A new synthesis of ampicillin and related investigations

Quaternization of (S)-α-bromophenylacetic acid amide (8) with hexamethylentetramine (hexamine) preceded with ca. 80% inversion of configuration. Accordingly, starting from the trimethylsilylester of N-(S)-(α-bromo-α-phenylacetyl)-6-aminopenicillanic acid (4) quaternization with hexamine and subsequent hydrolysis afforded N-(R)-α-phenylglycyl-6-aminopenicillanic acid (1, ampicillin). Some other model reactions have been investigated.     

Properties of Monocarboxy Cellulose Containing Sorbed Fe(III), Al(III), and Cr(III) Cations

Sorption of Fe(III), Al(III), and Cr(III) on monocarboxy cellulose at various pH, concentrations of metal chloride or sulfate in solution, and time was studied. The effect of type and amount of the cation sorbed on the physicomechanical properties, swelling, and stability in phosphate buffer of monocarboxy cellulose fibers was considered.     

Brillouin scattering and rotation translation coupling of (KCN)xX1−x mixed crystals

Brillouin scattering is used to study the concentration and temperature dependence of longitudinal and transverse phonon frequencies of KCN_χBr_1?χ, KCN_χC1_1?χ, and KCN_0.85I_0.15 mixed crystals. Unlike pure KCN, mixed crystals with χ < 0.7 show no phase transition upon cooling, and the transverse acoustic frequency ω_TA(110) displays a minimum at some characteristic temperature T_i.T_i is below the phase transition of pure KCN and depends on the C1^? concentration. The Brillouin data are discussed in terms of coupling of the acoustic phonons with orientational motion of CN^? ions and mean field theory.     

Kinetic studies in various media on some hydrogenation reactions catalyzed by polymer-anchored RhCl(PPh3)3

A study has been made of the hydrogenation of cyclohexene, 1-hexene and styrene at atmospheric pressure catalysed by RhCl (PPh₃)₃ supported on styrene-divinylbenzene copolymers with 1%, 2% and 4% cross linking. The dependence of the hydrogenation rate on the concentration of the olefin, the amount of catalyst, and the nature of the solvent was investigated. The hydrogenation rate is lower than for homogeneous catalysis but the dependence of the rate on the examined parameters is similar. The ratio between the rates for 1-hexene and cyclohexene is higher than that in the homogeneous phase. This increase in selectivity may due to steric hindrance around the active sites of the resin. The solvent effects revealed that the hydrogenation rate also depends on the degree of swelling of the resin.