- Heterogeneous Non-noble Catalyst for Highly Selective Production of Linear α-Olefins from Fatty Acids: A Discovery of NiFe/C
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Catalytic deoxygenation of even-numbered fatty acids into odd-chain linear α-olefins (LAOs) has emerged as a complementary strategy to oligomerization of ethylene, which only affords even-chain LAOs. Although enzymes and homogeneous catalysts have shown promising potential for this application, industrial production of LAOs through these catalytic systems is still very difficult to accomplish to date. A recent breakthrough involves the use of an expensive noble-metal catalyst, Pd/C, through a phosphine ligands-assisted method for LAOs production from fatty acid conversion. This study presents a unique, cost-friendly, non-noble bimetallic NiFe/C catalyst for highly selective LAOs production from fatty acids through decarbonylative dehydration. In the presence of acetic anhydride and phosphine ligand, a remarkable improvement in the yield of 1-heptadecene from the conversion of stearic acid was found over the supported bimetallic catalyst (NiFe/C) as compared to corresponding monometallic counterparts (Ni/C and Fe/C). Through optimization of the reaction conditions, a 70.1 % heptadecene yield with selectivity to 1-heptadecene as high as 92.8 % could be achieved over the bimetallic catalyst at just 190 °C. This unique bimetallic NiFe/C catalyst is composed of NiFe alloy in the material bulk phase and a surface mixture of NiFe alloy and oxidized NiFeδ+ species, which offer a synergized contribution towards decarbonylative dehydration of stearic acid for 1-heptadecene production.
- Zhang, Zihao,Lin, Wenwen,Li, Yafei,Okejiri, Francis,Lu, Yubing,Liu, Jixing,Chen, Hao,Lu, Xiuyang,Fu, Jie
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- Highly selective production of linear 1-heptadecene from stearic acid over a partially reduced MoO: X catalyst
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Here, a MoOx-T based catalyst was developed by a simple reduction of MoO3 precursors at different temperatures. Interestingly, a partially reduced MoOx-600 catalyst obtained by reducing the MoO3 precursor at 600 °C shows the co-existence of a mixture of different valence states (0, +4, ～+6) of Mo, and as a result, provides a superior catalytic activity.
- Chen, Hao,Chen, Kequan,Fu, Jie,Li, Yafei,Liu, Jixing,Liu, Miaomiao,Lu, Xiuyang,Okejiri, Francis,Ouyang, Pingkai,Zhang, Zihao
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Read Online
- Rate constants for reactions of alkyl radicals with water and methanol complexes of triethylborane
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(Chemical Equation Presented) Reactions of secondary alkyl radicals with triethylborane and several of its complexes were studied. The H-atom transfer reactions from Et3B-OH2 and Et3B-OD2 were suppressed by addition of pyridine to the reaction mixture. Rate constants for reactions of secondary alkyl radicals with triethylborane and its complexes with water, deuterium oxide, methanol, and THF at ambient temperature were determined by radical clock methods. Cyclization of the 1-undecyl-5-hexenyl radical and ring opening of the 1-cyclobutyldodecyl radical were evaluated as clock reactions. The cyclobutylcarbinyl radical ring opening had the appropriate velocity for relatively precise determinations of the ratios of rate constants for H-atom transfer trapping and rearrangement, and these ratios combined with an estimated rate constant for the cyclobutylcarbinyl radical ring opening gave absolute values for the rate constants for the H-atom transfer reactions. For example, the triethylborane-water complex reacts with a secondary alkyl radical in benzene at 20°C with a rate constant of 2 × 104 M -1 s-1. Variable temperature studies with the Et 3B-CH3OH complex in toluene indicate that the hydrogen atom transfer reaction has unusually high entropic demand, which results in substantially more efficient hydrogen atom transfer trapping reactions in competition with radical ring opening and cyclization reactions at reduced temperatures.
