Ethyl acetates, pyrolysis

While the direct carbonylation is well accepted by industry, the reductive and oxidative carbonylations are still in the research and development stage. Using Texaco technology (j, 7/ ) the combined synthesis of ethene and ethanol is feasible via homologation of acids according to Figure 3. Ethene can also be obtained from the reductive carbonylation of methyl acetate to ethyl acetate followed by pyrolysis (2 ). Both routes, so far, lack selectivity. 

Photolysis of carbethoxymethylenetriphenylphosphine in cyclohexene yields benzene, ethyl acetate, ethyl cyclohexylacetate, ethyl cyclohex-2-ene-l-acetate, phenylcyclohexane l,T-bicyclohex-2-ene (Quantum yield measured by use of a low pressure mercury lamp as a light source no yield in material) and diphenyl phosphinic acid. In this case, no triphenylphosphine is produced. On the other hand, pyrolysis of this carbethoxymethy-lene compound shows that only P=C bond fission occurs91. Using acetylmethylene-triphenylphosphine, the observed products are analogous20. However, the irradiation of... 

Electrophilic replacement constants crXr have been obtained for all the positions of benzo[6]thiophene from the solvolysis of isomeric l-(benzo[ >]thienyl)ethyl chlorides in 80% ethanol-water. These constants signify replacement of the entire benzene ring by another aromatic system (74JOC2828). The positional order of reactivity was determined to be 3>2>6>5>4>7, all positions being more reactive than benzene. The same order was also derived from the kinetic data for pyrolysis of the isomeric l-(benzo[6]thienyl)ethyl acetates (78JCS(P2)1053). A modified extended selectivity treatment has been developed to correlate electrophilic substitution data in benzo[Z> ]thiophene, which assumes a dual activation mechanism (79JOC724). 

M.B. Maurin, L.W. Dittert, and A.A. Hussain, Thermogravimetric analysis of ethylene-ethyl acetate copolymers with FTIR analysis of the pyrolysis products. Thermochim. Acta, 186, 97-102 (1991). 

BSF1149) and a plot of the tt densities against the log rates of pyrolysis of l-(thiazolyl)ethyl acetates is linear. The reactivity order for 1,2,5-diazoles from ir-density measurements is oxadiazole > selenadia-zole > thiadiazole (73CHE1331) the effects of substituents in 1,2,4-tri-azole have also been calculated (71CHE377). 

Kinetic Data for Pyrolysis of I-(2-Pyridyl)ethyl Acetates (9.120)... 

Fast pyrolysis of pine sawdust in a small vortex reactor operating at 10 to 20 kg/h and 480 to 520 °C produces high yields of primary pyrolysis oils (over 55% by weight on a dry basis). The vortex reactor transmits very high heat fluxes to the sawdust, causing primarily depolymerization of the constituent polymers into monomers and oligomers. A preliminary scheme separates the raw oils into a carbohydrate-derived aqueous fraction and a phenolic-rich ethyl acetate (EA) soluble fraction. The EA fraction is washed with water and with aqueous sodium bicarbonate to remove acids yielding 20% to 25% of the feed as phenols and neutrals (P/N) in the EA solution. 

Fractionation of Pyrolysis Oils. Pyrolysis oil obtained from the vortex reactor was fractionated according to the scheme shown in Figure 3. Whole oil (1 kg) was dissolved in ethyl acetate (EA) on a 1 1 (w/w) basis. The oil was then vacuum filtered through filter paper to remove fine char. Upon standing, the EA/pyrolysis oil separated into two phases-an organic rich, EA-soluble phase and an EA-insoluble phase. Most of the water formed during pyrolysis is contained in the EA-insoluble phase. The EA-soluble portion of the oil was washed with water (2 x 75 mL) to remove the remaining water-soluble derived products. 

Figure 5. High-performance size exclusion chromatograms of pine sawdust pyrolysis oils and fractions of acids, phenols, and neutrals contained in the ethyl acetate soluble oil.

