Decomposition products propylene

Polyethylene displays good heat resistance in the absence of oxygen in vacuum or in an inert gas atmosphere, up to the temperature of 290°C. Higher temperature brings about the molecular-chain scission followed by a drop in the molecular-weight average. At temperatures in excess of 360°C the formation of volatile decomposition products can be observed. The main components are as follows ethane, propane, -butane, n-pentane, propylene, butenes and pentenes [7]. 

It has been suggested however that isotacticity derives from polymerization occurring on colloidal particles formed by thermal decomposition of the catalysts. As stated previously, in the presence of the monomer even the allyl compounds are stable at 65°C and none of the thermal decomposition products (black to yellow solids) could be detected. As a check on these results a polymerization of propylene was carried out with Zr (benzyl) 4 in toluene at 0°C in a sealed tube. The reaction was very slow and analytical quantities of polymer could be obtained only after 312 hr. NMR analysis showed peaks assignable to isotactic sequences, and these were much stronger than the peaks assignable to syndiotactic diads. It was concluded... 

As with ethane and other paraffin hydrocarbons, propane is an important raw material for the ethylene petrochemical industry. The decomposition of propane in hot tubes to form ethylene also yields another important product, propylene. The oxidation of propane to compounds such as acetaldehyde is also of commercial interest. 

TG-IR has also been used to examine the thermally induced decomposition products of polyvinyl chloride (PVC), polyacrylamide, tetrafluoroethylene-propylene, styrene-... 

The methylvinyl radical (IV) can abstract a hydrogen atom from a feed or product molecule to form propylene or it can lose a hydrogen atom to form allene or propadiene as products. For the 2-butenes, steric factors inhibit methyl radical addition thus C5 products are formed to a far lesser extent than from 1-butene. While ethylene may be formed by a sequential decomposition of propylene, this cannot be the only path for its formation, as the yield of ethylene in the high conversion region increases about twice as rapidly as does the methane yield. An additional source of ethylene is the symmetrical cleavage of butadiene to vinyl radicals. 

The formation of cyclopropane as a minor primary product in the mercury photosensitized decomposition of propylene has been reported/ and the formation of methylcyclopropane from but-l-ene. (This may be evidence for the formation of some triplet propylene.)... 

In APCI mass spectra of carbamates, fragment ions are observed, which are most likely due to thermal decomposition in the heated nebulizer interface and snbseqnent ionization of the thermal decomposition products [11, 14, 20-23]. For example, base peaks were observed at m/z 163 for oxamyl, due to the loss of methyl isocyanate, at m/z 168 for propoxur, dne to the loss of propylene, and at m/z 157 for aldicarb, due to the loss of HjS. The APCI mass spectra of aldicaib and two of its metabolites, aldicarb sulfoxide and aldicarb snlfone, showed significant fragmentation. Major fragments for aldicarb were dne to the loss of carbamic acid (to m/z 116) and due to charge retention at [CH3-S-C(CH3)2]. For aldicarb sulfoxide and aldicarb sulfone, the loss of carbamic acid resnlted in the base peaks of the spectra (at m/z 132 and 148, respectively). 

The homogeneous, gas phase, thermal decomposition of thiiranes, ethylene episulfide, propylene episulfide, and 2-butene episulfide sheds additional light on the mechanism of the S + olefin reactions. Below ca, 250 °C the decomposition products are sulfur and the olefin. The rate of olefin formation is first order in episulfide concentration, and the reaction features an activation energy which is considerably lower than the... 

Hilado reported a calculation for the decomposition products of cellulose, polystyrene, poly(propylene oxide), and rigid polyurethane foam on the basis of Madorsky s data (Table 2.11). Following these results, he investigated the circumstances under which a specimen would ignite in a standard testing equipment used widely in the United States for building materials. 

The direct evidence of this reaction mechanism is the observation of carbonyl stretching signature at -1,650 cm" in FTIR spectrum. The decomposition products from lithium salt were also found through the XPS surface analysis, such as alkoxides or oxides, a competition reaction between solvents and salts. However, the formation of alkyl carbonate seems to be predominant when EC is the component of electrolyte because of the more reactive nature of EC toward cathodic reductions [28]. The formation of lithium alkyl carbonate was also confirmed in an independent work, where the reduction products of EC in a supporting electrolyte were hydrolyzed by DjO and then subject to NMR analysis, which identified ethylene glycol as the major products formed, as indicated by the singlet at H spectrum [29]. Therefore, Aurbach and co-workers concluded the reduction products of EC and PC, lithium ethylene dicarbonate (LEDC) and lithium propylene dicarbonate (LPDC), respectively ... 

