The synthesis of cofacial porphyrin dimers

1983 ◽  
Vol 61 (9) ◽  
pp. 2220-2223 ◽  
Author(s):  
John Hiom ◽  
John B. Paine III ◽  
Udo Zapf ◽  
David Dolphin
Keyword(s):  
Catalytic Hydrogenation ◽  
Hydrocarbon Chain ◽  
Hydrocarbon Chains ◽  
One Step ◽  
Acetylenic Group ◽  
Porphyrin Dimers

A cofacial dimeric porphyrin joined by two hydrocarbon chains has been prepared using a bis-porphyrin already linked by a single hydrocarbon chain. When each porphyrin bears an acetylenic group, copper catalyzed coupling followed by catalytic hydrogenation gives a doubly linked cofacial porphyrin. However, a far superior and more flexible route, involving the use of a dimeric biladiene-ac, gives in one step the same cofacial porphyrin. This latter route has been used to prepare dimeric porphyrins with hydrocarbon linkages of varying lengths.

scholarly journals Submicellar complexes may initiate the fungicidal effects of cationic amphiphilic compounds on Candida albicans.

1997 ◽  
Vol 41 (3) ◽  
pp. 544-550 ◽  
Author(s):  
B Ahlström ◽  
M Chelminska-Bertilsson ◽  
R A Thompson ◽  
L Edebo
Keyword(s):  
Candida Albicans ◽  
Membrane Damage ◽  
Hydrocarbon Chain ◽  
Hexadecyltrimethylammonium Bromide ◽  
Tetradecyltrimethylammonium Bromide ◽  
Low Concentrations ◽  
Hydrocarbon Chains ◽  
Absorbing Material ◽  
High Concentrations ◽  
Chain Lengths

The killing of Candida albicans by a series of amphiphilic quaternary ammonium compounds (QACs) with different hydrocarbon chain lengths was closely related to the binding of the compounds to the cells and damage of the cell membranes. The membrane damage was measured as the level of release of the UV-absorbing material into the medium in which the cells were suspended and as the level of uptake of propidium iodide in individual cells by flow cytometry. It was shown that of the compounds tested, hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide [CTAB]) bound most efficiently. Tetradecyl betainate chloride (B14), tetradecanoylcholine bromide (C14), tetradecyltrimethylammonium bromide (TTAB), and dodecyltrimethylammonium bromide (DTAB) followed and had declining degrees of binding efficiency. The proportion of CTAB bound was almost total at concentrations up to the critical micelle concentration (CMC) of the compound, whereas that of B14 was somewhat smaller. For the two remaining tetradecyl compounds (C14 and TTAB), still smaller proportions were bound at low concentrations, but the proportions rose disproportionally at increasing concentrations to a distinct maximum at concentrations of 0.2 to 0.5 times the CMC. We propose that interfacial micelle-like aggregates are formed at the cell surface as a step in the binding process. An analogous, but less conspicuous, maximum was seen for DTAB. Thus, great differences in the binding affinity of QACs with different hydrocarbon chains at different concentrations to C. albicans were observed. These differences were related to the CMC of the compound. In contrast, the binding of TTAB to Salmonella typhimurium 395 MS was almost total at low as well as high concentrations until saturation was attained, indicating fundamental differences between binding to the yeast and binding to gram-negative bacteria. The importance of lipid-type complexes or aggregates to the antifungal effect of membrane-active substances are discussed.

scholarly journals One-step preparation of biological aviation kerosene by catalytic hydrogenation of waste lard over Pt/SAPO-11

2017 ◽  
Vol 93 ◽  
pp. 012003 ◽  
Author(s):  
X Zhang ◽  
Y B Chen ◽  
X Y Li ◽  
D Souliyathai ◽  
S P Zhang ◽  
...  
Keyword(s):  
Catalytic Hydrogenation ◽  
Aviation Kerosene ◽  
One Step

Kinetics of the reaction of the hydrophobic ester 4-nitrophenyl decanoate with long-chain N-alkylimidazoles above and below their critical micelle concentration

