Lanthanum(Ⅲ) sorption studies on poly[dibenzo-18-crown-6] and its separation from uranium(Ⅵ) and thorium(Ⅳ) in L-valine medium

The sorption study of La(Ⅲ) was carried out on poly[dibenzo-18-crown-6] and L-valine medium. The quantitative adsorption of La(Ⅲ) was found at 1×10-2 to 1×10-5 mol/L L-valine. The various eluting agents were found efficient eluents for La(Ⅲ). The capacity of crown polymer for La(Ⅲ) was found to be 0.43 ±0.01 mmol/g. The tolerance limit of various cations and anions for La(Ⅲ) was determined. La(Ⅲ) was quantitatively separated from other metal ions in binary as well as multicomponent mixtures. The study was extended to sequential separation of La(Ⅲ), U(VI) and Th(IV). The good separation yields were obtained and had good reproducibility (±2%). The method incorporated the determination of La(Ⅲ) in real sample. The method was simple, rapid and selective.

Synthesis of a New β-Mercaptoalcohol

In this letter, (R)-1,1-diphenyl-2-mercapto-3-methyl-1-butanol was synthesized from L-valine and two synthetic routes have been tried.

Synthesis of Protected Tetrapeptide, N-o-Ns-N(Me)-Val-N(Me)-Val-N(Me)-Val-N(Me)-Phe-O^tBu

The protected tetrapeptide, N-o-Ns-N （ Me ） -Val-N （ Me ） -Val-N （ Me ） -Val- N （ Me ） -Phe- OtBu, was prepared from L-valine and L-phenylalanine. Ted-butyl acetate and HClO4 were used to protect carbonyl group, o-nitrobenzenesulfonyl chloride and triethyl amine were used to protect amino group, and N-alkylation was finished with iodomethane. Then the protected amino acid was turned into acid chloride which was taken as coupling reagent. After 14 steps, such as protection, alkylation, deprotection and coupling, the protected tetrapeptide was obtained with a yield of 26.9%. The structures of intermediates and target compound were identified with NMR spectra and high resolution mass spectra.

Study of the Incorporation Behavior of L-Leu and D-Leu in L-Val Crystallization

Branched-Chain Amino Acids (BCAAs) are essential amino acids mainly produced through fermentation. With respect to BCAA crystallization, the incorporation behavior of L-form BCAAs as a guest amino acid in the crystallization of L-form BCAAs is well known. However, the incorporation behavior of D-form BCAAs as a guest amino acid in the crystallization of L-form BCAAs is not clear. In this study, we focused on the crystal conformation and incorporation behavior of D-Leucine (D-Leu) and L-leucine (L-Leu) in the crystallization of L-valine (L-Val). Moreover, the difference in the incorporation behavior was investigated on the basis of the distribution ratio of crystals to mother liquor, and the crystal structure and interaction energy were calculated using a molecular dynamics method. The crystal composed of L-Leu in L-Val formed as a solid solution and L-Leu was substituted into the crystal lattice of L-Val. In the case where D-Leu was added as a guest amino acid during L-Val crystallization, D-Leu was not incorporated into the L-Vallattice because the interaction energy between a D-Leu molecule and the L-Val crystal lattice was substantially greater than that between an L-Leu molecule and the L-Val crystal lattice.

A simple and efficient synthesis of the valsartan

Valsartan 1, one of the most important agents used in antihypertensive therapy today, was synthesized starting from L-valin methyl ester hydrochloride 2 through four steps in an overall yield of 60%. The key step involves the palladium-catalyzed Suzuki coupling. This method overcomes many of the drawbacks associated with the previously reported syntheses and is more suitable for industrial production.

Biochirality and parity violating energy difference

Biochirality originates from the chiral influences in the universe. The parity non-conservation of weak neutral current, which takes place through the exchange of neutral boson Z0 combined with the long range Coulomb interaction in atoms and molecules, produces a parity violating energy difference (PVED). In this note, the fact is to be indicated that there is a λ -type second order phase transition of D- and L-alanine (valine) at a certain critical temperature Tc. The PVED is to be calculated as 6×10-5 eV/molecule by varieties of modern physical and chemical methods including the differential scanning calorimeter (DSC), SQUID, single crystal X-ray diffraction spectra, low-temperature 1H-MAS ssNMR, Raman spectra and ultrasonic measurement. A mechanism that differs from Salam’s hypotheses is also discussed here.