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1.
Prem C. Srivastava Marvin L. Tedjamulia Furn F. Knapp 《Journal of heterocyclic chemistry》1986,23(4):1167-1169
The synthesis and tissue distribution studies in rats of tetra[3H]-hydroberberine ([3H] 2 ) and 8-(p-[125I]iodobenzyl)tetrahydroberberine ([125I] 6 ) are described. Compound 2 was synthesized by sodium borohydride reduction of berberine hydrochloride ( 1 ). Treatment of berberine hydrochloride with p-bromo-benzylmagnesium bromide gave 8-(p-bromobenzyl)dihydroberberine ( 4 ) which after sodium borohydride reduction and iodine-125 bromine exchange gave [125I] 6 . The unsubstituted tetrahydro compound [3H] 2 showed significantly higher brain uptake (2.2% dose/gm after 5 minutes) as compared to the corresponding 8-substituted derivative [125I] 6 . Both radiolabeled compounds washed out from the brain relatively quickly. 相似文献
2.
Prem C. Srivastava Furn F. Knapp Carol D. Pruitt 《Journal of heterocyclic chemistry》1988,25(2):667-669
The synthesis of a 1,4-disubstituted dihydropyridine, 1-(E-1[125I]iodo-1-penten-5-yl)-4-(β-N-acetylaminoethyl)-1,4-dihydropyridine ([125I] 10 ), is described. Acetylation of 4-(β-aminoethylpyridine) with acetic anhydride followed by condensation with E-1-borono-5-iodo-1-pentene ( 7 ) gave 1-(E-1-borono-1-penten-5-yl)-4-(β-N-acetylaminoethyl)pyridinium iodide ( 8 ). Chloramine-T and sodium iodide iodination of 8 gave the corresponding E-1-iodo compound 9 which was reduced with sodium borohydride to furnish 1-(E-1-iodo-1-penten-5-yl)-4-(β-N-acetylaminoethyl)-1,4-dihydropyridine ( 10 ). The corresponding radioiodinated compound was prepared similarly using Na[125I]. The tissue distribution studies in rats indicate that [125I] 10 crosses the blood brain barrier (0.49% dose/g in the brain) but gradually washes out from the brain. 相似文献
3.
Takeshi Suwa Terutaka Watanabe Tadao Seguchi Jiro Okamoto Sueo Machi 《Journal of polymer science. Part A, Polymer chemistry》1979,17(1):111-127
The size, distribution, and number of PTFE particles formed by radiation-induced emulsifier-free polymerization were measured by electron microscope and automatic particle analyzer (centrifugation method). From the electron micrographs we found that the particles are formed within 5 min. The change in the number of polymer particles (np) with reaction time (t) depends on the relative concentration of growing polymer chains to stabilizing species produced by the radiolysis of water and monomer; that is, it was governed by TFE pressure/dose rate ratio and classified into three cases: case I, dnp/dt = 0 (e.g., at 3 × 104 rad/hr and 20 kg/cm2); case II, dnp/dt < 0 (e.g., at dose rate below 1.9 × 104 rad/hr and 20 kg/cm2); case III, dnp/dt > 0 (e.g., at 3 × 104 rad/hr and 2 kg/cm2). The polymer molecular weight above 106 is almost independent of the particle size. The polymerization loci are mainly on the surface of polymer particles dispersed in the aqueous phase in cases I and II except in the initial stage. In case III new particles are formed successively during polymerization. Therefore the polymerization loci are mainly in the aqueous phase. Especially in case I, we concluded that after the generation of particles the propagation proceeds mainly on the surface of polymer particles like the core shell model proposed by Granico and Williams. 相似文献
4.
