Gas chromatographic determination of residual hydrazine and morpholine in boiler feed water and steam condensates

Summary Hydrazine, an oxygen scavenger in boiler water, was derivatised to the corresponding acetone azine and determined at the ng ml^–1 level by gas chromatography. Morpholine, a corrosion inhibitor used in steam boilers, was estimated either directly (if >2.0 g ml^–1) or by quantitative preconcentration (0.1 ng – 2.0 g ml^–1). To obtain symmetrical peaks for these amines, the column packing was coated with KOH. Use of a nitrogen-specific detector improved accuracy of estimation of hydrazine and morpholine, giving a RSD of 1.9–3.6%. Chromatographic analysis of these amines in boiler feed water and steam condensate samples collected from boilers servicing a petroleum refinery is described. Environmental safety regulations calls for monitoring of hydrazine and the methods developed can easily be adapted for this purpose.     

An experimental and theoretical study of excited-state dipole moments of some flavones using an efficient solvatochromic method based on the solvent polarity parameter, E(N)(T)

The electronic absorption and fluorescence spectra of some biologically active natural flavones have been recorded at room temperature (298 K) in solvents of different polarities. The effects of the solvents upon the spectral properties are discussed. Difference in fluorescence intensity of flavones has been explained on the basis of intersystem crossing and degree of non-planarity calculated theoretically using Austin Model 1 (AM1) method. Excited-state dipole moments have been determined using the solvatochromic method based on the microscopic solvent polarity parameter, E(N)(T). A reasonable agreement has been observed between experimental and AM1 calculated dipole moment changes. Our results are found to be quite reliable in view of the fact that the correlation of the solvatochromic Stokes shifts with microscopic solvent polarity parameter, E(N)(T) is superior to that obtained using bulk solvent polarity functions for all the systems studied here.     

Polarographie von Indium(III) in Alkali-und Erdalkalinitratlösungen

Zusammenfassung Es wurde das polarographische Verhalten von Indium(III) in verschiedenen Nitraten in Abhängigkeit von der Konzentration untersucht. Die Ergebnisse wurden unter besonderer Beachtung der Faktoren Viskosität, Diffusionskoeffizienten und Ionensolvatation interpretiert. Die scheinbaren Geschwindigkeitskonstanten wurden nach dem Verfahren vonDelahay bestimmt und ein quasireversibles Verhalten festgestellt.

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Polarography of indium(III) in alkali and alkaline earth nitrates

Polarographic behavior of Indium(III) in several nitrates of varying concentrations has been studied and resuts interpreted in the light of factors viscosity, diffusion coefficients and ion solvation. The apparent rate constants were determined byDelahay's treatment which revealed its quasireversible behavior.

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An den allfällige Korrespondenz zu richten ist.     

A Theoretical Study of LiHe+ n , NaHe+ n , and MgHe+ n Complexes, with n=1, 2, 3, 4

The LiHe⁺ _n , the NaHe⁺ _n , and the MgHe⁺ _n complexes with n=1, 2, 3, 4 were studied using ab initio calculations with the MP2/6-311+G(3df, 3pd) method. The complexes are found to be stable. For the n=1 complexes, previous results were available and the calculations performed are in good agreement with those results. This lends credibility to the results obtained for the complexes with higher n.     

Photolysis of diacyl peroxides: a radical-based approach for the synthesis of functionalized amino acids

[reaction: see text] Photolysis of the amino acid derived symmetrical and unsymmetrical diacyl peroxides at 254 nm at low temperature (-78 to -196 degrees C) generates various bis(amino acids) in a concise manner and with orthogonal protection. The methodology was applied to the synthesis of (4R)-5-propyl-L-leucine (PrLeu), a component of HUN-7293.     

Synthesis of carpachromene and related isopentenylated derivatives of apigenin

Acacetin (4) on reaction with prenyl bromide in the presence of methanolic sodium methoxide yielded 6,8-di-C-prenyl-(5) and 6-C-prenyl-(10) derivatives. The former (5) formed the corresponding bisdihydropyrano derivative (8). Monomethyl derivative of 10 (12) gave monodihydropyrano derivative (13). DDQ reaction of 10 followed by methylation afforded di-O-methyl carpachromene (2); whereas that of 5 gave a mixture of 21 and 22.

Nuclear prenylation of apigenin (3) in a similar way gave 6,8-di-C-C-prenyl-(16), its 7-0-prenyl-(15) and 6-C-prenyl-(18) derivatives. DDQ reaction of 18 provided natural carpachromene.¹ The structure of the isopentylated apigenin isolated by Dreyer et al.² needs further consideration.     

Identification of Druggable Targets for Acinetobacter baumannii Via Subtractive Genomics and Plausible Inhibitors for MurA and MurB

Emergence of the multidrug-resistant pathogens has rendered the current therapies ineffective thereby, resulting in the need for new drugs and drug targets. The accumulating protein sequence data has initiated a drift from classical drug discovery protocols to structure-based drug designing. In the present study, in silico subtractive genomics approach was implemented to find a set of potential drug targets present in an opportunist bacterial pathogen, Acinetobacter baumannii (A. baumannii). Out of the 43 targets identified, further studies for protein model building and lead-inhibitor identification were carried out on two cell-essential targets, MurA and MurB enzymes (of A. baumannii designated as MurA_Ab and MurB_Ab) involved in the peptidoglycan biosynthesis pathway of bacteria. The homology model built for each of them was further refined and validated using various available programs like PROCHECK, Errat, ProSA energy plots, etc. Compounds showing activity against MurA and MurB enzymes of other organisms were collected from the literature and were docked into the active site of MurA_Ab and MurB_Ab enzymes. Three inhibitors namely, T6361, carbidopa, and aesculin, showed maximum Glide score, hydrogen bonding interactions with the key amino acid residues of both the enzymes and acceptable ADME properties. Furthermore, molecular dynamics simulation studies on MurA_Ab–T6361 and MurB_Ab–T6361 complexes suggested that the ligand has a high binding affinity with both the enzymes and the hydrogen bonding with the key residues were stable in the dynamic condition also. Therefore, these ligands have been propsed as dual inhibitors and promising lead compounds for the drug design against MurA_Ab and MurB_Ab enzymes.     

One-Pot Synthesis and Fungicidal Activity of Pyrimidinylidenamido- and Thiazolinylidenamidomonothiophosphoric Esters

A novel one-pot synthesis of four new classes of amidothiophosphoric esters and trisamidothiophosphoric esters is developed. (1-Alkyl-2-pyrimidinylidenamido)bis(diethylamido)thiophosphates, (1-alkyl-2-pyrimidinylidenamido)bis (O-2/4-methylphenyl)thiophosphates, (3-alkyl-2-thiazolinylidenamido)bis (diethylamido)thiophosphate and (3-alkyl-2-thiazolinylidenamido)bis(O-2/4-methylphenyl)thiophosphates are obtained from the nucleophilic substitution and oxidation of N-alkyl-2-cycloiminylidenaminodichlorophosphines generated in situ from the reaction of the corresponding N-alkyl-2-aminocycloiminium halide with phosphorus trichloride and triethylamine. The synthesized thiophosphoric esters have been investigated for fungicidal properties.