Zirconium(IV) fluorosulphates : Preparation and characterization

Zr(SO₃F)₄, (A); ZrO(SO₃F)₂, (B); Zr(O₂CCH₃)₂, (SO₃F)₂, (C); and Zr(O₂CCH₃)₃SO₃F, (D) have been prepared and characterized (elemental analysis,i.r. Spectra and thermal analysis). The SO₃F groups are bidentate in (A) – (C) but have C_3V symmetry in D where all the three oxygen atoms of SO₃F group are coordinated in an equivalent manner. (A) – (D) are good Lewis acids and form coordination complexes with pyridine, triphenylphosphine oxide and 2,2′-bipyridyl. The thermal decomposition of the fluorosulphates is complex.     

ENERGETICS OF DNA REPAIR IN UV-IRRADIATED PERIPHERAL BLOOD LEUKOCYTES FROM CHRONIC MYELOID LEUKAEMIA PATIENTS

Abstract— The relationship between energy metabolism and UV-induced (251 nm) DNA repair has been investigated in leukocytes obtained from peripheral blood of chronic myeloid leukaemia patients. Energy supply was modulated by using inhibitors of respiratory (antimvcin-A) and glycolytic (2-deoxy-o-glucose and other glucose analogues) pathways for adenosine-triphosphatc (ATP) production. DNA repair was measured by the unscheduled DNA synthesis technique. Parameters of energy metabolism like glucose utilization. lactate production and ATP content of cells. were measured under similar experimental conditions. The observations made indicate the following results: (1) ATP for DNA repair can be supplied by the respiratory and/or by the glycolytic pathway. (2) In the absence of respiration, the rate of glycolysis bears a linear correlation with DNA repair. (3) A minimum threshold rate of ATP-production is necessary for DNA repair.     

A simple and reliable semipreparative high-performance liquid chromatography technique for the isolation of marker-grade hyperforin from Hypericum perforatum L extract

The present work describes isolation of bioactive lipophilic constituent [namely, hyperforin from St. John's wort (Hypericum perforatum L.)], of approximately 98% purity by semipreparative high-performance liquid chromatography (LC). The extraction, isolation, and analysis of the collected compound is performed without the use of antioxidants and inert gas atmospheres at all the stages. Hyperforin, separated isocratically on a 12microm semiprep column, is obtained in high purity, lyophilized after the removal of the organic phase, and preserved at a low temperature. The purity of the collected marker compound is estimated by the use of LC-mass spectrometry and spectroscopic techniques.     

4-(Arylaminothiocarbonyl)-1-(1-o-methoxyphenylcarbamido)-ethylpiperazines as anticonvulsants

Several 4-(arylaminothiocarbonyl)-1-(1-o-methoxyphenylcarbamido)-ethylpiperazines were synthesized and evaluated for their anticonvulsant activity against pentylenetetrazol-induced seizures in mice. The ability of substituted piperazines to inhibit in vitro respiratory activity of rat brain homogenates was also determined to study their structure-activity relationship.     

Vibrational spectra and rotational isomerism of triallyl amine

The infrared spectra of triallyl amine in the vapour and liquid phases (as solutions in CS₂, CCl₄, CH₃Cl and CH₃CN), and in the solid state at low temperature were measured from 250 to 4000 cm⁻¹. The Raman spectrum of the liquid was recorded and qualitative depolarization measurements were made. It is shown that in the liquid and vapour phases the molecule exists as a mixture of at least two rotational isomers, while in the crystalline phase it assumes a single configuration having point-group symmetry C₃. A vibrational assignment for the observed bands in the infrared and Raman spectra is proposed on the basis of the C₃ point group symmetry for the more stable form of the molecule.     

o-Iodosobenzoate as an oxidimetric titrant

o-Iodosobenzoate has been used as a titrant at pH 7 with potassium iodide and starch as indicator, under Andrews' titration conditions with iodine monochloride as preoxidant, and in acid medium with potassium bromide and Methyl Red as indicator. Methods are described for the determination of tetrathionate (through disulphide cleavage by cysteine), hydrogen sulphite, thiosulphate, xanthates, cysteine and glutathione in certain combinations (involving masking of sulphite and thiols with acrylonitrile). Hexacyanoferrate(II) is determined in the presence of arsenic(III), antimony(III) and thallium(I). Sulphathiazole, sulphadiazine and sulphamerazine consume six equivalents of bromine per mole, but phthalation or diazotization of the aromatic amino group prevents disubstitution of bromine in the benzene ring. Chloramphenicol is determined by reduction of its aromatic nitro group to an amino group, followed by bromination. Rutin and vitamin C react with eight and two equivalents of bromine per mole respectively.     

Oxy-cope rearrangements of bicyclo[3.2.0]heptenones. Synthesis of bicyclo[4.2.1]non-1(4)-en-6-ones and bicyclo[5.2. 1]dec-1(10)-en-5-ones

6-exo-Methylbicyclo[3.2.0]hepten-7-ones and their 2-alkylidene analogues are readily prepared from dialkyl squarates. These compounds undergo facial oxy-Cope ring expansions upon treatment with vinyllithium; the former leads to bicyclo[4.2. 1]non-1(4)-en-6-ones and the latter to the first examples of bicyclo[5.2.1]dec-1(10)-en-5-ones, compounds having exceptionally strained bridgehead double bonds. The transformations are controlled by the 6-exo-methyl group in the starting material along with the substituent at position-1 (bridgehead) which force attack of the lithium reagent from the concave face of the starting material, thus allowing the cyclopentenyl or alkylidene groups to participate in the sigmatropic event.     

Determination of bromine in organic compounds by high-performance liquid chromatography

A method is proposed for the determination of bromine in organic compounds (which may also contain chlorine and iodine) by oxygen-flask combustion of the compound followed by pre-column reaction of bromide with acetanilide and 2-iodosobenzoic acid to form 4-bromoacetanilide which is then chromatographed on an ODS column with a mobile phase of methanol: water, 65:35 v/v, detection at 240 nm, and 4-N-acetylaminotoluene as internal standard. The method is rapid and precise (RSD 相似文献   

Determination of thiourea and its organic derivatives with iodine trichloride

Thiourea and its organic derivatives and thiosemicarbazide are determined in water, methanol or glacial acetic acid medium by reaction with an excess of iodine trichloride in the presence of mercuric chloride. The reaction is complete in 15 min. The excess of iodine trichloride is evaluated by adding potassium iodide and titrating the liberated iodine with thiosulphate. A variety of organic thioureas can be determined with an average accuracy and precision of 0.2%.     

Freezing temperatures of aqueous solutions of methyl formate and ethyl acetate with a variety of nonelectrolytes. Gibbs energy of interaction of the ester group with other functional groups

Freezing temperatures of dilute aqueous solutions of ethyl acetate and mixtures with myo-inositol, D-mannitol, formamide, 1,3,5-trioxane, 1,4-dioxane, acetamide, hexamethylenetetramine, and methyl formate have been measured. In addition, freezing temperatures of dilute aqueous solutions of methyl formate and mixtures with the above solutes have been measured. From these data, the pairwise molecular Gibbs energies of interaction between the molecules were calculated. Using the additivity principle, the pairwise functional group Gibbs energies of interaction were calculated for ester group interactions with a variety of other functional groups.