- Jin, Jing,Newcomb, Martin
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Read Online
- Synthesis and characterization of a supported Pd complex on carbon nanofibers for the selective decarbonylation of stearic acid to 1-heptadecene: The importance of subnanometric Pd dispersion
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Production of linear α-olefins from renewable sources is gaining increasing attention because it allows the transition from the current petrochemical synthesis route to a more sustainable scenario. In this work, we describe the synthesis and characterization of an innovative catalyst based on a di-μ-chloro-bis[palladium(ii) anthranilate] complex highly dispersed by incipient wetness impregnation over acyl chlorinated carbon nanofibers. The subnanometric dispersion of the metal complex allowed higher catalytic efficiency for the selective decarbonylation of stearic acid to 1-heptadecene as compared to the reference homogenous catalyst. The best catalytic performance (90 mol% selectivity, 71 mol% conversion, and TON = 484) was achieved under mild reaction conditions (atmospheric pressure, 140 °C) with a Pd loading in solution of 0.14 mol%. The post-mortem catalyst characterization and the recyclability tests evidenced the high stability of the catalyst. The highly dispersed catalyst developed in this work provides new opportunities in the rational design of more efficient catalytic systems for the sustainable transformation of fatty acids.
- Bitter, Harry,Fuertes, Sara,Henao, Wilson,Ochoa, Elba,Pinilla, Jose Luis,Scott, Elinor,Suelves, Isabel,Torres, Daniel,Van Haasterecht, Tomas
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p. 2970 - 2985
(2020/06/17)
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- A Method for preparing alpha-olefins from Biomass-derived fat and oil
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The present invention relates to a method for preparing alpha-olefins from biomass-derived fats and oils. According to the preparation method, all of the various saturated or unsaturated fatty acids in the biomass-derived fats and oils can be prepared into alpha-olefins, and a conventional problem that the saturated fatty acids do not participate in a reaction or a mixture is generated due to polyunsaturated fatty acids can be solved. Thus, the present invention can be advantageously used to prepare alpha-olefins from biomass.
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Paragraph 0191-0202; 0218-0222
(2020/09/22)
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- Alkene synthesis by photocatalytic chemoenzymatically compatible dehydrodecarboxylation of carboxylic acids and biomass
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Direct conversion of renewable biomass and bioderived chemicals to valuable synthetic intermediates for organic synthesis and materials science applications by means of mild and chemoselective catalytic methods has largely remained elusive. Development of artificial catalytic systems that are compatible with enzymatic reactions provides a synergistic solution to this enduring challenge by leveraging previously unachievable reactivity and selectivity modes. We report herein a dual catalytic dehydrodecarboxylation reaction that is enabled by a crossover of the photoinduced acridine-catalyzed O-H hydrogen atom transfer (HAT) and cobaloxime-catalyzed C-H-HAT processes. The reaction produces a variety of alkenes from readily available carboxylic acids. The reaction can be embedded in a scalable triple-catalytic cooperative chemoenzymatic lipase-acridine-cobaloxime process that allows for direct conversion of plant oils and biomass to long-chain terminal alkenes, precursors to bioderived polymers.
- Nguyen, Vu T.,Nguyen, Viet D.,Haug, Graham C.,Dang, Hang T.,Jin, Shengfei,Li, Zhiliang,Flores-Hansen, Carsten,Benavides, Brenda S.,Arman, Hadi D.,Larionov, Oleg V.
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p. 9485 - 9498
(2019/10/11)
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- The Effect of the Active Component Content on the Catalytic Activity of Nickel Sulfide Catalysts in Olefin Synthesis from Stearic Acid
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Abstract: The effect of active component content on the catalytic activity of supported sulfide catalysts in the synthesis of C17 olefins from stearic acid has been studied. It has been shown that an increase in the nickel content leads to a decrease in the catalyst activity; in addition, there is a negative correlation between the activity and the fraction of large particles on the support surface. The highest heptadecene selectivity (50–60%) is observed for alumina-supported catalysts owing to the higher degree of dispersion of the active component.
- Katsman,Danyushevsky, V. Ya.,Karpov,Kuznetsov,Shishilov,Berenblyum
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p. 622 - 628
(2019/06/24)
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- An Engineered Self-Sufficient Biocatalyst Enables Scalable Production of Linear α-Olefins from Carboxylic Acids
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Fusing the decarboxylase OleTJE and the reductase domain of P450BM3 creates a self-sufficient protein, OleT-BM3R, which is able to efficiently catalyze oxidative decarboxylation of carboxylic acids into linear α-olefins (LAOs) under mild aqueous conditions using O2 as the oxidant and NADPH as the electron donor. The compatible electron transfer system installed in the fusion protein not only eliminates the need for auxiliary redox partners, but also results in boosted decarboxylation reactivity and broad substrate scope. Coupled with the phosphite dehydrogenase-based NADPH regeneration system, this enzymatic reaction proceeds with improved product titers of up to 2.51 g L-1 and volumetric productivities of up to 209.2 mg L-1 h-1 at low catalyst loadings (～0.02 mol%). With its stability and scalability, this self-sufficient biocatalyst offers a nature-friendly approach to deliver LAOs.
