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[en] The emission spectra of a matrix of NE111 doped with benzophenone, acetophenone, and piperidine each at concentrations of 0, 1, 2, 5, and 10% were measured using low-energy dc-electron excitation. Absorption spectra covering the region of 300-500 nm were also measured. Based on the systematics observed in the above spectra, response measurements were performed wherein the emission spectrum incident on a detector was filtered by selected narrow band (<=10 nm) filters. The scintillator fluorescence was excited by 0.2 ns pulses of X-rays (<=2 keV) produced in a laser plasma with the LPARL Nd:glass laser facility. Fast time response measurements were performed using an S20 streak camera. In addition, the ratio of the integral of the emitted fluorescence in the first 8 ns to the integral out to 1 s, was determined as a function of emission wavelength. In neither of these experiments was it possible to produce relevant changes in the scintillator response by the introduction of filters. (Auth.)
[en] Ln-macrocyclic((20)DOTA) complexes, (Ln((20)DOTA)NO3)(H2O))(NO3)2·xH2O(Ln(III)=Pr, Sm, Gd, Dy), which had been synthesized from 2, 6-diformyl-p-cresol(DFPC), was placed in methanol for 2 days, and (Ln((20)DOTA)(NO3)(CH3OH))2+ was formed. The equilibrium constants(K) for the substitution of coordinated CH3OH in the Ln-(20)DOTA complexes by various auxiliary ligands, La(=monodentate ligands; pyridine, imidazole, triethylamine, diethylamine, piperidine) were determined spectroscopically at 25. deg. C and 0.1 M. The pKa of auxiliary ligand is in the order of pyridine < imidazole< triethylamine< diethylamine< piperidine, however the K has shown the trend of pyridine< imidazole< diethylamine< piperidine< triethylamine
[en] Unpretentious and exclusive methods for the spectrophotometric determination of trace amount of divalent palladium (II) have been developed with rubeanic acid (dithio-oxamide) in presence of secondary ligands like pyridine, piperidine and 3-picoline. Both direct and extraction spectrophotometry showed that coloured rubeanates are only stable in acidic medium. The violent yellow coloured products are formed below ph 5.0 with an absorption maxima at 416.0 and 422.0 (pyridine), 405.0 and 416.5 (piperidine) and 418.0 and 422.0 (3-picoline) both in direct and isoamyl alcohol (IAA) extracted system, respectively. Results indicate that the highest sensitivity and molar absorptivity of Pd-RA pyridine system in direct spectrophotometry were 0.01497 mu g Pd(II) cm/sup -2/ and 7107.89 L mol sup -1/ cm/sup -1/ respectively. IAA extracted Pd-RA-piperidine system was found to give a sensitivity of 0.01087 mu g(Pd(II) cm /sup -2/ and molar absorptivity of 9788.80 L mol /sup -1/ cm/sup -1/ which were the highest of all the system. The effects due to variation of pH, reagent concentrations, order of addition of reagents, time, temperature and solvent media on the absorption spectra have been investigated and the optimum conditions determined. The effects of diverse ions and their tolerance limit have also been studies. (author)
[en] Zeolites with different structures were synthesized from the hydrothermal synthesis condition employing simple structure directing agent (SDA) containing piperidine moiety. The gel containing 1.0SiO2:0.9SDA:0.062NaAlO2:0.217NaOH:20H2O was subject to hydrothermal synthesis at 413-453 K for 7 days. FER type zeolite was obtained at 433 K when piperidine was employed as SDA, whereas TON and MFI type zeolites were also obtained at 433 K when 2,6-dimethylpiperidine and 2,2,6,6-tetramethylpiperidine were used, respectively. Further increase of hydrothermal synthesis temperature to 453 K resulted in the formation of TON type zeolite when 2-mtheylpiperidine was used. The structural analysis of powder X ray diffraction pattern over FER type zeolite suggested that the SDA, piperidine interacted intimately with the zeolite where it located close to the framework
[en] An effective and facile multicomponent method for the synthesis of polysubstituted piperidines is described. The Michael–Mannich type cascade of benzylidenemalononitriles with aromatic aldehydes and ammonium acetate or aqueous ammonia provides convenient access to the stereoselective synthesis of 3,3,5,5-tetracyano-2,4,6-triarylpiperidines in good to excellent yields in one-pot manner. Ammonium acetate or aqueous ammonia plays a role both as a catalyst and as a nitrogen source. It is established that the reaction proceeds via sequence of equilibriums and a competitive mechanisms are implemented. Graphical abstract: .
