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41.
Optimum Obtention of Proferrorosamine A from Pseudomonas roseus fluorescens J. C. MARCHAL 1937. We have developed the best conditions for the culture of Pseudomonas roseus fluorescens, and a quantitative isolation of the Proferrorosamine A produced in the culture solution, in order to study the incorporation of 1-[14C]-glycerol in this propigment. 相似文献
42.
Setzer MJ 《Journal of colloid and interface science》2001,235(1):170-182
In contrast to the triple-point condition of bulk material, condensed matter in porous media can coexist stably as liquid, solid, and vapor over a wide temperature range. The necessary conditions are found by a thermodynamic approach starting with the potential which reflects the grand canonical distribution and is characterized by heat and matter exchange. The other parameters are volume and surface. Therefore, it is designated the free mechanical potential. General expressions for mechanical stability are given. On condensation and melting the nonwetting phases vanish. These are thermodynamically stable phase transitions. For the opposing effects evaporation and fusion, an energy barrier must be transgressed either by nucleation or by intrusion as discussed here. These are metastable states. Phase transitions are the conditions which limit the triple-phase region. Within this region high negative pressures are generated in the unfrozen liquid independent of the pore size where it exists. The findings are applied to water in the disperse matrix of hardened cement paste. They are the basis for "micro ice lens pumping". Copyright 2001 Academic Press. 相似文献
43.
Max Herberhold Udo Drfler Bemd Wrackmeyer 《Journal of organometallic chemistry》1997,530(1-2):117-120
1,2-Bis(dimethylamino)-1,2-dibora-[2]ferrocenophane (1) was prepared by the reaction of 1,1′-dilithioferrocene with 1,2-dichlorobis(dimethylamino)diborane(4). In addition to hindered rotation about the B-N bond (ΔG‡ > 80 kJ mol−1), another dynamic process was revealed by 1H and 13C NMR in solution at low temperature, and interpreted as motion of the cyclopentadienyl rings between staggered and eclipsed conformations (ΔG(233 K)‡ = 44 ± 1 kJ mol−1). 相似文献
44.
We have performed two molecular-dynamics simulations to study the structural and dynamical properties of water at the interface with phospholipid bilayers. In one of the simulations the bilayer contained neutral phospholipid molecules, dioleoylphosphatidylcholine (DOPC); in the second simulation the bilayer contained charged lipid molecules, dioleoylphosphatidylserine (DOPS). From the density profile of water we observe that water next to the DOPS bilayer is more perturbed as compared to water near the DOPC bilayer. Using an energetic criterion for the determination of hydrogen bonding we find that water molecules create strong hydrogen bonds with the headgroups of the phospholipid molecules. Due to the presence of these bonds and also due to the confinement of water, the translational and orientational dynamics of water at the interface are slowed down. The degree of slowing down of the dynamics depends upon the location of water molecules near a lipid headgroup. 相似文献
45.
Roland Prewo Jost H. Bieri Subhendu Narayan Ganguly Max Viscontini 《Helvetica chimica acta》1982,65(3):1094-1099
The Configuration at C(6) of Natural 5,6,7,8-Tetrahydro-L-biopterin and of its Pentaacetate The structure of (6.R)-pentaacetyl-5,6,7,8-tetrahydro-L-biopterin, one of two diastereoisomers obtained by catalytic hydrogenation and subsequent acetylation of L-biopterin, has been determined by X-ray diffraction analysis. The space group is P212121, a=8,053(l), b=14,955(3), c= 21,502 (4) Å. The asymmetric unit contains one molecule of the biopterin derivative and one of ethyl acetate. The R-configuration can be assigned to C(6) by reference to the known configurations of the other asymmetric C-atoms. As hydrolysis of this diastereoisomer yields the natural 5, 6,7,8-tetrahydro-L-biopterin, the latter also possesses the (6 R)-configuration. 相似文献
46.
47.
Max Winter Karl H. Schulte-Elte Alain Velluz Josef Limacher Wilhelm Pickenhagen Günther Ohloff 《Helvetica chimica acta》1979,62(1):131-134
Aroma Constituents of the Purple Passion Fruit. Two New Edulan Derivatives The isolation of (2R*, 4S*, 4aS*, 8aS*)-4,4a-epoxy-4,4a-dihydroedulan ( 1 ), and (2R*, 3S*, 8aS*)-3-hydroxyedulan ( 2 ), two new constituents of the purple passion-fruit (Passiflora edulis SIMS ), is reported. Racemic epoxide 1 was synthesized by oxidation of edulan 6 with peracidic acid, and racemate of alcohol 2 was obtained by reduction of ketone 7 , one of the chromic acid oxidation-products of edulan 6 . 相似文献
48.
