Products, benzene decomposition

The conductometric results of Meerwein et al. (1957 b) mentioned above demonstrate that, in contrast to other products of the coupling of nucleophiles to arenediazonium ions, the diazosulfones are characterized by a relatively weak and polarized covalent bond between the p-nitrogen and the nucleophilic atom of the nucleophile. This also becomes evident in the ambidentate solvent effects found in the thermal decomposition of methyl benzenediazosulfone by Kice and Gabrielson (1970). In apolar solvents such as benzene or diphenylmethane, they were able to isolate decomposition products arising via a mechanism involving homolytic dissociation of the N — S bond. In a polar, aprotic solvent (acetonitrile), however, the primary product was acetanilide. The latter is thought to arise via an initial hetero-lytic dissociation and reaction of the diazonium ion with the solvent (Scheme 6-11). 

Hydroxyl elimination is necessary for the formation of benzaldehyde and benzoic acid derivatives and, ultimately, benzene and toluene (Fig. 7.46).2 It is proposed that a cleavage between the hydroxyl group and aromatic ring leads to benzenoid species which undergo further cleavage coupled with oxidation to give various decomposition products. 

Decomposition products were captured in two traps immersed in dry ice followed by a third trap containing 5 ml of benzene. After 1 hour, the boat, tube, and traps were rinsed with benzene. The benzene solution was analyzed by gas chromatography using an electron capture detector to determine the concentration of unreacted 2,3,7,8-tetrachloro-dibenzo-p-dioxin. 

Starting materials other than sulphonyl azides have been used as possible sources of sulphonyl nitrenes. The decomposition of the triethyl-ammonium salt of iV- -nitrobenzenesulphonoxybenzenesulphonamide (26) in methanol, ethanol, and aniline gave products derived from a Lossen-type rearrangement 20> (Scheme 3). It was felt that the rearrangement did not involve a free sulphonyl nitrene since, when the decomposition was carried out in toluene-methylene chloride or in benzene, no products (benzenesulphonamides) of substitution of the aromatic solvent nucleus were found (as are usually found with sulphonyl nitrenes from the thermal decomposition of the corresponding azides). On the other... 

In addition to the chemicals included on the other lists, the CDC also included heavy metals such as arsenic, lead, and mercury volatile solvents such as benzene, chloroform, and bromoform decomposition products such as dioxins and furans polychlorinated biphenyls (PCBs) flammable industrial gases and liquids such as gasoline and propane explosives and oxidizers and all persistent and nonpersistent pesticides. Agents included in this volume are limited to those that are most likely to pose an acute toxicity hazard. 

Volatile decomposition products may include HCl, HBr, HCN, COCI2, nitrogen oxides (NO ), aromatic hydrocarbons such as benzene, and/or halogenated aromatic compounds. 

In a pyrogram of Bisphenol A poly(formal) (6), the peak products are identified as a-methylstyrene, phenol, 4-hydroxy-a-methylstyrene, and isopropyl phenol by Py-GC/MS. These products are identical with the degradation products from Bisphenol A. In addition to the decomposition products of Bisphenol A, 4-isopropenyl anisole is also identified as a product. The pyrograms of Bisphenol AF poly(formal) (7) contain only two major species, pentafluoroisopropenyl benzene (product T) and pentafluoroisopropenyl anisole (product 2 ). They correspond to a-methylstyrene, 4-hydroxy-amethylstyrene from Bisphenol A poly(formal) (6) and are produced by the cleavage of phenylene-oxy bonds and oxy-methylene bonds according to (Scheme 6). 

Berlin [69] also confirmed the importance of the presence of OH radicals in his investigation of the polymerisation of polystyrene in the presence of styrene monomer when he found the addition of water to the reaction solvent (benzene) greatly enhanced the yield of polymer. However, latterly it has been argued for these systems that the appearance ofwater decomposition products (e. g. H2O2) led to oxidation of the various impurities, which previously, may have acted as inhibitors in the polymerisation process. 

By-products formed during their preparation (e.g., ethylbenzene and divinyl-benzenes in styrene acetaldehyde in vinyl acetate) added stabilizers (inhibitors) autoxidation and decomposition products of the monomers (e.g., perox-... 

In solution these esters undergo a variety of transformations which are dependent on the reaction conditions. In benzene, decomposition to carbon monoxide and carbonyl compounds is observed either upon direct irradiation94 or with benzophenone sensitization.33 In cyclohexane a complex product mixture is obtained.95 Addition of solvent to the carbonyl group is observed when the reaction is carried out in cyclohexene.54 At room temperature photoreduction takes place when the reaction is carried out in a secondary alcohol.96-97 However, in the case of the phenylglyoxylates quite a different reaction is observed when the reaction is carried out at elevated temperatures. The ester is reduced to the mandelate ester of the solvent alcohol, and the alcohol moiety of the ester is oxidized to the corresponding carbonyl compound. The pyruvates have not been studied at an elevated temperature. 

