17252-77-6Relevant articles and documents
Synthesis of deuterated [D32]oleic acid and its phospholipid derivative [D64]dioleoylsn- glycero-3-phosphocholine
Darwish, Tamim A.,Luks, Emily,Moraes, Greta,Yepuri, Nageshwar R.,Holden, Peter J.,Jamesa, Michael
, p. 520 - 529 (2014/03/21)
Oleic acid and its phospholipid derivatives are fundamental to the structure and function of cellular membranes. As a result, there has been increasing interest in the availability of their deuterated forms for many nuclear magnetic resonance, infrared, mass spectroscopy and neutron scattering studies. Here, we present for the first time a straightforward, large-scale (gram quantities) synthesis of highly deuterated [D32]oleic acid by using multiple, yet simple and high yielding reactions. The precursors for the synthesis of [D32]oleic acid are [D14]azelaic acid and [D17]nonanoic acid, which were obtained by complete deuteration (>98% D) of their 1H forms by using metal catalysed hydrothermal H/D exchange reactions. The oleic acid was producedwith ca. 94% D isotopic purity and with no contamination by the trans-isomer (elaidic acid). The subsequent synthesis of [D64]dioleoyl-sn-glycero-3-phosphocholine from [D32]oleic acid is also described. Copyright
Ionization Energies and Entropies of Cycloalkanes. Kinetics of Free Energy Controlled Charge-Transfer Reactions.
Sieck, L. Wayne,Mautner, Michael
, p. 3646 - 3650 (2007/10/02)
Enthalpies and entropies of ionization (ΔH0ion and ΔS0ion) of alkylcyclohexanes, as well as cycloheptane, cyclooctane, and trans-Decalin, have been determined by charge-transfer equilibrium measurements.Values of ΔHion, in units of kcal mol-1 (or eV), range from 229.6 (9.96) for cycloheptane to 210.7 (9.14) for trans-Decalin.A major effect of alkyl substitution is observed following substitution at a site α to a tertiary hydrogen atom (as from methylcyclohexane to 1,2-dimethylcyclohexane), or following replacement of a tertiary hydrogen atom (as from methylcyclohexane to 1,1-dimethylcyclohexane).In both cases, ΔH0 ion decreases by ca. 5 kcal mol-1.Entropies of ionization are near zero for alkylcyclohexanes but range up to 5 cal deg-1 mol-1 for nonsubstituted cycloalkanes (cyclooctane).The charge-transfer reactions involving the cycloalkanes are shown to be fast processes; i.e., the sum of the reaction efficiencies (r=k/kcollision) of the forward and reverse processes is near unity.The efficiencies of these processes appear to be determined uniquely by the overall free energy change (or equilibrium constant K).Specifically, the reaction efficiencies are defined, within a factor of 2 by the relation r=K/(1+K), which can be justified by using transition-state theory applied to the decomposition of a collision complex over surfaces lacking energy barriers.These reactions are defined as intrinsically fast processes in that they are slowed only by the overall reaction thermochemistry and not by any properties or reactions of the intermediate complex.
Ionization of Normal Alkanes: Enthalpy, Entropy, Structural, and Isotope Effects
Meot-Ner (Mautner), M.,Sieck, L.W.,Ausloos, P.
, p. 5342 - 5348 (2007/10/02)
Enthalpies and entropies of ionization (ΔHi0, ΔSi0) of C4 to C11 normal alkanes were determined from charge-transfer equilibrium measurement between 300 and 420 K by using photoionization high-pressure mass spectrometry.Large negative ΔSi0 values are observed in C7 and larger n-alkanes, from -4.7 cal mol-1 K-1 (-19.6 J mol-1 K-1) in heptane to -13.9 cal mol-1 K-1 (-58.1 J mol-1 K-1) in undecane; in contrast, ΔSi0 of C4-C7 n-alkanes is negligible. ΔHi0 values range from 10.35 eV (997.6 kJ mol-1) (butane) to 9.45 eV (910.9 kJ mol-1) (undecane); the incremental ΔHi0 values also suggest the occurence of an effect that stabilizes C7 and higher but not the lower molecular ions.Analogy with disubstituted alkanes suggests that the negative ΔSi0 values and excess stabilization in C7 and higher alkane ions are due to constrained cyclic conformations which result from noncovalent intramolecular bonding between the terminal -C2H5 groups in the large, flexible molecular ions.These effects are more pronounced in n-alkanes than in 2-methylalkanes.Isotope effects on ΔHi0 as measured by the equilibrium constant K290 for n-CmD2m+2+ + n-CmH2m+2 ->/+ + n-CmD2m+2 are significant for ethane (k291 = 4.5) but decrease with increasing m: in propane K290 = 3.2 and in hexane and octane K291 = 1.0.However, the isotope effects in cyclic alkanes are much larger than in corresponding normal alkanes: in cyclohexane, K321 = 3.3 compared with that in n-hexane, were K320 = 1.0.
