Search results for "gas [monitoring]"

STUDIEN ZUM VORGANG DER WASSERSTOFFÜBERTRAGUNG 621HERSTELLUNG UND ELEKTROREDUKTIVE SPALTUNG EINIGER ARYLDISULFONSÄUREDERIVATE

1982

Abstract Benzene-disulfonylchlorides were converted to the corresponding dialkyl-and diphenylesters, N-alkyl-and N-aryl disulfonamides. The half-wave-potentials E1/2 1 and E1/2 2 were measured and the products obtained on potentiostatic fission at E1/2 1 were isolated and characterized. The electroreduction of benzene-1,4-disulfonic acid-diphenylester in methanol yields phenol in a quantity approximately corresponding to the current passed, but no corresponding quantity of sulfinic acid. In dry acetonitrile, benzene-1,4-disulfonic acid diesters and diamides undergo potentiostatic fission (at E1/2 1) in good chemical and current yields, giving the corresponding monosulfonate-sulfinic acid or…

ChemInform Abstract: First Evidence of Proline Acting as a Bifunctional Catalyst in the Baylis-Hillman Reaction Between Alkyl Vinyl Ketones and Aryl …

2008

Proline in the presence of sodium hydrogen carbonate has been found to be an effective catalyst for the Baylis–Hillman reaction between methyl or ethyl vinyl ketone and aryl aldehydes. Screening of several amine catalysts showed that an ionizable carboxylic function directly linked to the secondary amine catalyst plays an important role in the synthesis of the desired product in good yield. The data obtained has allowed us to suggest, for the first time, that proline, sarcosine, pipecolinic acid and homoproline may act as bifunctional catalysts via a bicyclic enaminolactone species as intermediate. Quantum-mechanical calculations (PM3/COSMO and ab initio 3-21G/COSMO) support this mechanism …

Fluorous TBAF: A Convenient and Selective Reagent for Fluoride-Mediated Deprotections

2009

A fluorous analogue of TBAF has been developed for its use in the clean removal of silicon-derived protecting groups. Purification of the crude mixtures by fluorous solid-phase extractions allowed alcohols, amines, and carboxylic acids to be obtained in high purity, with no need of chromatographic separations. The moderate reactivity of fluorous TBAF was exploited in selective deprotections of several bifunctional molecules.

Synthese und13C-NMR-Spektroskopie cyclischer und acyclischer β-Phosphonioenamine

1979

Quartare Phosphoniumsalze, die auser einem Allyl- einen Alkinylrest (z. B. 1) oder einen Acylmethylrest tragen (z. B. 4–6) reagieren mit primaren Aminen zu den bisher unbekannten 1,2,3,4-Tetrahydro-1,4-azaphosphoriniumsalzen 2, 3, 8–12, 19 und 25. Die Umsetzung von 4 liefert in Abhangigkeit vom eingesetzten Amin auser 8–12 die 5-Amino-1,2,3,4-tetrahydro-3-methylphosphoriniumsalze 13–16 die im sauren Medium schnell zu 17 hydrolysieren. Als Zwischenstufen der Cyclisierung von 4 konnen die offenkettigen β-Phosphonioenamine 18, 20 und 21 isoliert werden. Die Cyclisierung von 18 zu 19 gelingt erst in Gegenwart von Triethylamin als Base. Struktur und Konfiguration der neuen Verbindungen werden mi…

An Unexpected Three-Component Condensation Leading to Amino- (3-oxo-2,3-dihydro-1H-isoindol-1-ylidene)- acetonitriles

2004

The reaction of 2-carboxybenzaldehyde with primary amines in the presence of cyanide leads to the formation of 2-substituted amino(3-oxo-2,3-dihydro-1H-isoindol-1-ylidene)acetonitriles. These compounds originate from the condensation of 2-carboxybenzaldehyde with the amine and two molecules of hydrogen cyanide and represent a novel class of isoindolinones.

Preparation of N,O-Aminals as Synthetic Equivalents of H2C=NAr and (H2C=NHAr)+ Ions: Neutral and Acid-promoted Transformations

1988

A general method for the synthesis of N,O-aminals derived from primary aromatic amines is described. The reactivity of these compounds under neutral and acidic conditions has been studied and the title compounds can be envisaged as general purpose H2C=NAr or (H2C=NHAr)+ equivalents. N,O-Aminals have been converted into perhydrotriazines by moderate heating and into bis(4-aminoaryl) methane derivatives or N-benzylarylamines, respectively when heated in acidic media with pH control. Reduction of N, O-acetals with sodium cyanoborohydride has revealed that the C-O bond is broken exclusively in acidic media.

Binding of acrylic and sulphonic polyanions by open-chain polyammonium cations

2000

Abstract The interactions between some acrylic and sulphonic polyanions and some protonated amines (diamines NH 2 -(CH 2 ) x -NH 2 , x =2,…,10; linear tri-, tetra-, penta- and hexa-amines) were studied potentiometrically in aqueous solution, at 25°C. For both types of polyanions AL 2 H i (L − , monomer of polyanion, A, amine) species are formed, with i =1,…, n ( n =number of amino groups in the amine). The stability of these species is strictly dependent on the polyammonium cation charge, and fairly independent of the type of amine (in diamine species maximum stability is observed for x =4, 5). Acrylic and sulphonic polyanion complexes are considerably stronger than analogous species formed…

1987

Drug carriers were prepared by combining oligopeptidic sequences with synthetic polymeric chains. Soluble copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) were synthesized containing oligopeptidic side chains terminating in a drug model (p-nitroaniline). The susceptibility of these oligopeptidic sequences to degradation on incubation with lysosomal enzymes and human serum was evaluated by monitoring the p-nitroaniline liberation. It was shown that the drug model can be attached to the polymer carrier by means of an oligopeptidic spacer stable in blood serum and degradable after the polymer has been in contact with intracellular lysosomal enzymes. The studied polymer carriers were used…

Antimykotische Wirkstoffe, 16. Mitt. Halogenierte Cyanaminomethylenpiperidine und -piperazine

1984

Die in Gegenwart der sekundaren Amine 5a-e mit Hilfe von s-Triazin (2) als Dreikomponentenreaktion durchgefuhrte Aminomethinylierung von Cyanamid (1) liefert die korrespondierenden als Dehydro-N-Mannich-Basen aufzufassenden Cyanaminomethylenheterocyclen 6a-e. Insbesondere 6a und 6e besitzen antimykotische Wirksamkeit. Antimycotic Agents, XVI: Halogenated (Cyanaminomethylene)piperidines and -piperazines The aminomethinylation of cyanamide (1) by means of s-triazine (2), carried out as three-component reaction in the presence of the secondary amines 5a–e, yields the cyanaminomethylene heterocycles 6a–e, which are to be classed as dehydro-N-Mannich bases. Compounds 6a and 6e in particular show…

1,3-Di(hetero)aryl-7-substituted Pyrenes—An Undiscovered Area of Important Pyrene Derivatives

2019

Despite the pyrene derivatives have been covered extensively by scientists during the last years, many interesting properties and applications of pyrene derivatives have been presented, nowadays there are still areas of pyrenes’ chemistry that need to be fulfilled. Most of the described in literature pyrenes are 1,3,6,8-tetrasubstituted followed by 4,5,9,10-tetrasubstituted, 2,7-, and 1,6-, and 1,8-disubstituted pyrene derivatives. In the case of 1,3-di(hetero)aryl-7-substituted, there are only a few examples of derivatives containing at position 7 - tert-butyl group. In this work, the necessity of synthesis of 1,3-di(hetero)aryl-7-substituted pyrenes is presented based on the results of th…