Energy Transition Structures Research Articles

A Contribution to Social Acceptance of PV in an Oil-Rich Country: Reflections on Governmental Organisations in Iran

To examine the social acceptance of renewable energy infrastructures regarding their position in the success of energy transition, attitudes towards these technologies have been increasingly recognised to play an important role. Notably, most of empirical literature has focused on the global northern countries, with bottom-up transition governance structure. In this paper, we study attitudes towards photovoltaics in Iran, as a fossil fuel-rich country of the global south, with a top-down energy transition structure and committed to UNFCCC. We focused on governmental organisations as a key stakeholder group regarding their role in winning public acceptance. Aiming at finding determinants of attitudes towards PV, we conducted 15 qualitative interviews in 10 governmental organisations in Golestan, Guilan and Tehran. Taking an inductive approach to the data, we considered the acceptance and attitude theories as sensitising concepts to investigate common and specific issues in terms of social acceptance in Iran. We find accessing electricity and diversifying electricity resources via PV as the key technical drivers, and the upstream policies as the key political drivers towards PV adoption. Though the weak policies (design and implementation), privileging economic and technical obstacles, do hinder the PV adoption and shape negative attitudes toward it. We realise that the previous literature overlooked the fossil fuel-rich countries and their energy transition governance structure. Our findings imply that better-designed upstream policies with a more enabling policy framework are needed to motivate actions on the governmental organisation level.

Theoretical Analysis of the Fragmentation of (CO)5: A Symmetry-Allowed Highly Exothermic Reaction that Follows a Stepwise Pathway.

B3LYP and CCSD(T) calculations, using an aug-cc-pVTZ basis set, have been carried out on the fragmentation of 1,2,3,4,5-cyclopentanepentone, (CO)(5), to five molecules of CO. Although this reaction is calculated to be highly exothermic and is allowed to be concerted by the Woodward-Hoffmann rules, our calculations find that the D(5h) energy maximum is a multidimensional hilltop on the potential energy surface. This D(5h) hilltop is 16-20 kcal/mol higher in energy than a C(2) transition structure for the endothermic cleavage of (CO)(5) to (CO)(4) + CO and 11-15 kcal/mol higher than a C(s) transition structure for the loss of two CO molecules. The reasons for the very high energy of the D(5h) hilltop are discussed, and the geometries of the two lower energy transition structures are rationalized on the basis of mixing of the e(2)' HOMO and the a(2)″ LUMO of the hilltop.

Nitrosation of dialkylhydroxylamines, and computational and NMR investigations of the interconversion of conformational isomers of N -nitroso-dimethylhydroxylamine

The effect of acidity upon the rate of nitrosation of N-benzyl,O-methylhydroxylamine (3) in 1:1 (v/v) H2O/MeOH at 25 °C has been investigated. The pseudo-first-order rate constant (kobs) for loss of HNO2 as the limiting reagent decreases as [H3O+] increases. This is compatible with two parallel reaction channels (Scheme 2). One involves the direct reaction of the free hydroxylamine with HNO2 (k1 = 1.4 × 102 dm3 mol−1 s−1, 25 °C) and the other involves the reaction of the free hydroxylamine with NO+ (k2 = 5.9 × 109 dm3 mol−1 s−1). In contrast, there is only a very slight increase in kobs with increasing [H3O+] for nitrosation of N,O-dimethylhydroxylamine (4) in dilute aqueous solution at 25 °C to give N-nitroso-dimethylhydroxylamine, 5. This also fits a two-channel mechanism (Scheme 3). Again, one involves the nitrosation of the free base by NO+ (k2 = 8 × 109 dm3 mol−1 s−1, 25 °C) but the other channel now involves catalysis by chloride (k3 = 1.3 × 108 dm3 mol−1 s−1). Arising from these results, we propose an estimate of pKa ∼ −5 for protonated nitrous acid, (O = NOH), which is appreciably different from the literature value of +1.7. The interconversion of cis and trans conformational isomers of 5 has been investigated by temperature-dependent NMR spectroscopy in CDCl3, methanol-d4, toluene-d8 and dimethyl sulfoxide-d6. Enthalpies and entropies of reaction and of activation have been determined and compared with computational values obtained at the B3LYP/6-31G* level of theory. The cis form is slightly more stable at normal temperatures and no solvent effects upon the thermodynamics or kinetics of the conformational equilibrium were predicted computationally or detected experimentally. In addition, key geometric parameters and dipole moments have been calculated for the cis and trans forms, and for the lowest energy transition structure for their interconversion, in the gas phase and in chloroform. These results indicate electronic delocalisation in the ground states of 5 which is lost in the transition structure for their interconversion. Copyright © 2010 John Wiley & Sons, Ltd.