- Lu, Chen,Shen, Fenglin,Wang, Shuaibo,Wang, Yuyang,Liu, Juan,Bai, Wen-Ju,Wang, Xiqing
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p. 5794 - 5798
(2018/06/01)
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- Amines as effective ligands in iridium-catalyzed decarbonylative dehydration of biosourced substrates
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Linear α-olefins (LAOs) and linear internal olefins (LIOs) are essential intermediates in the synthesis of surfactants, lubricants, and polymers. Concurrently with petroleum-based industrial processes, the production of LAOs and LIOs from renewable feedstocks has gained increasing interest in recent years. Organometallic catalysts have been developed designedly, especially Pd, Fe and Ir catalysts. However, such catalysts are mostly stabilized by phosphanes, ligands sometimes difficult to handle especially on large scales. Alternatives to phosphanes would thus be highly desirable. In the present study, we demonstrate that Ir catalysts coordinated by amines are suitable to decarbonylate a wide range of biosourced substrates under mild conditions. The resulting LAOs and LIOs are obtained with good conversion provided that the nature and the quantity of the amines are controlled accurately. The LAO/LIO selectivity can also be tuned by a judicious choice of experimental conditions. Interestingly, the Ir-based catalytic system is applicable to the decarbonylative dehydration of saturated, unsaturated and polyunsaturated fatty acids.
- Ternel, Jérémy,Léger, Bastien,Monflier, Eric,Hapiot, Frédéric
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p. 3948 - 3953
(2018/08/16)
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- Revealing the Influence of Silver in Ni–Ag Catalysts on the Selectivity of Higher Olefin Synthesis from Stearic Acid
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Results on the conversion of stearic acid to olefins over Ni–Ag/γ-Al2O3 catalysts are presented. XANES and EXAFS experiments in situ and DFT calculations were applied to reveal the structure of active sites therein. It is shown that the introduction of Ag to Ni catalysts leads to an increase in the olefin yield. After a reduction in hydrogen (350°C, 3 h) alumina-supported nanoparticles of nickel sulfides and metallic Ag are formed. The role of metal hydrides formed during the reaction is extensively discussed.
- Danyushevsky, V. Ya.,Murzin, V. Yu.,Kuznetsov,Shamsiev,Katsman,Khramov,Zubavichus,Berenblyum
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- Anhydride-Additive-Free Nickel-Catalyzed Deoxygenation of Carboxylic Acids to Olefins
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A nickel-catalyzed route for direct, anhydride-additive-free deoxygenation of fatty acids to the corresponding olefins has been developed. The transformation is catalyzed by simple nickel salts of the type NiX2 (X = halide, acetate, acetylacetonate), uses PPh3 as a stoichiometric reductant, and exhibits selectivity for generation of linear α-olefin products. The reaction was rendered cocatalytic in PPh3 using 1,1,3,3-tetramethyldisiloxane (TMDS) as terminal reductant for the in situ reduction of OPPh3 and catalytic Cu(OTf)2
- John, Alex,Hillmyer, Marc A.,Tolman, William B.
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supporting information
p. 506 - 509
(2017/04/21)
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- Selective Decarbonylation of Fatty Acid Esters to Linear α-Olefins
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Selective decarbonylation of p-nitrophenol esters of fatty acids to the corresponding linear α-olefins (LAOs) was achieved using palladium catalysis. After extensive ligand screening, a mixed-ligand system exploiting the trans-spanning diphosphine XantPhos and an N-heterocyclic carbene (IPr) was identified as the most effective in yielding high α-selectivity and high conversions of the ester (>98% selectivity, >90% conversion using 2.5 mol % of PdCl2 and 5 mol % of the ligands, 190 °C, 2-2.5 h). On the basis of insights from modeling at the density functional level of theory, we propose that the mixed-ligand set achieves high α-selectivity by promoting olefin dissociation from the palladium center following β-hydride elimination, which is especially facilitated both by the combined steric bias of the mixed-ligand set and by the ability of the XantPhos ligand to coordinate in both mono- and bidentate fashions.
- John, Alex,Dereli, Büsra,Ortunìo, Manuel A.,Johnson, Hillis E.,Hillmyer, Marc A.,Cramer, Christopher J.,Tolman, William B.