Ufheil J., Wiirsig A., Schneider O. D., Novak P. Acetone as oxidative decomposition product in propylene carbonate containing battery electrolyte, Electrochem. Commun. 2005, 7,... 

Ufheil, J. Wursig, A. Schneider, O. D. Novak, P., Acetone as Oxidative Decomposition Product in Propylene Carbonate Containing Battery Electrolyte. Electrochem. Commun. 2005, 7,1380-1384. 

The thermal decomposition of propylene involves a series of primary and secondary reactions leading to a complex mixture of products. Studies showed that the distribution of pyrolysis products varies considerably with the pyrolysis conditions and the type of reactor used. There is agreement among the studies on propylene pyrolysis that the three major products of pyrolysis are methane, ethylene, and hydrogen. However, there is disagreement on the types and amounts of minor or secondary product species. Ethane, butenes, acetylene, methylacetylene, allene, and heavier aromatic components are reported in different studies, Laidler and Wojciechowski (1960), Kallend, et al. (1967), Amano and Uchiyama (1963), Sakakibara (1964), Sims, et al. (1971), Kunugi, et al. (1970), Mellouttee, et al. (1969), conducted at different conversion and temperature levels. Carbon was also reported as a product in the early work of Hurd and Eilers (1943) and in the more recent work of Sims, et al. (1971). 

One feature of the pyrolysis reaction which is not fully understood is the role of reactor surface. Although the thermal decomposition of propylene has been at least implicitly assumed in some cases to be a completely homogeneous gas-phase reaction, the influence of reactor surfaces has been demonstrated frequently. Factors such as the material of construction, surface-volume ratio of the reactor, and chemical treatment of reactor surface often affect the rate of reaction and/or the product distribution. Many previous investigations are of limited value in determining the role of surface in the pyrolysis reaction. The literature on surface effects contains predominantly qualitative information and often contradictions and anomalies. Early studies... 

A more detailed analysis of the composition of the volatile portion by the method of mass spectrometry showed that the products liberated from polyvinyl chloride at 400°C under vacuum in 30 min contain not only hydrogen chloride, but also 26 different aliphatic and aromatic compounds saturated and unsaturated hydrocarbons, diehloroethane, allqrl-and alkylenebenzenes are detected ethylene, propylene, ethane, pentane, hexane, benzene, and toluene predominate quantitatively [30]. It has been found by the methods of chromatography and IR- and UV-spectrom-etry that when the pyrolysis temperature is raised to 450-500°C, substances with three to five condensed aromatic nuclei appear among the volatile decomposition products of polyvinyl chloride [31]. 

An original chemical method elaborated for the quantitative study of the monomer unit distribution (137,142) consists of copolymer pyrolysis with subsequent gas-chromatograph analysis of the decomposition products. Good correlation was found between the experimentally measured frequency distribution of fragments of copolymers with up to 50 mol-% of propylene and those calculated from r, t2 values [system VOCI3—Al2(C2H5)3Cl3, =0.87] (142). 

High amount of n-hexane, all decomposition products identified for ethylene-1-hexene copolymer Propylene, w-C, butene, benzene, toluene, traces of styrene, CyC5, MCyC5,... 

The process of decomposition of sodium iso-propoxide commences at 550 K. In this case too the rate of decomposition is low up to a reaction fraction of 0.1 beyond which the decomposition is rapid as shown in Figure 15.17. The gaseous decomposition products are mainly methane (mass 16), propylene (mass 42) and butylene (mass 56) with minor quantity of ethylene (mass 28). Formation of methane is high when compared to other products, propylene and butylene. 

The formation of larger amounts of propylene in the case of decomposition of sodirnn M-propoxide and methane in the case of decomposition of iso-propoxide could be due to the normal chain and branched chain of alkyl group attached to -ONa in these com-poimds. Decomposition of sodium iso-propoxide follows the pattern similar to that of sodiiun ethoxide, where methane is found to be the major decomposition product. The weight loss observed for sodium iso-propoxide is 24 wt. %. 

Infrared spectroscopy and thermogravimetry have been used in polymer analysis for many years. By coupling the effluent of thermogravimetry to an infrared gas cell, TG/IR (sometimes known as evolved gas analysis) has been used to examine the thermally induced decomposition products a variety of polymers including of poly(vinyl chloride) (7), polyacrylamide (2), tetrafluoroethylene-propylene (3) and ethylene-vinyl acetate (4) copolymers, as well as styrene-butadiene composite (5). 

