A convenient method for asymmetric alkylation of glycine imine esters using solid supports

Asymmetric alkylation of butyl glycinate-benzophenone Schiff base proceeded smoothly on clays and alumina at room temperature to afford alkylated products in high yields and good enantioselectivities.     

Collection of mercury from artificial sea-water with activated carbon

Nanogram amounts of mercury(II) and methylmercury in artificial sea-water containing mineral acids as preserving reagents were shown to be collected quantitatively with activated carbon. Mercury concentrated on activated carbon was determined directly by combustion, trapping on gold and electrothermal atomic-absorption spectrophotometry. The activated carbon was purified by heating at 350 degrees for 2 hr. Sulphuric acid and hydrochloric acid were purified by treatment with activated carbon. Interference from iodide was eliminated by using a carbonate buffer wash before the atomic-absorption measurement. Less than 4 ng of mercury in 200-300 ml of artificial sea-water, whether acidified or not (with sulphuric, hydrochloric or nitric acid), was satisfactorily collected with 100 mg of activated carbon. Mercury was also collected quantitatively after oxidative treatment of artificial sea-water.     

Solid state photoreactions occurring at the interface between crystallites of two different organic compounds

This paper deals with the solid state bimolecular photoreactions occurring at the interface between crystallites of two different organic compounds prepared as a polycrystalline mixture by melting-resolidification. The photoreactions include the photoaddition of NH compounds to aromatic and olefinic double bonds, hydrogen abstraction, condensation reaction via photoelectron transfer and [2+2] photoaddition. Particular attention is focused on the characterization of the polycrystalline mixture, the selectivity of the photoreactions in the solid state compared with those in the solution phase and the factors controlling the photoreactions.     

Helicity Control in the Preparation of Chiral Co-crystals from Tryptamine and Achiral Carboxylic Acids by Pseudo-seeding

Abstract

Chiral crystals of tryptamine and achiral carboxylic acids such as p-chlorobenzoic acid, cinnamic acid, p-chlorocinnarnic acid and p-methylcinnamic acid were prepared by crystallization from the solutions of both components. All the crystals belonged to typical chiral space group P2₁2₁2₁. The crystal chirality is generated through the formation of a unidirectional twofold helix between the two components through quaternary ammonium salt interaction and hydrogen bonding in the lattice. This kind of spontaneous crystallization necessarily gives crystals of both clockwise and counterclockwise helicites. Here, pseudo-seeding based on utilizing these crystals as seed crystals was examined, resulting in successful helicity control in crystallization from solutions of tryptamine and different carboxylic acids.     

A dual pathway in the solid-state photoreaction of nitrobenzaldehydes with indole

The solid-state photoreaction of the mixed crystals between nitrobenzaldehydes and indole was found to give nitrophenyl-(bis-3-indolyl)methane ( 3 ) and nitrophenyl-(3-indolyl)methanol ( 4 ). The structure of the ortho isomer 4c was established by X-ray crystallographic analysis. A dual pathway from an oxetane intermediate 5 is proposed for the formation of 3 and 4 .     

Enantioselective synthesis mediated by chiral crystal of achiral hippuric acid in conjunction with asymmetric autocatalysis

Enantiomorphous crystals composed of achiral hippuric acid, i.e., naturally occurring N-benzoylglycine, have been used successfully as chiral inducers in enantioselective synthesis in combination with asymmetric autocatalysis to afford the product with extremely high enantiomeric excess.     

Single-crystal-to-single-crystal photocyclization of 4-(2,4,6-triisopropylbenzoyl)benzoic acid in the salt crystal with (S)-phenylethylamine

Ultraviolet irradiation of a salt crystal of 4-(2,4,6-triisopropylbenzoyl)benzoic acid with (S)-phenylethylamine promoted single-crystal-to-single-crystal photocyclization to give an enantiopure (R,R)-cyclopentenol and almost racemic cyclobutenol. The reaction paths were elucidated by X-ray crystallographic analysis of the crystal before and after irradiation.     

Separation of rhenium by extraction with crown ethers and flow-injection extraction—spectrophotometric determination with Brilliant Green

The extraction behavior of perrhenate with crown ethers was studied and methods for the separation and determination of rhenium were developed. The distribution ratio of perrhenate with dicyclohexano-18-crown-6 (DC18C6) increases with increases in the dielectric constant of organic solvents and in the potassium ion concentration of aqueous solution. The molar ratios of crown ether to KReO₄ in the extracted species are probably 1:1 for DC18C6, dibenzo-18-crown-6 and 18-crown-6 and 2:1 for benzo-15-crown-5 and 15-crown-5. Microgram amounts of rhenium were satisfactorily separated from large amounts of molbdenum(VI) by extraction with DC18C6 in 1,2-dichloroethane from 2 M potassium hydroxide solution containing tartrate and by back-extraction with sodium phosphate buffer solution after the addition of a twofold volume of hexane to the organic phase. Rhenium was determined by the flow-injection extraction-photometric method with Brilliant Green. Rhenium was satisfactory determined in molybdenite and other ore samples.     

SOLID-STATE PHOTOCHEMISTRY OF INDOLES WITH NAPTHALENE AND PHENANTHRENE

Abstract— Solid-state irradiation of mixed crystals prepared by meltinga 1:3 molar mixture of indole and phenanthrene followed by resolidifying the melt gave an adduct 2a in 13.5% yield. An adduct 2b was obtained by irradiation of the mixed crystals of 3-methylindole and phenanthrene. Irradiation of the same mixtures of indoles and phenanthrene in solution gave no photoproduct. Irradiation of the mixed crystals of indole and naphthalene gave a similar photoadduct 3a, which was also formed in solution. The 1:1 mixed crystals of indole and phenanthrene and of indole and naphthalene were characterized by various spectroscopic methods. Among them powder X-ray diffraction spectral analysis and differential scanning calorimetry revealed that the former mixed crystal is a simple mixture of microcrystals of indole and phenanthrene, while the latter forms a molecular compound.     

N‐bromosuccinimide catalyzed condensations of indoles with carbonyl compounds under solvent‐free conditions

NBS was found to be an efficient catalyst for condensations of indoles with aldehydes or ketones in the absence of solvent.