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p. 2956 - 2964
(2017/08/21)
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- CATALYTIC ESTER DECARBONYLATION
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A process of preparing olefins of the formula (I) is described herein: with R1 being a substituted or unsubstituted (C1-C30)hydrocarbyl, and R2 being a substituted or unsubstituted (C1-C20)hydrocarbyl. The process includes reacting a compound of formula (II) wherein Ar is chosen from in the presence of a palladium-based catalyst and an organic solvent. A process of preparing olefins of the formula (III) is also described: with R3 being a substituted or unsubstituted (C1-C30)hydrocarbyl, R4 being a substituted or unsubstituted (C1-C20)hydrocarbyl, and R5 being a substituted or unsubstituted (C1-C30) hydrocarbyl. The process includes reacting a compound of formula (IV) wherein Ar is chosen from with a compound of formula (V) wherein Ar is chosen from in the presence of a palladium-based catalyst and an organic solvent.
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Paragraph 0087-0088
(2016/08/07)
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- Catalytic decarbonylation of biosourced substrates
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Linear α-olefins (LAO) are one of the main targets in the field of surfactants, lubricants, and polymers. With the depletion of petroleum resources, the production of LAO from renewable feedstocks has gained increasing interest in recent years. In the present study, we demonstrated that Ir catalysts were suitable to decarbonylate a wide range of biosourced substrates under rather mild conditions (160 °C, 5 h reaction time) in the presence of potassium iodide and acetic anhydride. The resulting LAO were obtained with good conversion and selectivity provided that the purity of the substrate, the nature of the ligand, and the amounts of the additives were controlled accurately. The catalytic system could be recovered efficiently by using a Kugelrohr distillation apparatus and recycled.
- Ternel, Jérémy,Lebarbé, Thomas,Monflier, Eric,Hapiot, Frédéric
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p. 1585 - 1592
(2015/05/20)
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- Effective deoxygenation of fatty acids over Ni(OAc)2 in the absence of H2 and solvent
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Different metal acetate salts were systematically examined for the catalytic deoxygenation of stearic acid in the absence of H2 and solvent for the first time. Ni(OAc)2 exhibited the highest activity with 62% yield achieved at 350°C for 4.5 h with only 1 mol% (0.2 wt%) of the catalyst. Even with 0.25 mol% (0.05 wt%) catalyst, around 28% yield was achieved within 2 h at 350°C with 89% selectivity to C17 hydrocarbons. The activity based on C17 yields per Ni was 14.5 mol mol-1 h-1, considerably higher than that in previous reports. The catalytically active species were identified to be in situ generated Ni nanoparticles (8-10 nm) formed from the decomposition of the metal precursor with stearic acid as a stabilizer. A new reaction pathway of alkane formation from stearic acid via anhydride intermediate decarbonylation under an inert gas atmosphere was proposed. The excellent stability of the catalyst was demonstrated by re-adding a substrate to the system, during which the activity remained constant through four consecutive runs. The novel catalytic system was found to be applicable to a range of fatty acids and triglycerides with varying activities.
- Li, Wenjing,Gao, Yongjun,Yao, Siyu,Ma, Ding,Yan, Ning
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p. 4198 - 4205
(2015/08/11)
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- Photobiocatalytic decarboxylation for olefin synthesis
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Here, we describe the combination of OleTJE with a light-driven in situ H2O2-generation system for the selective and quantitative conversion of fatty acids into terminal alkenes. The photobiocatalytic system shows clear advantages regarding enzyme activity and yield, resulting in a simple and efficient system for fatty acid decarboxylation.
- Zachos, Ioannis,Ga?meyer, Sarah Katharina,Bauer, Daniel,Sieber, Volker,Hollmann, Frank,Kourist, Robert
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supporting information
p. 1918 - 1921
(2015/02/05)
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- Palladium-catalyzed decarbonylative dehydration of fatty acids for the production of linear alpha olefins
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A highly efficient palladium-catalyzed decarbonylative dehydration reaction of carboxylic acids is reported. This method transforms abundant and renewable even-numbered natural fatty acids into valuable and expensive odd-numbered alpha olefins. Additionally, the chemistry displays a high functional group tolerance. The process employs a low loading of palladium catalyst and proceeds under solvent-free and relatively mild conditions.
- Liu, Yiyang,Kim, Kelly E.,Herbert, Myles B.,Fedorov, Alexey,Grubbs, Robert H.,Stoltz, Brian M.