Wendy M. Schluchter Gaozhong Shen Jindong Zhao † Donald A. Bryant † 《Photochemistry and photobiology》1996,64(1):53-66
The psal and psaL genes were characterized from the cyanobacterium Synechococcus sp. strain PCC 7002. The gene organization was different from that reported for other cyanobacteria with psal occurring upstream and being divergently transcribed from the psaL gene. Mutants lacking Psal or PsaL were generated by interposon mutagenesis and characterized physiologically and biochemically. Mutant strains PR6307 (Δpsal?), PR6308 (psal) and PR6309 (psaL?) had doubling times similar to that of the wild type under both high- and low-intensity white light, but all grew more slowly than the wild type in green light. Only monomeric photosystem I (PS I) complexes could be isolated from each mutant strain when Triton X-100 was used to solubilize thylakoid membranes; however, approximately 10% of the PS I complexes from the psal mutants, but not the psaL mutant, could be isolated as trimers when n-do-decyl β-D-maltoside was used. Compositional analyses of the mutant PS I complexes indicate that the presence of PsaL is required for trimer formation or stabilization and that Psal plays a role in stabilizing the binding of both PsaL and PsaM to the PS I complex. Strain PR6309 (psaL?) was capable of performing a state 2 to state 1 transition approximately three times more rapidly than the wild type. Because the monomeric PS I complexes of this mutant should be capable of diffusing more rapidly than trimeric complexes, these data suggest that PS I complexes rather than phycobilisomes might move during state transitions. A “mobile-PS I” model for state transitions that incorporates these ideas is discussed. 相似文献
5.
Judith E. Durham Peter Kovacic 《Journal of polymer science. Part A, Polymer chemistry》1977,15(11):2701-2706
Hydrogenation of poly(p-phenylene) (I) in cyclohexane at high temperature and pressure with rhodium catalyst gave, in low yield, oligomers of 1,4-cyclohexylene(II) in the range of 2–16 cyclohexyl units per chain. Apparently only the low molecular weight fraction in I is reduced because of extreme insolubility. II, which appears to be a novel class, was characterized by molecular weight, 1H-NMR, 13C-NMR, and infrared spectra, gas chromatography, and microanalyses. Dicyclohexyl and perhydro-p-sexiphenyl served as model compounds for comparison in characterization of II. 相似文献
6.
1,3-bis(Dimethylhydroxysilyl)adamantane(I) has been prepared. Thermal condensation polymerization of this monomer yields poly-1,3-adamantyl-1,1,3,3-tetramethyldisiloxane. Condensation of I with bis(dimethylamino)dimethylsilane or 1,3-bis(dimethylamino)-1,1,3,3-tetramethyldisiloxane gave the expected 1,3-adamantyl dimethylsiloxane copolymers (II and III) respectively. These polymers have been characterized by 1H,13C, and 29SiNMR as well as GPC and TGA. They have unusually high thermal stability. 相似文献
7.
Prem C. Srivastava Clarence E. Guyer Furn F. Knapp 《Journal of heterocyclic chemistry》1983,20(4):1081-1084
Two new 125I-labeled barbituric acid analogs, 5-ethyl-5-(E-1-iodo-1-penten-5-yl)2-thiobarbituric acid ( 4 ) and 5-ethyl-5-( m -iodophenyl)barbituric acid ( 7 ), have been prepared and evaluated in rats as potential cerebral perfusion agents. Annulation of 2-ethyl-2-(E-1-iodo-1-penten-5-yl)malonate ( 3 ) with thiourea in the presence of sodium ethoxide gave the 5-ethyl-5-(E-1-iodo-1-penten-5-y1)-thiobarbituric acid ( 4 ). Diethyl 2-ethyl-2-phenyl-malonate was treated with thallium(III) trifluoroacetate followed by addition of aqueous potassium iodide to provide diethyl 2-ethyl-2-(m-iodophenyl)malonate ( 10 ). The malonic ester derivative 10 was condensed with urea in the presence of sodium hydride to give the desired 5-ethyl-5-(m-iodophenyl)barbituric acid ( 7 ), and a decarbethoxylation product, 2-(m-iodophenyl)butyric acid ( 11 ). Iodine-125-labeled 4 and 7 were synthesized in the same manner and the tissue distribution of these new agents evaluated in rats. Both [125I] 4 and [125I] 7 showed high brain uptake. Significant in vivo deiodination was detected with [125I] 4 whereas [125I] 7 was found to be stable to deiodination. 相似文献
8.
Products of the radical reactions arising from t-Bu2O2, CF3I, and CH3I at 146°C in the vapor phase have been measured over a 33-fold range of CH3I/CH3I ratios and shown to be governed by the rapidly established equilibrium Together with K estimated by thermochemical methods, the results yield, for the rate of recombination for CF3· radicals, kr = 109.7 ± 0.5 M?1 sec?1. 相似文献
9.
