- Production of liquid hydrocarbon fuels with acetoin and platform molecules derived from lignocellulose
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Acetoin, a novel C4 platform molecule derived from new ABE (acetoin-butanol-ethanol) type fermentation via metabolic engineering, was used for the first time as a bio-based building block for the production of liquid hydrocarbon fuels. A series of diesel or jet fuel range C9-C14 straight, branched, or cyclic alkanes were produced in excellent yields by means of C-C coupling followed by hydrodeoxygenation reactions. Hydroxyalkylation/alkylation of acetoin with 2-methylfuran was investigated over a series of solid acid catalysts. Among the investigated candidates, zirconia supported trifluoromethanesulfonic acid showed the highest activity and stability. In the aldol condensation step, a basic ionic liquid [H3N+-CH2-CH2-OH][CH3COO-] was identified as an efficient and recyclable catalyst for the reactions of acetoin with furan based aldehydes. The scope of the process has also been studied by reacting acetoin with other aldehydes, and it was found that abnormal condensation products were formed from the reactions of acetoin with aromatic aldehydes through an aldol condensation-pinacol rearrangement route when amorphous aluminium phosphate was used as a catalyst. And the final hydrodeoxygenation step could be achieved by using a simple and handy Pd/C + H-beta zeolite system, and no or a negligible amount of oxygenates was observed after the reaction. Excellent selectivity was also observed using the present system, and the clean formation of hydrocarbons with a narrow distribution of alkanes occurred in most cases.
- Zhu, Chenjie,Shen, Tao,Liu, Dong,Wu, Jinglan,Chen, Yong,Wang, Linfeng,Guo, Kai,Ying, Hanjie,Ouyang, Pingkai
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supporting information
p. 2165 - 2174
(2016/04/19)
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- Ring closure reactions of substituted 4-pentenyl-1-oxy radicals. The stereoselective synthesis of functionalized disubstituted tetrahydrofurans
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N-(Alkyloxy)pyridine-2(1H)-thiones 3 and benzenesulfenic acid O-esters 5 have been synthesized from substituted 4-pentenols 1 or the derived tosylates. Compounds 3 and 5 are efficient sources of free alkoxy radicals 6 which undergo synthetically useful fast ring closure reactions 6 → 8 [k(exo) = (2 ± 1) x 108 s-1 to (6 ± 2) x 109 s-1 (T = 30 ± 0.2°C)]. Tetrahydrofurfuryl radicals 8 can be trapped with, e.g., hydrogen or chlorine atom donors to afford either trans- or cis-disubstituted tetrahydrofurans 10 or 12 depending on the substitution pattern of the 4-pentenyloxy radical. Substituted tetrahydropyrans 11 or 13 are formed in the minor 6-endo-trig cyclization. According to the data of competition kinetics, the observed stereoselectivities in free alkoxy radical cyclizations arise from steric interactions between the substituents in the transition state of the ring closure reactions. Alkyl substituents cause small differences in the measured relative rate constants of 5-exo cyclizations which are reminiscent of the data obtained from the rearrangements of alkyl-substituted 5-hexenyl radicals. Likewise, a stereochemical model for oxygen radical cyclization is proposed where the pentenyloxy chain adopts a six-membered, chairlike transition state with the alkyl substituents preferentially situated in the pseudoequatorial positions leading to 2,5-trans-, 2,4-cis-, and 2,3-trans-substituted tetrahydrofurfuryl radicals 8 as the major intermediates.
- Hartung,Gallou
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p. 6706 - 6716
(2007/10/03)
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- Cobalt(II) Chloride Catalyzed Acylation of Alcohols with Acetic Anhydride: Scope and Mechanism
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Cobalt(II) chloride catalyzes the acetylation of a variety of alcohols with acetic anhydride in excellent yield.Primary hydroxyl groups can be selectively acylated in the presence of secondary and tertiary ones while the secondary hydroxyl groups can be preferentially acetylated in the presence of tertiary ones.Tertiary alcohols have been found to give ketones, acetoacetates, olefins, and diketene in addition to the acetate.The β-hydroxy esters and ketones can be acylated under these conditions without any elimination, and this reaction has been compared with 4-(dimethylamino)pyridine (DMAP)-mediated acylations where elimination of the resulting β-acetoxy carbonyl compound is observed.A detailed investigation of the acylation of tertiary alcohols has revealed that these reactions proceed via a tertiary alkoxy radical and ketene.A mechanism for these acylations is proposed by invoking an electron-transfer process.
- Iqbal, Javed,Srivastava, Rajiv Ranjan
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p. 2001 - 2007
(2007/10/02)
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- FERROUS ION INDUCED DECOMPOSITION OF ALKYL HYPOCHLORITES
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The decomposition of primary, secondary and tertiary alkyl hypochlorites induced by ferrous and other one-electron oxidizable metal ions leads to δ-chloro alcohols in yields of 34-76percent.In decomposition of tertiary alkyl hypochlorites, β-fragmentation competes with intramolecular δ-chlorination.Tertiary cycloalkyl hypochlorites containing five- or six-membered rings undergo β-cleavage giving the corresponding ο-chloro ketones, while 1-methylcycloheptyl and 1-methylcyclooctyl hypochlorites by decomposition with ferrous ion proceed by transannular functionalization of δ-carbon atom and β-cleavage as a competing reaction.
- Cekovic, Zivorad,Djokic, Gordana
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p. 4263 - 4268
(2007/10/02)
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