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supporting information
p. 130 - 136
(2014/03/21)
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- Tandem isomerization-decarboxylation for converting alkenoic fatty acids into alkenes
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We report a facile Ru-catalyzed route to alkenes from unsaturated fatty acids (alkenoic fatty acids) via readily accessible catalyst precursors, [Ru(CO)2RCO2]n and Ru3(CO)12. The catalyst apparently functions in a tandem mode by dynamically isomerizing the positions of double bonds in an aliphatic chain and, subsequently, decarboxylating specific isomers with lower activation barriers. Substrates capable of tandem isomerization-decarboxylation processes (oleic acid, undecylenic acid) are readily converted to mixtures of alkenes. A catalytic cycle is proposed that relies on isomerization positioning double bonds proximate to the acid function to enable facile decarboxylation. To elucidate the proposed mechanistic pathway, substrates that do not undergo decarboxylation under these catalytic conditions (methyl oleate) are compared with those that cannot isomerize the position of unsaturation (cinnamic acid). Both were shown to be operational under these catalytic reaction conditions. Another illustrative comparison shows that the saturated octadecanoic acid is 28 times less reactive than the unsaturated counterpart when reacted using this precatalyst.
- Murray, Rex E.,Walter, Erin L.,Doll, Kenneth M.
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p. 3517 - 3520
(2015/02/19)
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- Catalytic deoxygenation of fatty acids: Elucidation of the inhibition process
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Catalytic deoxygenation of unsaturated fatty acids in the absence of H2 is known to suffer from significant catalyst inhibition. Thus far, no conclusive results have been reported on the cause of deactivation. Here we show that C-C double bonds present in the feed or the products dramatically reduce the deoxygenation activity of supported palladium catalysts. In the case of stearic acid deoxygenation the addition of 0.1 equivalents of a mono-unsaturated fatty acid or olefin already reduces the catalytic deoxygenation activity by 60%. This effect becomes more pronounced with an increasing number of double bonds. The inhibition is shown to be reversible in H2 atmosphere, indicating no significant contribution from irreversibly deposited hard coke. Furthermore, the type of support material has no apparent effect on catalyst inhibition. Hence we propose that initial catalyst inhibition proceeds through reversible adsorption of C-C double bonds on the palladium active sites.
- Hollak, Stefan A. W.,De Jong, Krijn P.,Van Es, Daan S.
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p. 2648 - 2655
(2015/04/14)
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- Investigation of hydrocarbon generation mechanism by polarizing the carboxy-group of fatty acid salt with microwave radiation
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Triglycerides can be converted to renewable hydrocarbons fuel which can be used as engine fuels by alkali pyrolysis decarboxylation and cracking processes. The purpose of present study was to explore decarboxylation mechanism of fatty acid salt with microwave radiation. Sodium stearate, potassium stearate, sodium oleate and sodium laurate was chosen as a model compound. The carboxy-terminal of this dipolar molecule was further polarized with microwave radiation. The Lorentz force of ions of dipolar molecules were moved in accordance with the way of electromagnetic waves, contribute to the formation of carbanion, which effectively promote the decarboxylation reaction. Moreover, the polarity of carboxy-terminal was stronger, more easily decarboxylation. The surface of glycerol formed a High-Temperature Locus in microwave radiation reaction system, facilitate the decarboxylation processe, in adition to played a role as the hydrogen donor for this high dielectric value compound. C8-C20 n-alkanes and n-alk-1-enes were arranged regular in liquid products. It proved the feasibility to derive renewable hydrocarbon fuel from sodium salt of fatty acids by microwave pyrolysis.
- Wang,Liu,Ruan,Wen,Wan,Zhang
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p. 369 - 375
(2014/06/09)
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- PALLADIUM-CATALYZED DECARBONYLATION OF FATTY ACID ANHYDRIDES FOR THE PRODUCTION OF LINEAR ALPHA OLEFINS
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The present invention is directed to methods of forming olefins, especially linear alpha olefins from fatty acids or anhydrides, each method comprising: contacting an amount of precursor carboxylic acid anhydride with a palladium catalyst comprising a bidentate bis-phosphine ligand in a reaction mixture so as to form an olefin in a product with the concomittant formation and removal of CO and water from the reaction mixture, either directly or indirectly, wherein the reaction mixture is maintained with a sub-stoichiometric excess of a sacrificial carboxylic acid anhydride, an organic acid, or both, said sub-stoichiometric excess being relative to the amount of the precursor carboxylic acid anhydride. The precursor carboxylic acid anhydride may be added to the reaction mixture directly or formed in situ by the reaction between at least one precursor carboxylic acid with a stoichiometric amount of the sacrificial acid anhydride.