[en] Second-order-rate constants (kN) have been measured spectrophotometrically for the reactions of 4-nitrophenyl 2-thiophenecarboxylate (1a) with a series of secondary alicyclic amines in H2O containing 20 mole % DMSO at 25.0 .deg. C. The ester 1a is less reactive than 4-nitrophenyl 2-furoate (1b) but more reactive than 4-nitrophenyl benzoate (1c) except towards piperazinium ion. The Broensted-type plots for the aminolyses of 1a,1b and 1c are linear with a βnuc value of 0.92, 0.84 and 0.85, respectively, indicating that the replacement of the CH=CH group by a sulfur or an oxygen atom in the benzoyl moiety of 1c does not cause any mechanism change. The reaction of piperidine with a series of substituted phenyl 2-thiophenecarboxylates gives a linear Hammett plot with a large ρ- value (ρ-=3.11) when σ- constants are used. The linear Broensted and Hammett plots with large βnuc and ρ- values suggest that the aminolysis of 1a proceeds via rate-determining break-down of the addition intermediate to the products
[en] The effect additions of n-butylamine, tert-butylamine, piperidine, and morpholine have on the kinetics of the complexation of zinc acetate with octa(m-trifluoromethylphenyl)porphyrazine in benzene is studied. A possible scheme of the complexation reaction is proposed. It is established that the rate of the reaction slows with the branching of the hydrocarbon chain in the amine, and it grows along with the pKa of the nitrogen-containing base.
[en] A variety of 4(1-pyrrolidinyl) piperidine analogs 2-6 with variable substituents on phenyl ring of phenacyl moiety were synthesized and evaluated for their analgesic inhibitory potential by tail flick method revealed significant analgesic activity. The synthetic compounds exhibit analgesic inhibitory potential was ranging from significant to highly significant activity. Compounds were evaluated by thermal stimuli (tail immersion method) at the dose of 50 mg/kg of body weight. The compounds 2-5 showed significant and highly significant analgesic activity. Pethidine was used as reference drug. Same compounds tested at the dose of 75mg/kg of body weight showed toxicity. The size of the substituent, electron donating or withdrawing affect of substituents as well as the position of substituent on phenyl ring affected the activity. These compounds could be considered to develop a new class of analgesics. (author)
[en] A mild and simple technique for preparing of 4-benzyl-1-(3-[125I]iodobenzylsulfonyl)piperidine, 4-(3-[125I]iodobenzyl)-1-(benzylsulfonyl)piperazine and their derivatives, as sigma-1 receptor ligands, with relatively high radiochemical yields via nucleophilic substitution reaction by means of isotopic and non-isotopic exchange reactions is described. Some factors affecting the radiochemical yield were commonly studied in presence of acidic medium at elevated temperature. Unfortunately, the radiochemical yields were weak. Some attempts were carried out in presence of polar aprotic solvents to enhance the radiochemical yield. N,N-Dimethylformamide was proved highly efficient for preparing of radioiodinated 4-benzyl-1-(3-iodobenzylsulfonyl)piperidine (4-B-[125I]-IBSP, 70 ± 5.7 %) and 4-(3-iodobenzyl)-1-(benzylsulfonyl)piperazine (4-[125I]-IBBSPz, 72 ± 6.0 %) at moderate temperature (100-105 deg C) within 8 h. The specific activities of 4-B-[125I]-IBSP and 4-[125I]-IBBSPz (6,534.2 and 5,927.4 MBq/mmol) were obtained respectively. (author)