Peptide Bonds in the Interstellar Medium: Facile Autocatalytic Formation from Nitriles on Water-Ice Grains

A recent suggestion that acetamide, \ce{CH3C(O)NH2}, could be readily formed on water-ice grains by the acid induced addition of water across the \ce{CN} bond is now shown to be valid. Computational modelling of the reaction between \ce{R-CN} (R = H, \ce{CH3}) and a cluster of 32 molecules of water and one \ce{H3O+} proceeds auto-catalytically to form firstly a hydroxy imine \ce{R-C(OH)=NH} and secondly an amide \ce{R-C(O)NH2}. Quantum mechanical tunnelling, computed from small-curvature estimates, plays a key role in the rates of these reactions. This work represents the first credible effort to show how amides can be formed from abundant substrates, namely nitriles and water, reacting on a water-ice cluster containing catalytic amounts of hydrons in the interstellar medium with consequential implications towards the origins of life.Comment: 19 pages, 8 Figure

Analysing the present: drawing on the legacy of Vere Foster in public policy debate on futures of schools

This paper sets out a framing analysis for a public policy debate on the future of schools that resonates with practitioners in teaching and teacher education on the island of Ireland, north and south, but also in other countries. This is informed by a democratic impulse to facilitate public policy debates, particularly on the ways schools and higher education institutions are directed and constrained by budget cuts and the shrinking of public funding in this age of austerity and gross inequalities. This is also informed by a need for policy learning about global neoliberal agendas, free-market capitalism and its push towards profit-making schools in systems that are deregulated but experience tighter centralized control, which can result in the domination and control of teachers’ work by politicians, corporate-funded think-tanks, entrepreneurs and business managers. Even though Ireland boasts checks and balances in the form of current structures and education legislation in both jurisdictions, the global financial crisis and the collapse of the ‘Celtic Tiger’ together with the ‘troika’ bail-out and Ireland’s exit from the troika in tandem with the unravelling of the common economic model built up over the last three decades have troubled the constituent social and political settlements with regard to teaching and teacher education. The authors also take inspiration from Vere Foster (1819–1900), an Anglo-Irish gentleman, philanthropist and ‘social worker’ with the poor in post-famine Ireland, as well as a significant social campaigner renowned for his contribution to emigration and education. His ideas, generated at a time of great social upheaval, can be reworked to be appropriate in the Ireland of today to address the neoliberal agenda that has brought the Republic of Ireland economy to the brink of disaster. It is argued that imaginative responses about future possibilities for teaching and teacher education, their form, regulation and accountability are but a few of the terms needed for public policy debate that engages the profession on the type of schooling that would best meet the needs of Irish society now and into the future

Barriometry - an enhanced database of accurate barrier heights for gas-phase reactions

The kinetics of many reactions are critically dependent upon the barrier heights for which accurate determination can be difficult. From the perspective of attaining such quantities using computational quantum chemistry, it is important to appropriately validate routine and efficient methodologies such as density functional theory (DFT) procedures. In the present study, we embark on the journey of establishing diverse databases using a consistent high-level quantum chemistry procedure, against which new and existing methodologies can be assessed. Thus, we have used the composite protocol W3X-L to provide more than 100 refined reference values for existing databases [e.g., Y. Zhao and D. G. Truhlar, J. Phys. Chem. A, 2005, 109, 5656] and additionally establish benchmark data that are of interest to atmospheric and combustion chemists. While our endeavor has just begun, assessment of various DFT methods with our existing results lends support to the use of MN15 as an adequate method for general kinetics applications. We also recommend the use of less-costly W2X and WG composite protocols for obtaining adequately accurate reference thermochemical values for larger molecular systems

Kinetics and Thermochemistry of 2,5-Dimethyltetrahydrofuran and Related Oxolanes: Next Next-Generation Biofuels