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Page/Page column
(2014/06/23)
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- Iridium-catalyzed addition of aroyl chlorides and aliphatic acid chlorides to terminal alkynes
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Iridium complexes show high catalytic activity in intermolecular additions of acid chlorides to terminal alkynes to afford valuable (Z)-β-chloro- α,β-unsaturated ketones. Ligands in the catalytic system play a crucial role in this reaction. An N-heterocyclic carbene (NHC) is an efficient ligand for the addition of aroyl chlorides, while dicyclohexyl(2-methylphenyl) phosphine (PCy2(o-Tol)) is indispensable for the reaction of aliphatic acid chlorides. The addition reactions proceed regio- and stereoselectively with suppression of decarbonylation and β-hydrogen elimination, which have been two major intrinsic problems in transition-metal-catalyzed reactions. Stoichiometric reactions of active iridium catalysts with aroyl chlorides and aliphatic acid chlorides are carried out to gain insights into the reaction mechanisms.
- Iwai, Tomohiro,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
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supporting information; experimental part
p. 1268 - 1274
(2012/03/12)
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- Iron-catalyzed decarbonylation reaction of aliphatic carboxylic acids leading to α-olefins
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The catalytic decarbonylation reaction of aliphatic carboxylic acids can be carried out in the presence of an iron complex, and it proceeds smoothly to give α-olefins with high selectivity. The Royal Society of Chemistry 2012.
- Maetani, Shinji,Fukuyama, Takahide,Suzuki, Nobuyoshi,Ishihara, Daisuke,Ryu, Ilhyong
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scheme or table
p. 2552 - 2554
(2012/03/26)
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- Fe5C2 nanoparticles: A facile bromide-induced synthesis and as an active phase for Fischer-Tropsch synthesis
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Iron carbide nanoparticles have long been considered to have great potential in new energy conversion, nanomagnets, and nanomedicines. However, the conventional relatively harsh synthetic conditions of iron carbide hindered its wide applications. In this
- Yang, Ce,Hou, Yanglong,Zhao, Huabo,Ma, Ding
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p. 15814 - 15821,8
(2020/08/24)
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- Efficient iridium-catalyzed decarbonylation reaction of aliphatic carboxylic acids leading to internal or terminal alkenes
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Vaska's complex, IrCl(CO)(PPh3)2, when combined with KI as an additive, served as an excellent catalyst for the decarbonylation of long-chain aliphatic carboxylic acids to give internal alkenes with high selectivity. On combination with KI and Ac2O as additives under controlled temperatures, decarbonylation proceeded to give terminal alkenes with high selectivity.
- Maetani, Shinji,Fukuyama, Takahide,Suzuki, Nobuyoshi,Ishihara, Daisuke,Ryu, Ilhyong
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experimental part
p. 1389 - 1394
(2011/04/25)
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- PROCESS FOR PRODUCTION OF OLEFIN
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The present invention provides a process for producing an olefin from a carboxylic acid having a β-hydrogen atom or a derivative thereof using the compound containing iodine and at least one metal elements selected from the group consisting of Groups 6, 7, 8, 9, 10 and 11 metals as a catalyst.
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Page/Page column 6; 7
(2011/06/23)
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- Selective preparation of terminal alkenes from aliphatic carboxylic acids by a palladium-catalysed decarbonylation-elimination reaction
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Trialkylamines were used as additives in the decarbonylation-elimination reaction catalysed by the combination of palladium(II) chloride and DPE-Phos. Aliphatic carboxylic acids were transformed at relatively low temperature into terminal alkenes in high yield and high selectivity, without the need for distillation, thereby avoiding isomerisation.
- N?tre, Jér?me Le,Scott, Elinor L.,Franssen, Maurice C. R.,Sanders, Johan P. M.
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experimental part
p. 3712 - 3715
(2010/08/19)
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- Total synthesis of new lipocarbazoles isolated from the actinomycete tsukamurella pseudospumae acta 1857
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New lipocarbazoles were synthesized by a sequence of three palladium-mediated coupling reactions and an improved protecting group strategy.