Akira Matsumoto Masayoshi Oiwa 《Journal of polymer science. Part A, Polymer chemistry》1970,8(3):751-762
Radical polymerization studies on diallyl oxalate (DAO), diallyl malonate (DAM), diallyl succinate (DASu), diallyl adipate (DAA), and diallyl sebacate (DAS) have been conducted kinetically from the standpoint of cyclopolymerization. Benzoyl peroxide was employed as the initiator. The initial overall rate of polymerization, Rp was not proportional to the square root or the first power of the initiator concentration, [I]. But Rp/[I]1/2 and [I]1/2 bore a linear relationship, provided the monomer concentration was kept constant. The residual unsaturation of the polymers decreased with decreasing monomer concentration. The ratio of the rate constant of the unimolecular cyclization reaction to that of the bimolecular propagation reaction of the uncyclized radical, Kc, was evaluated from the above relationship between the residual unsaturation and the monomer concentration at 60°C. The Kc values obtained were 3.6, 3.2, 2.8, 2.5, and 1.2 mole/l. for DAO, DAM, DASu, DAA, and DAS, respectively. The overall activation energies of polymerization were found to be 21.1 (DAO), 24.2 (DAM), 21.7 (DASu), 22.0 (DAA), and 22.2 (DAS) kcal/mole. 相似文献
10.
F. Ciardelli O. Pieroni C. Carlini C. Menicagli 《Journal of polymer science. Part A, Polymer chemistry》1972,10(3):809-822
The synthesis of optically active p-sec-butylstyrene (I) has been carried out starting with (S)-2-phenylbutane (II) having optical purity 88–91%. The optical purity of I thus obtained was found to be 73–75%. The polymerization of I with stereospecific coordinated anionic catalysts gave amorphous polymers, as in the case of many other p-substituted styrene derivatives. The fractions obtained from these polymers have very similar rotatory power at 589 nm which is practically equal to that of polymer of I obtained by nonstereospecific radical initiator and of low molecular weight structural models. Accordingly the 1Lb electronic transition of the aromatic chromophore shows a very low rotatory strength in all samples examined. This result is related to the lack in solution of conformations with a predominant single chirality of the main chain of the macromolecules derived from I. 相似文献
11.
The 19F chemical shifts and geminal coupling constants have been measured for 3,3-dimethyl- (I), 3,3,5-trimethyl- (II) and 3,3,5,5-tetramethyl-1, 1-difluorocyclohexane (III) and 3,3-difluorobicyclo [3.2.1]octane (IV). The Eyring parameters for the ring inversion were obtained for I and III. Representative values for the Arrhenius activation energy (Ea), ΔG?, ΔH?, and ΔS? are: 11.0, 9.4, 10.4 kcal/mole and 4.5 e.u. for I, and 10.0, 8.3, 9.7 kcal/mole and 8.3 e.u. for III. It appears that the syn-axial methyl-fluorine interaction has a negligible effect on the inversion process. However, the syn-axial methyl-methyl interaction, as found in III, significantly increases the rate of inversion. Substituent effects on the 19F shifts are marked. Introduction of methyl at C-3 in an equatorial position leads to shielding of the equatorial and axial fluorines (+1.8 and + 1.3 ppm). Substitution in the axial C-3 position causes deshielding of the equatorial and axial fluorines (?5.9 and ?4.9 ppm). 相似文献
12.
Ming-Qing Chen Takeshi Serizawa Akio Kishida Mitsuru Akashi 《Journal of polymer science. Part A, Polymer chemistry》1999,37(13):2155-2166
Monodisperse polymeric nanospheres, which consist of polystyrene cores and poly(ethylene glycol) (PEG) branches on their surfaces, were prepared by the dispersion copolymerization of styrene (St) with PEG macromonomers that had a methacryloyl (MMA-PEG) or p-vinylbenzyl (St-PEG) end group in various organic solvent/water media. Electron spectroscopy for chemical analysis (ESCA) of the nanosphere surfaces indicated that PEG macromonomer chains were favorably located on their surfaces. The morphologies of the nanospheres were observed via a scanning electron micrograph (SEM), and particle sizes were estimated by a submicron particle analyzer. When both the concentration of macromonomers and molecular weight were higher, small nanospheres in diameter were obtained. Larger nanospheres in diameter were obtained using macromonomers with low molecular weight at lower concentration. The functions that correlate the diameter (Dn) on different concentration units were Dn = K[St]0.64[MMA-PEG]−0.53±0.01[I]−0.49 and Dn = K[St]0.80[St-PEG]−0.69±0.01[I]−0.22, where [I], [St], [MMA-PEG], and [St-PEG] are initiator, styrene, MMA-PEG, and St-PEG macromonomer concentration in feed, respectively. When the reaction parameters such as the molecular weight of the macromonomers were properly chosen, the particle size could be controlled in a range from ca. 80 to 3100 nm. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2155–2166, 1999 相似文献
13.