Substituent Effects on Tandem Alkenyl Migration/Electrophilic Aromatic Substitution Reactions: A Theoretical Study

Quantum mechanical calculations (B3LYP/6-31G(d)) were used to study the substituent effects and the concertedness of the alkenyl migration/electrophilic aromatic substitution reactions recently reported by Oshima and co-workers. Our calculations suggest that these systems prefer stepwise mechanisms with their aryl attack steps having the highest energy transition structures, but that in some highly substituted cases, effectively concerted but very asynchronous processes may occur.

Mechanism of the hydrogen transfer from the OH group to oxygen-centered radicals: proton-coupled electron-transfer versus radical hydrogen abstraction.

High-level ab initio electronic structure calculations have been carried out with respect to the intermolecular hydrogen-transfer reaction HCOOH+.OH-->HCOO.+H(2)O and the intramolecular hydrogen-transfer reaction .OOCH2OH-->HOOCH(2)O.. In both cases we found that the hydrogen atom transfer can take place via two different transition structures. The lowest energy transition structure involves a proton transfer coupled to an electron transfer from the ROH species to the radical, whereas the higher energy transition structure corresponds to the conventional radical hydrogen atom abstraction. An analysis of the atomic spin population, computed within the framework of the topological theory of atoms in molecules, suggests that the triplet repulsion between the unpaired electrons located on the oxygen atoms that undergo hydrogen exchange must be much higher in the transition structure for the radical hydrogen abstraction than that for the proton-coupled electron-transfer mechanism. It is suggested that, in the gas phase, hydrogen atom transfer from the OH group to oxygen-centered radicals occurs by the proton-coupled electron-transfer mechanism when this pathway is accessible.

Thermal and photochemical rearrangement of bicyclo[3.1.0]hex-3-en-2-one to the ketonic tautomer of phenol. Computational evidence for the formation of a diradical rather than a zwitterionic intermediate.

The ground state (S(0)) and lowest-energy triplet state (T(1)) potential energy surfaces (PESs) concerning the thermal and photochemical rearrangement of bicyclo[3.1.0]hex-3-en-2-one (8) to the ketonic tautomer of phenol (11) have been extensively explored using ab initio CASSCF and CASPT2 calculations with several basis sets. State T(1) is predicted to be a triplet pipi lying 66.5 kcal/mol above the energy of the S(0) state. On the S(0) PES, the rearrangement of 8 to 11 is predicted to occur via a two-step mechanism where the internal cyclopropane C-C bond is broken first through a high energy transition structure (TS1-S(0)()), leading to a singlet intermediate (10-S(0)()) lying 25.0 kcal/mol above the ground state of 8. Subsequently, this intermediate undergoes a 1,2-hydrogen shift to yield 11 by surmounting an energy barrier of only 2.7 kcal/mol at 0 K. The rate-determining step of the global rearrangement is the opening of the three-membered ring in 8, which involves an energy barrier of 41.2 kcal/mol at 0 K. This high energy barrier is consistent with the fact that the thermal rearrangement of umbellulone to thymol is carried out by heating at 280 degrees C. Regarding the photochemical rearangement, our results suggest that the most efficient route from the T(1) state of 8 to ground state 11 is the essentially barrierless cleavage of the internal cyclopropane C-C bond followed by radiationless decay to the S(0) state PES via intersystem crossing (ISC) at a crossing point (S(0)()/T(1)()-1) located at almost the same geometry as TS1-S(0)(), leading to the formation of 10-S(0)() and the subsequent low-barrier 1,2-hydrogen shift. The computed small spin-orbit coupling between the T(1) and S(0) PESs at S(0)()/T(1)()-1 (1.2 cm(-)(1)) suggests that the ISC between these PESs is the rate-determining step of the photochemical rearrangement 8 --> 11. Finally, computational evidence indicates that singlet intermediate 10-S(0)() should not be drawn as a zwitterion, but rather as a diradical having a polarized C=O bond.