- H?nchen, Anne,Süssmuth, Roderich D.
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body text
p. 2483 - 2486
(2010/01/07)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Electroorganic synthesis 65. Anodic homocoupling of carboxylic acids derived from fatty acids
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Fatty acid derived carboxylic acids with double bonds, hydroxy-, amino-, keto-, ester- and epoxy groups are anodically coupled to dimers (Kolbe electrolysis) in 29 to 81% yield and up to a 2.5 mol scale. Problems due to the low conductivity of fatty acid salts were overcome by the use of a flow cell with a narrow electrode gap. Fatty acids with branched alkyl chains gave dimers with interesting emulsifying properties. Dimethyl hexadecanedioate, accessible from methyl azelate, could be cyclized and further converted into homomuscone and muscone in a few steps. A commercial mixture of dimeric fatty acids (C36-dicarboxylic acids) has been coupled to give C70-diesters. Acta Chemica Scandinavica 1998. Part 64: Nielsen, M. F., Batanero, B.,.
- Weiper-Idelmann, Andreas,Aus Dem Kahmen, Martin,Schaefer, Hans J.,Gockeln, Marianne
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p. 672 - 682
(2007/10/03)
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- Investigations of cylindrical reaction cavities from ordered phases of alkyl alkanoates and their influence on some Norrish-Yang and photo-fries reactions
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The Norrish-Yang photochemistry of three isomeric p-alkyl alkanophenones (p-propyl nonadecanophenone, p-pentyl heptadecanophenone and p-octyl tetradecanophenone) and the photo-Fries reactions of 2-naphthyl myristate have been investigated in the ordered (layered) phases of three isomeric alkyl alkanoates. Comparisons of photoproduct selectivity for irradiation of one substrate in the isotropic and ordered phases of one host ester provide information concerning the influence of the cylindrically shaped reaction cavities on the relative motions and conformational changes necessary to convert the reactants to products. Comparisons of photoproduct distributions from one substrate in comparable phases of two or more esters provide details concerning the "wall stiffness" and importance of functional group interactions of the reaction cavities. Finally, comparisons using one substrate and two ordered phases of the same ester indicate the role of wall stiffness on photoproduct selectivity. The results show that the course of the photochemical reactions can be controlled effectively within the ordered media and provide an indication of how to design and select ordered media to effect other photochemical transformations selectively.
- Baldvins, Jon E.,Cui, Changxing,Weiss, Richard G.
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p. 726 - 734
(2007/10/03)
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- Pyrolysis of Alkyl Acetates. A Radical Pathway for the Formation of Minor Products
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Decyl acetate and decene pyrolysis under the same reaction conditions show that the formation of the minor products during the pyrolysis of esters occurs by a parallel, and not a secondary, reaction.The radioactivity observed in the CO2 and CO produced during the pyrolysis of 1-hexyl acetate-1-14C and the radioactivity in the methane from the pyrolysis of 1-hexyl acetate-2-14C strongly suggested a radical reaction pathway for the formation of the minor products.Considering the above results together with the radioactivity data of gas samples from the pyrolysis of 1-decyl-1-14C acetate, 1-hexyl-1-14C acetate, and 1-heptadecyl-1-14C acetate leads to the conclusion that the mechanism of pyrolysis of esters may be viewed as a cyclo-DEDNAN mechanism for the formation of the major alkene product and a radical mechanism for the formation of minor products.A useful synthetic procedure for the preparation of high carbon number alkenes (>10) also results from this study.
- Shi, Buchang,Ji, Ying,Dabbagh, Hossein A.,Davis, Burtron H.
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p. 845 - 849
(2007/10/02)
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- A Highly Catalytic and Selective Conversion of Carboxylic Acids to 1-Alkenes of One Less Carbon Atom
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An equimolar mixture of a carboxylic acid and acetic anhydride produces a reagent combination that undergoes a highly efficient decarbonylation/dehydration at 250 deg C using either Pd- or Rh-based catalyst systems, affording excellent yields of the corresponding 1-alkenes of one less carbon atom.
- Miller, Joseph A.,Nelson, Jeffrey A.,Byrne, Michael P.
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- Decarboxylative radical addition to vinylsulphones and vinylphosphonium bromide: Some further novel transformations of geminal (pyridine-2-thiyl) phenylsulphones
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Irradiation of O-acyl derivatives 1 of N-hydroxy-2-thiopyridone with visible light in the presence of phenyl vinyl sulphone or vinyl triphenylphosphonium bromide leads to the corresponding adducts 8 and 9 which can undergo a wide variety of further transformations.
