Sulfonation of 2-aminobenzimidazole (I) in PPA proceeds at the 5(6)-position whereas the acylation proceeds at the exocyclic nitrogen atom. -(MEL'NIKOVA, E. B.; EL'CHANINOV, M. M.; LUKYANOV, B. S.; Chem. Heterocycl. Compd. (N. Y.) 41 (2005) 7, 938-939; Novocherkassk State Tech. Univ., Novocherkassk 346400, Russia; Eng.) -M. Bohle 16-130

High‐temperature reactions in the aqueous systems La2O3‐Sb2O3‐KF‐H2O2‐H2O or Pr6O11‐Sb2O3‐KF‐H2O afford the hitherto unknown monocrystalline phases of the compounds Ln2SbO5F (Ln: La, Pr).

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The change in bioluminescence field intensity at night in the western part of the Black Sea has been investigated. A difference in the dynamics of the bioluminescence field intensity in the upper (0-35 m) and deep (>35 m) layers has been shown. It is elucidated with multivariate statistical analysis that the biolu minescent species are in the space of influence of several factors, including both biotic and abiotic. Biotic fac tors are shown to exhibit the greatest effect on the periodicity of the bioluminescence field intensity increase and decrease at night. Abiotic factors are less significant in the bioluminescence circadian rhythms.

The electrophilic reactions (nitration, bromination, hydroxymethylation, formylation, acylation) and radical substitution reactions (nitration, arylation) of 2-(2-furyl)benzothiazole have been studied. It was found that all of the reactions occur at position 5 of the furan ring. Only nitration in PPA gave the 5',6-dinitro derivative. Quantum-chemical calculation data for the electron density distribution in the neutral and protonated 2-(2-furyl)benzothiazole molecules are given.Keywords: 2-(2-furyl)benzothiazole, quantum-chemical calculations, substituents orientation, electrophilic and radical substitution reactions.In continuing our search for novel biologically active compounds and organic luminophores amongst 2-hetaryl-substituted benzazoles we aimed to develop or select a convenient method for the synthesis and study of the relative reactivity of the 2-(2-furyl)benzothiazole (1) compared with its benzimidazole analog 2. O S N O N N Me 1 2Only the results of bromination [1, 2] and formylation [3] of compound 1 were known at the beginning of our work. Hence it was of interest to broaden the range of electrophilic substitution reactions by carrying out some of these using radical and oxidative reagents.It has previously been shown [4] that, in contrast to other methods [5, 6], the synthesis of 2-(2-furyl)-benzothiazole (1) gives best results via condensation of furoyl chloride with o-aminothiophenol in DMF. The work carried out by us has confirmed that this method permits the preparation of compound 1 in 85% yield. Compound 1 was then treated with electrophilic reagents including a mixture of nitric acid in PPA, bromine in dichloroethane, formalin in the presence of hydrochloric acid, hexamethylenetetramine in PPA, acetic anhydride in the presence of perchloric acid, and carboxylic acids in PPA. Radical substitution reactions were also carried out including nitration in dilute nitric acid and Meerwein arylation. _______ * Dedicated to Boris Aleksandrovich Trofimov on his 70 th jubilee. __________________________________________________________________________________________