35 research outputs found
THE VIBRATIONAL SPECTRA AND HARMONIC AS INITIO FORCE FIELDS FOR BICYCLO[2.2.1]HEPTANE AND SEVERAL ANALOGS
Address: Department of Chemistry, University of Calgary, Calgary, Alberta, T2N IN4 Canada.Author Institution:The vibrational spectra in the region of 4000-100 are reported for 7-oxa- and 7-thiabicyclo[2.2.1]heptane and bicyclo[2.2.1]hept-2-ene. The spectra of bicyclo[2.2.1]heptane and 2,5-diene are included for comparison. The ab initio force fields are calculated at the STO-3G and 3-21G levels for each molecule. The force constants are scaled to fit the observed spectra. The transferability of the scaling factors within this series of compounds is examined for the two basis sets. The optimized force fields are compared with respect to eigenvectors and calculated frequencies
Dihydroxyacetone Reductase from Mucor javanicus. 2. Identification of the Physiological Substrate and Reactivity towards Related Compounds
Solvolysis of 3-substituted 4-homoadamantyl methanesulphonates. Can the ?-substituent effect distinguish between classical and non-classical ion intermediates?
Fatty Acid Synthetase from Pig Liver. 2. Characterization of the Enzyme Complex with Oxidoreductase Activity for Alicyclic Ketones as a Fatty Acid Synthetase
The seismo-hydromechanical behavior during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in situ stimulation experiment
In this
contribution, we present a review of scientific research results that address
seismo-hydromechanically coupled processes relevant for the development of a
sustainable heat exchanger in low-permeability crystalline rock and introduce
the design of the In situ Stimulation and Circulation (ISC) experiment at the
Grimsel Test Site dedicated to studying such processes under controlled
conditions. The review shows that research on reservoir stimulation for deep
geothermal energy exploitation has been largely based on laboratory
observations, large-scale projects and numerical models. Observations of
full-scale reservoir stimulations have yielded important results. However,
the limited access to the reservoir and limitations in the control on the
experimental conditions during deep reservoir stimulations is insufficient to
resolve the details of the hydromechanical processes that would enhance
process understanding in a way that aids future stimulation design.
Small-scale laboratory experiments provide fundamental insights into various
processes relevant for enhanced geothermal energy, but suffer from
(1) difficulties and uncertainties in upscaling the results to the field
scale and (2) relatively homogeneous material and stress conditions that lead
to an oversimplistic fracture flow and/or hydraulic fracture propagation
behavior that is not representative of a heterogeneous reservoir. Thus, there
is a need for intermediate-scale hydraulic stimulation experiments with high
experimental control that bridge the various scales and for which access to
the target rock mass with a comprehensive monitoring system is possible. The
ISC experiment is designed to address open research questions in a naturally
fractured and faulted crystalline rock mass at the Grimsel Test Site
(Switzerland). Two hydraulic injection phases were executed to enhance the
permeability of the rock mass. During the injection phases the rock mass
deformation across fractures and within intact rock, the pore pressure
distribution and propagation, and the microseismic response were monitored at
a high spatial and temporal resolution
The seismo-hydromechanical behavior during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in situ stimulation experiment
In this
contribution, we present a review of scientific research results that address
seismo-hydromechanically coupled processes relevant for the development of a
sustainable heat exchanger in low-permeability crystalline rock and introduce
the design of the In situ Stimulation and Circulation (ISC) experiment at the
Grimsel Test Site dedicated to studying such processes under controlled
conditions. The review shows that research on reservoir stimulation for deep
geothermal energy exploitation has been largely based on laboratory
observations, large-scale projects and numerical models. Observations of
full-scale reservoir stimulations have yielded important results. However,
the limited access to the reservoir and limitations in the control on the
experimental conditions during deep reservoir stimulations is insufficient to
resolve the details of the hydromechanical processes that would enhance
process understanding in a way that aids future stimulation design.
Small-scale laboratory experiments provide fundamental insights into various
processes relevant for enhanced geothermal energy, but suffer from
(1) difficulties and uncertainties in upscaling the results to the field
scale and (2) relatively homogeneous material and stress conditions that lead
to an oversimplistic fracture flow and/or hydraulic fracture propagation
behavior that is not representative of a heterogeneous reservoir. Thus, there
is a need for intermediate-scale hydraulic stimulation experiments with high
experimental control that bridge the various scales and for which access to
the target rock mass with a comprehensive monitoring system is possible. The
ISC experiment is designed to address open research questions in a naturally
fractured and faulted crystalline rock mass at the Grimsel Test Site
(Switzerland). Two hydraulic injection phases were executed to enhance the
permeability of the rock mass. During the injection phases the rock mass
deformation across fractures and within intact rock, the pore pressure
distribution and propagation, and the microseismic response were monitored at
a high spatial and temporal resolution
Gas-phase diastereoselectivity of secondary 5-substituted (X)-adamant-2-yl (X= F, Si (CH 3)3) cations
Secondary 5-X-adamant-2-yl cations IX (X = F, Si(CH3)3) were generated in the gas phase (total pressure = 760 torr) from protonation-induced defluorination of epimeric 2-F-5-X-adamantanes 1X and their kinetic diastereoselectivity toward CH318OH studied in the 40-160 C range. The facial selectivity of IX is insensitive to the compn. of the starting 1X epimers as well as to the presence and the concn. of a powerful base (N(C2H5)3). This kinetic picture, supported by B3LYP/6-31G* calcns., is consistent with a single stable pyramidalized structure for IX, i.e., (Z)-5-F-adamant-2-yl (IZF) and (E)-5-Si(CH3)3-adamant-2-yl cations (IESi). The temp. dependence of the IX diastereoselectivity lends support to the intermediacy of noncovalent adducts [IX.bul.CH318OH], characterized by a specific C2-H+O18(H)CH3 hydrogen bonding interaction. Their conversion to the covalently bonded O-methylated (Z)- (IIZX) and (E)-5-X-adamantan-2-ols (IIEX; X = F, Si(CH3)3) is governed by activation parameters, whose magnitude depends on the specific IX face accommodating CH318OH. The gas-phase diastereoselectivity of IX toward CH318OH is compared to that exhibited in related gas-phase and soln. processes. The emerging picture indicates that the factors detg. the diastereoselectivity of IX toward simple nucleophiles in the gaseous and condensed media are completely different