Charles U. Pittman Paul L. Grube 《Journal of polymer science. Part A, Polymer chemistry》1971,9(11):3175-3186
N-Vinyl-2-pyrrolidone(I) has been copolymerized with vinylferrocene(II) and vinylcyclopentadienyl manganese tricarbonyl(III) in degassed benzene solutions with the use of azobisisobutyronitrile (AIBN) as the initiator. The polymerizations proceed smoothly, and the relative reactivity ratios were determined as r1 = 0.66, r2 = 0.40 (for copolymerization of I with II, M1 defined as II) and r1 = 0.14 and r2 = 0.09 (for copolymerization of I with III, M1 defined as III). These copolymers were soluble in benzene, THF, chloroform, CCl4, and DMF. Molecular weights were determined by viscosity and gel-permeation chromatography studies (universal calibration technique.) The copolymers exhibited values of M?n between 5 × 103 and 10 × 103 and M?w between 7 × 103 and 17 × 103 with M?w/M?n < 2. Upon heating to 260°C under N2, copolymers of III underwent gas evolution and weight loss. The weight loss was enhanced at 300°C, and the polymers became in creasingly insoluble. Copolymers of vinylferrocene were oxidized to polyferricinium salts upon treatment with dichlorodicyanoquinone (DDQ) or o-chloranil (o-CA) in benzene. Each unit of quinone incorporated into the polysalts had been reduced to its radical anion. The ratio of ferrocene to ferricinium units in the polysalts was determined. The polysalts did not melt at 360°C and were readily soluble only in DMF. 相似文献
14.
15.
The spectrophotometric determination of the rate of iodine atom catalyzed geometrical isomerization of diiodoethylene in the gas phase from 502.8 to 609.1°K leads to a rate constant for the bimolecular reaction between I and trans-diiodoethylene of log kt?c(M?1 sec?1) = 8.85 ± 0.12 ? (11.01 ± 0.30)/θ. Estimates of the entropy and enthalpy change for the addition of I atoms to trans-diiodoethylene (process a.b) lead to log Ka.b(M?1) = ?2.99 ? 4.0/θ, and thus to log kc (sec?1) = log kt?c – log Kab = 11.8 ?7.0/θ for the rate constant for rotation about the single bond in the adduct radical. The theory for calculation of the rotation rate constant is presented and it is shown that while the exact value depends on the barrier height, a value of 6.8 kcal/mole for this quantity leads to log k (sec?1) = 11.8 ?6.7/θ. The activation energy points to a better value of the group contribution to heat of formation of the group C -(I)2(H)(C) than one based on bond additivity. 相似文献
16.
J. W. Mcfarland T. H. Kozel K. R. Stuhlmacher T. S. Chevalier 《Journal of heterocyclic chemistry》1980,17(2):273-276
4-Toluenesulfonyl isocyanate (I) reacted with 2-aminoethanol and 3-amino-l-propanol to give 2:1 isocyanate/amino alcohol addition products. 1-Amino-2-propanol and I gave 1:1 and 2:1 adducts while 2-amino-2-methyl-l-propanol afforded only a 1:1 adduct. 4-Toluenesulfonyl isothio-cyanate (III) gave 1:1 adducts with 2-aminoethanol, l-amino-2-propanol and 3-amino-l-propanol, the first two of which were cyclized by concentrated sulfuric acid to 1-(4-toluenesulfonyl)-imidazoline-2-thiones and the third to 1-(4-toluenesulfonyl)hexahydropyrimidine-2-thione. A 1:2 adduct was obtained from III and 2-amino-2-methyl-l-propanol. Amino acids reacted with I and with 4-chlorobenzenesulfonyl isocyanate (II) to give N-(arylsulfonyl)-N1-(carboxylic acid)-ureas. N-(4-Toluenesulfonyl)-N1-(acetic acid)-urea (XVI) was converted to the methyl ester (XIX) by concentrated sulfuric acid and methanol and to water-soluble unrecoverable products by sulfuric acid alone. Glycine and III gave N-(4-toluenesulfonyl)-N1-(acetic acid)-thiourea (XX) which was converted to the methyl ester (XXII) by concentrated sulfuric acid/methanol and to the cyclic 1-(4-toluenesulfonyl)imidazolin-5-one-2-thione (XXI) by sulfuric acid alone. 相似文献
17.
