Ethyl pyrolysis

Many other recovery alternatives have been proposed that iaclude ion exchange (qv), pyrolysis, and wet combustion. However, these have not gained general acceptance. A limited number of calcium-based mills are able to utilize their spent pulpiag liquors to produce by-products such as lignosulfates for oil-weU drilling muds, vanillin, yeast, and ethyl alcohol (see PETROLEUM Vanillin). 

Chlorinated by-products of ethylene oxychlorination typically include 1,1,2-trichloroethane chloral [75-87-6] (trichloroacetaldehyde) trichloroethylene [7901-6]-, 1,1-dichloroethane cis- and /n j -l,2-dichloroethylenes [156-59-2 and 156-60-5]-, 1,1-dichloroethylene [75-35-4] (vinyhdene chloride) 2-chloroethanol [107-07-3]-, ethyl chloride vinyl chloride mono-, di-, tri-, and tetrachloromethanes (methyl chloride [74-87-3], methylene chloride [75-09-2], chloroform, and carbon tetrachloride [56-23-5])-, and higher boiling compounds. The production of these compounds should be minimized to lower raw material costs, lessen the task of EDC purification, prevent fouling in the pyrolysis reactor, and minimize by-product handling and disposal. Of particular concern is chloral, because it polymerizes in the presence of strong acids. Chloral must be removed to prevent the formation of soflds which can foul and clog operating lines and controls (78). 

By-products from EDC pyrolysis typically include acetjiene, ethylene, methyl chloride, ethyl chloride, 1,3-butadiene, vinylacetylene, benzene, chloroprene, vinyUdene chloride, 1,1-dichloroethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane [71-55-6] and other chlorinated hydrocarbons (78). Most of these impurities remain with the unconverted EDC, and are subsequendy removed in EDC purification as light and heavy ends. The lightest compounds, ethylene and acetylene, are taken off with the HCl and end up in the oxychlorination reactor feed. The acetylene can be selectively hydrogenated to ethylene. The compounds that have boiling points near that of vinyl chloride, ie, methyl chloride and 1,3-butadiene, will codistiU with the vinyl chloride product. Chlorine or carbon tetrachloride addition to the pyrolysis reactor feed has been used to suppress methyl chloride formation, whereas 1,3-butadiene, which interferes with PVC polymerization, can be removed by treatment with chlorine or HCl, or by selective hydrogenation. 

Butyl acrylate has been prepared by direet esterifieaLion/ by debromination of -butyl ,/3-dibromopropionate with zinc, by treatment of either butyl /3-chloropropionate or butyl /3-bromopropionate with diethylaniline, and by the pyrolysis of butyl (3-acetoxypropionated Direct esterification and alcoholysis of methyl or ethyl acrylate have been recommended for the preparation of the higher alkyl acrylates. ... 

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-... 

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). 

On the other hand, poly(ethoxycarbonylimino-4-vi-nylpyridinium ylide) (Scheme 13) was prepared essentially by the same method from 1-ethoxycarbonylimino-pyridinium ylide, as described by Hafner [15] from the reaction of poly (4-vinylpyridine) with nitrene, generated from the pyrolysis of ethyl azidoformate. 

Cyclohexadiene has been prepared by dehydration of cyclohexen-3-ol,3 by pyrolysis at 540° of the diacetate of cyclohexane-1,2-diol,4 by dehydrobromination with quinoline of 3-hromocyclohexene,6 by treating the ethyl ether of cyclohexen-3-ol with potassium bisulfatc,6 7 by heating cyclohexene oxide with phthalic anhydride,8 by treating cyclohexane-1,2-diol with concentrated sulfuric acid,9 by treatment of 1,2-dibromocyclo-hexane with tributylamine,10 with sodium hydroxide in ethylene glycol,10 and with quinoline,6 and by treatment of 3,6-dibromo-cyclohexene with sodium.6... 

Because of the high pyrolysis temperature, the C4-fraction contains quantities of vinyl acetylene and ethyl acetylene, the removal of which prior to the recovery of butadiene is necessary in certain cases, particularly if butadiene of low acetylene content is desired. Similar considerations apply to effractions obtained by the dehydrogenation of n-butane and n-butenes. 

Dimethyl-1,5-benzodiazepine, formulated as its 3H tautomer (445), underwent vapor-phase pyrolysis (850°C, 0.02 mmHg, 15 min) to give a mixmre from which three quinoxalines were isolated 2,3-dimethyl- (446, R = Me) (7%), 2-ethyl-3-methyl- (446, R = Et) (10%), and 2-methyl-3-vinylquinoxa-line (447) (1%). ... 

MOCVD reactions are used increasingly, such as the pyrolysis of tantalum ethylate, Ta(OC2H5)5, in oxygen and nitrogen at 340-450°C and at a pressure of <1 Torr. This is followed by an annealing cycle at 600-900°C.P l Tantala is also deposited by the pyrolysis of the tantalum dichlorodiethoxy acetylacetonate at 300-500°C.P ]... 

For rate studies of pyrolysis of some p-alkyl substituted ethyl bromides, see Chuchani, G. Rotinov, A. Dominguez, R.M. Martin, I. Int. J. Chem. Kinet., 1987, 19, 781. 

Koplitz and co-workers have studied the photolysis of C2H5 via the A2A (3s) state by using 248-nm photolysis radiation and hot ethyl radicals generated from photolysis of ethyl halides.125,126 Chen and co-workers have investigated the photodissociation of jet-cooled ethyl (produced by flash pyrolysis of ethyl iodide and n-propylnitrite) in the region of 245-264 nm... 

Houser and Lee [J. Phys. Chem., 71 (3422), 1967] have studied the pyrolysis of ethyl nitrate using a stirred flow reactor. They iiave proposed the following mechanism for the reaction. 

Figure 11.11 Pyrogram of a paint sample collected from a decorative frame of the Universal Judgement by Bonamico Buffalmacco (fourteenth century, Monumental Cemetery of Pisa, Italy). Pyrolysis was performed with a microfurnace pyrolyser, at 600°C, in the presence of HMDS. 1, Benzene 2, ethyl acrylate 3, methyl methacrylate 4, acetic acid, trimethyl silyl ester 5, pyrrole 6, toluene 7, 2 methylpyrrole 8, 3 methylpyrrole 9, crotonic acid 10, ben zaldehyde 11, phenol 12, 2 methylphenol 13, 4 methylphenol 14, 2,4 dimethyl phenol 15, benzyl nitrile 16, 3 phenylpropionitrile 17, indole 18, phthalate 19, phthalate 20, ben zyl benzoate HMDS pyrolysis products [27]...

Internal nitrenes normally react at the adjacent position. Reduction of 2-(2-nitrophenyl)furan by ethyl phosphite yields furoindole derivatives in fair yield (34%) only, whereas much better results attend the pyrolysis of 2-(2-azidophenyl)furan.280 Furopyrazoles are obtained similarly.281 Azidofurans yield nitrenes that insert into adjacent CH links to form furo-pyrroles.282 Quite different results attend either the pyrolysis or the photolysis of azide 107a for the expected insertion into the side chain occurs giving the related indole but it is accompanied by the surprising replacement of furan oxygen by nitrogen producing 107b and similar products.283... 

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