From the decomposition mechanism and the products formed it can be deduced that DCP primarily generates cumyloxy radicals, which further decompose into highly reactive methyl radicals and acetophenone, having a typical sweet smell. Similarly, tert-butyl cumyl peroxide (TBCP) forms large quantities of acetophenone, as this compound still half-resembles DCP. From the decomposition products of l-(2-6 rt-butylperoxyisopropyl)-3-isopropenyl benzene ( ), it can be deduced that the amount of aromatic alcohol and aromatic ketone are below the detection limit (<0.01 mol/mol decomposed peroxide) furthermore no traces of other decomposition products could be identified. This implies that most likely the initially formed aromatic decomposition products reacted with the substrate by the formation of adducts. In addition, unlike DCP, there is no possibility of TBIB (because of its chemical structure) forming acetophenone. As DTBT contains the same basic tert-butyl peroxide unit as TBIB, it may be anticipated that their primary decomposition products will be similar. This also explains why the decomposition products obtained from the multifunctional peroxides do not provide an unpleasant smell, unlike DCP [37, 38]. 

Tetraphenylborate (TPB) was used at Savannah River to recover cesium from alkaline solutions, but attempts to treat HLW tanks with TPB resulted in the production of benzene (a TPB decomposition product) at levels that did not permit the safe operation of the process.8 Crown ethers and dicarbollides were proposed as extractants to remove cesium from acidic HAW, but these compounds are not selective enough to allow cesium to be removed from solutions containing large amounts of nitric acid or sodium nitrate.9 Dicarbollides were used in Russia at industrial scale to recover cesium from HAW, but the removal of cesium was only possible after partial denitration of the liquid waste.10... 

The high ratio of biphenyl to naphthalene may reflect a contribution from a second path, via the primary decomposition product in stepwise loss of carbon dioxide and carbon monoxide, paralleling the reaction sequence known to occur under electron impact. The intermediate species (11) could add to benzene to give biphenyl by subsequent loss of carbon monoxide or fluorenone by ring closure and loss of hydrogen ... 

Other workers [358] carried out the acylation of estrogens in acetone and reported the following conditions as optimal for the preparation of tris-HFB-estriol 0.1—0.3 jul of acetone per 1 jug of the substrate and 0.05 ml of HFB anhydride at room temperature for 10 min. The use of a larger amount of another solvent (benzene, methylene chloride, dimethyl sulphoxide, diethyl ether, dioxane) was said to result in the formation of a number of by-products. Poole and Morgan [359], however, stated that the HFB derivatives of some steroids are not thermally stable and that only the decomposition product is detected, e.g., cholesta-3,5-diene is produced from cholesterol. This leads to a considerably lower ECD response, so that the detection limit, which under favourable circumstances can be as low as 0.005 ng, is usually not achieved. As steroids that form unstable HFB derivatives they reported cholesterol, lumisterol, ergosterol, estradiol, pregnanetriol and others. 

The alkali fusion of benzene-m-disulfonic acid yields resorcinol only in the absence of water. With aqueous sodium hydroxide under pressure, phenol-m-sul-fonic acid is formed, and if the temperature is increased, phenol and decomposition products are formed, but not resorcinol. The formation of some phenol as a byproduct cannot be avoided completely. ... 

Trifluoromethyl)phenylcopper was found to be an octamer by consideration of the kinetics of its decomposition, and by cryoscopy and vapor pressure osmometry in benzene solution 36). Its F NMR spectrum in ether at room temperature is a sharp singlet. Consequently, the suggested structure is a central copper cube with equivalent bridging benzotri-fluoride groups. The initial decomposition product, Cu8( n-CF3CgH4)e, is considered to be a Cu(0)—Cu(I) octanuclear cluster compound 36). For the octameric m-(trifluoromethyl)phenylcopper, the tetrameric ortho isomer, and pentafluorophenylcopper tetramer, the F NMR spectra were found to vary with temperature. The changes are not considered to involve important structural alterations, but only variations in solvent complexes and rotamer populations 32, 37). The spectra also... 

The success of the fluidized bed in eliminating interference from thermal or photochemical decomposition products is evident in the spectra characterizing benzene adsorbed in Fl-USY zeolite shown in Fig. 6. The strong peak at 990 cm in liquid benzene (6a) is assigned to a symmetric ring-breathing mode. This band is... 

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