Study of Preparation and Properties of Imidazolium Betaines

To investigate the posibility for the preparation of 1,3-dicarboxyalkyl( benz)imidazolium betaines a number of monosubstituted 1-carboxyalkyl(benz)imidazoles has been prepared (I-X) and their basic pKa value determined. The betaines (XI~XIV) can be prepared only from the imidazole derivatives which had basic (N3) pKa values above 3--4 pKa units. !-Substituted benzimidazoles decomposed under reaction conditions employed ·for quaternization, yielding N,N\u27-dicarboxyalkyl o-phenylenediamines. Dimethylformamide when used as the solvent under highly basic reaction conditions reacted with halogen carboxylic acid.s giving · rise to the formation · of betaines of dimethyl-dicarboxyalkyl amines (XV, XVI) and hydrochlorides of dimethyl-carboxyalkyl amines (XVII, XVIII), respectively. The reaction course of 1,3-disubstitution is briefly discussed, as well as some chemical and physical properties of the betaines are described

Scientific Research in Academy and Chemical Industry Dichotomy or Different Philosophies, Achievements and Consequences

Rasprave na temu što je zajedničko, a što razlikuje znanstvena istraživanja u akademskim institucijama i industrijskim istraživačkim centrima česte su u svim područjima kemije. Nova znanstvena saznanja u akademskim istraživanjima s jedne strane te uspješna znanstvena i tehnološka rješenja u industriji, koja su iz temelja promijenila uvjete života u razvijenom svijetu, postavila su ova dostignuća iz različitih razloga u konkurentan položaj. Ako je dihotomija dijeljenje ili podijeljenost cjeline na dva dijela, u kojoj nešto što je dio jedne polovine ne može biti nikako dio druge polovine, onda imamo danas velik broj zagovornika ovog odnosa izme?u dva pristupa znanstvenim istraživanjima. U ovom prikazu bit će ponu?ena argumentacija koja otklanja ovakvu podjelu znanstvenih istraživanja u kemiji te opisana neka dostignuća u znanstvenim istraživanjima i posljedice po okoliš zbog nebrige u tehnološkoj izvedbi.Disputes on the topic what is in common and what differentiates scientific research in the academic institutions and in the industrial research centers are ongoing among scientists in all fields of chemistry. New, original scientific knowledge in academic research on one hand, and successful scientific and technological solutions in industry, which have substantially improved life in the developed world on the other, have opposed these achievements and put them for various reasons in the concurrent positions. If dichotomy represents division of the whole in two halves, wherein nothing which belongs to one part can be the part of the second half, then we nowadays have a large number of prophets for this relation between two approaches to scientific research. This article offers argumentation which intends to remove this division in chemistry, and describes some achievements in research but also environmental consequences due to careless technological realization

Syntheses of the New Indole Derivatives Related to Indomethacin

Syntheses and properties of the new indole derivatives 18-33, being potential antiinflammatoric agents, are described. 1-p-Chlorobenzoyl- 2-methyl-3-(2\u27-methyl-4\u27-nitroimidazol-1\u27-yl)-5-methoxyindole (32) have been found to possess pronounced antiinflammatoric activity and very low ulcerogenity. Attempting preparation of N-benzoylindole derivative 38 via sigmatropic rearrangement of the open chain precursor 35, as a model procedure for the new synthesis of indomethacin, very low yields on the desired cyclic product 38 have inevitably been obtained

Circular Dichroism of Optically Active 1,4-Benzodiazepines

Assignment of the CD-bands of 1,4-benzodiazepin-2-one derivatives (1-14, 26), and their 2-deoxo-congeners (15-25) has been performed by applying the qualitative MO theory and the exc1iton coupling theory. It has been found that the longest wavelength band (about 310 nm), as well as that around 250 nm correspond to the B2u and B1u transition of the chiral partial chromophore A, respectively, while the corresponding transitions for the partial chromophore C give rise to the bands at 285 nm and 250 nm (Figures 2-4). The CD-signs for several of these Cotton effects can be derived in a nonempirical manner. 7-Nitro derivatives, 23-25 scape above analysis, however, since the nitro-group is a very strong perturber, which has its own absorption bands in the same region. Model cyclic and acyclic compounds 27-36 have been prepared, and their CD-spectra analysed in the same way

Chiral 1,4-Benzodiazepines. VIII. Concerning the Rate of WD Exchange and Optical Stability of the Chiral Centre C(3).

Various chiral substituted 1,4-benzodiazepin-2-ones with 3- -acyloxy (general formula I), 3-hydroxy- and 3-alkoxy (general formula II), 3-alkyl (general formula III) and 3-quaternary ammonium (general formula IV) groups as substituents were subjected to C(3)-H-D exchange rate measurements in order to obtain information on the optical stability of the chiral centre and on the mechandsm of racemization. Only type IV compounds (IVa-j) exhibited H/D exchange, but acid catalyzed racemization took place in type I and II compounds, indkating some other mechani. sms in this process. Type III compounds as free bases (IIIa-c), N4-protonated acids, or N4-oxides (III, e; f) underwent no H/D exchange and are optically sfable as well. In cases whe,re deprotonation- reprotonation mechanism of racemization can be excluded two other mechanisms are discussed, i. e. acid-\u27catalyzed ring-chain tautomerism and identity substitution with alkoxide ion