- Barton,Boivin,Crepon nee da Silva,Sarma,Togo,Zard
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p. 7091 - 7108
(2007/10/02)
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- Process for making olefins
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Carboxylic acids are converted in high yields to olefins or high purity α-olefins by contacting a mixture of carboxylic acid and a carboxylic acid anhydride in the presence of a Group VIII metal or copper-containing catalyst at a temperature of from about 100° C. to about 300° C.
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- SOME FURTHER NOVEL TRANSFORMATIONS OF GEMINAL (PYRIDINE-2-THIYL) PHENYLSULPHONES
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Geminal (pyridine-2-thiyl) phenylsulphones, obtained by decarboxylative radical addition of O-acyl derivatives of N-hydroxy-2-thiopyridone onto phenyl vinyl sulphone, undergo a wide variety of further transformations when subjected to sodium telluride or to organoaluminum reagents.
- Barton, Derek H. R.,Boivin, Jean,Sarma, Jadab,Silva, Elisabeth da,Zard, Samir Z.
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p. 4237 - 4240
(2007/10/02)
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- LIQUID-CRYSTALLINE SOLVENTS AS MECHANISTIC PROBES. 23. NORRISH II REACTIONS OF 2- AND SYM-ALKANONES IN THE ISOTROPIC, SMECTIC B, AND CRYSTALLINE PHASES OF n-BUTYL STEARATE.
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n-Alkanones with the carbonyl group at the 2 or central positions (1 and 2, respectively) have been irradiated in the isotropic, smectic B, and two solid phases of n-butyl stearate (BS).The lengths of the ketones were varied from 11 to 31 carbons.The ratios of elimination/cyclization products and diastereomeric cyclobutanol products were measured for each as a function of temperature and BS phase.The effect of 1 and 2 on the phase transition temperatures of BS has been correlated with changes in the product ratios.The experiments demonstrate that a very sensitive cooperative relationship exists between the ease with which 1 and 2 fit into the ordered phases of BS and the degree to which the solvent matrices influence ketone photochemistry.The influence of solvent order on the product ratios is distinctly different for 1 and 2, and for the two product ratios from one ketone.
- Treanor, Richard L.,Weiss, Richard G.
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p. 1371 - 1392
(2007/10/02)
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- SELECTIVE MIXED COUPLING OF CARBOXYLIC ACIDS (II). -PHOTOLYSIS OF UNSYMMETRICAL DIACYLPEROXIDES WITH ALKENYL-, HALO-, KETO-, CARBOXYL-GROUPS AND A CHIRAL α-CARBON. COMPARISON WITH THE MIXED KOLBE ELECTROLYSIS.
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- Alkenoyl and functionalized alkanoyl dodecanoyl peroxides are prepared in 70 to 97 percent yield and photolyzed at -78 deg C.Thereby 4- to 10-alkenoyl and 4-alkynoyl peroxides afford good yields (56 - 68 percent) of unsymmetrical coupling products.Similarly α- to δ-haloalkanoyl, cholanoyl or 3- and 4-carboxyalkanoyl peroxides can be coupled (40 - 70 percent).The α-chiral diacyl peroxide 1s undergoes the photochemical coupling reaction with 80 percent retention of its configuration.The photolysis of diacyl peroxides at -78 deg C proves to be a favorable supplement of the Kolbe-electrolysis in cases, where the electrolysis fails or produces low yields.
- Feldhues, Michael,Schaefer, Hans J.
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p. 4213 - 4236
(2007/10/02)
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- PHOTOLYSIS OF α-DIAZO CARBONYL COMPOUNDS IN THE PRESENCE OF IMIDAZOLE. A NEW METHOD FOR THE PREPARATION OF NOR OLEFINS AND ITS APPLICATION TO BILE ACID SIDE CHAIN DEGRADATION
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α-Diazomethyl ketones derived from carboxylic acids are photolyzed in the presence of imidazole to give the corresponding nor olefins or, in the case of aryl diazo ketones, the corresponding, stable imidazolides.The application of the method to a novel degradation of bile acid side chain is reported.
- Pellicciari, Roberto,Natalini, Benedetto,Cecchetti, Sergio,Santucci, Sergio
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p. 3103 - 3106
(2007/10/02)
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