition at the Bemidji, Minnesota, aquifer site. This study provides presumptive evidence that o-xylene can be degraded under iron-reducing conditions. 

MIL-47 packed with four xylenes decomposition of the adsorption energy... 

Complex Formation. AH four Cg aromatic isomers have a strong tendency to form several different types of complexes. Complexes with electrophilic agents ate utilized in xylene separation. The formation of the HE-BF —MX complex is the basis of the Mitsubishi Gas—Chemical Company (MGCC) commercial process for MX recovery, discussed herein. Equimolar complexes of MX and HBr (mp — 77°C) and EB and HBr (mp — 103°C) have been reported (32,33). Similatly, HCl complexes undergo rapid formation and decomposition at —80°C (34). 

Bismuth ttiiodide may be prepared by beating stoichiometric quantities of the elements in a sealed tube. It undergoes considerable decomposition at 500°C and is almost completely decomposed at 700°C. However, it may be sublimed without decomposition at 3.3 kPa (25 mm Hg). Bismuth ttiiodide is essentially insoluble in cold water and is decomposed by hot water. It is soluble in Hquid ammonia forming a red triammine complex, absolute alcohol (3.5 g/100 g), benzene, toluene, and xylene. It dissolves in hydroiodic acid solutions from which hydrogen tetraiodobismuthate(Ill) [66214-37-7] HBil 4H2O, may be crystallized, and it dissolves in potassium iodide solutions to yield the red compound, potassium tetraiodobismuthate(Ill) [39775-75-2] KBil. Compounds of the type tripotassium bismuth hexaiodide [66214-36-6] K Bil, are also known. 

A solid solution of starch in urea may also be employed. Reflux 1 g of soluble starch and 19 g of urea with xylene. At the boiling point of the organic solvent the urea melts with little decomposition, and the starch dissolves in the molten urea. Allow to cool, then remove the solid mass and powder it store the product in a stoppered bottle. A few milligrams of this solid added to an aqueous solution containing iodine then behaves like the usual starch indicator. 

Careful chromatographic and detailed HNMR spectroscopic analysis of the products from the thermolyses of ethyl azidoformate in o-, m- and p-xylene revealed in all cases a mixture of 1 //-azepines.80 In o-xylene, only two of the four possible isomers were separated and characterized, namely, ethyl 4,5-dimethy 1-1 //-azepine-1 -carboxylate (9 %) and ethyl 3,4-dimethyl-l H-azepine-1-carboxylate (7 %). w-Xylene yielded a 2 3 mixture of ethyl 3,5-dimethyl-l//-azepine-1-carboxylate and ethyl 2,4-dimethyl-l//-azepine-l-carboxylate. The 2,4-dimethyl isomer (20 %) can be isolated from the mixture by removal of the 3,5-dimethyl isomer as its Diels-Alder cycloadduct with ethenetetracarbonitrile. p-Xylene gave a mixture of the two possible isomeric azepines which were partially separated by column chromatography. A pure sample of ethyl 2,5-dimethyl-1//-azepine-1-carboxylate (26%) was obtained from the mixture by selective decomposition of the 3,6-dimethyl isomer with refluxing alcoholic potassium hydroxide. 

The reaction scheme is rather complex also in the case of the oxidation of o-xylene (41a, 87a), of the oxidative dehydrogenation of n-butenes over bismuth-molybdenum catalyst (87b), or of ethylbenzene on aluminum oxide catalysts (87c), in the hydrogenolysis of glucose (87d) over Ni-kieselguhr or of n-butane on a nickel on silica catalyst (87e), and in the hydrogenation of succinimide in isopropyl alcohol on Ni-Al2Oa catalyst (87f) or of acetophenone on Rh-Al203 catalyst (87g). Decomposition of n-and sec-butyl acetates on synthetic zeolites accompanied by the isomerization of the formed butenes has also been the subject of a kinetic study (87h). 

Lithiochloromethyl phenyl sulfoxide 99 was found to react with aryl or alkyl halides in the presence of one equivalent of hexamethylphosphoramide to afford alkylated products 100 in high yields135. Thermal decomposition of these products in the presence of a catalytic amount of hydroquinone in xylene gave the corresponding vinyl compounds 101. 

Whereas cycHzation of the cu-keto-co -hydroxyamide 1466 in boihng toluene or xylene in the presence of camphorsulfonic acid (CSA) results in decomposition of the starting material 1466, heating of 1466 with excess TMSOTf 20 and N-methyl-morphoHne in 1,2-dichloroethane affords 46% of the desired cycHzation product 1467 [30] (Scheme 9.16). The close relationship of product 1467 to d -oxazolines suggests that reaction of carboxylic acids 11 with free (or C-substituted) ethanola-mines 1468 and HMDS 2/TCS 14 might lead analogously, via the silylated intermediates 1469, to d -oxazolines 1470 and HMDSO 7. As demonstrated in the somewhat related cyclization of 1466 to 1467, combination of TMSOTf 20 with N-... 