Solvolysis of 4-Alkydenbicyclo[3.2.0]hept-2-en-6-oles. Synthesis of 1-Vinylfulvenes and 8,8-Diphenylheptafulvene Four 4-alkylidenebicyclo[3.2.0]hept-2-en-6-ones 2–5 , obtained via ketene cycloaddition to fulvenes, were reduced to separated mixtures of the ‘endo’ -alcohols ‘endo’- 6 to ‘endo’- 9 (68–73%) and ‘exo’- 6 to ‘exo’- 9 (3–20%). Treatment of some of these alcohols with (CF3SO2)2O in CH2Cl2/pyridine caused a spontaneous solvolysis to yield unsaturated 7-membered rings as pyridinium triflates 10–12 or 1-vinylfulvenes 13 and 14 , a new class of reactive tetraenes: Both ‘endo’- 9 and ‘exo’- 9 , having two methyl groups at C(7), were converted into the vinylfulvene 13 (≈ 80%). The alcohols with two H-atoms at C(7) exhibited a stereochemically controlled reaction selectivity, inasmuch as ‘endo’- 6 to ‘endo’- 8 afforded only the corresponding 7-membered-ring pyridinium salts 10–12 (66–79%), while ‘exo’- 6 produced only the vinylfulvene 14 (77%). A stereoelectronic control argument explains the C(1), C(5)-bond cleavage with ‘endo’- B and ‘endo’– 6 -‘endo’- 8 , as well as the C(1), C(7)-bond cleavage with ‘exo’- B , ‘exo’- 6 , and with both ‘endo’- and ‘exo’- 9 . Thermolysis (120°) of the pyridinium triflates 10 and 11 yielded the 3-isopropenyl-cycloheptatrienes 18 and 19 , respectively (≈90%); similar conditions (145°) applied to the triflate 12 produced the doubly cyclized fluorene derivative 21 (60%). When the iodide 22 derived from the triflate 12 with Nal was heated in refluxing toluene, 8,8-diphenylheptafulvene ( 23 , 86%) was obtained. 相似文献
49.
Teh-Chang Chou Holger Lange Rolf Gleiter Tibor Ggh Miroslav Krí Max H. Pfenninger Marian Valentíny Camille Ganter 《Helvetica chimica acta》1995,78(8):2011-2025
Three 1,4-dimethylidenecyclohexanes, bridged in the 2,6- and 3,5-positions by two ethano ( 4 ), one ethano and one propano ( 5 ), and two propano bridges ( 6 ) have been synthesized. The interaction of the two exocyclic methylidene groups has been investigated by He(I) photoelectron (PE) spectroscopy. It revealed a slightly larger energy difference (0.8 eV) for 4 and 5 as compared to the parent 1,4-dimethylidenecyclohexane ( 7 ) (0.7 eV). The interpretation of the PE spectra was based on the comparison with PE data of related systems and with the results of semiempirical calculations on 4–6 . 相似文献
50.
Reactions of Ferrocenol and 1,1′-Ferrocendiol with Cyclotriphosphazenes, P3N3F6 and P3N3Cl6 The hexahalogeno-cyclotriphosphazenes, P3N3X6 (X ? F ( 1 a ), Cl ( 1 b )), react with ferrocenol (FcOH) in a molar ratio 1 : 1 to give the ferrocenoxy derivatives, FcO[P3N3X5] (X ? F ( 3 a ), Cl ( 3 b )); in an analogous manner the tetrameric ring P4N4Cl8 ( 2 b ) is converted to FcO[P4N4Cl7] ( 4 b ). 1 Abkürzungen: Fc = Ferrocenyl, (C5H5)Fe(C5H4?); fc = 1,1′-ferrocendiyl, Fe(C5H4?)2; rc = 1,1′-ruthenocendiyl, Ru(C5H4?)2. Fluorphosphazene werden mit a , Chlorphosphazene mit b gekennzeichnet. With 1,1′-ferrocenediol, (fc(OH) 2 ), the cyclo triphosphazenes react in a molar ratio 1 : 1 to produce fcO 2 [P 3 N 3 X 4 ] (X ? F ( 5 a ), Cl ( 5 b )). According to the x-ray structure analysis, the 1,1′-ferrocenediolato group in 5 a , b is bound to two different phosphorus atoms. On the contrary, the 1,1′-ferrocenedithiolato- and 1,1′-ferrocenediselenolato units in fcS 2 [P 3 N 3 X 5 ] (X ? F ( 6 a ), Cl ( 6 b )) and fcSe 2 [P 3 N 3 X 5 ] (X ? F ( 7 a ), Cl ( 7 b )) are attached to only one phosphorus atom, and spirocyclic 1,3-dichalcogena-2-phospha-[3]ferrocenophanes are formed. All new products have been characterized on the basis of their 1 H, 13 C and 31 P NMR as well as EI mass spectra. The molecular structures of 5 a , b and 6 a have been determined by x-ray structure analyses. 相似文献