Butyl acetate, pyrolysis

Figure 12.11 shows the pyrograms of vinyl paints from two monochromes by the Italian artist Piero Manzoni. The two paints are clearly different in composition acetic acid (peak 1) and benzene (peak 2) are present as common markers of the PVAc binder in both cases, but sample (a) contains dibutyl phthalate (peak 6) as external plasticizer. Peak 5 was recognized as bis(2-methylpropyl)-phthalate which is formed from dibutylphthalate isomerization, while butyl acetate (peak 3) and butyl benzoate (peak 4) are secondary products of recombination reactions occurring during the pyrolysis. Sample (b), however,... 

Smith and Wetzel (1951) have shown qualitatively that the strength of the acid and the rate of ester pyrolysis increased in the same direction. This conclusion is borne out by the work of Emovon (1963) who found for the series t-butyl acetate, t-butyl chloroacetate and t-butyl dichloro-acetate that the rates at 250°C were in the ratio 1 4-4 18-6. 

Indium trichloride is a very common precursor for spray pyrolysis. The compound was dissolved in different solvents such as water [103], methanol [103], ethanol [101], isopropanol [98], butyl acetate [96, 97] and mixtures of them [99, 100, 102,103]. There are no reports on the kinetic behavior of the deposition. 

The pyrolysis derivatization approach may also be used. THM results in the formation of dimethyl terephthalate when PET fibers are subjected to the procedure. Tetrabutyl ammonium hydroxide may be used to replace TMAH in the reaction to confirm the presence of vinyl acetate in acrylonitrile-vinyl acetate copolymer acrylic fibers. The derivatized product is butyl acetate. ... 

The primary products obtained from 2-butanol are of mechanistic. significance and may be compared with other eliminations in the sec-butyl system 87). The direction of elimination does not follow the Hofmann rule 88) nor is it governed by statistical factors. The latter would predict 60% 1-butene and 40% 2-butene. The greater amount of 2-alkene and especially the unusual predominance of the cis-olefin over the trans isomer rules out a concerted cis elimination, in which steric factors invariably hinder the formation of cis-olefin. For example, the following ratios oicisjtrans 2-butene are obtained on pyrolysis of 2-butyl compounds acetate, 0.53 89, 90) xanthate, 0.45 (S7) and amine oxide, 0.57 86) whereas dehydration of 2-butanol over the alkali-free alumina (P) gave a cisjtrans ratio of 4.3 (Fig. 3). 

Homolytic substitution has been little studied, and work has been confined to the reaction of dibenzofuran with carboxymethyl radicals produced from acetyl peroxide or di-tcrt-butyl peroxide in boiling acetic acid or by pyrolysis of chloroacetylpolyglycolic acids. The method of analysis of the resultant mixture of 1- (55%), 4- (30%), and 3-dibenzofuranacetic acid (15%) was crude, but the results were in accord with simple HMO calculations. The amount of the 1-substituted product is perhaps surprising in view of the steric hindrance at this position. 

Twenty-five years ago the only oxygenated aliphatics produced in important quantities were ethyl and n-butyl alcohols and acetone made by the fermentation of molasses and grain, glycerol made from fats and oils, and methanol and acetic acid made by the pyrolysis of wood. In 1927 the production of acetic acid (from acetylene) and methanol (from synthesis gas) was begun, both made fundamentally from coal. All these oxygenated products are still made from the old raw materials by the same or similar processes, but the amount so made has changed very little in the past quarter century. Nearly all the tremendous growth in the production of this class of compounds has come from petroleum hydrocarbons. 

Addition of aryl tellurium trihalides to cyclohexene produces trails-] -aryldihalotelluro-2-halocyclohexanes when the reactions are carried out in chloroform, and trans-1-aryldihalotelluro-2-methoxycyclohexanes when methanol is used as the reaction medium. Treatment of the 2-chlorocyclohexyl 4-methoxyphenyl tellurium dichloride with terf.-butyl hydroperoxide in acetic acid yielded tram-l,2-dichlorocyclohexane and aryl chloride. Bis[4-methoxyphenyl] tellurium dichloride did not yield any aryl chloride under these conditions1. Pyrolysis of tran.s-2-methoxycydohexyl phenyl tellurium dibromidc afforded Crum- l-bromo-2-methoxycyclohexane1. 

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 same acetates give products labelled vice versa when anti-elimination is induced with potassium t-butoxide. The great preference for trani-stilbene formation is caused by the necessity to avoid eclipsing of the phenyl groups in the transition states. Similar "syn" stereospecificity is demonstrated for pyrolysis of 2-butyl-3-phenylxanthates , the threo isomer yielding t/j-di-methylstyrene (137) while the erythro isomer gives the tran -olefin (138). 

The principal factors affecting orientation in acetate decompositions have been adequately summarised by DePuy and King Essentially three influences were recognised, these being termed statistical, steric and thermodynamic effects. Statistical control is observed in pyrolysis of simple aliphatic esters which under the elevated reaction temperatures experience little resistance to conformational rotation and the number of beta hydrogen atoms in each branch determines the direction of elimination (147)= 37o distortion in statistical control is imposed by the steric influence of a t-butyl substituent (148), and is also illustrated by the predominance of trans- over m-olefin formation (148, 149) due to eclipsing effects . The latter example, however, may also arise from thermodynamic influences which are more certainly demonstrated by preferential elimination towards a phenyl rather than an alkyl substituent (150) . The influence of substituents on olefin stability rather than beta hydrogen acidity seems more critical as elimination occurs more often towards a p-methoxyphenyl rather than a phenyl substituent (151... 

Slightly greater variations in the activation entropy are noted in ester than the halide thermolyses, but the A values again approximate to 10 and indicate the cyclic unimolecular nature of the transition states. With changing ester, the rate of pyrolysis and strength of the liberated acid qualitatively increase in the same direction" . The dichloroacetate, chloroacetate and acetate of t-butyl alcohol exemplify this relationship and at 250°C their rates of pyrolysis follow the order 18.6 4.4 1 (ref. 406). Nucleophilicity of the carbonyl function cannot be the dominating influence as a reverse order of reactivity would be predicted . 

Two routes were originally developed for the synthesis of intermediate diketone 18 ( R= butyl).One involved introduction of the two carbonyl groups by oxidation of the corresponding dibutyl heptacyclic terpyridine. The other route is similar to that shown in Fig. 2, except that 14 was prepared by pyrolysis of the trimethylhydrazonium derivative of 12. An improved method for this 1/3+1/3 coupling reaction involves condensing the HCl salt of Mannich derivative 13 with ketone 12 and ammonium acetate, giving heptacyclic terpyridyl 14 in 70% yield. The synthesis of 9-butyloctahydroacridine (9) and its conversion to N-oxide... 

The gas-phase pyrolysis of chrysanthanyl acetate affords a mixture of acyclic unsaturated aldehydes and enol acetates, all of which are probably derived from the 1,4-biradical (625). ° Results are also discussed of the pyrolyses of chrysanthanyl alcohol and other emio-pinen-7-ols. The photochemical free radical reaction between P-pinene and t-butyl hypochlorite has been studied, and the oxidative addition of cyclopentanone to p-pinene in the presence of cupric salts has been observed. Photoaddition of iV-nitrosopiperidine to P-pinene at — 40 gave the a-piperidinium... 

Other examples are the autoxidation of r-butyl alcohol to acetic acid, acetone, carbon dioxide, and water (

= 2). 

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