In order to obtain compounds with Ti-O-P and Zr-O-P units, the hexaethoxy-derivative, NsPaCOEOg, was treated with titanium and zirconium tetrachlorides. In each case, hygroscopic solids of the type NaPaCOEOiOaMCU (M = Ti or Zr) and ethyl chloride were obtained. The degree of polymerization of these solids was 1.6—1.8, and on the basis of their i.r. and n.m.r. spectra, two alternative structures, (46) and (47), were proposed. In an alternative route to the same type of compound, N3P3CI6 was treated with tetra-n-butoxytitanium in o-xylene. Butyl chloride was liberated and a solid was obtained which has been assigned the structure (48). Its thermal decomposition was studied by differential thermal analysis. 

The family of true clathrates based on hydrocarbons only is further enriched by the inclusion compounds of 48 with benzene (1 1) and p-xylene (2 1) 90> (Table 19). Figure 28 illustrates the structure of 48 benzene (1 1). The structure of the p-xylene clathrate shows intercalated guest molecules at centers of symmetry in the crystal lattice. Both clathrates are rather unstable at ambient temperatures and decompose easily, e.g. on exposure to X-rays (even in the presences of mother liquor). The 48 p-xylene clathrate is unstable to such a degree that decomposition occurs at low temperature. 

An attempt to chlorinate xylene with the dichlorohy dantoin caused a violent explosion [1], The haloimide undergoes immediate self accelerating decomposition in presence of solvents. Safe conditions (including lower temperatures and progressive addition of reagent to match its consumption) can be developed for its use [2],... 

Some examples of the lateral cyclization of suitable O-allyl and O-propargyl derivatives were discussed in CHEC-11(1996) <1996CHEC-II(8)747>. Thermal reaction of silyl diazoacetate 303 in xylene provides unspecific decomposition and a minor amount (about 2%) of a colorless solid can be precipitated with ether. The X-ray diffraction analysis identified the structure 305, which is a product of the lateral criss-cross cycloaddition of primarily formed azine 304 (Scheme 43) <2000T4139>. 

Kinetic studies of the thermolysis of diazomethane were carried out by various authors. These experiments demonstrated that the decomposition of diazomethane was a first order reaction 41-43) Similar investigations of the p5n olysis of diphenyl-diazomethane in xylene or 1-methylnaphthalene also showed that the disappearance of diphenyl-diazomethane is a first order process. It may be concluded that a free carbene is involved in these reactions, in accordance with the following scheme ). 

Isomeric l,3a,4,6a- (220) and l,3a,6,6a- (91) dibenzotetraazapentalenes can be prepared from the thermal decomposition of 2-((9-azidophenyl)-2//-benzotriazole (224) and - o-azidophenyl)-2//-benzotriazole (230), respectively, in high boiling solvents such as 0-dichlorobenzene and decalin. This synthesis was improved upon when it was found that (220) and (91) can be prepared from the reactions of 2-((9-nitrophenyl)-2//-benzotriazole (226) and l-(o-nitrophenyl)-2//-benzotriazole (229), respectively, with triethyl phosphite in refluxing xylene. ... 

The alkali and alkaline earth metals - such as sodium, potassium, barium, and calcium — would make excellent high-energy fuels, but, except for magnesium, they are too reactive with moisture and atmospheric oxygen. Sodium metal, for example, reacts violently with water and must be stored in an inert organic liquid, such as xylene, to minimize decomposition. 

Another example of a stable nitrile ylide (2 R,R = alkyl) was generated by the thermal decomposition of 7-azido-l,3-disubstituted lumazines in xylene (2). The product is formed via a complex multistep process. As in the case of 1, the stability is attributed to strong resonance stabilization of the anionic moiety but it is notable that this is the first isolable nitrile ylide that does not also rely on the presence of a bulky substituent at the nitrihum carbon. 

AIkynyl(diisopropylsilyl)oxy-diazoacetates (295) undergo intramolecular 1,3-dipolar cycloaddition in good yield when R = H (isolation of silver pyrazolide 296 was possible) and R, R = Me,Me or (CH2)s, but no reaction occurred when R = H, R = H or R =Me (340). The silicon substimtion is apparently crucial. Replacement of the Si(i-Pr)2 in 295 (R = R = H) by Si(f-Bu)2 allowed an uncatalyzed intramolecular [3 + 2] cycloaddition to take place [xylene, 140-160 °C, 11% yield (340)], while Ag(I) catalysis led to decomposition. A diazoacetic acid (2-propyn-l-yl)oxysilyl ester also produced a bicyclic pyrazole, but in low yield. On the other hand, the same diazo compound 295, which reacted intm-molecularly under silver ion catalysis, underwent dimerization by an /nfermolecular... 

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