The preparation of O-methylimidates from alpha-aminonitriles and their subsequent co-cyclization with primary amines to afford 4-substituted 5-aminoimidazoles was studied. It was found that the mildly acidic pyridinium p-toluenesulfonate efficiently catalyzed each stage of the reaction sequence: (a) the formation of the O-methylimidates, (b) their co-cyclization with a variety of primary amines...

Developing new efficient catalytic systems to convert abundant and renewable feedstocks into valuable products in a compact, flexible, and target-specific manner is of high importance in modern synthetic chemistry. Here, we describe a versatile set of mild catalytic conditions utilizing a single gold-based solid catalyst that enables the direct and additive-free preparation of four distinct and...

Upgrading C1 chemicals (for example, CO, CO/H2, MeOH and CO2) with C-C bond formation is essential for the synthesis of bulk chemicals. In general, these industrially important processes (for example, Fischer Tropsch) proceed at drastic reaction conditions (>250 °C; high pressure) and suffer from low selectivity, which makes high capital investment necessary and requires additional purification...

The purpose of the report is to describe dissection techniques for preparing the crayfish hindgut and to demonstrate how to make physiological recordings with a force transducer to monitor the strength of contraction. In addition, we demonstrate how to visually monitor peristaltic activity, which can be used as a bioassay for various peptides, biogenic amines and neurotransmitters. This prepara...

Phthalic, maleic and succinic anhydrides have been reacted with aromatic amines to obtain the corresponding monoacid monoamides. The latter have been each transformed into the corresponding cyclic imide derivatives by treating with SOCl2. Alternatively, anhydrides have been reacted with methanolic KOH to obtain monomethyl ester derivatives which on reaction with aromatic amines in the presence ...

Chromatographic system for simultaneous determination of levodopa, biogenic amines, and methylxanthines in food has been developed. Chromatographic column and precolumn with octadecylsilane phase and simultaneously fluorescence and DAD detectors have been used. Gradient elution with acetate buffer (pH=4.66) with acetonitrile has been applied. Examination included levodopa, norepinephrine, dopam...

A general method has been developed for the preparation of microspheres of nanoporous pigments, their formulation into chemically responsive pigment inks, and the printing of these inks as colorimetric sensor arrays. Using an ultrasonic-spray aerosol-gel synthesis from chemically responsive dyes and common silica precursors, 16 different nanoporous pigment microspheres have been prepared and ch...

Aliphatic and aromatic mono-, diand polyamines are naturally occurring compounds formed as metabolic products in microorganisms, plants and animals, in which the principal routes of amine formation include the decarboxylation of amino acids, amination of carbonyl compounds and degradation of nitrogen-containing compounds. Accordingly, amines are important indicators of a wide variety of biochem...

In natural gas treatment, the removal of CO2 and H2S in acid gases is a critical concern. There are various purification technologies that can be used for the removal of acid gas impurities. Absorption of acid gas into amines is one preferred method in gas industries. In the past, single amines was used, but recently in order to improve absorption performance, mixed amines with different solubi...