- Electrochemical Coupling of Biomass-Derived Acids: New C8 Platforms for Renewable Polymers and Fuels
-
Electrolysis of biomass-derived carbonyl compounds is an alternative to condensation chemistry for supplying products with chain length >C6for biofuels and renewable materials production. Kolbe coupling of biomass-derived levulinic acid is used to obtain 2,7-octanedione, a new platform molecule only two low process-intensity steps removed from raw biomass. Hydrogenation to 2,7-octanediol provides a chiral secondary diol largely unknown to polymer chemistry, whereas intramolecular aldol condensation followed by hydrogenation yields branched cycloalkanes suitable for use as high-octane, cellulosic gasoline. Analogous electrolysis of an itaconic acid-derived methylsuccinic monoester yields a chiral 2,5-dimethyladipic acid diester, another underutilized monomer owing to lack of availability.
- Wu, Linglin,Mascal, Mark,Farmer, Thomas J.,Arnaud, Sacha Pérocheau,Wong Chang, Maria-Angelica
-
p. 166 - 170
(2017/01/17)
-
- Selective ethylene oligomerization with chromium complexes bearing pyridine-phosphine ligands: Influence of ligand structure on catalytic behavior
-
Chromium complexes bearing a series of pyridine-phosphine ligands have been synthesized and examined for their catalytic behavior in ethylene oligomerization. The choice of solvent, toluene versus methylcyclohexane, shows a pronounced influence on the catalytic activity for all these complexes. Variations of the ligand system have been introduced by modifying the phosphine substituents affecting ligand bite angles and flexibility. It has been demonstrated that minor differences in the ligand structure can result in remarkable changes not only in catalytic activity but also in selectivity toward α-olefins versus polyethylene and distribution of oligomeric products. Ligand PyCH2N(Me)PiPr2, in combination with CrCl3(THF)3 afforded selective ethylene tri- and tetramerization, giving 1-hexene and 1-octene with good overall selectivity and high purity, albeit with the presence of small amounts of PE.
- Yang, Yun,Gurnham, Joanna,Liu, Boping,Duchateau, Robbert,Gambarotta, Sandro,Korobkov, Ilia
-
p. 5749 - 5757
(2015/02/19)
-
- Catalytic dehydrogenation of cyclooctane with titanium, zirconium and hafnium metallocene complexes
-
Metallocene complexes in combination with cocatalysts like methylalumoxane (MAO) are not only excellent catalysts for olefin polymerization but also appropriate catalysts for the activation of alkanes in homogeneous (autoclave) and heterogeneous (fixed be
- Taubmann, Sandra,Denner, Christine E.,Alt, Helmut G.
-
scheme or table
p. 2005 - 2019
(2009/09/26)
-
- Avoiding olefin isomerization during decyanation of alkylcyano α,ω-dienes: A deuterium labeling and structural study of mechanism
-
(Chemical Equation Presented) A two-step synthetic pathway involving decyanation chemistry for the synthesis of pure alkyl α,ω-dienes in quantitative yields is presented. Prior methodologies for the preparation of such compounds required 6-9 steps, sometimes leading to product mixtures resulting from olefin isomerization chemistry. This isomerization chemistry has been eliminated. Deuteration labeling and structural mechanistic investigations were completed to decipher this chemistry. Deuterium labeling experiments reveal the precise nature of this radical decyanation chemistry, where an alcohol plays the role of hydrogen donor. The correct molecular design to avoid competing intramolecular cyclization, and the necessary reaction conditions to avoid olefin isomerization during the decyanation process are reported herein.
- Rojas, Giovanni,Wagener, Kenneth B.
-
p. 4962 - 4970
(2008/12/20)
-
- Cyclization of methyl-substituted 6-heptenyl radicals
-
(Matrix presented) The behavior of a series of methyl-substituted 6-heptenyl radicals, generated from the corresponding iodides ((Me3Si)3SiH, AIBN in benzene at 80°C), has been investigated. The stereoselectivity of the 6-exo cyclizations, affording dimethylcyclohexanes, is low, and sizable quantities of methylcycloheptane, generated via 7-endo cyclization, are also produced.
- Bailey, William F.,Longstaff, Sarah C.
-
p. 2217 - 2219
(2007/10/03)
-
- Hydrogenolysis of Small Cycloalkanes, X. - Catalytic Hydrogenation of Bicycloalkanes
-
Dependent on n different products are obtained from bicycloalkanes by hydrogenation on Pt and Pd/C catalysts: from n = 5 onward only methylcycloalkanes of the same ring size; with n = 4 additionally 2-7 percent of cycloheptane is formed; with n = 3 ring enlargement increases to 5-20 percent and with n = 2 cyclopentane is the only product.Mainly butane is formed from bicyclobutane and no intermediate could be detected.Explanations are attempted.The expected products are produced on hydrogenation of methyl-substituted derivatives and spiroalkanes.
- Stahl, Karl-Johannes,Hertzsch, Winfried,Musso, Hans
-
p. 1474 - 1484
(2007/10/02)
-