43146-97-0Relevant articles and documents
Giant vesicles from rehydrated crude mixtures containing unexpected mixtures of amphiphiles formed under plausibly prebiotic conditions
Fiore, Michele,Madanamoothoo, Warren,Berlioz-Barbier, Alexandra,Maniti, Ofelia,Girard-Egrot, Agnès,Buchet, René,Strazewski, Peter
, p. 4231 - 4240 (2017)
Giant lipid vesicles resemble compartments of biological cells, mimicking them in their dimension, membrane structure and partly in their membrane composition. The spontanenous appearance of closed membranes composed of bilayers of self-assembling amphiphiles was likely a prerequisite for Darwinian competitive behavior to set in at the molecular level. Such compartments should be dynamic in their membrane composition (evolvable), and sufficiently stable to harbor macromolecules (leak-free), yet semi-permeable for reactive small molecules to get across the membrane (stay away from chemical equilibrium). Here we describe bottom-up experiments simulating prebiotic environments that support the formation of simple amphiphilic molecules capable of self-assembling into vesicular objects on the micrometer scale. Long-chain alkyl phosphates, together with related amphiphilic compounds, were formed under simulated prebiotic phosphorylation conditions by using cyanamide, a recognized prebiotic chemical activator and a precursor for several compound classes. Crude dry material of the thus obtained prebiotic mixtures formed multilamellar giant vesicles once rehydrated at the appropriate pH and in the presence of plausibly prebiotic co-surfactants, as observed by optical microscopy. The size and the shape of lipid aggregates tentatively suggest that prebiotic lipid assemblies could encapsulate peptides or nucleic acids that could be formed under similar chemical prebiotic conditions. The formation of prebiotic amphiphiles was monitored by using TLC, IR, NMR and ESI-MS and UPLC-HRMS. In addition we provide a spectroscopic analysis of cyanamide under simulated prebiotic conditions in the presence of phosphate sources and spectroscopic analysis of O-phosphorylethanolamine as a plausible precursor for phosphoethanolamine lipids.
Effect of Alcohol Structure on the Kinetics of Etherification and Dehydration over Tungstated Zirconia
Rorrer, Julie,Pindi, Suresh,Toste, F. Dean,Bell, Alexis T.
, p. 3104 - 3111 (2018/09/06)
Linear and branched ether molecules have attracted recent interest as diesel additives and lubricants that can be produced from biomass-derived alcohols. In this study, tungstated zirconia was identified as a selective and green solid acid catalyst for the direct etherification of primary alcohols in the liquid phase, achieving ether selectivities of >94 % for C6–C12 linear alcohol coupling at 393 K. The length of linear primary alcohols (C6–C12) was shown to have a negligible effect on apparent activation energies for etherification and dehydration, demonstrating the possibility to produce both symmetrical and asymmetrical linear ethers. Reactions over a series of C6 alcohols with varying methyl branch positions indicated that substituted alcohols (2°, 3°) and alcohols with branches on the β-carbon readily undergo dehydration, but alcohols with branches at least three carbons away from the -OH group are highly selective to ether. A novel model compound, 4-hexyl-1dodecanol, was synthesized and tested to further demonstrate this structure–activity relationship. Trends in the effects of alcohol structure on selectivity were consistent with previously proposed mechanisms for etherification and dehydration, and help to define possible pathways to selectively form ethers from biomass-derived alcohols.
A direct, straightforward conversion of methoxymethyl ethers into acetates
Bosch,Petschen,Guerrero
, p. 300 - 304 (2007/10/03)
The direct transformation of MOM-protected alcohols into the corresponding acetates by acetic anhydride/ferric chloride in CH2Cl2, in a one-step process and good to excellent yields, is reported. The reaction has been applied to a variety of substrates and occurs with retention of configuration.
