Kinetics analysis of the idealized heavy hydrocarbon system comprising a reactant A(1) = mu H-1 converting through a Rice-Herzfeld chain in the presence of a chain transfer solvent A(2) = mu H-2 revealed the conditions and structural features of A(2) for optimal rate enhancement E-1 = r(A1) (A(1), A(2))/r(A1)(A(1)) = (1 + (k) over capS theta)/(1 + (k) over capS), where (k) over cap= k(12)/k(21) is the index of chain transfer and theta = k(21)/k(11) is the index of the kinetic effect of chain transfer. Imposition of the Evans Polanyi relationship for these two hydrogenabstraction reactions rendered El as a function of the mu(2)-H bond strength x = d(mu 2H)(o) for a given reactant A(1). Qualitatively, (K) over cap decreases and 0 increases with increasing values of x. For low values of S, the intuitive optimum is where the balance between these two dependencies is found. For higher values of S, the optimal value of x is defined by the condition d theta/(theta-1) = d (K) over cap S/((K) over capS(1+(K) over cap S)).

An empirical correlation has been derived between accepted atmospheric lifetimes of a set of hydrofluorocarbons and hydrofluoroethers and relative rates of reaction with photolyzed chlorine in excess at ambient temperature. These kinetic systems were studied by nuclear magnetic resonance (NMR) spectroscopy in the gas phase, marking the first application of NMR spectroscopy to this field. The square of the Pearson coefficient R for the linear correlation between observed reaction rates and accepted atmospheric lifetimes was 0.87 for compounds of lifetime less than 20 years. The method was extended to the study of ethene and propene; the rate of reaction of propene was found to be 1.25 times that of ethene at 23 degrees C. The chief advantage of this method is its simplicity and reliance only on common tools and techniques of an industrial chemical laboratory.

The reactions of acrylonitrile, crotonitrile, propionitrile, and a small set of related reaction products were investigated in high-temperature water. Hydrolysis of the cyano group yielded the corresponding amides, which underwent similar hydrolysis to yield the carboxylic acids. The conversion of acrylonitrile was more rapid than that of its saturated analogue propionitrile, as the unsaturated site of acrylonitrile provided a facile pathway for the formation of alcohols, amines, and ethers. Carbon-carbon bond cleavage pathways involving the hydration of the olefin moiety were also observed for acrylonitrile.

The reaction chemistry of acetonitrile and benzonitrile in High Temperature Water (HTW) was investigated. The reaction products were the associated amides and carboxylic acids. A kinetic model incorporating two autocatalytic steps captured the kinetics observed. The optimized rate constants highlighted differences in the reaction chemistry of aliphatic and aromatic nitrites at these reaction conditions. 6 refs., 3 figs., 2 tabs.

Pyrolysis of two representative poly(aryl ether sulfones) (PAES) with anti without the isopropylidene link revealed its important role in controlling the overall thermal stability. This was probed quantitatively by the development of mechanistic pyrolysis models for single components and model compound mixtures of phenyl sulfone (PS), phenyl ether (PE) and 2,2-diphenylpropane (DPP). Model development on the computer allowed ''on-the-fly'' calculation of species' properties using computational quantum chemistry. This also provided quantitative values of model parameters. The reactivity differences of the polymers were interpreted in terms of the predicted changes in the product spectra when PS and PE were pyrolyzed with and without the reactant DPP. The increased selectivity to benzene and the decreased selectivity to (phenylsulfonyl)biphenyl with DPP present suggested an increase in the ratio of bond scission to bond formation that accounted for the decreased tendency of the isopropylidene-containing PAES for molecular weight increase and gel formation, two global measures of thermal stability.

The kinetics analysis aimed at specifing the attributes of an optimal chain-transfer solvent for coal liquefaction was extended to include the reality of the distributions of functional groups and bonds in coal. In particular, the possibility that the desirable enhancement predicted for the liquefaction rate was an artifact of the two-lump coal-solvent model, with the coal being characterized as a single pseudo species, was tested. Thus, Gaussian-distributed coal and solvent bond strengths were considered to assess the importance of the off-optimal interactions that could be anticipated in a multicomponent mixture. The results show that significant enhancement can be maintained in the mixture. Indeed, in several instances, the distribution of coal bond strengths improved the obtained enhancement.

