Beta-carboline alkaloids from a New Zealand marine bryozoan,Cribricellina cribraria

The crude extract of a New Zealand marine bryozoan Cribricellina cribraria was examined and resulted in the isolation of the previously described, 6-hydroxyharman (1) and the new beta-carboline metabolite, 8-hydroxyharman (2).     

The stereochemistry of sulfonium ylides derived from 9-alkylidenethioxanthenes– The relationship between ring inversion and S+?C− bond rotation

A series of sulfonium ylides has been prepared by the reaction of 9-alkylidenethioxanthenes with dimethyl diazomalonate. The e' electron pair on sulfur is more efficient than the a' in trapping the “carbenes” generated by copper(II) catalyzed decomposition of diazo compounds. Consequently, e' ylides are the kineti-cally-controlled reaction products. Varying the C2 substituent does not alter this. Sulfides and sulfonium ylides containing the isopropylidene moiety do not undergo rapid ring inversion. Rotation about the S+? C^? bond occurs in the pseudo-axial conformation but not the pseudo-equatorial. The use of the anisochronicity of portions of the malonylide fragment as a criterion for heterocyclic ring inversion is presented. It is suggested that the sulfoxides of phenothiazine, phenoxathiin, thianthrene, and related sulfoxides, undergo rapid ring inversion.     

Milling of lignocellulosic biomass

Ethanol is being considered as an attractive alternative transportation fuel for the future. One method of producing ethanol from lignocellulose involves reducing the size of biomass to smaller particles, and using acid or enzyme treatments to hydrolyze the biomass to sugars. The size-reduction step is necessary to eliminate mass- and heat-transfer limitations during the hydrolysis reactions. However, milling to small size consumes large amounts of energy, and reducing the energy usage is critical to the overall process economics. In this study, the energy requirements and size distribution for milling wood were measured for various pilot-scale size-reduction equipment. Hammer milling used less energy than disk milling, but produced particles with a larger-size distribution. Additionally, energy requirements were measured for shredding paper and switchgrass.     

Separation of Am(III), Cm(III) and Eu(III) by electro-spun polystyrene-immobilized CyMe4-BTPhen

The synthesis of a novel 5-(4-vinylphenyl)-CyMe₄-BTPhen actinide selective ligand using selenium free synthetic procedures is reported. For the first time, we report the electrospinning of this actinide selective ligand into a polystyrene fiber and investigate its selective removal of Am(III) from Eu(III) and Am(III) from Cm(III). At 4?M HNO₃, the resulting fibrous solid extractant produced separation factors of SF_Am/Eu?≈?57 and a small, but significant separation of SF_Am/Cm?≈?2.9.     

Spectrophotometric Analysis of Ternary Uranyl Systems to Replace Tri- N -butyl Phosphate (TBP) in Used Fuel Reprocessing

In this report, the interaction of monoamide/diamide and monoamide/diglycolamide mixtures with $${\text{UO}}_{2}^{2 + }$$ are investigated in pH = 1 methanolic nitric acid media. These monoamides include N,N-dimethylacetamide (DMAA), N,N-diethylacetamide (DEAA), N,N-dibutylacetamide (DBAA) and N,N-dibutylbutanamide (DBBA). N,N,N′N′-tetraethylmalonamide (TEMA) and N,N,N′,N′-tetraethyldiglycolamide (TEDGA), which were chosen as model diamides and diglycolamides, respectively. Complex stability constants for each ligand were modelled using the Stability Quotients Using Absorbance Data program using UV–visible data. Complex stoichiometry of ligand mixtures was determined using Job plots and UV–Vis spectrometry. Monoamides were confirmed to produce only disolvate complexes with $${\text{UO}}_{2}^{2 + }$$ in solution. The log10(K) values for monoamides were found to be independent of amine-side chain length, but were slightly dependent on the carbonyl-side chain length. TEDGA was found to produce multiple uranyl complexes in solution. Job plot data indicated that the uranyl cation strongly prefers to bond either only with the monoamide or diamide in ternary monoamide–diamide–UO2 systems. Monoamide–diglycolamide–UO2 systems were more complicated, with Job plot data indicating the potential for multiple ternary species being present is dependent on the monoamide structure.     

Carbamate Ions as Propagating Species in N-Carboxy Anhydride Polymerizations

Polymerizations of N-carboxy anhydrides of L-phenylalanine, γ-benzyl-L-glutamate, O-carbobenzoxy-L-tyrosine, L-leucine, and sarcosine, as initiated by primary, secondary, and tertiary amines in N₂ or CO₂ atmospheres and in the presence or absence of NaH, indicate that they proceed via carbamate salt intermediates. This conclusion is supported by radiotracer studies as well as by NMR studies of the initial products of NCA-amine reaction mixtures.

The “activated monomer” mechanism of strong-base initiated polymerizations is discounted on the bases that polypeptides are not formed in aprotic tertiary amine-initiated systems (hydantoins and diketopiperazines are obtained instead) and that methoxyl end groups are detected in polypeptides initiated with ¹⁴C-labeled NaOCH₃.