Pyrolysis tertiary

With aldehydes, primary alcohols readily form acetals, RCH(OR )2. Acetone also forms acetals (often called ketals), (CH2)2C(OR)2, in an exothermic reaction, but the equiUbrium concentration is small at ambient temperature. However, the methyl acetal of acetone, 2,2-dimethoxypropane [77-76-9] was once made commercially by reaction with methanol at low temperature for use as a gasoline additive (5). Isopropenyl methyl ether [116-11-OJ, useful as a hydroxyl blocking agent in urethane and epoxy polymer chemistry (6), is obtained in good yield by thermal pyrolysis of 2,2-dimethoxypropane. With other primary, secondary, and tertiary alcohols, the equiUbrium is progressively less favorable to the formation of ketals, in that order. However, acetals of acetone with other primary and secondary alcohols, and of other ketones, can be made from 2,2-dimethoxypropane by transacetalation procedures (7,8). Because they hydroly2e extensively, ketals of primary and especially secondary alcohols are effective water scavengers. 

The alkanes have low reactivities as compared to other hydrocarbons. Much alkane chemistry involves free-radical chain reactions that occur under vigorous conditions, eg, combustion and pyrolysis. Isobutane exhibits a different chemical behavior than / -butane, owing in part to the presence of a tertiary carbon atom and to the stability of the associated free radical. 

Phosphonium salts are typically stable crystalline soHds that have high water solubiUty. Uses include biocides, flame retardants, the phase-transfer catalysts (98). Although their thermal stabiUty is quite high, tertiary phosphines can be obtained from pyrolysis of quaternary phosphonium haUdes. The hydroxides undergo thermal degradation to phosphine oxides as follows ... 

However, when the temperature is increased to 120°C, the principal reaction is the elimination to olefin. The thermal decomposition of dimethyl dodecyl amine oxide at 125°C in a sealed system, as opposed to a vacuum used by Cope and others, produces 2-methyl-5-decyhsoxa2ohdine, dimethyl dodecyl amine, and olefin (23). The amine oxide oxidi2es XW-diaLkylhydroxylainine to the nitrone during the pyrolysis and is reduced to a tertiary amine in the process. 

Recycling plastics back to hydrocarbons (tertiary recycling) may offer significant promise. Three different options currently being evaluated for the tertiary recycling of polyolefins - refinery recycling, pyrolysis and depolymerisation - are discussed. 

Goodacre, R. Neal, M. J. Kell, D. B. Rapid and quantitative analysis of the pyrolysis mass spectra of complex binary and tertiary mixtures using multivariate calibration and artificial neural networks. Anal. Chem. 1994, 66,1070-1085. 

The preparation of ketenes has been discussed by Hanford and Sauer in Organic Reactions Dimethylketene has been prepared by the treatment of a-bromoisobutyryl bromide with zinc,3 and by the pyrolysis of isobutyrylphthalimide,4 dimethylmalonic anhydride,6 or a-carbomethoxy-a,j3-dimethyl- -butyrolactone. Dimethylketene dimer has been prepared by heating isobutyryl chloride with a tertiary amine. Pyrolysis of the dimer yields dimethylketene.7... 

The mechanism of thermal decomposition (pyrolysis) of methane has been extensively studied [90,91]. Because C-H bonds in the methane molecule are significantly stronger than C-H and C-C bonds of the products, the secondary and tertiary reactions contribute at the very early stages of the reaction, which obscure the initial processes. According to Holmen et al. [92], the overall methane thermal decomposition reaction at high temperatures can be described as a stepwise dehydrogenation as follows ... 

The two polymer substrates investigated as part of the study of DBDPO mixtures were polypropylene (PP) and linear high density polyethylene (HDPE). while both PP and HDPE decompose by similar random chain scission, radical mechanisms, chain transfer occurs much more teadily during the pyrolysis of PP because of the presence of the tertiary hydrogens. In addition, only primary chain end radicals are formed when the HDPE chain cleaves homolytically. Therefore, a comparison of the PP/DBDPO and the HDPE/DBDPO mixtures volatile product distributions was undertaken. 