The liquid ammonia was then driven off, an equivalent of the ketone was added, and the mixture refluxed for completion of the aldolization. Lithium amide proved to be superior to sodium amide for these condensations. /-Butyl esters were preferred because they are readily cleaved by pyrolysis or by acid. Dehydration to the a,fi-unsaturated esters could be effected with thionyl chloride and pyridine. Hauser and Lindsay succeeded in effecting aldol condensation with ethyl acetate, which undergoes self-condensation very readily two equivalents of base were used. Sisido has reported further alkylations of /-butyl esters. 

The Arrhenius A factor for the first-order gas-phase pyrolysis of ethyl acetate is 1012 5. Which of the two postulated mechanisms shown below does this favour ... 

Ishida et al. [103] used different solvents in spray pyrolysis to grow ITO films, which were then incorporated into a ITO/Si02/Si-solar cell. The best results were obtained with a mixture of methanol ethyl acetate water = 5 5 1 J = 33 m Acm , K>e = 575 mV, efficiency = 14% and fill factor = 0.727). All mentioned characteristics of solar cells were considerably affected by the choice of solvent. 

Ethyl acetate can be formed over a NAFION catalyst from acetic acid and ethylene in the vapor phase at 135°C. Conversions were 48Z based on acetic acid and after 100 hours, the activity of the catalyst was undimlnlshed (36). The reverse of the above reaction has been demonstrated by the pyrolysis of ethyl acetate to ethylene at 185 C with NAFION tubing (37). The conversion of ethyl acetate is 19.4%, and ethene is the only gaseous product. Without the polymeric catalyst, the pyrolysis... 

The effects of a-methylation on the gas-phase reaction kinetics and the mechanism of the pyrolysis of ethyl acetates have been theoretically studied at semi-empirical PM3 level. All the calculations showed that the thermal decomposition of alkyl acetates is a concerted asynchronous process via a six-membered cyclicTS, with the a-methyl substitution having a steric releasing effect in the TS. 

Many variations exist of pyrolysis-based biorefineries, and an early (1920s) example is the production of charcoal and various other products in the continuous wood distillation plant of the Ford Motor Company in Michigan, USA. This plant used 400 tons per day of scrap wood from the automobile body plant.The Ford plant not only produced make acetic acid (among charcoal and other products) but also ethyl acetate (via esterification with bioethanol), which the company required in its lacquer and artificial leather departments. The first T-Fords used bioethanol as their transportation fuel. Figure 8.2 gives a schematic overview of the plant that was completely self-sufficient with regard to its heat demand. 

Silicones have been extracted from environmental samples with solvents such as hexane, diethyl ether, methyl isobutylketone, ethyl acetate, and THF, using either sequential or Soxhlet techniques (690-695). Silicones of a wide range of molecular weights and polarities are soluble in THF. This feature, coupled with its volatility and miscibility with water, makes THF an excellent solvent for the extraction of silicones from wet samples, ie, soils and sediments. Trace levels of silicones extracted from environmental samples have been measured by a number of techniques, including atomic absorption spectroscopy (AA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), pyrolysis GC-MS, as well as H and Si NMR spectroscopy (674,684,692,696-700). The use of separation techniques, such as gel permeation and high pressure liquid chromatography interfaced with sensitive, silicon-specific AA or ICP detectors, has been particularly advantageous for the analysis of silicones in environmental extracts (685,701-704). 

In a typical Knof procedure, 3jS-hydroxyandrost-5-en-17-one acetate is epoxidized with perbenzoic acid (or m-chloroperbenzoic acid ) to a mixture of 5a,6a- and 5)5,6)5-epoxides (75) in 99 % yield. Subsequent oxidation with aqueous chromium trioxide in methyl ethyl ketone affords the 5a-hydroxy-6-ketone (76) in 89% yield. Baeyer-Villiger oxidation of the hydroxy ketone (76) with perbenzoic acid (or w-chloroperbenzoic acid ) gives keto acid (77) in 96% yield as a complex with benzoic acid. The benzoic acid can be removed by sublimation or, more conveniently, by treating the complex with benzoyl chloride and pyridine to give the easily isolated )5-lactone (70) in 40% yield. As described in section III-A, pyrolysis of j5-lactone (70) affords A -B-norsteroid (71). Knof used this reaction sequence to prepare 3)5-hydroxy-B-norandrost-5-en-17-one acetate, B-noran-... 

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