1974 ◽  
Vol 27 (10) ◽  
pp. 2149 ◽  
Author(s):  
DG Oakenfull ◽  
DE Fenwick
Keyword(s):  
Critical Micelle Concentration ◽  
Chain Length ◽  
Mole Fraction ◽  
Rate Constants ◽  
Hydrophobic Interactions ◽  
Hydrocarbon Chain ◽  
Hydrocarbon Chain Length ◽  
Hydrocarbon Chains ◽  
Kinetics Of ◽  
Long Chain

The kinetics of the reaction of 4-nitrophenyl decanoate with a series of straight-chain N-alkylimidazoles have been studied at 25� in water and aqueous ethanol. In water, below the critical micelle concentration of the N-alkylimidazole, hydrophobic interaction between the hydrocarbon chains of the reactants caused substantial increases in the reaction rate (up to about 200-fold) compared with the rate of reaction of 4-nitrophenyl acetate with N-methylimidazole. The rate constants, though, differed from those previously reported which were measured with a higher initial concentration of ester. No increase in rate with increasing hydrocarbon chain length could be detected in the presence of a large concentration of ethanol (mole fraction of 0.31) but a rate increase did occur in the presence of a more moderate concentration of ethanol (mole fraction of 0.10), confirming that hydrophobic interactions persist in this mixed solvent. The long-chain ester reacts rapidly with N-alkylimidazole micelles. Association constants (K) for binding the ester to the micelles and rate constants for the reaction of the bound ester (km) were estimated by following the conventional treatment of the kinetics of micelle-catalysed reactions. The value of K was found to increase sharply with increasing hydrocarbon chain length of the micelle but km showed the opposite trend.

Hydrophobic interaction in deuterium oxide

1975 ◽  
Vol 28 (4) ◽  
pp. 715 ◽  
Author(s):  
DG Oakenfull ◽  
DE Fenwick
Keyword(s):  
Free Energy ◽  
Hydrophobic Interaction ◽  
Deuterium Oxide ◽  
Hydrocarbon Chain ◽  
Micellar Solutions ◽  
Hydrocarbon Chain Length ◽  
Hydrocarbon Chains ◽  
Methylene Groups ◽  
Free Energy Of Binding ◽  
Kinetics Of

Methods previously used to study hydrophobic interaction in ordinary water have been used to measure the free energy of hydrophobic interaction between hydrocarbon chains in deuterium oxide at 25�: ��� (1) Conductance measurements on micellar solutions of a series of hexadecyltrimethylammonium carboxylates give the effect of hydrocarbon chain length on the free energy of binding a counter-ion (carboxylate ion) to the micelle, and hence the free energy of hydrophobic interaction. ��� (2) Comparison of the kinetics of the reaction between decylamine and 4-nitrophenyl decanoate with the kinetics of the corresponding reaction without hydrophobic side chains (the reaction between ethylamine and 4-nitrophenyl acetate) gives the extent to which hydrophobic interaction stabilizes the transition state. This then provides another estimate of the free energy of hydrophobic interaction. ��� The free energy of hydrophobic interaction in D2O was found to be - 1.76 kJ mol-1, for each contact between two methylene groups, compared with -1.40 kJ mol-1 in H2O. Hydrophobic interaction is therefore stronger in D2O than in H2O.

Coding of odor molecules by mitral/tufted cells in rabbit olfactory bulb. I. Aliphatic compounds

1992 ◽  
Vol 68 (6) ◽  
pp. 1986-2002 ◽  
Author(s):  
K. Imamura ◽  
N. Mataga ◽  
K. Mori
Keyword(s):  
Fatty Acids ◽  
Olfactory Bulb ◽  
Functional Group ◽  
Hydrocarbon Chain ◽  
Main Olfactory Bulb ◽  
Aliphatic Aldehydes ◽  
Aliphatic Compounds ◽  
Hydrocarbon Chains ◽  
Tufted Cells ◽  
Chain Lengths