Summary Crystalline copper(I) complexes of the general formula [LCuCl] and [L2CuCl] were prepared for imidazolidine-2-thiones and 1,3-diazinane-2-thiones by the reduction of copper(II) halides with an excess of the ligands. The13C n.m.r. and i.r. spectra of these complexes are consistent with thione sulphur (ligand) donation in all cases. The magnitude of the high-field shift in the13C resonance of the thioureide carbon in the complexes as compared with that of the free ligands is interpreted in terms of coordination geometry around the metal atoms. A comparison of the chemical shifts for gold(I), silver(I) and copper(I) revealed a displacement ofca. 6–8 ppm for the mono- and 2–4 ppm for the bis-complexes, respectively. 相似文献
18.
Electrochemically generated anions of Co and Ni chelate complexes can be alkylated with BunBr, BunI, and (dmgH)2CoMe (dmgH is the dimethylglyoximate anion). Unlike the anionic Co complexes, the anionic Ni complex cannot be alkylated with
BunBr; however, it reacts with stronger alkylating agents (BunI and (dmgH)2CoMe). It is assumed that the electrochemical alkylation of the Ni complex with (dmgH)2CoMe can serve as a model for alkylation occurring in biological synthesis of acetyl coenzyme A. Reactions of some Co chelate
anions with BunI can proceedvia the reduction of the latter.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 55–58, January, 2000. 相似文献
19.
Electrochemically generated anions of Co and Ni chelate complexes can be alkylated with BunBr, BunI, and (dmgH)2CoMe (dmgH is the dimethylglyoximate anion). Unlike the anionic Co complexes, the anionic Ni complex cannot be alkylated with
BunBr; however, it reacts with stronger alkylating agents (BunI and (dmgH)2CoMe). It is assumed that the electrochemical alkylation of the Ni complex with (dmgH)2CoMe can serve as a model for alkylation occurring in biological synthesis of acetyl coenzyme A. Reactions of some Co chelate
anions with BunI can proceedvia the reduction of the latter.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 55–58, January, 2000. 相似文献
20.
Ahmad Hasan Furn F. Knapp Michael R. Kilbourn Donald J. Buchsbaum 《Journal of heterocyclic chemistry》1993,30(5):1351-1355
The design, synthesis and biological activities of several acyclonucleoside analogues related to misoni-dazole are described. The hydroxy- 5 , bromo- 6 , iodo- 7 , and fluoro- 8 derivatives of ethoxymethylazomycin and iodopropenyloxymethylazomycin ( 12 ) have been prepared. Alkylation of silylated azomycin with haloethoxy-methylene chloride gave the corresponding acyclonucleosides. Similarly, propargyloxymethylene chloride gave propargyloxymethylazomycin ( 10 ), which after hydrostannylation and subsequent iododestannylation yielded iodopropenyloxymethylazomycin ( 12 ). The radiolabeled [125I] or [18F] compounds were prepared from the corresponding substrates. Biodistribution results of the radiolabeled analogues in mice showed that compound 7 had good tumor uptake (2.0% injected dose/g at 1 hour). The high radioactive levels in blood and stomach, however, were perhaps due to in vivo deiodination or metabolism. Compound [125I]- 12 showed the highest tumor uptake (4.8 and 3.6% injected dose/g at 1 and 4 hours respectively) of all of the compounds tested. Relatively low thyroid uptake of radioactivity in mice dosed with compound [125I]- 12 indicates significantly reduced in vivo deiodination in comparison to compound [125I]- 7. 相似文献