Butyl formate, pyrolysis

Iminoboianes have been suggested as intermediates in the formation of compounds derived from the pyrolysis of azidoboranes (77). The intermediate is presumed to be a boryl-substituted nitrene, RR BN, which then rearranges to the amino iminoborane, neither of which has been isolated (78). Another approach to the synthesis of amino iminoboranes involves the dehydrohalogenation of mono- and bis(amino)halobotanes as shown in equation 21. Bulky alkah-metal amides, MNR, have been utilized successfully as the strong base,, in such a reaction scheme. Use of hthium-/i /f-butyl(ttimethylsilyl)amide yields an amine, DH, which is relatively volatile (76,79). 

An informative IR spectrum of the t-butyl radical, containing 18 bands, has been recorded after freezing of the products of vacuum pyrolysis of azoisobutane [110] and 2-nitrosoisobutane [111] in an argon matrix at 10 K (Pacansky and Chang, 1981). This spectrum is in agreement with a pyramidal structure of the radical (CH3)3C (symmetry C3v) which has elongated CH bonds in positions trans to the radical centre. On the basis of experimental vibrational frequencies and ab initio calculations of the radical geometry the enthalpy value [// (300)] of its formation has been calculated as 44 kJ moP. ... 

Pyrolysis of the phosphorodichloridothioate (59) at 550 °C gives mainly dibenzothiophen and a smaller amount of the cyclic phosphonochlorido-thioate (60). Thermal decomposition of di-t-butyl peroxide in triethyl phosphate gives rise to diethyl methyl phosphate in a reaction which may be interpreted as resulting from attack of methyl radical on the phosphoryl oxygen. An extension of this mechanism accounts for the formation of (61) from tri-isopropyl phosphate under the same conditions. 

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). 

Sulfenic acid (3) has been synthesized in the gas phase by low-pressure, high-temperature pyrolysis of di-t-butyl sulfoxide (4) and characterized by means of matrix isolation and gas-phase IR spectroscopy (Scheme 4).32 The mechanism of formation of (3) by flash pyrolysis of (4) has been studied by quantum chemical calculations, and different pyrolysis experiments monitored by mass spectrometry. In agreement... 

Mass spectral fragmentation patterns in the spectra of these compounds are in accord with the formation of alkynes. The first step in the fragmentation of 1,2,3-selenadiazoles is the loss of N2 followed by extrusion of selenium and formation of the corresponding alkyne. The abundance of the alkynic ion in the mass spectrum appears to be dependent on the nature of the substituent group present in the selenadiazole. When the alkynic ion cannot be stabilized by the formation of a cation on the adjacent carbon atoms, the abundance of the alkynic ion decreases (10% in the parent compound and zero for 4-f-butyl-l,2,3-selenadiazole). On the basis of the mass spectral pattern it is possible to predict the yield of the alkynic compound formed through pyrolysis or photolysis of a given... 

The oxidation of 1,4-dicarboxylic acids with LTA in benzene results in double decarboxylation with the formation of a double bond (equation 16). Similarly, the pyrolysis of the di-r-butyl peroxy esters of... 

The oxidation of 1,4-dicarboxylic acids with LTA in benzene results in double decarboxylation with the formation of a double bond (equation 16). Similarly, the pyrolysis of the di-r-butyl peroxy esters of 1,4-dicarboxylic acids in high boiling solvents leads to the formation of double bonds (equation 17). The method is especially useful in so far as 1,4-diacids are readily available from Diels-Alder reactions using derivatives of mtdeic and fumaric acid as the dienophile. Apparently, application of the 0-acyl thiohydroxamate method to 1,4-diacids does not result in the formation of double bonds but rather in the product of double decarboxylative rearrangement (Section S.4.6.1). ... 

The proposed transition states have been supported by deuterium isotope studies Evidence such as the decomposition behaviour in solution and the nature of the increases in the rates of decomposition along the series of chloro-formates methyl, ethyl, isopropyl, 2-butyl, /-butyl suggests that the transition states are somewhat polar °> . Lewis and Herndon found 2-methylbut-1-ene and 2-methylbut-2-ene as the olefinic products of the elimination reaction of neopentyl chloroformate, and the kinetic evidence supports a Wagner-Meerwein rearrangement in the gas-phase as in the case of neopentyl chloride pyrolysis (refs. 407, 408, 566). 

In connection with the formation of modern electronic materials such as gallium phosphide, there have been a number of fundamental studies of the course of pyrolysis of t-butyl-phosphine.. in a related area, adducts of diphenyl-phosphine with trialkylgallium acceptors have been described. ... 

Flash-vacuum pyrolysis (FVP) of 4-aryl-l,2,3-benzotriazines 9 (R = aryl) led under well-defined conditions to the red benzazetes 10 (R = aryl). The stability of the benzazetes 10 depends on the substituent. When the temperature of the pyrolysis is too high, benzyne is the main product. Flash-vacuum pyrolysis of 4-alkyl-l,2,3-benzotriazines 9 (R = alkyl) was also studied. Only in the case of 4-rm-butyl-l,2,3-benzotiiazine (9, R = r-Bu) was evidence for the intermediate formation of 2-/f>r/-butylbenzazcte (10, R = /-Bu) obtained.10,218,301 306... 

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... 

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. ... 

Conditions for the formation of PAHs are most favorable during the pyrolysis of organic matter in air-deficient environments at temperatures in the range 650-900°C. The aromatic compounds formed are more stable than their precursors that include acetylene, butadiene, and butyl benzene. 

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