Practical Method for Preparation of ()-2-Amino-5,5,5-trifluoropentanoic Acid via Dynamic Kinetic Resolution.

This work reports an operationally convenient ∼20 g scale synthesis of ()-2-amino-5,5,5-trifluoropentanoic acid and its Fmoc-derivative via dynamic kinetic resolution of the corresponding racemate.

Large-Scale Asymmetric Synthesis of Fmoc-()-2-Amino-6,6,6-Trifluorohexanoic Acid.

Here we report the first large-scale synthesis of Fmoc-()-2-amino-6,6,6-trifluorohexanoic acid via asymmetric alkylation of chiral Ni(II)-complex of glycine Schiff base with CF(CH)I. The synthesis was performed on over 100 g scale and can be recommended as the most advanced procedure for reliable preparation of large amounts of enantiomerically pure Fmoc-()-2-amino-6,6,6-trifluorohexanoic acid for protein engineering and drug design. Chiral auxiliary used in this protocol can be >90 % recovered and reused.

Development of an Exhaled Breath Monitoring System with Semiconductive Gas Sensors, a Gas Condenser Unit, and Gas Chromatograph Columns.

Various volatile organic compounds (VOCs) in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS) for development of an exhaled breath monitoring prototype system involving metal oxide gas sensors, a gas condenser, and gas chromatography columns. The gas condenser-GC/MS analysis identified concentrations of 56 VOCs in the breath exhaled by the test population of 136 volunteers (107 patients with lung cancer and 29 controls), and selected four target VOCs, nonanal, acetoin, acetic acid, and propanoic acid, for use with the condenser, GC, and sensor-type prototype system. The prototype system analyzed exhaled breath samples from 101 volunteers (74 patients with lung cancer and 27 controls).

Retention Behavior of Halogenated Benzenes on a Stationary Phase Having a 2,4-Dibromophenoxy Group as the Halogen Recognition Functional Group.

A stationary phase with a dipole interaction was synthesized by immobilizing the 2,4-dibromophenoxy (DBP) group onto a hydrophilic base resin. The chromatographic properties for halogenated benzenes were evaluated on the DBP-resin by reversed phase mode. The separation efficiency of the DBP-resin for p-xylene and 1,4-dihalogenated benzenes was better than that of the column packed with octadecylsilane (ODS).

Retention of halogenated solutes on stationary phases containing heavy atoms.

To examine the effects of weak intermolecular interactions on solid-phase extraction (SPE) and chromatographic separation, we synthesized some novel stationary phases with a heavy atom effect layer by immobilizing halogenated aromatic rings and hydroxyl groups onto the surface of a hydrophilic base polymer. Using SPE cartridges packed with the functionalized materials, we found that the heavy atom stationary phases could selectively retain halophenols in organic solvents, such as 1-propanol which blocks the hydrogen bonding, or acetonitrile which blocks the π-π interaction. The extraction efficiency of the materials toward the halophenols depended on the dipole moments of phenoxy groups present as functional groups.

Development of a variable-wavelength optical rotation detector in the ultraviolet region.

A new type of optical rotation (OR) detector based on the phase retardation of the first-order diffraction beam has been constructed. The proposed detector responded to only OR properties by eliminating the circular dichroism (CD) effect. Thus, it could measure the optical rotatory dispersion curves in the Cotton band.

Determination of adulteration in apple juice by HPLC with novel optical rotation detector.

A simple HPLC method for the determination of adulteration in apple juice was developed. The method is based on the detection of D-malate, derived from racemic malic acid, which is added as an acidulant. A variable-wavelength optical rotation detector was used to determine the enantiomeric excess (ee).