2396-80-7Relevant articles and documents
Selective Production of Terminally Unsaturated Methyl Esters from Lactones Over Metal Oxide Catalysts
Brentzel, Zachary J.,Ball, Madelyn R.,Dumesic, James A.
, p. 3072 - 3081 (2018/08/22)
Metal oxide catalysts were studied for their selectivity for the production of a terminally unsaturated methyl ester, methyl 5-hexenoate (M5H), from a 6 carbon, 6-membered ring lactone, δ-hexalactone (DHL). A 15?wt% Cs/SiO2 catalyst had a selectivity of 55% to M5H. This selectivity was the highest of the metal oxide catalysts studied, which were Cs/SiO2, MgO, SrO, CeO2, ZrO2, Ta2O5, MgAl2O4, and a Mg–Zr mixed oxide. The Cs/SiO2 catalyst was utilized for the ring-opening of γ-valerolactone (GVL), a 5 carbon, 5-membered ring lactone. The catalyst was 88% selective to the terminally unsaturated methyl ester, methyl 4-pentenoate (M4P). Weight hourly space velocity studies determined that the unsaturated ester distributions remained constant and no C=C double bond isomerization occurred. Liquid phase transesterification reactions with DHL and methanol and nuclear magnetic resonance spectroscopy confirmed that DHL undergoes ring-opening transesterification to produce an?ω-1 hydroxy methyl ester, methyl 5-hydroxyhexanoate (M5HH). Liquid phase transesterification reactions and thermochemistry calculations established that the equilibrium for GVL transesterification with methanol was favored towards the ring-closed lactone instead of the ring-opened hydroxy ester because of the decreased ring strain of GVL compared to DHL. The difference in terminally unsaturated methyl ester selectivity between GVL and DHL manifests from the difference in ring-strain energy. DHL passes through the M5HH intermediate as a result of greater ring strain, while the production of M4P from GVL most likely occurs through a direct, concerted mechanism. Graphical Abstract: [Figure not available: see fulltext.].
Polymers and surfactants on the basis of renewable resources
Warwel, Siegfried,Bruese, Falk,Demes, Christoph,Kunz, Michael,Klaas, Mark Ruesch gen
, p. 39 - 48 (2007/10/03)
A new strategy for the preparation of different polymers and special surfactants was developed. First, unsaturated fatty acid methyl esters obtained from plant oils were converted to terminally unsaturated esters and α-olefins by metathesis with ethylene using heterogeneous rhenium or homogeneous ruthenium catalysts. These esters were directly copolymerized with ethylene by an insertion-type palladium-catalyzed polymerization to functionalized polyolefins. Polyesters were synthesized by metathetical dimerization of ω-unsaturated esters and subsequent polycondensation of the produced internally unsaturated dicarboxylic esters or by acidic transesterification with petrochemical diols and additional acyclic diene metathesis polymerization, ω-epoxy fatty acid methyl esters, achieved by a new method of chemo-enzymatic epoxidation, were converted into polyethers with comb-structure catalyzed by aluminoxanes on the one hand and into sugar surfactants by nucleophilic ring-opening with amino carbohydrates on the other hand.
The Synthesis of Specifically and Selectively Deuteriated 4,4'-Bisalkoxyazoxybenzene Derivatives
Boden, Neville,Bushby, Richard J.,Clark, Leslie D.
, p. 543 - 551 (2007/10/02)
In connection with deuterium n.m.r. studies of molecular motion in liquid crystals we have developed a number of methods for the synthesis of selectively deuteriated 4,4'-bisalkoxyazoxybenzenes.This paper is concerned with (i) the labelling of specific methylene segments of the alkoxy-chains, (ii) the labelling of the aromatic nucleus, and (iii) the selective enrichment of the deuterium content of one alkoxy-chain relative to the other.Our studies of the n.m.r. spectra of these liquid crystals have shown that there is not (as has sometimes been supposed) a monotonic decrease in C-D quadrupole splitting in passing from the oxygen to the CD3 end of the alkoxy-chain.In -PAA (p-azoxyanisole) we have also shown that the smaller splitting is associated with the CD3O group nearest to the NO end of azoxy-group.Whereas the photorearrangement of azoxy-compounds is normally regiospecific, the photorearrangement of PAA selectively deuteriated in one methoxy-group is unusual in that it leads to isotopically scrambled products.
