Abstract: A method of increasing enantioselectivity in a reduction reaction of a prochiral substrate with a borane reagent including a borohydride species (for example, a borohydride stabilized borane-tetrahydrofuran complex) catalyzed by a chiral catalyst includes the step of maintaining the concentration of borohydride species in the borane reagent below approximately 0.005 M during the reduction of the prochiral substrate. A method of increasing enantioselectivity in a reduction reaction of a prochiral substrate with a borane reagent including a borohydride species that is catalyzed by a chiral catalyst includes the step of reducing the detrimental effect the borohydride species has on enantioselectivity by adding a Lewis acid. For example, the prochiral substrate can be a ketone and the chiral catalyst can be a chiral oxazaborolidine.
Type:
Grant
Filed:
January 26, 2001
Date of Patent:
August 26, 2003
Assignee:
Mine Safety Appliances Company
Inventors:
Karl Matos, Joseph A. Corella, II, Elizabeth R. Burkhardt, Shawn M. Nettles
Abstract: A method for synthesizing highly soluble metal alkoxides includes the step of reacting a tertiary alcohol having the formula:
wherein R1, R2, and R3 are, independently, the same or different, an alkyl group, an alkenyl, an alkynyl group or an aryl group, and at least one of R1, R2, and R3 is a group of at least 3 carbon atoms, with at least a stoichiometric amount of a metal reagent. The metal reagent is generally a group I metal, a group II metal, zinc, a metal alloy of a group I metal, a metal alloy of a group II metal, a metal alloy of zinc, a compound of a group I metal, a compound of a group II metal or a compound of zinc.
Type:
Grant
Filed:
May 30, 2000
Date of Patent:
September 3, 2002
Assignee:
Mine Safety Appliances Company
Inventors:
Elizabeth R. Burkhardt, Joseph A. Corella, II, David H. Ellenberger, Christopher P. Sutton
Abstract: A synthetic route for forming lithium trisubstituted borohydride compounds comprises the step of reacting a processed lithium hydride reactant with a trisubstituted borane wherein the reaction is maintained for a period of time in a temperature range of approximately 15° C. to approximately 42° C. A method of synthesizing LiH comprises the step of reacting an alkyl lithium (for example, n-butyl lithium) with hydrogen in the presence of tetrahydrofuran. The reaction temperature is preferably maintained in the range of approximately −78° C. to approximately 25° C.
Type:
Grant
Filed:
January 24, 2000
Date of Patent:
April 24, 2001
Assignee:
Mine Safety Appliances Company
Inventors:
Elizabeth R. Burkhardt, Christopher P. Sutton, Joerg Bruening, David F. Rouda
Abstract: The present invention provides a low-cost alternative to currently available electrochemical sensors. In general, the present invention provides an electrochemical sensor for the detection of an analyte comprising a first metallic housing member and a second metallic housing member. The first metallic housing member and the second metallic housing member are brought together in sealed connection to create a sealed enclosure therebetween. Contained within the enclosure are a first electrode, at which the analyte reacts, and a second electrode, at which a reaction complimentary to the reaction of the analyte at the first electrode takes place. An acidic electrolyte is also contained within the enclosure of the first metallic housing member and the second metallic housing member.
Type:
Grant
Filed:
March 15, 1996
Date of Patent:
September 16, 1997
Assignee:
Mine Safety Appliances Company
Inventors:
Alan A. Schneider, Towner B. Scheffler, Brian K. Davis
Abstract: The present invention provides a sizing guide for assisting in the initial determination of an appropriate size of respirator mask for a user thereof. The sizing guide has at least a first sizing gap having a known width such that comparison of the width of the first sizing gap with the length between a pair of facial landmarks such as the sellion landmark and the menton landmark provides an initial determination of the appropriate size respirator mask for the user which can then be fit tested. Preferably, the sizing guide also has a second sizing gap having a known width different from the width of the first sizing gap.