Thermal investigations on γ-radiation processed natural medicinal products (Ashwagandha,Amla and Hartiki)

DSC and TG studies were carried out on -radiation processed Indian natural products of medicinal importance, namely Ashwagandha (Withania Somnifera), Amla (Emblica Officinalis) and Hartiki (Terminalia chebula). DSC thermoanalytical curves were recorded from 35 to 400°C in air and nitrogen atmosphere. Similarly, TG thermoanalytical curves were taken from 35 to 700°C in air and nitrogen atmosphere. Irradiated products gave significantly different thermoanalytical profiles in comparison to non-irradiated samples. The differences were observed above decomposition temperature of 200°C and were non-linear with respect to radiation dose. Partial oxidation of the products during irradiation in air could be responsible for the observed differences.     

Recoil reactions of38Cl and128I in some heterocyclic systems

Halogen recoil following /n, / reaction has been studied in some heterocyclic systems. The organic yields are 60% for irradiation as solids: exceptions are dioxanide furoate /34%/ and 5-chloro isatoic anhydride /31%/. As solutions in 11 THF + benzene and 11 HTF+DMSO, these yields are lower by 10% and decrase further when only THF is the solvent. Mass-spectroscopy data revealed the possible fragmentation pattern.     

Studies on binuclear hydroxo/carboxylato-bridged manganese(III) complexes and a mononuclear manganese(III) complex involving salen type ligands

Synthesis of six hydroxo-bridged binuclear manganese(III) complexes of formulae [MnL-X-MnL](ClO₄) [X = OH (1–6)] along with a mononuclear manganese(III) complex (7) [Mn(L)(L′)(MeOH)₂] [HL′ = 2-(2-hydroxy-phen-yl)benzimidazole] and two carboxylate-bridged binuclear manganese(III) complexes (8) and (9) are described. The complexes have been characterized by the combination of i.r., u.v.-vis spectroscopy, magnetic moments and by their redox properties. The electronic spectra of all the complexes exhibit almost identical features consisting of two d–d bands at ca. 550 and 600 nm, one MLCT band at ca.400 nm, together with two π–π^* intra-ligand transitions at ca. 250 nm and ca.300 nm. Room temperature magnetic data range from μ = 2.7–3.0 BM indicates some super-exchange between the binuclear metal centers via bridging hydroxo/carboxylato groups. The X-ray crystal structure of the binuclear complex (5) revealed that it has a symmetric Mn^IIIN₂O₂ core bridged by a hydroxyl group. The X-ray analysis of the mononuclear complex (7) showed that the manganese-center possesses a distorted octahedral geometry. Electrochemical properties of hydroxo-bridged manganese(III) complexes (1–6) show identical features consisting of an irreversible and a quasi-reversible reduction corresponding to the Mn₂^III → Mn^IIMn^III → Mn^IIMn^II couples in the voltammogram. It was found that electron withdrawing substituents on the ligand result in easier reduction. Complex (7) displays an irreversible reduction at 0.08 V and a reversible oxidation at 0.45V assignable to the Mn^III → Mn^II reduction and Mn^III → Mn^IV oxidation, respectively. The carboxylate-bridged compound (8) exhibits two irreversible oxidations at 0.4 and 0.6 V, probably due to Mn₂^III → Mn^IIIMn^IV → Mn^IVMn^IV oxidations and shows a quasi-reversible reductive wave at −0.85 V, tentatively assigned to Mn₂^III → Mn^IIMn^III reduction.     

Reaction of 3,6-diphenyl-1,2,4,5-tetrazine with cis,cis-1,5-cyclooctadiene : An attempt at preparing some dihydropyridazine derivatives

The reaction of 3,6-diphenyl-1,2,4,5-tetrazine 1 with cis,cis-cycloocta-1,5-diene 7 has been studied with a view to preparing some interesting dihydropyridazine derivatives. Refluxing a mixture of 1 with excess of 7 in benzene solution for 8hr resulted in the formation of a mixture of products consisting of 1,4-diphenyl-10a-hydroperoxy-4a, 5,6,9,10,10a-hexahydrocycloocta[d]pyridazine (8, 27%) and 2,4a,5,6,8,10a,11,12-octahydro-1,4,7,10-tetraphenyldipyridazo[4,5-a:4',5'-e]cyclooctene ( However, when the reaction of 1 with 7 was carried out in refluxing benzene for nearly 40 hr, the products formed were a 14% yield of 8, a 17% yield of 9 and a 37% yield of 1,4-diphenyl-5,6,9,10-tetrahydrocycloocta[d]pyridazine (10). Neat heating of 1 with 7 around 150° for 10 hr, on the other hand, gave a 20% yield of 9, as the only isolable product. Thermolysis of 8 around 155° gave a mixture of products consisting of 2-oxocyclooct-5-enyl phenyl ketone N-benzoylhydrazone (15,30%) and 1H-3-phenyl-4,5,8,9-tetrahydrocycloocta[d]pyrazole (16, 22%). Nickel peroxide-oxidation of the adduct 9 gave a 67% yield of 1,4,7,10-tetraphenyldipyridazo[4,5-a:4',5'-e]cyclooctene (27). Acetylation of 9, on the other hand, gave a 70% yield of 2,3,8,9-tetraacetyl-2,3,5,6,8,9,11,12-octahydro-1,4,7,10-tetraphenyldipyridazo[4,5-a:4',5'-e]cyclooctene(28).     

Non-isothermal studies of adduct molecules of metallic halides with oxo-compounds in solid state. V

Non-isothermal studies of some adduct molecules of metallic halides with tetrahydropyran as the type MX₂(THP)_y in solid state, were carried out with a Derivatograph, where M  Mn(II), Co(II), Ni(II), Cu(II) or Cd(II), XCl^- or Br^-, THPtetrahydropyran and y0.1–1. These adduct molecules lost tetrahydropyran in single or multiple steps upon heating. Thermally stable intermediate products were isolated and characterised by elemental analysis and IR spectral measurement. The activation energy for each step of decomposition of the adduct was evaluated from the analysis of TG, DTG and DTA curves of the respective derivatogram. The enthalpy change was evaluated from the DTA peak area and the order of reaction was found to be unity, for each step of decomposition. Thermal parameters for the above adducts were compared with the adducts of other oxocompounds like dioxan, tetrahydrofuran, ethylene glycol dimethyl ether and diisopropyl ether.     

On the relationship between distinction and irreducibility of parabolic induction

Let $U_{2n}$ denote the quasi-split unitary group over 2n variables with respect to a quadratic extension $E/F$ of p-adic fields. In this short note, we relate ${\mathrm{GL}}_n(F)$-distinction of ladder representations of ${\mathrm{GL}}_n(E)$ with irreducibility of its Siegel parabolic induction in $U_{2n}$.