Synthesis of chiral ferrosalen ligands and their applications in asymmetric catalysis

A new series of chiral ferrosalen ligands was designed and synthesized. The special feature of the ferrosalen ligands is that the chirality originated from the planar chiral ferrocenyl structure. For most known salen ligands, chirality comes from central and axial chiral centers. The key building block for the construction of these ferrosalen ligands was synthesized stereoselectively by a chiral auxiliary approach. This approach does not consume any chiral material, and does not require chiral HPLC resolution. Using this method, nine ligands were prepared using ferrocene as the starting material. In addition, the steric hindrance was modulated by changing the cyclopentadienyl group to the more bulky pentamethylcyclopentadienyl- and pentaphenylcyclopentadienyl- groups. The structure of these ligands was established by 1H and 13C NMR. The structure of a ferrosalen-Cu (II) complex was determined by single crystal X-ray diffraction analysis. All the chiral ferrosalen ligands were tested in catalytic asymmetric reactions including enantioselective carbonyl-ene reaction, enantioselective Strecker-type reaction and enantioselective silylcyanation. For the carbonyl-ene reaction, up to 99% yield and 29% enantiomeric excess (ee) were obtained using ligand-Co (III) as the catalysts; For the Strecker-type reaction, a maximum of 20% ee was obtained using ligand-AlCl as the catalyst; For the silylcyanation reaction, up to 99% yield and 26% ee were obtained using ligand-AlCl as the catalyst.

MATURE FINE TAILINGS (MFTs): A STUDY OF COMPRESSIVE STRENGTH AND RHEOLOGICAL PROPERTIES OF ATHABASCA OIL SANDS PETROLEUM MINING WASTE APPLIED IN CONCRETE MIXTURES

This study investigates the compressive properties of concrete incorporating Mature Fine Tailings (MFTs) waste stream from a tar sands mining operation. The objectives of this study are to investigate material properties of the MFT material itself, as well as establish general feasibility of the utilization of MFT material in concrete mixtures through empirical data and visual observations. Investigations undertaken in this study consist of moisture content, materials finer than No. 200 sieve, Atterburg Limits as well as visual observations performed on MFT material as obtained. Control concrete mixtures as well as MFT replacement mixture designs (% by wt. of water) were guided by properties of the MFT material that were experimentally established. The experimental design consists of compression testing of 4”-diameter concrete cylinders of a control mixture, 30% MFT, 50% MFT and 70% MFT replacement mixtures with air-entrainer additive, as well as a control mixture and 30% MFT replacement mixture with no air-entrainer. A total of 6 mixtures (2 control mixtures, 4 replacement mixtures) moist-cured in lime water after 24 hours initial curing were tested for ultimate compressive strength at 7 days and 28 days in accordance to ASTM C39. The test results of fresh concrete material show that the addition of air-entrainer to the control mixture increases slump from 4” to 5.5”. However, the use of MFT material in concrete mixtures significantly decreases slump as compared to controls. All MFT replacement mixtures (30%, 50%, and 70%) with air-entrainer present slumps of 1”. 30% MFT with no air-entrainer presents a slump of 1.5”. It was found that 7-day ultimate compressive stress was not a good predictor of 28-day ultimate compressive stress. 28-day results indicate that the use of MFT material in concrete with air-entrainer decreases ultimate compressive stress for 30%, 50% and 70% MFT replacement amounts by 14.2%, 17.3% and 25.1% respectively.