Reaction modelling techniques using Monte Carlo Simulation are applied to the reactions of poly (arylether sulfones). We find that structure, reactions and diffusions may be described quantitatively in terms of a dynamic reaction lattice.

The continuity of the liquid and gaseous states, and the existence of critical temperatures for specific gases, was discovered by Thomas Andrews in 1861. This had important implications for the liquefaction of the supposedly 'permanent' gases and the creation of an important new industry. Currently, the chemistry of reactions in supercritical fluids, especially water, is the subject of much research, especially in the context of treating industrial waste.

A well-mixed reactor was developed to study the initial reaction pathways and mechanisms of direct coal liquefaction. This pulse-injection flow vessel exploits the reactor residence time distribution to obtain an isothermal series of samples of well-defined holding times from 10 to 900 s. The reactor design also allowed for quick and efficient procurement of optimally spaced and sized samples. The operation of this reactor is illustrated using both model compound and coal liquefaction experiments.

Mechanism-derived rate laws for kinetically coupled Rice-Herzfeld pyrolysis were used to deduce the form of semiempirical rate laws (SERLs) that nevertheless represent the mechanistic chemistry. These SERLs strike a balance between the CPU demands of mechanistic models and the lack of chemical,significance of purely empirical models. The mechanism-derived pyrolysis rate laws were phrased in terms of a pure component, initiation, propagation, and termination groups, akin to the kinetic term, the driving force, the adsorption group, and exponent of Langmuir-Hinshelwood-Hougen-Watson models. Taylor series expansions of the pyrolysis groups provided polynomial representations of each, which combined to form the SERL. Convergence of the Taylor series expansions further provides a relationship between the elementary step kinetic parameters of the mechanism and the parameters of the SERL. The coupled pyrolyses of (1) dibenzyl ether and phenethyl phenyl ether; (2) pentadecylbenzene (PDB); and (3) PDB and tridecylcyclohexane were well represented by SERLs.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuantitative use of model compound information: Monte Carlo simulation of the reactions of complex macromoleculesJohn B. McDermott, Cristian Libanati, Concetta LaMarca, and Michael T. KleinCite this: Ind. Eng. Chem. Res. 1990, 29, 1, 22–29Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://pubs.acs.org/doi/10.1021/ie00097a004https://doi.org/10.1021/ie00097a004research-articleACS PublicationsRequest reuse permissionsArticle Views314Altmetric-Citations39LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The aggregation of coal liquefaction elementary steps into representative reaction families allowed further organization into the Rice-Herzfeld kinetic formalism. Solution of this model and subsequent imposition of the Evans-Polanyi structure-reactivity correlation revealed the attributes of an optimal chain-transfer solvent. In particular, the optimal chain-transfer solvent will have an intermediate C-H bond strength for catalysis of coal degradation chemistry. The results suggest a homogeneous analogue of the classical principle of Sabatier in heterogeneous catalysis.

The reaction kinetics of multicomponent mixtures were explored through the mathematical and experimental analyses of binary pyrolysis systems. The mathematical model was of parallel Rice-Herzfeld chains that were coupled through hydrogen transfer and termination elementary steps. Analytical rate expressisons for the coupled systems led to criteria for the classification of binary interactions. This, in turn, provided rationale for “optimizing” the type of observed interaction. Experiments with the model compounds dibenzyl ether and phenethyl phenyl ether provided an experimental example of kinetically coupled Rice-Herzfeld pyrolysis chains.

The separation of host and recombinant Escherichia coli bacterial cells has been studied using the surface-sensitive technique of partitioning in aqueous two-phase polymer systems. Experiments were designed to probe charge-and hydrophobicity-related property differences of antibiotic-resistant recombinant cells and their antibiotic-sensitive hosts. Differential partitioning was observed in both charge-sensitive and non-charge-sensitive phase systems for three host-recombinant cell systems, but the non-charge-related effects appear to have a greater impact on partitioning behavior. This result suggests that plasmid-encoded products related to antibiotic resistance modify the surface hydrophobicity of the E. coli bacterial cell and that these differences can be exploited for cell separation.