immobilized lipoamide dehydrogenase in 30 % (v/v) dioxan. The rate constants for inactivation in dioxan, like those for thermal inactivation at 90°C, increase with increasing distance from the matrix and eventually approach that for the inactivation of the native enzyme in 30% (v/v) dioxan, i.e. 0.01 min-'. These data can be rationalized by the fact that the hydrophilic Sepharose matrix probabl...

LUCITE NOT A SUBSTITUTE FOR CANADA BALSAM WHEN MOUNTING MICROSCOPE SLIDES' LUCITE2 is a crystal-clear methyl methacrylate polymere which has a refractive index nearly the same as glass and is readily soluble in dioxan. Dioxan3 has proven useful as a dehydrating agent for the preparation of sections and objects to be mounted for observation with the microscope. Thus with the Lucite in dioxan sol...

The zwitterionic compounds Im-E-Mel [9, E S (a), Se (b), Te (c), Im 2-{1,3-diisopropyl-4,5-dimethylimidazolium}, Mel 5-{2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylide}] are obtained from the corresponding 2-chalcogeno-1,3-diisopropyl-4,5-dimethylimidazolines 8 and 5-bromo-2,2-dimethyl-4,6-dioxo-1,3-dioxan (7) in the presence of triethylamine in excellent yields. The crystal structures of the thermal...

[reaction: see text] A practical and environmentally friendly organocatalytic strategy designed to mimic the DHAP aldolases has been developed and shown to be effective in the preparation of carbohydrates and aminosugars. (S)-Proline and (S)-2-pyrrolidine-tetrazole catalyzed the aldol reaction between dihydroxy acetone variants such as 1,3-dioxan-5-one and 2,2-dimethyl-1,3-dioxan-5-one with ald...

Equilibria between carbonyl compounds and their enamines (from O-TBDPS-derived prolinol) have been examined by NMR spectroscopy in DMSO-d(6). By comparing the exchange reactions between pairs (enamine A + carbonyl B → carbonyl A + enamine B), a quite general scale of the tendency of carbonyl groups to form enamines has been established. Aldehydes quickly give enamines that are relatively more s...

IN the course of work carried out in this laboratory on the constitution of complex mould metabolic products-many of which are polybasic acids, or otherwise highly oxygenated compounds, very sensitive to the action of heat or mild reagents-the need for a neutral, chemically inert, non-hydroxylic liquid of extensive solvent powers and of convenient freezing-point just below room temperature, has...

Dihydroxyacetone variants have been explored as donors in organocatalytic aldol reactions with various aldehyde and ketone acceptors. The protected form of dihydroxyacetone that was chosen for in-depth study was 2,2-dimethyl-1,3-dioxan-5-one, 1. Among the catalysts surveyed here, proline proved to be superior in terms of yield and stereoselectivities in the construction of various carbohydrate ...

In dioxan-chloroform medium the acceptor chloranilic acid forms 1:1 molecular complexes with the alkaloids atropine, pilocarpine and strychnine, with maximum absorption at 535, 527.5 and 535 nm respectively. Conformity with Beer's law allows the use of the complexes for the assay of these drugs.

Abstract Alkalimetalldihydrogenantimonide [M(L) x SbH 2 ], kurz: Alkalimetallantimonide (M=Li, Na, K, Rb, Cs; 1 : L=pmdta; L=Kronenether), wurden aus Stiban und n ‐Butyllithium, M(hmds) (hmds=Hexamethyldisilazan) bzw. MO t Bu hergestellt. Wir haben einen allgemein anwendbaren Syntheseweg für diese Verbindungen entwickelt die erhaltenen auf ihre Stabilität in Abhängigkeit vom verwendeten Alkalim...

We study simulated annealing techniques for crystal structure determination from diffraction data. We demonstrate that for this problem the efficiency of simulated annealing can be systematically improved by an iterative simulation protocol. Our approach is tested for the example of 9-(methylamino)-1 H-phenalen-1-one-1, 4-dioxan-2-yl hydroperoxide solvate (C18H19NO5).