As the chain length of the primary alcohols increases, thermal decomposition through fracture of C—C bonds becomes more prevalent. In the pyrolysis of n-butanol, following the rupture of the C3Ht—CH2OH bond, the species found are primarily formaldehyde and small hydrocarbons. However, because of the relative weakness of the C—OH bond at a tertiary site, f-butyl alcohol loses its OH group quite readily. In fact, the reaction... 

In an attempt to delineate the degree of preservation of lignin in pre-Tertiary coal, we examined numerous coalified wood samples ranging in age from Carboniferous to Cretaceous. The samples were initially screened by solid-state l C nuclear magnetic resonance to detect the possible presence of methoxyl carbon. Once such carbons were detected, the samples were subjected to analytical pyrolysis to determine the relative yields of methoxyphenols which would provide an indication of the state of preservation of the lignin-derived structu units. We report here on the identification of lignin-derived methoxyphenols in the coalified wood samples selected for analytical pyrolysis. 

The mechanisms for ambient temperature oxidations become more complex as the alkyl radical R becomes more complex and as the reactions proceed. Thus, with azo-2-methylpropane (52) the pyrolysis of the tert-butoxy radical must be included, and in all but the initial stages, reactions of alkoxy radicals with products containing weak C—H bonds must be included. Numerous tertiary reactions can then occur. As with most free radical systems, useful information can be obtained only if the degree of conversion of the starting material is kept low. 

HOFMANN DEGRADATION. Formation of an olefin and a tertiary amine hy pyrolysis of a quaternary ammonium hydroxide useful for the preparation of some cyclic olefins and for opening nitrogen-containing ring compounds. 

The total yield of 201 was increased and the synthesis time reduced by extracting [nC]butyric acid from its lithium salt by dry 0.1% HCl/He gas mixture and carrying out its pyrolysis at 530 °C over glass beads (equation 104). The relative reactivity of 201 to primary, secondary and tertiary alcohols (equation 105a, b, c) has been found to be as 1 0.4 0.1, respectively. Several bioactive compounds have been labelled with [nC]propyl ketene, such as carbohydrate compounds193 and IV-butyl compounds, for instance /V- 11 C]butyryl THPO, 202, and some phorbol esters192, 203, 204 and 205. 

In addition to pyrolysis, transamination, and dehydrohalogenation with tertiary amines several other reactions have been described which yield access to the 1,3,2-diazaboracycloalkane system. For example, Abel and Bush 19> reported the ready replacement of silicon by boron in certain heterocyclic systems as illustrated in Eq. (6). It seems quite likely that this procedure can be developed into a general synthesis. On the other hand, the interaction of trialkylboranes with bis(l,3-diphenylimidazolid-... 

This study on the kinetic chlorine isotope effect in ethyl chloride50 was extended to secondary and tertiary alkyl halides pyrolyses51. The isotope effects on isopropyl chloride and terf-butyl chloride pyrolysis were found to be primary and exhibited a definite dependence on temperature. They increased with increasing methyl substitution on the central carbon atom. The pyrolysis results and model calculations implied that all alkyl chlorides involve the same type of activated complex. The C—Cl bond is not completely broken in the activated complex, yet the chlorine participation involves a combination of bending and stretching modes. 

Compounds of type R3ASX2 are generally low-melting, crystalline solids, soluble in alcohol but only slightly soluble or insoluble in nonpolar solvents. These can readily be reduced to tertiary arsanes. They are hydrolyzed by water or alkali. Compounds containing at least one alkyl group yield on pyrolysis an alkyl halide and a haloarsane (49) ... 

Ketene itself is usually made by high-temperature pyrolysis of acetone but some ketenes are easily made in solution. The very acidic proton on dichloroacetyl chloride can be removed even with a tertiary amine and loss of chloride ion then gives dichloroketene in an ElcB elimination reaction. 

Pyrolysis of the alkaloid chloride at 210° smoothly gives the corresponding tertiary base, normelinonine A, C21H24N2O3, which can be methylated at Nb to regenerate melinonine A. Normelinonine A is not... 

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