The enthalpies of formation, entropies, specific heats at constant pressure, enthalpy functions, and all carbon–hydrogen and carbon–methyl bond dissociation energies have been computed using high-level methods for the cyclic ethers (oxolanes) tetrahydrofuran, 2-methyltetrahydrofuran, and 2,5-dimethyltetrahydrofuran. Barrier heights for hydrogen-abstraction reactions by hydrogen atoms and the methyl radical are also computed and shown to correlate with reaction energy change. The results show a pleasing consistency and considerably expands the available data for these important compounds. Abstraction by ȮH is accompanied by formation of both pre- and postreaction weakly bound complexes. The resulting radicals formed after abstraction undergo ring-opening reactions leading to readily recognizable intermediates, while competitive H-elimination reactions result in formation of dihydrofurans. Formation enthalpies of all 2,3- and 2,5-dihydrofurans and associated radicals are also reported. It is probable that the compounds at the center of this study will be relatively clean-burning biofuels, although formation of intermediate aldehydes might be problematic

Thermochemistry and Kinetics of Angelica and Cognate Lactones

The enthalpies of formation, bond dissociation energies, ionization potentials, and kinetics of reaction with hydrogen atoms and methyl radicals have been systematically calculated for angelica lactone and a number of related furanones. The objective was to provide comprehensive thermodynamic and kinetic data of compounds that are projected to play a role as intermediates in the production of platform chemicals and biofuels

Enthalpies of formation and bond dissociation energies of lower alkyl hydroperoxides and related hydroperoxy and alkoxy radicals

The enthalpies of formation and bond dissociation energies, D(ROO-H), D(RO-OH), D(RO-O), D(R-O-2) and D(R-OOH) of alkyl hydroperoxides, ROOH, alkyl peroxy, RO, and alkoxide radicals, RO, have been computed at CBS-QB3 and APNO levels of theory via isodesmic and atomization procedures for R = methyl, ethyl, n-propyl and isopropyl and n-butyl, tert-butyl, isobutyl and sec-butyl. We show that D(ROO-H) approximate to 357, D(RO-OH) approximate to 190 and D(RO-O) approximate to 263 kJ mol(-1) for all R, whereas both D(R-OO) and D(R-OOH) strengthen with increasing methyl substitution at the cc-carbon but remain constant with increasing carbon chain length. We recommend a new set of group additivity contributions for the estimation of enthalpies of formation and bond energies

Crystallization of organic salts from the gas phase: When does proton transfer take place?

Salt formation with proton transfer is observed in crystals grown by cosublimation of the salt coformers. Diflunisal salts were obtained with 4-[3-(pyridin-4-yl)propyl]pyridine, piperazine, and 4-dimethylaminopyridine. Modeling studies indicate that proton transfer does not take place for an acid–base H-bonded adduct in the gas phase. However, modeling larger molecular clusters shows that proton transfer can take place spontaneously within a molecular cluster in the absence of a solvent.This publication has emanated from research supported in part by a research grant from Science Foundation Ireland (SFI) and is co-funded under the European Regional Development Fund under Grant Number 12/RC/2275-P2. JMS thanks the Irish Centre for High-End Computing (ICHEC, project ngche071b) for the provision of resources.peer-reviewed2021-12-1

Crystallization of organic salts from the gas phase: When does proton transfer take place?

Salt formation with proton transfer is observed in crystals grown by cosublimation of the salt coformers. Diflunisal salts were obtained with 4-[3-(pyridin-4-yl)propyl]pyridine, piperazine, and 4-dimethylaminopyridine. Modeling studies indicate that proton transfer does not take place for an acid–base H-bonded adduct in the gas phase. However, modeling larger molecular clusters shows that proton transfer can take place spontaneously within a molecular cluster in the absence of a solvent.This publication has emanated from research supported in part by a research grant from Science Foundation Ireland (SFI) and is co-funded under the European Regional Development Fund under Grant Number 12/RC/2275-P2. JMS thanks the Irish Centre for High-End Computing (ICHEC, project ngche071b) for the provision of resources.2021-12-1