The light-catalysed decomposition of thietan yields ethylene and thio-formaldehyde as the primary products. Propylene, formerly considered as a primary product, is believed to arise from a secondary photoreaction of thioformaldehyde and thietan. A similar light-catalysed cleavage occurs with 2-phenyl-2-alkoxythietans. The kinetics of thermolysis at 860—1170K of thietan to thioformaldehyde and ethylene have been investigated thermolysis at 490 °C also is believed to yield thioformaldehyde. Thietan-2,4-diones decompose thermally to ketens. ... 

Other procedures are based upon determination of the decomposition products of poly-oxyalkalene compounds. By reaction with phosphoric acid, ethylene oxide and propylene oxide moieties are converted, with 80-90% yield, to acetaldehyde and propionaldehyde, which may be measured spectrophotometrically (106). By more drastic decomposition with perchloric acid and periodate ion, the oxyalkalene compounds are converted to formaldehyde, with 55-65% yield, which may be distilled and determined colorimetrically (107). Neither of these methods has been much used. 

In actual fact a considerable yield of ethylene is obtained from polybutene-1, whereas the production of propylene is much smaller because this can only emanate from the principal chain. The complicated structure of polybutene-1, as compared with the structures of PE and polypropylene, gives rise to the formation of a markedly larger number of structurally isomeric degradation products. Theoretically with a maximum molecular size of Cg, 37 different hydrocarbon decomposition products should be obtainable from polybntene-1 and, in fact, Voigt [68] was able to identify, or indicate the probable existence of 33 compounds for polybutene-1. 

The most widely used process for the production of phenol is the cumene process developed and Hcensed in the United States by AHiedSignal (formerly AHied Chemical Corp.). Benzene is alkylated with propylene to produce cumene (isopropylbenzene), which is oxidized by air over a catalyst to produce cumene hydroperoxide (CHP). With acid catalysis, CHP undergoes controUed decomposition to produce phenol and acetone a-methylstyrene and acetophenone are the by-products (12) (see Cumene Phenol). Other commercial processes for making phenol include the Raschig process, using chlorobenzene as the starting material, and the toluene process, via a benzoic acid intermediate. In the United States, 35-40% of the phenol produced is used for phenoHc resins. 

Other by-products include acetone, carbonaceous material, and polymers of propylene. Minor contaminants arise from impurities in the feed. Ethylene and butylenes can form traces of ethyl alcohol and 2-butanol. Small amounts of / -propyl alcohol carried through into the refined isopropyl alcohol can originate from cyclopropane [75-19-4] in the propylene feed. Acetone, an oxidation product, also forms from thermal decomposition of the intermediate sulfate esters, eg. 

Ethylbenzene Hydroperoxide Process. Figure 4 shows the process flow sheet for production of propylene oxide and styrene via the use of ethylbenzene hydroperoxide (EBHP). Liquid-phase oxidation of ethylbenzene with air or oxygen occurs at 206—275 kPa (30—40 psia) and 140—150°C, and 2—2.5 h are required for a 10—15% conversion to the hydroperoxide. Recycle of an inert gas, such as nitrogen, is used to control reactor temperature. Impurities ia the ethylbenzene, such as water, are controlled to minimize decomposition of the hydroperoxide product and are sometimes added to enhance product formation. Selectivity to by-products include 8—10% acetophenone, 5—7% 1-phenylethanol, and <1% organic acids. EBHP is concentrated to 30—35% by distillation. The overhead ethylbenzene is recycled back to the oxidation reactor (170—172). 

Sheratte55 reported the decomposition of polyurethane foams by an initial reaction with ammonia or an amine such as diethylene triamine (at 200°C) or ethanolamine (at 120°C) and reacting the resulting product containing a mixture of polyols, ureas, and amines with an alkylene oxide such as ethylene or propylene oxide at temperatures in the range of 120-140°C to convert the amines to polyols. The polyols obtained could be converted to new rigid foams by reaction with the appropriate diisocyanates. 

Fluidized-bed CVD was developed in the late 1950s for a specific application the coating of nuclear-fuel particles for high temperature gas-cooled reactors. PI The particles are uranium-thorium carbide coated with pyrolytic carbon and silicon carbide for the purpose of containing the products of nuclear fission. The carbon is obtained from the decomposition of propane (C3H8) or propylene... 

A question that intrigued several kineticists around 1920 was the following. For bi-molecular reactions of the type A -1- B = Products collision theory gave at least a plausible conceptual picture If the collision between A and B is sufficiently vigorous, the energy barrier separating reactants and products can be crossed. How, though can one explain the case of monomolecular elementary reactions, e.g. an isomerization, such as cyclopropane to propylene, or the decomposition of a mol-... 

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