1. Recordings of extracellular spike responses were made from single mitral/tufted cells in the main olfactory bulb of urethan-anesthetized rabbits. Olfactory epithelium ipsilateral to the recorded olfactory bulb was stimulated with homologous series of aliphatic compounds using periodic artificial inhalations. 2. In the dorsomedial part of the main olfactory bulb, single mitral/tufted cells were activated by subsets of n-fatty acids with similar hydrocarbon chain lengths. Response selectivities of single mitral/tufted cells were examined in detail using a series of n-fatty acids at five different concentrations. The results indicate that although the range of effective fatty acids is broader at the higher concentrations, the best response at higher concentrations was similar to that determined at lower concentrations. 3. Analysis of single-unit responses to the panel of fatty acids, including those with branched hydrocarbon chains, suggested that the determinants for the response specificities of individual mitral/tufted cells in the dorsomedial region include the overall size of hydrocarbon chains of the odor ligand molecules. 4. Single mitral/tufted cells in the dorsomedial region tended to be activated not only by fatty acids but also by n-aliphatic aldehydes. For a panel of a homologous series of n-aldehydes at five different concentrations, individual mitral/tufted cells showed response selectivity to subsets of aldehydes with similar hydrocarbon chain lengths. 5. In most cases, normal aliphatic alcohols and alkanes were ineffective in activating mitral/tufted cells in the dorsomedial region. This suggests that carbonyl group (--C = O) in the odor molecules plays an important role in determining response specificity of these neurons. 6. Examination with an expanded panel of stimulus odor molecules that included ketones and esters indicated that single mitral/tufted cells sensitive to subsets of fatty acids and n-aliphatic aldehydes were also responsive to subsets of ketones and/or esters having hydrocarbon chain lengths similar to those of the effective fatty acids and aldehydes. 7. The present results show a clear correlation between the tuning specificity of individual mitral/tufted cells and the stereochemical structure of the odor molecules, with respect to 1) length and/or structure of hydrocarbon chain, 2) difference in functional group, and 3) position of the functional group within the molecule. 8. A hypothetical diagram suggesting functional convergence of olfactory nerve input to individual glomeruli is proposed to explain the mechanism for selective activation of individual mitral/tufted cells by a range of odor molecules with similar stereochemical structures.

Catalytic hydrogenation and one step hydrogenation-esterification to remove acetic acid for bio-oil upgrading: model reaction study

2016 ◽  
Vol 6 (21) ◽  
pp. 7783-7792 ◽  
Author(s):  
Minghao Zhou ◽  
Peng Liu ◽  
Kui Wang ◽  
Junming Xu ◽  
Jianchun Jiang
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Catalytic Hydrogenation ◽  
Model Reaction ◽  
Reaction Study ◽  
Bio Oil ◽  
One Step

NiMo/CNT catalysts exhibited satisfactory catalytic activity for the conversion of acetic acid by either hydrogenation or hydrogenation-esterification with acetaldehyde.

PROTON MAGNETIC RESONANCE ABSORPTION IN ANHYDROUS SODIUM STEARATE

1960 ◽  
Vol 38 (12) ◽  
pp. 2395-2401 ◽  
Author(s):  
R. F. Grant ◽  
B. A. Dunell
Keyword(s):  
Phase Transition ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Abrupt Change ◽  
Sodium Stearate ◽  
Longitudinal Axis ◽  
Hydrocarbon Chain ◽  
Resonance Absorption ◽  
Fixed Position ◽  
Hydrocarbon Chains

The proton magnetic resonance absorption in anhydrous sodium stearate has been investigated over the temperature range −182 °C to 200 °C. An abrupt change in the line width and the second moment has been observed between 113 °C and 114 °C, which corresponds to a known phase transition. The results suggest that at temperatures below 114 °C the motion of the hydrocarbon-chain portion of the sodium stearate molecule is chiefly one of oscillation or rotation about the chain longitudinal axis. The hydrocarbon chains may be free to move about other axes at temperatures above 114 °C, although the molecule as a whole retains a fixed position in the crystal lattice.

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