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“Functional Poly(ethylene glycol)”: PEG-Based Random Copolymers with 1,2-Diol Side Chains and Terminal Amino Functionality
2010
A series of poly(ethylene glycol-co-isopropylidene glyceryl glycidyl ether) (P(EO-co-IGG)) random copolymers with different fractions of 1,2-isopropylidene glyceryl glycidyl ether (IGG) units was synthesized. After acidic hydrolysis a new type of "functional PEGs", namely poly(ethylene glycol-co-glyceryl glycerol) (P(EO-co-GG)) was obtained. Using an initiator that releases a terminal amino moiety after deprotection, functional end groups with orthogonal reactivity to the in-chain groups were obtained. All polymers showed narrow molecular weight distributions (1.07-1.19), and control of the molecular weights was achieved in the range 5000-30 000 g/mol. Random incorporation of both comonomer…
Counterintuitive Mechanisms of the Addition of Hydrogen and Simple Olefins to Heavy Group 13 Alkene Analogues
2013
The mechanism of the reaction of olefins and hydrogen with dimetallenes ArMMAr (Ar = aromatic group; M = Al or Ga) was studied by density functional theory calculations and experimental methods. The digallenes, for which the most experimental data are available, are extensively dissociated to gallanediyl monomers, :GaAr, in hydrocarbon solution, but the calculations and experimental data showed also that they react with simple olefins, such as ethylene, as intact ArGaGaAr dimers via stepwise [2 + 2 + 2] cycloadditions due to their considerably lower activation barriers vis-à-vis the gallanediyl monomers, :GaAr. This pathway was preferred over the [2 + 2] cycloaddition of olefin to monomeric…
Understanding the mechanisms of [3+2] cycloaddition reactions. The pseudoradical versus the zwitterionic mechanism
2014
Abstract Analysis of 12 three-atom-components (TACs) participating in [3+2] cycloaddition (32CA) reactions towards ethylene and acetylene allows establishing good correlations between the pseudodiradical character, the hardness η, and the nucleophilicity N index of the TAC with the feasibility of these non-polar reaction. These results allow the introduction of the pr index, which comprises the two aforementioned DFT reactivity indices. The increase of the pr index for an allylic-type TAC goes accompanied by a linear decrease of the activation enthalpy of the reaction. The present study makes it possible to establish a useful classification of 32CA reactions into zw-type reactions involving…
A molecular electron density theory study of the insertion of CO into frustrated Lewis pair boron-amidines: a [4 + 1] cycloaddition reaction
2019
The insertion of CO into hydrogenated boron-amidine 1 yielding five-membered diazaborolone (5DAB) 3 has been studied within the molecular electron density theory (MEDT) at the DFT ωB97X-D/6-311G(d,p) level. This is a domino process comprised of two consecutive reactions: (i) the dehydrogenation of 1 yielding the frustrated Lewis pair (FLP) boron-amidine 4, which quickly equilibrates with four-membered diazaborolone (4DAB) 2; and (ii) the addition of CO into FLP 4, yielding the final 5DAB 3. Analysis of the Gibbs free energies indicates that the extrusion of H2 demands a high ΔG≠ of 28.6 kcal·mol-1, being endergonic by 6.7 kcal·mol-1. The subsequent addition of CO into FLP 4 presents a low Δ…
Synthesis, molecular structure and stability of fused bicyclic Δ4-1,2,4-oxadiazoline Pt(II) complexes
2015
Abstract The reaction of trans -[PtCl 2 (NCR) 2 ] (R 1 = CH 2 CO 2 Me ( 1a ), R 2 = CH 2 Cl ( 1b )) with pyrroline N -oxide − O + N CHCH 2 CH 2 C Me 2 ( 4 ), at room temperature for 15 min, furnishes via [3+2] cycloaddition the fused bicyclic Δ 4 -1,2,4-oxadiazoline Pt(II) complexes trans- [PtCl 2 { N C(R)O N C(H)CH 2 CH 2 C Me 2 } 2 ] (R 1 = CH 2 CO 2 Me ( 5a ), R 2 = CH 2 Cl ( 5b )). Compounds 5a and 5b were refluxed in CH 2 Cl 2 for 1 week to afford the derived ketoimine Pt(II) complexes trans- [PtCl 2 {N(C( O)(R)) C CH 2 CH 2 C(Me 2 ) N H} 2 ] (R 1 = CH 2 CO 2 Me ( 6a ), R 2 = CH 2 Cl ( 6b )), respectively, as a result of the N–O bond cleavage of the oxadiazoline ring in 5 . The c…
On thermoeconomics of energy systems at variable load conditions: integrated optimization of plant design and operation
2007
Abstract Thermoeconomics has been assuming a growing role among the disciplines oriented to the analysis of energy systems, its different methodologies allowing solution of problems in the fields of cost accounting, plant design optimisation and diagnostic of malfunctions. However, the thermoeconomic methodologies as such are particularly appropriate to analyse large industrial systems at steady or quasi-steady operation, but they can be hardly applied to small to medium scale units operating in unsteady conditions to cover a variable energy demand. In this paper, the fundamentals of thermoeconomics for systems operated at variable load are discussed, examining the cost formation process an…
Thermoeconomic optimization of a renewable polygeneration system serving a small isolated community
2015
During the last years, special attention has been paid to renewable polygeneration technologies, able of simultaneously producing thermal, cooling, electrical energy and desalinated water from seawater. This paper focuses on an innovative polygeneration system driven by renewable energy sources, including the following technologies: hybrid photovoltaic/thermal collectors, concentrating parabolic trough (CPVT), a biomass heater, a single-stage absorption chiller and a multiple-effect distillation desalination system. The system is designed to cover the base load of an isolated small community. In previous papers, the dynamic simulation model about plant operation is discussed. In this paper,…
Performance maps for an air-cooled air conditioning system as a preliminary instrument for the diagnosis of evaporator fouling
2019
Abstract During the past few decades, there has been increased interest in the development of automated approaches for detecting and diagnosing faults in air conditioning systems. Among them, thermoeconomic diagnosis is a technique which involves the use of exergy analysis. As a first step towards improving its performance, this work is focused on the thermodynamic and exergy analysis of a direct expansion air conditioning system used in small commercial building applications. The analysis was carried out by means of experimental activities on a 17.5 kW rooftop unit installed at the Herrick Laboratories, Purdue University, Indiana (USA). The system under investigation was equipped with a va…
A Stackelberg-game approach to support the design of logistic terminals
2014
This paper deals with the design of logistic terminals taking Sicily, in the South of Italy, as a case study. It focuses on consolidation terminals for truckers and addresses the problem of optimising location pattern and public share in investments. This problem is solved through a Stackelberg game between the designer and the collective of road carriers. So a bilevel approach combines a system-optimum problem, at the upper level, with the carrier equilibrium problem, at the lower level. The choice behaviour of the lower-level player is simulated by a random utility model. The output of the game suggests that private companies and society should share the investments and the public contrib…
Futures pricing in electricity markets based on stable CARMA spot models
2012
We present a new model for the electricity spot price dynamics, which is able to capture seasonality, low-frequency dynamics and the extreme spikes in the market. Instead of the usual purely deterministic trend we introduce a non-stationary independent increments process for the low-frequency dynamics, and model the large uctuations by a non-Gaussian stable CARMA process. The model allows for analytic futures prices, and we apply these to model and estimate the whole market consistently. Besides standard parameter estimation, an estimation procedure is suggested, where we t the non-stationary trend using futures data with long time until delivery, and a robust L 1 -lter to nd the states of …